2.7.2.4: aspartate kinase
This is an abbreviated version!
For detailed information about aspartate kinase, go to the full flat file.
Word Map on EC 2.7.2.4
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2.7.2.4
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corynebacterium
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glutamicum
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threonine-sensitive
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l-lysine
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l-threonine
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dihydrodipicolinate
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i-homoserine
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diaminopimelate
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semialdehyde
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feedback-resistant
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aspartate-derived
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feedback-insensitive
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aec
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l-isoleucine
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s-2-aminoethyl-l-cysteine
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lysine-producing
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flavum
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thialysine
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meso-diaminopimelate
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ectoine
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synthesis
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agriculture
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medicine
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nutrition
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food industry
- 2.7.2.4
- corynebacterium
- glutamicum
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threonine-sensitive
- l-lysine
- l-threonine
- dihydrodipicolinate
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i-homoserine
- diaminopimelate
- semialdehyde
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feedback-resistant
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aspartate-derived
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feedback-insensitive
- aec
- l-isoleucine
- s-2-aminoethyl-l-cysteine
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lysine-producing
- flavum
- thialysine
- meso-diaminopimelate
- ectoine
- synthesis
- agriculture
- medicine
- nutrition
- food industry
Reaction
Synonyms
AK, AK II, AK III, AK-HSDH, AK-HSDH I, AK-HSDH1, AK-HSDH2, AK-HseDH, AK-R7, AK-ts31d, AK1, AK2, AK3, AKbeta, AKII, AKIII, AKsyn, Ask, ASK1, ASK2, Ask_Ect, Ask_LysC, Asp kinase-homoserine dehydrogenase, aspartate kinase, aspartate kinase (phosphorylating), aspartate kinase 1, aspartate kinase 2, aspartate kinase 3, aspartate kinase beta, aspartate kinase I, aspartate kinase II, aspartate kinase III, aspartic kinase, aspartokinase, aspartokinase 1-homoserine dehydrogenase 1, aspartokinase 2, aspartokinase 3, aspartokinase I, aspartokinase II, aspartokinase III, aspartokinase-homoserine dehydrogenase, beta-aspartokinase, bifunctional aspartate kinase-homoserine dehydrogenase, BT, BTT, CgAK, dap-aspartokinase, HOM3 product, HOM3-R7 product, HOM3-ts31d product, HseDH, LT-aspartokinase, lysC, lysine-sensitive aspartokinase 3, More, MtbAKbeta, nspJ, Thr-sensitive aspartate kinase, thrA, thrA1, thrA2, TM_0547, XbAK
ECTree
2.7.2.4 aspartate kinaseAdvanced search results
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results (Engineering
Engineering on EC 2.7.2.4 - aspartate kinase
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PROTEIN VARIANTS 
ORGANISM
UNIPROT
COMMENTARY 
LITERATURE
S2207A/pM1-1
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mutant S2207A complemented with plasmid pM1-1, phenotype Thr+ Met+ Ura+
G10D/G324W
G345D
A279T
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isolated from Corynebacterium glutamicum strain IWJ001, aspartate kinase mutant AKA279T is encoded by gene lysC1. The mutant enzymes is completely resistant to feed-back inhibition by L-threonine and L-lysine
D45A
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the inhibition of CgAK by lysine is substantially reduced in D45A mutant
E114A
F115A
G110A
mutant enzyme shows normal and negligible response to Thr and Lys, dimerized by Thr
G28A
Q49A
S301F
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the S301F mutant exhibits resistance to feedback inhibition by lysine and threonine, showing activity in the presence of both lysine and threonine
T112A
V111A
A279T
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isolated from Corynebacterium glutamicum strain IWJ001, aspartate kinase mutant AKA279T is encoded by gene lysC1. The mutant enzymes is completely resistant to feed-back inhibition by L-threonine and L-lysine
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A380I
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the mutant has 11.32fold higher enzyme activity than the wild type enzyme, enhanced thermal stability and shows weakened inhibition with L-lysine
M372I/T379W
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the mutant shows 16.51fold higher activity, weakened inhibitory effect of L-lysine and significantly improved thermostability as compared to the wild type enzyme
R169A
site-directed mutagenesis, the Km for aspartate is decreased compared to the wild-type enzyme
R169D
site-directed mutagenesis, the mutant shows 2.57fold higher catalytic activity with aspartate than the wild-type enzyme
R169H
site-directed mutagenesis, the mutant shows 2.13fold higher catalytic activity with aspartate than the wild-type enzyme
R169P
site-directed mutagenesis, the mutant shows 2.25fold higher catalytic activity with aspartate than the wild-type enzyme
R169Y
site-directed mutagenesis, the mutant shows 4.7fold higher catalytic activity with aspartate than the wild-type enzyme. The three-dimensional structure of R169Y is more stable than that of the wild-type
T379 F
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the mutant shows 2.65fold higher enzymatic activity compared to the wild type enzyme
T379E
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the mutant shows 4.66fold higher enzymatic activity compared to the wild type enzyme
T379K
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the mutant shows 5.25fold higher enzymatic activity compared to the wild type enzyme
T379L
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the mutant shows 9.16fold higher enzymatic activity compared to the wild type enzyme
Y198N/D201M
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the mutant shows 18.26fold increased activity compared to the wild type enzyme, is less inhibited by L-lysine and L-threonine and activated by Lys + Met, Thr + Met, Lys + Thr + Met at 5 and 10 mM concentration
M372I/T379W
Corynebacterium pekinense ATCC 13032
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the mutant shows 16.51fold higher activity, weakened inhibitory effect of L-lysine and significantly improved thermostability as compared to the wild type enzyme
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DR1365
C428R
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mutation is not directly involved in L-lysine binding. Mutation located within regulatory domain, participates in the allosteric regulation within regulatory domain. Mutation greatly reduces L-lysine inhibition
E346A
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mutation reduces feedback-inhibition of AK1 by L-threonine without significant change in enzymatic activity
E346R
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mutation within L-lysine binding site desensitizes AK3 from L-lysine inhibition. Mutant shows reduced L-lysine inhibition
F329R
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mutation is not directly involved in L-lysine binding. Mutation located within regulatory domain, participates in the allosteric regulation within regulatory domain. Mutation greatly reduces L-lysine inhibition
G323D
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mutation within L-lysine binding site desensitizes AK3 from L-lysine inhibition. Mutant shows reduced L-lysine inhibition
G433R
site-directed mutagenesis, strain HS33/pACYC-pycP458S-thrAG433R-lysC shows increased homoserine dehydrogenase activity (62.4% of the maximum theoretical yield)
H320A
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mutation is not directly involved in L-lysine binding. Mutation located within regulatory domain, participates in the allosteric regulation within regulatory domain. Mutation greatly reduces L-lysine inhibition
I337P
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mutation is not directly involved in L-lysine binding. Mutation located within regulatory domain, participates in the allosteric regulation within regulatory domain. Mutation greatly reduces L-lysine inhibition
I344P
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mutation reduces feedback-inhibition of AK1 by L-threonine without significant change in enzymatic activity
I427P
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mutation reduces feedback-inhibition of AK1 by L-threonine without significant change in enzymatic activity
L325F
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mutation within L-lysine binding site desensitizes AK3 from L-lysine inhibition. Mutant shows reduced L-lysine inhibition
M251P
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mutation destroys van der Waals interaction significantly which releases L-lysine inhibition
M318I
M417I
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mutation is not directly involved in L-lysine binding. Mutation located within regulatory domain, participates in the allosteric regulation within regulatory domain. Mutation greatly reduces L-lysine inhibition
N424A
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mutation reduces feedback-inhibition of AK1 by L-threonine without significant change in enzymatic activity
N426A
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mutation reduces feedback-inhibition of AK1 by L-threonine without significant change in enzymatic activity
P458S
site-directed mutagenesis, strain HS33/pACYC-pycP458S-thrAG433R-lysC shows increased homoserine dehydrogenase activity (62.4% of the maximum theoretical yield)
Q351A
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mutation reduces feedback-inhibition of AK1 by L-threonine without significant change in enzymatic activity
R305A
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mutation destroys van der Waals interaction significantly which releases L-lysine inhibition
R416A
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mutation is not directly involved in L-lysine binding. Mutation located within regulatory domain, participates in the allosteric regulation within regulatory domain. Mutation greatly reduces L-lysine inhibition
S315A
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mutation is not directly involved in L-lysine binding. Mutation located within regulatory domain, participates in the allosteric regulation within regulatory domain. Mutation greatly reduces L-lysine inhibition
S338L
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mutation within L-lysine binding site desensitizes AK3 from L-lysine inhibition. Mutant shows reduced L-lysine inhibition
S345L
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mutation within L-lysine binding site desensitizes AK3 from L-lysine inhibition. Mutant shows reduced L-lysine inhibition
T253R
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mutation leads to repulse interaction with Arg305 which destroys the allosteric regulation by L-lysine
T344M
T352I
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mutation is not directly involved in L-lysine binding. Mutation located within regulatory domain, participates in the allosteric regulation within regulatory domain. Mutation greatly reduces L-lysine inhibition
V339A
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mutation within L-lysine binding site desensitizes AK3 from L-lysine inhibition. Mutant shows reduced L-lysine inhibition
V347M
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mutation is not directly involved in L-lysine binding. Mutation located within regulatory domain, participates in the allosteric regulation within regulatory domain. Mutation greatly reduces L-lysine inhibition
V349M
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mutation is not directly involved in L-lysine binding. Mutation located within regulatory domain, participates in the allosteric regulation within regulatory domain. Mutation greatly reduces L-lysine inhibition
M318I
Escherichia coli LATR11
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mutant enzyme T344M is more conducive to L-lysine production than mutant M318I
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T344M
Escherichia coli LATR11
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mutant enzyme T344M is more conducive to L-lysine production than mutant M318I
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G433R
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site-directed mutagenesis, strain HS33/pACYC-pycP458S-thrAG433R-lysC shows increased homoserine dehydrogenase activity (62.4% of the maximum theoretical yield)
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S449L
transgenic plants expressing the mutant enzyme show a 6.6fold increased free lysine content
T448M
transgenic plants expressing the mutant enzyme show about 2fold increased free lysine content
D182/R184A
the mutations decrease the enzyme activities to about 65%
G152L
the mutant shows about 35% activity compared to the wild type enzyme
N371A/I372A
the mutations do not affect the ATP binding with threonine
R150A
the mutant shows about 30% activity compared to the wild type enzyme
S378A/E202A
V357/M351A
the mutant shows reduced activity compared to the wild type enzyme
A406T
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site-directed mutagenesis, 30fold more strongly inhibited by threonine
E254A
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9.1fold decrease in kcat for aspartate and 11fold decrease in kcat for ATP
E279A
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kcat is decreased 47 times for aspartate and 44 times for ATP
G25D
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site-directed mutagenesis, reduced affinity for its substrates aspartate and ATP
H292A
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4.5 times increase in Km for ATP and 120 times decrease in kcat for ATP
K18R
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Km values for aspartate similar to wildtype, Km value for ATP 2.9fold decreased
K26I
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site-directed mutagenesis, reduced affinity for its substrates aspartate and ATP
R419A
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10fold decrease in kcat for aspartate and 8.9fold decrease in kcat for ATP
S23A
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differs significantly only in the kcat/Km ratio, which is decreased 4fold for aspartate and 3.7fold for ATP
I119V/M68V/T309
random mutagenesis by error-prone PCR and subsequent site-directed mutagenesis, the mutations remove the regulation from the Ask wild type enzyme and conferre a feedback-inhibition resistance
I19V/M68V/T309A
removes regulation from the Ask wild type enzyme and conferrs a feedback-inhibition resistance, assay mixture with 100 mM L-lysine plus 100 mM L-threonine reveals more than 80% activity
M68V
I119V/M68V/T309
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random mutagenesis by error-prone PCR and subsequent site-directed mutagenesis, the mutations remove the regulation from the Ask wild type enzyme and conferre a feedback-inhibition resistance
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I19V/M68V/T309A
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removes regulation from the Ask wild type enzyme and conferrs a feedback-inhibition resistance, assay mixture with 100 mM L-lysine plus 100 mM L-threonine reveals more than 80% activity
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M68V
G10D/G324W
construction of an engineered chimeric mutant enzyme containing the N-terminal catalytic region from Bacillus subtilis AKII and the C-terminal region from Thermus thermophilus AKII, through random mutagenesis and then screened using a high throughput synthetic RNA device which comprises of an L-lysine-sensing riboswitch and a selection module. Of three evolved aspartate kinases, the best mutant BT3 shows 160% increased in vitro activity compared to the wild-type enzyme from Bacillus subtilis. The mutant enzymes is feedback-resistant to L-lysine
E257K
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mutation of the conserved Glu-257 to Lys or the double mutations T359I/E257K render the enzyme insensitive to L-lysine with 86- and 112fold increases in IC50 values, respectively, when compared to the wild-type enzyme. E257K and E257K/T359I alleles exhibit a 1.2- to 1.7fold decrease in Vmax value and 2- to 6fold decrease in kcat/Km value for either substrate compared to wild-type
T359I
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mutation increases the L-lysine IC50 value by 104fold, but no substantial differences are observed in kinetic parameters except lower Km ATP value compared to the wild-type enzyme. Seed-specific expression of the feedback-resistant mutant T359I or mutant E257K results in increases of free L-threonine levels of up to 100fold in R1 soybean seed when compared to wild-type
T359I/E257K
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mutation of the conserved Glu-257 to Lys or the double mutations T359I/E257K render the enzyme insensitive to L-lysine with 86- and 112fold increases in IC50 values, respectively, when compared to the wild-type enzyme. E257K and E257K/T359I alleles exhibit a 1.2- to 1.7fold decrease in Vmax value and 2- to 6fold decrease in kcat/Km value for either substrate compared to wild-type
additional information
G10D/G324W
construction of an engineered chimeric mutant enzyme containing the N-terminal catalytic region from Bacillus subtilis AKII and the C-terminal region from Thermus thermophilus AKII, through random mutagenesis and then screened using a high throughput synthetic RNA device which comprises of an L-lysine-sensing riboswitch and a selection module. Of three evolved aspartate kinases, the best mutant BT3 shows 160% increased in vitro activity compared to the wild-type enzyme from Bacillus subtilis. The mutant enzymes is feedback-resistant to L-lysine
G10D/G324W
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construction of an engineered chimeric mutant enzyme containing the N-terminal catalytic region from Bacillus subtilis AKII and the C-terminal region from Thermus thermophilus AKII, through random mutagenesis and then screened using a high throughput synthetic RNA device which comprises of an L-lysine-sensing riboswitch and a selection module. Of three evolved aspartate kinases, the best mutant BT3 shows 160% increased in vitro activity compared to the wild-type enzyme from Bacillus subtilis. The mutant enzymes is feedback-resistant to L-lysine
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E114A
changes in the inhibitory profile upon addition of Thr, monomer even with the addition of Thr
E114A
changes in the inhibitory profile upon addition of threonine, monomer even with the addition of Thr
F115A
changes in the inhibitory profile upon addition of Thr, pentamer or hexamer in the presence and in the absence of Thr
F115A
changes in the inhibitory profile upon addition of threonine, pentamer or hexamer in the presence and in the absence of Thr
G28A
changes in the inhibitory profile upon addition of Thr
G28A
changes in the inhibitory profile upon addition of threonine
Q49A
changes in the inhibitory profile upon addition of Thr, monomer even with the addition of Thr
Q49A
changes in the inhibitory profile upon addition of threonine, monomer even with the addition of Thr
T112A
changes in the inhibitory profile upon addition of Thr, monomer even with the addition of Thr
T112A
changes in the inhibitory profile upon addition of threonine, monomer even with the addition of Thr
V111A
changes in the inhibitory profile upon addition of Thr, pentamer or hexamer in the presence and in the absence of Thr
V111A
changes in the inhibitory profile upon addition of threonine, pentamer or hexamer in the presence and in the absence of Thr
DR1365
disruption mutant does not grow in the minimal medium, Deinococcus radiodurans uses DR1365 for biosyntheses of methionine and threonine, but does not use it for lysine biosynthesis, the growth rate is lower than that of the wild type
DR1365
Deinococcus radiodurans R1 / ATCC 13939 / DSM 20539
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disruption mutant does not grow in the minimal medium, Deinococcus radiodurans uses DR1365 for biosyntheses of methionine and threonine, but does not use it for lysine biosynthesis, the growth rate is lower than that of the wild type
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M318I
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mutation within L-lysine binding site desensitizes AK3 from L-lysine inhibition. Mutant shows reduced L-lysine inhibition
M318I
mutant enzyme T344M is more conducive to L-lysine production than mutant M318I
T344M
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mutation is not directly involved in L-lysine binding. Mutation located within regulatory domain, participates in the allosteric regulation within regulatory domain. Mutation greatly reduces L-lysine inhibition
T344M
mutant enzyme T344M is more conducive to L-lysine production than mutant M318I
S378A/E202A
the mutant shows slightly increased activity (about 108%) compared to the wild type enzyme
S378A/E202A
the mutations do not affect the ATP binding with threonine
M68V
is almost fully resistant to feedback inhibition, increase in the catalytic activity, homologous expression reveals increase in varepsilon-poly-lysine productivity
M68V
random mutagenesis by error-prone PCR and subsequent site-directed mutagenesis, fully resistant to feedback inhibition, increase in epsilon-poly-L-lysine productivity
M68V
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is almost fully resistant to feedback inhibition, increase in the catalytic activity, homologous expression reveals increase in varepsilon-poly-lysine productivity
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M68V
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random mutagenesis by error-prone PCR and subsequent site-directed mutagenesis, fully resistant to feedback inhibition, increase in epsilon-poly-L-lysine productivity
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additional information
generation of ak-hsdh1 mutants, and double mutants from ak-hsdh1 and ak genes. Near-unanimous increases of Asp, Lys, and Ile in the single mutants that are not observed in the double mutants at the same age. A Thr increase is observed in mutant ak-hsdh1-1, it also has an increased Met content, overview. The contents of Asp, Lys, and Met in ak1-1, ak2-1, ak3-1, ak-hsdh1-1, ak-hsdh2-1, and ak-hsdh2-2 are significantly higher than those in the wild-type. Increases of Asp, Lys, and Met in ak-hsdh2 are also observed in mutants ak1-1, ak2-1, ak3-1, and ak-hsdh1-1. The Thr increase in ak-hsdh2 is observed in ak-hsdh1-1 but not in ak1-1, ak2-1, or ak3-1. Transcript levels of AK and AK-HSDH genes in leaves of 4-week-old engineered plants, mutant plant phenotypes, overview
additional information
generation of ak-hsdh1 mutants, and double mutants from ak-hsdh1 and ak genes. Near-unanimous increases of Asp, Lys, and Ile in the single mutants that are not observed in the double mutants at the same age. A Thr increase is observed in mutant ak-hsdh1-1, it also has an increased Met content, overview. The contents of Asp, Lys, and Met in ak1-1, ak2-1, ak3-1, ak-hsdh1-1, ak-hsdh2-1, and ak-hsdh2-2 are significantly higher than those in the wild-type. Increases of Asp, Lys, and Met in ak-hsdh2 are also observed in mutants ak1-1, ak2-1, ak3-1, and ak-hsdh1-1. The Thr increase in ak-hsdh2 is observed in ak-hsdh1-1 but not in ak1-1, ak2-1, or ak3-1. Transcript levels of AK and AK-HSDH genes in leaves of 4-week-old engineered plants, mutant plant phenotypes, overview
additional information
generation of ak-hsdh1 mutants, and double mutants from ak-hsdh1 and ak genes. Near-unanimous increases of Asp, Lys, and Ile in the single mutants that are not observed in the double mutants at the same age. A Thr increase is observed in mutant ak-hsdh1-1, it also has an increased Met content, overview. The contents of Asp, Lys, and Met in ak1-1, ak2-1, ak3-1, ak-hsdh1-1, ak-hsdh2-1, and ak-hsdh2-2 are significantly higher than those in the wild-type. Increases of Asp, Lys, and Met in ak-hsdh2 are also observed in mutants ak1-1, ak2-1, ak3-1, and ak-hsdh1-1. The Thr increase in ak-hsdh2 is observed in ak-hsdh1-1 but not in ak1-1, ak2-1, or ak3-1. Transcript levels of AK and AK-HSDH genes in leaves of 4-week-old engineered plants, mutant plant phenotypes, overview
additional information
generation of ak-hsdh1 mutants, and double mutants from ak-hsdh1 and ak genes. Near-unanimous increases of Asp, Lys, and Ile in the single mutants that are not observed in the double mutants at the same age. A Thr increase is observed in mutant ak-hsdh1-1, it also has an increased Met content, overview. The contents of Asp, Lys, and Met in ak1-1, ak2-1, ak3-1, ak-hsdh1-1, ak-hsdh2-1, and ak-hsdh2-2 are significantly higher than those in the wild-type. Increases of Asp, Lys, and Met in ak-hsdh2 are also observed in mutants ak1-1, ak2-1, ak3-1, and ak-hsdh1-1. The Thr increase in ak-hsdh2 is observed in ak-hsdh1-1 but not in ak1-1, ak2-1, or ak3-1. Transcript levels of AK and AK-HSDH genes in leaves of 4-week-old engineered plants, mutant plant phenotypes, overview
additional information
generation of ak-hsdh1 mutants, and double mutants from ak-hsdh1 and ak genes. Near-unanimous increases of Asp, Lys, and Ile in the single mutants that are not observed in the double mutants at the same age. A Thr increase is observed in mutant ak-hsdh1-1, it also has an increased Met content, overview. The contents of Asp, Lys, and Met in ak1-1, ak2-1, ak3-1, ak-hsdh1-1, ak-hsdh2-1, and ak-hsdh2-2 are significantly higher than those in the wild-type. Increases of Asp, Lys, and Met in ak-hsdh2 are also observed in mutants ak1-1, ak2-1, ak3-1, and ak-hsdh1-1. The Thr increase in ak-hsdh2 is observed in ak-hsdh1-1 but not in ak1-1, ak2-1, or ak3-1. Transcript levels of AK and AK-HSDH genes in leaves of 4-week-old engineered plants, mutant plant phenotypes, overview
additional information
generation of ak-hsdh2 mutants, and double mutants from ak-hsdh2 and ak genes. Near-unanimous increases of Asp, Lys, and Ile in the single mutants that are not observed in the double mutants at the same age, only ak-hsdh2-1/ak2-1 has an increased Asp content. The Thr increase observed in mutants ak-hsdh1-1, ak-hsdh2-1, and ak-hsdh2-2 single mutants is absent in ak-hsdh2-1/ak1-1 and ak-hsdh2-1/ak2-1 double mutants. The ak-hsdh2-1/ak3-1 double mutant still has a high amount of Thr (280% higher than the wild type), and all three double mutants have increased Met contents, overview. In the ak-hsdh2-1/ak1-1 double mutant, both AK1 and AK-HSDH2 transcripts are completely abolished, and there is a 64% decrease in total AK-HSDH transcripts. Simultaneous loss of AK-HSDH2 and monofunctional AK1 or AK2 has an additive effect on the reduction of overall AK activity. The contents of Asp, Lys, and Met in ak1-1, ak2-1, ak3-1, ak-hsdh1-1, ak-hsdh2-1, and ak-hsdh2-2 are significantly higher than those in the wild-type. Increases of Asp, Lys, and Met in ak-hsdh2 are also observed in mutants ak1-1, ak2-1, ak3-1, and ak-hsdh1-1. However, the Thr increase in ak-hsdh2 is observed in ak-hsdh1-1 but not in ak1-1, ak2-1, or ak3-1. Transcript levels of AK and AK-HSDH genes in leaves of 4-week-old engineered plants, mutant plant phenotypes, overview
additional information
generation of ak-hsdh2 mutants, and double mutants from ak-hsdh2 and ak genes. Near-unanimous increases of Asp, Lys, and Ile in the single mutants that are not observed in the double mutants at the same age, only ak-hsdh2-1/ak2-1 has an increased Asp content. The Thr increase observed in mutants ak-hsdh1-1, ak-hsdh2-1, and ak-hsdh2-2 single mutants is absent in ak-hsdh2-1/ak1-1 and ak-hsdh2-1/ak2-1 double mutants. The ak-hsdh2-1/ak3-1 double mutant still has a high amount of Thr (280% higher than the wild type), and all three double mutants have increased Met contents, overview. In the ak-hsdh2-1/ak1-1 double mutant, both AK1 and AK-HSDH2 transcripts are completely abolished, and there is a 64% decrease in total AK-HSDH transcripts. Simultaneous loss of AK-HSDH2 and monofunctional AK1 or AK2 has an additive effect on the reduction of overall AK activity. The contents of Asp, Lys, and Met in ak1-1, ak2-1, ak3-1, ak-hsdh1-1, ak-hsdh2-1, and ak-hsdh2-2 are significantly higher than those in the wild-type. Increases of Asp, Lys, and Met in ak-hsdh2 are also observed in mutants ak1-1, ak2-1, ak3-1, and ak-hsdh1-1. However, the Thr increase in ak-hsdh2 is observed in ak-hsdh1-1 but not in ak1-1, ak2-1, or ak3-1. Transcript levels of AK and AK-HSDH genes in leaves of 4-week-old engineered plants, mutant plant phenotypes, overview
additional information
generation of ak-hsdh2 mutants, and double mutants from ak-hsdh2 and ak genes. Near-unanimous increases of Asp, Lys, and Ile in the single mutants that are not observed in the double mutants at the same age, only ak-hsdh2-1/ak2-1 has an increased Asp content. The Thr increase observed in mutants ak-hsdh1-1, ak-hsdh2-1, and ak-hsdh2-2 single mutants is absent in ak-hsdh2-1/ak1-1 and ak-hsdh2-1/ak2-1 double mutants. The ak-hsdh2-1/ak3-1 double mutant still has a high amount of Thr (280% higher than the wild type), and all three double mutants have increased Met contents, overview. In the ak-hsdh2-1/ak1-1 double mutant, both AK1 and AK-HSDH2 transcripts are completely abolished, and there is a 64% decrease in total AK-HSDH transcripts. Simultaneous loss of AK-HSDH2 and monofunctional AK1 or AK2 has an additive effect on the reduction of overall AK activity. The contents of Asp, Lys, and Met in ak1-1, ak2-1, ak3-1, ak-hsdh1-1, ak-hsdh2-1, and ak-hsdh2-2 are significantly higher than those in the wild-type. Increases of Asp, Lys, and Met in ak-hsdh2 are also observed in mutants ak1-1, ak2-1, ak3-1, and ak-hsdh1-1. However, the Thr increase in ak-hsdh2 is observed in ak-hsdh1-1 but not in ak1-1, ak2-1, or ak3-1. Transcript levels of AK and AK-HSDH genes in leaves of 4-week-old engineered plants, mutant plant phenotypes, overview
additional information
generation of ak-hsdh2 mutants, and double mutants from ak-hsdh2 and ak genes. Near-unanimous increases of Asp, Lys, and Ile in the single mutants that are not observed in the double mutants at the same age, only ak-hsdh2-1/ak2-1 has an increased Asp content. The Thr increase observed in mutants ak-hsdh1-1, ak-hsdh2-1, and ak-hsdh2-2 single mutants is absent in ak-hsdh2-1/ak1-1 and ak-hsdh2-1/ak2-1 double mutants. The ak-hsdh2-1/ak3-1 double mutant still has a high amount of Thr (280% higher than the wild type), and all three double mutants have increased Met contents, overview. In the ak-hsdh2-1/ak1-1 double mutant, both AK1 and AK-HSDH2 transcripts are completely abolished, and there is a 64% decrease in total AK-HSDH transcripts. Simultaneous loss of AK-HSDH2 and monofunctional AK1 or AK2 has an additive effect on the reduction of overall AK activity. The contents of Asp, Lys, and Met in ak1-1, ak2-1, ak3-1, ak-hsdh1-1, ak-hsdh2-1, and ak-hsdh2-2 are significantly higher than those in the wild-type. Increases of Asp, Lys, and Met in ak-hsdh2 are also observed in mutants ak1-1, ak2-1, ak3-1, and ak-hsdh1-1. However, the Thr increase in ak-hsdh2 is observed in ak-hsdh1-1 but not in ak1-1, ak2-1, or ak3-1. Transcript levels of AK and AK-HSDH genes in leaves of 4-week-old engineered plants, mutant plant phenotypes, overview
additional information
generation of ak-hsdh2 mutants, and double mutants from ak-hsdh2 and ak genes. Near-unanimous increases of Asp, Lys, and Ile in the single mutants that are not observed in the double mutants at the same age, only ak-hsdh2-1/ak2-1 has an increased Asp content. The Thr increase observed in mutants ak-hsdh1-1, ak-hsdh2-1, and ak-hsdh2-2 single mutants is absent in ak-hsdh2-1/ak1-1 and ak-hsdh2-1/ak2-1 double mutants. The ak-hsdh2-1/ak3-1 double mutant still has a high amount of Thr (280% higher than the wild type), and all three double mutants have increased Met contents, overview. In the ak-hsdh2-1/ak1-1 double mutant, both AK1 and AK-HSDH2 transcripts are completely abolished, and there is a 64% decrease in total AK-HSDH transcripts. Simultaneous loss of AK-HSDH2 and monofunctional AK1 or AK2 has an additive effect on the reduction of overall AK activity. The contents of Asp, Lys, and Met in ak1-1, ak2-1, ak3-1, ak-hsdh1-1, ak-hsdh2-1, and ak-hsdh2-2 are significantly higher than those in the wild-type. Increases of Asp, Lys, and Met in ak-hsdh2 are also observed in mutants ak1-1, ak2-1, ak3-1, and ak-hsdh1-1. However, the Thr increase in ak-hsdh2 is observed in ak-hsdh1-1 but not in ak1-1, ak2-1, or ak3-1. Transcript levels of AK and AK-HSDH genes in leaves of 4-week-old engineered plants, mutant plant phenotypes, overview
additional information
generation of ak1 mutants, and double mutants from ak-hsdh2 and ak genes. Near-unanimous increases of Asp, Lys, and Ile in the single mutant are not observed in the double mutants at the same age. The Thr increase observed in mutants ak-hsdh1-1, ak-hsdh2-1, and ak-hsdh2-2 single mutants is absent in ak-hsdh2-1/ak1-1 double mutant. In the ak-hsdh2-1/ak1-1 double mutant, both AK1 and AK-HSDH2 transcripts are completely abolished, and there is a 64% decrease in total AK-HSDH transcripts. Simultaneous loss of AK-HSDH2 and monofunctional AK1 or AK2 has an additive effect on the reduction of overall AK activity. The contents of Asp, Lys, and Met in ak1-1, ak2-1, ak3-1, ak-hsdh1-1, ak-hsdh2-1, and ak-hsdh2-2 are significantly higher than those in the wild-type. Increases of Asp, Lys, and Met in ak-hsdh2 are also observed in mutants ak1-1, ak2-1, ak3-1, and ak-hsdh1-1. The Thr increase in ak-hsdh2 is observed in ak-hsdh1-1 but not in ak1-1, ak2-1, or ak3-1. Transcript levels of AK and AK-HSDH genes in leaves of 4-week-old engineered plants, mutant plant phenotypes, overview
additional information
generation of ak1 mutants, and double mutants from ak-hsdh2 and ak genes. Near-unanimous increases of Asp, Lys, and Ile in the single mutant are not observed in the double mutants at the same age. The Thr increase observed in mutants ak-hsdh1-1, ak-hsdh2-1, and ak-hsdh2-2 single mutants is absent in ak-hsdh2-1/ak1-1 double mutant. In the ak-hsdh2-1/ak1-1 double mutant, both AK1 and AK-HSDH2 transcripts are completely abolished, and there is a 64% decrease in total AK-HSDH transcripts. Simultaneous loss of AK-HSDH2 and monofunctional AK1 or AK2 has an additive effect on the reduction of overall AK activity. The contents of Asp, Lys, and Met in ak1-1, ak2-1, ak3-1, ak-hsdh1-1, ak-hsdh2-1, and ak-hsdh2-2 are significantly higher than those in the wild-type. Increases of Asp, Lys, and Met in ak-hsdh2 are also observed in mutants ak1-1, ak2-1, ak3-1, and ak-hsdh1-1. The Thr increase in ak-hsdh2 is observed in ak-hsdh1-1 but not in ak1-1, ak2-1, or ak3-1. Transcript levels of AK and AK-HSDH genes in leaves of 4-week-old engineered plants, mutant plant phenotypes, overview
additional information
generation of ak1 mutants, and double mutants from ak-hsdh2 and ak genes. Near-unanimous increases of Asp, Lys, and Ile in the single mutant are not observed in the double mutants at the same age. The Thr increase observed in mutants ak-hsdh1-1, ak-hsdh2-1, and ak-hsdh2-2 single mutants is absent in ak-hsdh2-1/ak1-1 double mutant. In the ak-hsdh2-1/ak1-1 double mutant, both AK1 and AK-HSDH2 transcripts are completely abolished, and there is a 64% decrease in total AK-HSDH transcripts. Simultaneous loss of AK-HSDH2 and monofunctional AK1 or AK2 has an additive effect on the reduction of overall AK activity. The contents of Asp, Lys, and Met in ak1-1, ak2-1, ak3-1, ak-hsdh1-1, ak-hsdh2-1, and ak-hsdh2-2 are significantly higher than those in the wild-type. Increases of Asp, Lys, and Met in ak-hsdh2 are also observed in mutants ak1-1, ak2-1, ak3-1, and ak-hsdh1-1. The Thr increase in ak-hsdh2 is observed in ak-hsdh1-1 but not in ak1-1, ak2-1, or ak3-1. Transcript levels of AK and AK-HSDH genes in leaves of 4-week-old engineered plants, mutant plant phenotypes, overview
additional information
generation of ak1 mutants, and double mutants from ak-hsdh2 and ak genes. Near-unanimous increases of Asp, Lys, and Ile in the single mutant are not observed in the double mutants at the same age. The Thr increase observed in mutants ak-hsdh1-1, ak-hsdh2-1, and ak-hsdh2-2 single mutants is absent in ak-hsdh2-1/ak1-1 double mutant. In the ak-hsdh2-1/ak1-1 double mutant, both AK1 and AK-HSDH2 transcripts are completely abolished, and there is a 64% decrease in total AK-HSDH transcripts. Simultaneous loss of AK-HSDH2 and monofunctional AK1 or AK2 has an additive effect on the reduction of overall AK activity. The contents of Asp, Lys, and Met in ak1-1, ak2-1, ak3-1, ak-hsdh1-1, ak-hsdh2-1, and ak-hsdh2-2 are significantly higher than those in the wild-type. Increases of Asp, Lys, and Met in ak-hsdh2 are also observed in mutants ak1-1, ak2-1, ak3-1, and ak-hsdh1-1. The Thr increase in ak-hsdh2 is observed in ak-hsdh1-1 but not in ak1-1, ak2-1, or ak3-1. Transcript levels of AK and AK-HSDH genes in leaves of 4-week-old engineered plants, mutant plant phenotypes, overview
additional information
generation of ak1 mutants, and double mutants from ak-hsdh2 and ak genes. Near-unanimous increases of Asp, Lys, and Ile in the single mutant are not observed in the double mutants at the same age. The Thr increase observed in mutants ak-hsdh1-1, ak-hsdh2-1, and ak-hsdh2-2 single mutants is absent in ak-hsdh2-1/ak1-1 double mutant. In the ak-hsdh2-1/ak1-1 double mutant, both AK1 and AK-HSDH2 transcripts are completely abolished, and there is a 64% decrease in total AK-HSDH transcripts. Simultaneous loss of AK-HSDH2 and monofunctional AK1 or AK2 has an additive effect on the reduction of overall AK activity. The contents of Asp, Lys, and Met in ak1-1, ak2-1, ak3-1, ak-hsdh1-1, ak-hsdh2-1, and ak-hsdh2-2 are significantly higher than those in the wild-type. Increases of Asp, Lys, and Met in ak-hsdh2 are also observed in mutants ak1-1, ak2-1, ak3-1, and ak-hsdh1-1. The Thr increase in ak-hsdh2 is observed in ak-hsdh1-1 but not in ak1-1, ak2-1, or ak3-1. Transcript levels of AK and AK-HSDH genes in leaves of 4-week-old engineered plants, mutant plant phenotypes, overview
additional information
generation of ak2 mutants, and double mutants from ak-hsdh2 and ak2 genes. Near-unanimous increases of Asp, Lys, and Ile in the single mutant are not observed in the double mutants at the same age, only ak-hsdh2-1/ak2-1 has an increased Asp content. The Thr increase observed in mutants ak-hsdh1-1, ak-hsdh2-1, and ak-hsdh2-2 single mutants is absent in ak-hsdh2-1/ak2-1 double mutant. The contents of Asp, Lys, and Met in ak1-1, ak2-1, ak3-1, ak-hsdh1-1, ak-hsdh2-1, and ak-hsdh2-2 are significantly higher than those in the wild-type. Increases of Asp, Lys, and Met in ak-hsdh2 are also observed in mutants ak1-1, ak2-1, ak3-1, and ak-hsdh1-1. Simultaneous loss of AK-HSDH2 and monofunctional AK1 or AK2 has an additive effect on the reduction of overall AK activity. The Thr increase in ak-hsdh2 is observed in ak-hsdh1-1 but not in ak1-1, ak2-1, or ak3-1. Transcript levels of AK and AK-HSDH genes in leaves of 4-week-old engineered plants, mutant plant phenotypes, overview
additional information
generation of ak2 mutants, and double mutants from ak-hsdh2 and ak2 genes. Near-unanimous increases of Asp, Lys, and Ile in the single mutant are not observed in the double mutants at the same age, only ak-hsdh2-1/ak2-1 has an increased Asp content. The Thr increase observed in mutants ak-hsdh1-1, ak-hsdh2-1, and ak-hsdh2-2 single mutants is absent in ak-hsdh2-1/ak2-1 double mutant. The contents of Asp, Lys, and Met in ak1-1, ak2-1, ak3-1, ak-hsdh1-1, ak-hsdh2-1, and ak-hsdh2-2 are significantly higher than those in the wild-type. Increases of Asp, Lys, and Met in ak-hsdh2 are also observed in mutants ak1-1, ak2-1, ak3-1, and ak-hsdh1-1. Simultaneous loss of AK-HSDH2 and monofunctional AK1 or AK2 has an additive effect on the reduction of overall AK activity. The Thr increase in ak-hsdh2 is observed in ak-hsdh1-1 but not in ak1-1, ak2-1, or ak3-1. Transcript levels of AK and AK-HSDH genes in leaves of 4-week-old engineered plants, mutant plant phenotypes, overview
additional information
generation of ak2 mutants, and double mutants from ak-hsdh2 and ak2 genes. Near-unanimous increases of Asp, Lys, and Ile in the single mutant are not observed in the double mutants at the same age, only ak-hsdh2-1/ak2-1 has an increased Asp content. The Thr increase observed in mutants ak-hsdh1-1, ak-hsdh2-1, and ak-hsdh2-2 single mutants is absent in ak-hsdh2-1/ak2-1 double mutant. The contents of Asp, Lys, and Met in ak1-1, ak2-1, ak3-1, ak-hsdh1-1, ak-hsdh2-1, and ak-hsdh2-2 are significantly higher than those in the wild-type. Increases of Asp, Lys, and Met in ak-hsdh2 are also observed in mutants ak1-1, ak2-1, ak3-1, and ak-hsdh1-1. Simultaneous loss of AK-HSDH2 and monofunctional AK1 or AK2 has an additive effect on the reduction of overall AK activity. The Thr increase in ak-hsdh2 is observed in ak-hsdh1-1 but not in ak1-1, ak2-1, or ak3-1. Transcript levels of AK and AK-HSDH genes in leaves of 4-week-old engineered plants, mutant plant phenotypes, overview
additional information
generation of ak2 mutants, and double mutants from ak-hsdh2 and ak2 genes. Near-unanimous increases of Asp, Lys, and Ile in the single mutant are not observed in the double mutants at the same age, only ak-hsdh2-1/ak2-1 has an increased Asp content. The Thr increase observed in mutants ak-hsdh1-1, ak-hsdh2-1, and ak-hsdh2-2 single mutants is absent in ak-hsdh2-1/ak2-1 double mutant. The contents of Asp, Lys, and Met in ak1-1, ak2-1, ak3-1, ak-hsdh1-1, ak-hsdh2-1, and ak-hsdh2-2 are significantly higher than those in the wild-type. Increases of Asp, Lys, and Met in ak-hsdh2 are also observed in mutants ak1-1, ak2-1, ak3-1, and ak-hsdh1-1. Simultaneous loss of AK-HSDH2 and monofunctional AK1 or AK2 has an additive effect on the reduction of overall AK activity. The Thr increase in ak-hsdh2 is observed in ak-hsdh1-1 but not in ak1-1, ak2-1, or ak3-1. Transcript levels of AK and AK-HSDH genes in leaves of 4-week-old engineered plants, mutant plant phenotypes, overview
additional information
generation of ak2 mutants, and double mutants from ak-hsdh2 and ak2 genes. Near-unanimous increases of Asp, Lys, and Ile in the single mutant are not observed in the double mutants at the same age, only ak-hsdh2-1/ak2-1 has an increased Asp content. The Thr increase observed in mutants ak-hsdh1-1, ak-hsdh2-1, and ak-hsdh2-2 single mutants is absent in ak-hsdh2-1/ak2-1 double mutant. The contents of Asp, Lys, and Met in ak1-1, ak2-1, ak3-1, ak-hsdh1-1, ak-hsdh2-1, and ak-hsdh2-2 are significantly higher than those in the wild-type. Increases of Asp, Lys, and Met in ak-hsdh2 are also observed in mutants ak1-1, ak2-1, ak3-1, and ak-hsdh1-1. Simultaneous loss of AK-HSDH2 and monofunctional AK1 or AK2 has an additive effect on the reduction of overall AK activity. The Thr increase in ak-hsdh2 is observed in ak-hsdh1-1 but not in ak1-1, ak2-1, or ak3-1. Transcript levels of AK and AK-HSDH genes in leaves of 4-week-old engineered plants, mutant plant phenotypes, overview
additional information
generation of ak3 mutants, and double mutants from ak-hsdh2 and ak genes. Near-unanimous increases of Asp, Lys, and Ile in the single mutants are not observed in the double mutants at the same age. The ak-hsdh2-1/ak3-1 double mutant still has a high amount of Thr (280% higher than the wild type), and all three double mutants have increased Met contents, overview. The contents of Asp, Lys, and Met in ak1-1, ak2-1, ak3-1, ak-hsdh1-1, ak-hsdh2-1, and ak-hsdh2-2 are significantly higher than those in the wild-type. Increases of Asp, Lys, and Met in ak-hsdh2 are also observed in mutants ak1-1, ak2-1, ak3-1, and ak-hsdh1-1. The Thr increase in ak-hsdh2 is observed in ak-hsdh1-1 but not in ak1-1, ak2-1, or ak3-1. Transcript levels of AK and AK-HSDH genes in leaves of 4-week-old engineered plants, mutant plant phenotypes, overview
additional information
generation of ak3 mutants, and double mutants from ak-hsdh2 and ak genes. Near-unanimous increases of Asp, Lys, and Ile in the single mutants are not observed in the double mutants at the same age. The ak-hsdh2-1/ak3-1 double mutant still has a high amount of Thr (280% higher than the wild type), and all three double mutants have increased Met contents, overview. The contents of Asp, Lys, and Met in ak1-1, ak2-1, ak3-1, ak-hsdh1-1, ak-hsdh2-1, and ak-hsdh2-2 are significantly higher than those in the wild-type. Increases of Asp, Lys, and Met in ak-hsdh2 are also observed in mutants ak1-1, ak2-1, ak3-1, and ak-hsdh1-1. The Thr increase in ak-hsdh2 is observed in ak-hsdh1-1 but not in ak1-1, ak2-1, or ak3-1. Transcript levels of AK and AK-HSDH genes in leaves of 4-week-old engineered plants, mutant plant phenotypes, overview
additional information
generation of ak3 mutants, and double mutants from ak-hsdh2 and ak genes. Near-unanimous increases of Asp, Lys, and Ile in the single mutants are not observed in the double mutants at the same age. The ak-hsdh2-1/ak3-1 double mutant still has a high amount of Thr (280% higher than the wild type), and all three double mutants have increased Met contents, overview. The contents of Asp, Lys, and Met in ak1-1, ak2-1, ak3-1, ak-hsdh1-1, ak-hsdh2-1, and ak-hsdh2-2 are significantly higher than those in the wild-type. Increases of Asp, Lys, and Met in ak-hsdh2 are also observed in mutants ak1-1, ak2-1, ak3-1, and ak-hsdh1-1. The Thr increase in ak-hsdh2 is observed in ak-hsdh1-1 but not in ak1-1, ak2-1, or ak3-1. Transcript levels of AK and AK-HSDH genes in leaves of 4-week-old engineered plants, mutant plant phenotypes, overview
additional information
generation of ak3 mutants, and double mutants from ak-hsdh2 and ak genes. Near-unanimous increases of Asp, Lys, and Ile in the single mutants are not observed in the double mutants at the same age. The ak-hsdh2-1/ak3-1 double mutant still has a high amount of Thr (280% higher than the wild type), and all three double mutants have increased Met contents, overview. The contents of Asp, Lys, and Met in ak1-1, ak2-1, ak3-1, ak-hsdh1-1, ak-hsdh2-1, and ak-hsdh2-2 are significantly higher than those in the wild-type. Increases of Asp, Lys, and Met in ak-hsdh2 are also observed in mutants ak1-1, ak2-1, ak3-1, and ak-hsdh1-1. The Thr increase in ak-hsdh2 is observed in ak-hsdh1-1 but not in ak1-1, ak2-1, or ak3-1. Transcript levels of AK and AK-HSDH genes in leaves of 4-week-old engineered plants, mutant plant phenotypes, overview
additional information
generation of ak3 mutants, and double mutants from ak-hsdh2 and ak genes. Near-unanimous increases of Asp, Lys, and Ile in the single mutants are not observed in the double mutants at the same age. The ak-hsdh2-1/ak3-1 double mutant still has a high amount of Thr (280% higher than the wild type), and all three double mutants have increased Met contents, overview. The contents of Asp, Lys, and Met in ak1-1, ak2-1, ak3-1, ak-hsdh1-1, ak-hsdh2-1, and ak-hsdh2-2 are significantly higher than those in the wild-type. Increases of Asp, Lys, and Met in ak-hsdh2 are also observed in mutants ak1-1, ak2-1, ak3-1, and ak-hsdh1-1. The Thr increase in ak-hsdh2 is observed in ak-hsdh1-1 but not in ak1-1, ak2-1, or ak3-1. Transcript levels of AK and AK-HSDH genes in leaves of 4-week-old engineered plants, mutant plant phenotypes, overview
additional information
site-directed mutagenesis is used to construct a mutant of the region coding for regulatory beta-subunit in the aspartate kinase by replacing the codon TCC-GTC to deregulate it from feedback inhibition, which results in improved L-lysine production. The mutant enzymes are resistant against S-(2-aminoethyl)-L-cysteine and feedback inhibition, phenotype, overview
additional information
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site-directed mutagenesis is used to construct a mutant of the region coding for regulatory beta-subunit in the aspartate kinase by replacing the codon TCC-GTC to deregulate it from feedback inhibition, which results in improved L-lysine production. The mutant enzymes are resistant against S-(2-aminoethyl)-L-cysteine and feedback inhibition, phenotype, overview
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additional information
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AK DR1365 disruption mutant, does not grow in minimal medium, growth rate in minimal medium supplemented with methionine and threonine is identical to that supplemented with methionine, threonine and lysine, this phenotype is similar to a Thermus thermophilus AK TTC0166 disprution mutant
additional information
AK DR1365 disruption mutant, does not grow in minimal medium, growth rate in minimal medium supplemented with methionine and threonine is identical to that supplemented with methionine, threonine and lysine, this phenotype is similar to a Thermus thermophilus AK TTC0166 disprution mutant
additional information
Deinococcus radiodurans R1 / ATCC 13939 / DSM 20539
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AK DR1365 disruption mutant, does not grow in minimal medium, growth rate in minimal medium supplemented with methionine and threonine is identical to that supplemented with methionine, threonine and lysine, this phenotype is similar to a Thermus thermophilus AK TTC0166 disprution mutant
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additional information
key metabolic pathway for construction of an inducer-free L-homoserine-producing strain to maximize the productivity of L-homoserine based on genetic-engineering tools, comparison of L-homoserine production, cell growth, and glucose consumption in different engineered strains, overview. L-Homoserine is a nonessential amino acid for the biosynthesis of L-threonine and L-methionine. It is also an important precursor for the production of isobutanol, 1,4-butanediol, L-phosphinothricin, 2,4-ihydroxybutyrate, and 1,3-propanediol. The initial L-homoserine-producing strain HS1 is obtained by blocking the degradative and competitive pathways and overexpressing thrA (encoding homoserine dehydrogenase) based on an O-succinyl homoserine-producing strain, using the pull-push-block strategy, an efficient method to engineer microorganisms involved in biosynthesizing target products by modifying metabolic networks. L-homoserine-converting pathway-related genes (thrB, encoding homoserine kinase, and metA, encoding homoserine O-succinyltransferase) are successively deleted to block L-homoserine degradation. Gene thrAis overexpressed to push the carbon flux to L-homoserine production. Then, the lysine-auxotrophic strain HS2 is generated by deleting lysA to eliminate a precursor competing metabolic pathway on L-homoserine production. For strengthening the capability of the L-homoserine transport system and the transformation of other toxic intermediate metabolites, gene rhtA, encoding the inner membrane transporter that is involved in the export of L-homoserine, is overexpressed chromosomally by replacing the native promoter with the trc promoter to obtain strain HS3 (Trc-rhtA). The strain shows increased activity. Increase in the L-homoserine export capacity and relieve the growth burden of homoserine-producing strains to enable survival via replacement of the native promoter of the eamA gene by the trc promoter in strain HS4 (Trc-eamA). Two rhtA gene copies (the native rhtA gene and replacement of the lacI gene) and eamA are overexpressed under the trc promoter in the chromosome to construct strain HS5 (DELTAlacI::Trc-rhtA Trc-rhtA Trc-eamA). Under batch culture, strain HS5, with modification of the transport system and construction of a constitutive expression system, can produce 3.14 g/l L-homoserine, which is 54.2% higher than strain HS2 production. In addition, the specific production of strain HS5 is also increased. Repression of candidate genes by the CRISPRi system to further enhance L-homoserine production
additional information
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key metabolic pathway for construction of an inducer-free L-homoserine-producing strain to maximize the productivity of L-homoserine based on genetic-engineering tools, comparison of L-homoserine production, cell growth, and glucose consumption in different engineered strains, overview. L-Homoserine is a nonessential amino acid for the biosynthesis of L-threonine and L-methionine. It is also an important precursor for the production of isobutanol, 1,4-butanediol, L-phosphinothricin, 2,4-ihydroxybutyrate, and 1,3-propanediol. The initial L-homoserine-producing strain HS1 is obtained by blocking the degradative and competitive pathways and overexpressing thrA (encoding homoserine dehydrogenase) based on an O-succinyl homoserine-producing strain, using the pull-push-block strategy, an efficient method to engineer microorganisms involved in biosynthesizing target products by modifying metabolic networks. L-homoserine-converting pathway-related genes (thrB, encoding homoserine kinase, and metA, encoding homoserine O-succinyltransferase) are successively deleted to block L-homoserine degradation. Gene thrAis overexpressed to push the carbon flux to L-homoserine production. Then, the lysine-auxotrophic strain HS2 is generated by deleting lysA to eliminate a precursor competing metabolic pathway on L-homoserine production. For strengthening the capability of the L-homoserine transport system and the transformation of other toxic intermediate metabolites, gene rhtA, encoding the inner membrane transporter that is involved in the export of L-homoserine, is overexpressed chromosomally by replacing the native promoter with the trc promoter to obtain strain HS3 (Trc-rhtA). The strain shows increased activity. Increase in the L-homoserine export capacity and relieve the growth burden of homoserine-producing strains to enable survival via replacement of the native promoter of the eamA gene by the trc promoter in strain HS4 (Trc-eamA). Two rhtA gene copies (the native rhtA gene and replacement of the lacI gene) and eamA are overexpressed under the trc promoter in the chromosome to construct strain HS5 (DELTAlacI::Trc-rhtA Trc-rhtA Trc-eamA). Under batch culture, strain HS5, with modification of the transport system and construction of a constitutive expression system, can produce 3.14 g/l L-homoserine, which is 54.2% higher than strain HS2 production. In addition, the specific production of strain HS5 is also increased. Repression of candidate genes by the CRISPRi system to further enhance L-homoserine production
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