Information on EC 2.5.1.45 - homospermidine synthase (spermidine-specific)

Please wait a moment until all data is loaded. This message will disappear when all data is loaded.
Specify your search results
Select one or more organisms in this record:
Show additional data
Do not include text mining results
Include (text mining) results (more...)
Include results (AMENDA + additional results, but less precise; more...)

The enzyme appears in viruses and cellular organisms

EC NUMBER
COMMENTARY hide
2.5.1.45
-
RECOMMENDED NAME
GeneOntology No.
homospermidine synthase (spermidine-specific)
REACTION
REACTION DIAGRAM
COMMENTARY hide
ORGANISM
UNIPROT
LITERATURE
spermidine + putrescine = sym-homospermidine + propane-1,3-diamine
show the reaction diagram
the reaction of this enzyme occurs in three steps: i. NAD-dependent dehydrogenation of spermidine, ii. transfer of the 4-aminobutylidene group from dehydrospermidine to putrescine, iii. reduction of the imine intermediate to form homospermidine. Hence the overall reaction is transfer of a 4-aminobutyl group. This enzyme is more specific than EC 2.5.1.44, homospermidine synthase, which is found in bacteria, as it cannot use putrescine as donor of the 4-aminobutyl group. Forms part of the biosynthetic pathway of the poisonous pyrrolizidine alkaloids of the ragworts, Senecio
-
-
-
REACTION TYPE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
aminobutyl group transfer
-
-
-
-
PATHWAY
BRENDA Link
KEGG Link
MetaCyc Link
homospermidine biosynthesis
-
-
SYSTEMATIC NAME
IUBMB Comments
spermidine:putrescine 4-aminobutyltransferase (propane-1,3-diamine-forming)
The reaction of this enzyme occurs in three steps, with some of the intermediates presumably remaining enzyme-bound: (a) NAD+-dependent dehydrogenation of spermidine, (b) transfer of the 4-aminobutylidene group from dehydrospermidine to putrescine and (c) reduction of the imine intermediate to form homospermidine. This enzyme is more specific than EC 2.5.1.44, homospermidine synthase, which is found in bacteria, as it cannot use putrescine as donor of the 4-aminobutyl group. Forms part of the biosynthetic pathway of the poisonous pyrrolizidine alkaloids of the ragworts (Senecio).
CAS REGISTRY NUMBER
COMMENTARY hide
259168-77-9
-
76106-84-8
-
ORGANISM
COMMENTARY hide
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
-
-
-
Manually annotated by BRENDA team
gene hss1
UniProt
Manually annotated by BRENDA team
Eupatorium pauciflorum
-
-
-
Manually annotated by BRENDA team
gene hss
-
-
Manually annotated by BRENDA team
gene hss
-
-
Manually annotated by BRENDA team
gene hss
-
-
Manually annotated by BRENDA team
gene hss
-
-
Manually annotated by BRENDA team
gene hss
-
-
Manually annotated by BRENDA team
GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
evolution
malfunction
-
transgenic tobacco plants are generated expressing Senecio vernalis homospermidine synthase. Analyses of the polyamine content reveals that, in the transgenic plants, about 80% of spermidine is replaced by homospermidine without any conspicuous modifications of the phenotype. Tracer-feeding experiments and gas chromatographic analyses suggest that these high levels of homospermidine are not sufficient to explain the formation of alkaloid precursors
metabolism
additional information
SUBSTRATE
PRODUCT                       
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
putrescine + spermidine
N-(4-aminobutyl)butane-1,4-diamine + propane-1,3-diamine
show the reaction diagram
putrescine + spermidine
sym-homospermidine + propane-1,3-diamine
show the reaction diagram
putrescine + spermine
sym-homospermine + propane-1,3-diamine
show the reaction diagram
spermidine + putrescine
sym-homospermidine + propane-1,3-diamine
show the reaction diagram
NATURAL SUBSTRATES
NATURAL PRODUCTS
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
REVERSIBILITY
r=reversible
ir=irreversible
?=not specified
putrescine + spermidine
sym-homospermidine + propane-1,3-diamine
show the reaction diagram
putrescine + spermine
sym-homospermine + propane-1,3-diamine
show the reaction diagram
spermidine + putrescine
sym-homospermidine + propane-1,3-diamine
show the reaction diagram
COFACTOR
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
INHIBITORS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
1,3-Diaminopropane
-
competitive
cadaverine
-
mixed type inhibition
Homospermidine
-
competitive
spermidine
-
competitive
spermine
-
mixed type inhibition
KM VALUE [mM]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
0.003
NAD+
-
NAD+ functions as an enzyme-bound redoxsystem that is reduced in the first and reoxidized in the second part of the overall reaction. It functions as a coenzyme and not a cosubstrate
0.0135 - 0.015
putrescine
0.012
spermidine
-
at 0.1 mM putrescine
additional information
additional information
-
-
-
TURNOVER NUMBER [1/s]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
0.0032
putrescine
Senecio vernalis
-
+ spermidine
Ki VALUE [mM]
INHIBITOR
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
0.0063
1,3-Diaminopropane
-
-
0.058
cadaverine
-
-
0.95
Homospermidine
-
-
0.094
spermidine
-
-
0.0022
spermine
-
-
SPECIFIC ACTIVITY [µmol/min/mg]
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
0.062
-
purified recombinant enzyme, pH and temperature not specified in the publication
0.136
-
purified recombinant enzyme, pH and temperature not specified in the publication
pH OPTIMUM
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
pH RANGE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
8.7 - 9.9
-
about 55% of maximal activity at pH 8.7 and at pH 9.9
SOURCE TISSUE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
SOURCE
-
young flower buds, but not mature flowers, express homospermidine synthase and are able to catalyze pyrrolizidine alkaloid biosynthesis
Manually annotated by BRENDA team
-
HSS expression stops just before the flower buds open
Manually annotated by BRENDA team
additional information
LOCALIZATION
ORGANISM
UNIPROT
COMMENTARY hide
GeneOntology No.
LITERATURE
SOURCE
MOLECULAR WEIGHT
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
40700
4 * 40700, calculation from sequence of cDNA
40740
4 * 40740, calculation from sequence of cDNA
41000
-
x * 41000, SDS-PAGE
44500
4 * 44500, SDS-PAGE
45000
4 * 45000, SDS-PAGE
174000
gel filtration
SUBUNITS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
tetramer
GENERAL STABILITY
ORGANISM
UNIPROT
LITERATURE
increased instability with higher purification grade
-
STORAGE STABILITY
ORGANISM
UNIPROT
LITERATURE
4°C, crude extract, 0.5-1 mM spermidine, 0.5-1 mM NAD+, 1 week, 30% loss of activity
-
Purification/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
recombinant tagged enzyme from Escherichia coli by affinity chromatography
using Ni-NTA chromatography
-
Cloned/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
expressed as a C-terminal his-tagged fusion protein
-
expressed in Escherichia coli
expression in Escherichia coli
-
gene hss, DNA and amino acid sequence determination and analysis, sequence comparisons and phylogenetic analysis, recombinant expression of tagged enzyme in Escherichia coli
gene HSS, semiquantitative RT-PCR expression analysis in tissues
gene hss1, DNA and amino acid sequence determination and analysis, cloning from cDNA library of lower leaf epidermis cells from leaves and stems, quantitative real-time PCR expression analysis in epidermis cells
gene hss1, DNA and amino acid sequence determination and analysis, sequence comparissons, quantitative real-time PCR enzyme expression analysis
EXPRESSION
ORGANISM
UNIPROT
LITERATURE
exogenously applied nitrate has no impact on polyamine biosynthesis, and enzyme expression
no effect on enzyme expression by methyl jasmonate
polymanines in Crotalaria are detectable only when the plants form nodules after infection with their rhizobial partner, nodulation is induced by infection with a Bradyrhizobium strain and triggers the polyamine biosynthesis, leading to induction of the enzyme HSS in nodules
ENGINEERING
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
I277D
-
site-directed mutagenesis, the mutant shows increased HSS activity with putrescine and slightly reduced deoxyhypusine synthase activity compared to the wild-type
I277D/N281D
-
site-directed mutagenesis, the mutant shows increased HSS activity with putrescine and reduced deoxyhypusine synthase activity compared to the wild-type
N266H
-
site-directed mutagenesis, the mutant shows increased HSS activity with putrescine and reduced deoxyhypusine synthase activity compared to the wild-type
N266H/I277D
-
site-directed mutagenesis, the mutant shows increased HSS activity with putrescine, but unaltered deoxyhypusine synthase activity compared to the wild-type
N266H/I277D/N281D
-
site-directed mutagenesis, the mutant shows increased HSS activity with putrescine and reduced deoxyhypusine synthase activity compared to the wild-type
N266H/N281D
-
site-directed mutagenesis, the mutant shows increased HSS activity with putrescine and reduced deoxyhypusine synthase activity compared to the wild-type
N281D
-
site-directed mutagenesis, the mutant shows slightly reduced HSS activity with putrescine and reduced deoxyhypusine synthase activity compared to the wild-type