Information on EC 3.4.21.88 - Repressor LexA

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The enzyme appears in viruses and cellular organisms

EC NUMBER
COMMENTARY hide
3.4.21.88
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RECOMMENDED NAME
GeneOntology No.
Repressor LexA
REACTION
REACTION DIAGRAM
COMMENTARY hide
ORGANISM
UNIPROT
LITERATURE
Hydrolysis of Ala84-/-Gly bond in repressor LexA
show the reaction diagram
REACTION TYPE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
hydrolysis of peptide bond
CAS REGISTRY NUMBER
COMMENTARY hide
84721-00-6
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ORGANISM
COMMENTARY hide
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
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UniProt
Manually annotated by BRENDA team
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Manually annotated by BRENDA team
strain ATCC 13032, gene lexA
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Manually annotated by BRENDA team
strain K12
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Manually annotated by BRENDA team
no activity in Streptococcus thermophilus
a small DNA region upstream of the recA transcriptional start site carries all the information needed for normal regulation of the S. thermophilus recA gene
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Manually annotated by BRENDA team
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SwissProt
Manually annotated by BRENDA team
strain UA1876, ATCC 14028
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Manually annotated by BRENDA team
strain UA1876, ATCC 14028
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Manually annotated by BRENDA team
potent chimeric transcription factor XV comprising the DNA-binding domain of LexA and the transactivation domain of herpes simplex virus regulatory protein VP16
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Manually annotated by BRENDA team
strain HK386 and modified lysogen strain HK138
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Manually annotated by BRENDA team
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Manually annotated by BRENDA team
GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
malfunction
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Bacillus thuringenis LexA binds to dinBox sequences in the temperate phage GIL01, repressing phage gene expression during lysogeny and providing the switch necessary to enter lytic development
physiological function
SUBSTRATE
PRODUCT                       
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
DNA + H2O
DNA-loop + ?
show the reaction diagram
DNA + H2O
LexA-DNA complexes
show the reaction diagram
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detected by electrophoretical mobility shift assays, LexA repressor is the key regulatory protein of the DNA repair system, the SOS response. LexA is directly involved in SOS induction of the Staphylococcus aureus pathogenicity islands, SaPIs. LexA represses SaPI operon I containing ORF5, ORF7, 8 and 9
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?
Repressor LexA + H2O
LexA cleavage products
show the reaction diagram
additional information
?
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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
additional information
?
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INHIBITORS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
RecA
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additional information
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LexA protein is the repressor, which, during normal bacterial growth downregulates its own expression
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ACTIVATING COMPOUND
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
RecA protein
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RecA protein and single-stranded DNA are required for activity being attributed to a Ser/Lys dyad. The LexA protein represses the SOS regulon, which regulates the genes involved in DNA repair. In the presence of single-stranded DNA, the RecA protein interacts with repressor LexA, causing it to undergo an autocatalytic cleavage which disrupts the DNA-binding part of the repressor, and inactivates it. The consequent derepression of the SOS regulon leads to DNA repair
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single-stranded DNA
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RecA protein and single-stranded DNA are required for activity being attributed to a Ser/Lys dyad. The LexA protein represses the SOS regulon, which regulates the genes involved in DNA repair. In the presence of single-stranded DNA, the RecA interacts with repressor LexA, causing it to undergo an autocatalytic cleavage which disrupts the DNA-binding part of the repressor, and inactivates it. The consequent derepression of the SOS regulon leads to DNA repair
additional information
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pH OPTIMUM
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
7
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binding affinity of LexA repressor for operator is greatest near neutral pH
pH RANGE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
3.9 - 9.3
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TEMPERATURE OPTIMUM
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
37
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assay at
pI VALUE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
5.6
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and 5.8 and 6.1, isoelectric focusing
5.7
calculated from the deduced amino acid sequence
5.8
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and 5.6 and 6.1, isoelectric focusing; calculated
5.95
calculated from the deduced amino acid sequence
6.1
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and 5.6 and 5.8, isoelectric focusing
6.13
calculated from the deduced amino acid sequence
LOCALIZATION
ORGANISM
UNIPROT
COMMENTARY hide
GeneOntology No.
LITERATURE
SOURCE
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specifically and predominantly localized in the core region of the cytoplasm, with a rather ristricted diffusion toward outer regions of the cell, and decorates the DNA in an evenly distributed pattern
Manually annotated by BRENDA team
PDB
SCOP
CATH
ORGANISM
UNIPROT
Escherichia coli (strain K12)
Escherichia coli (strain K12)
Escherichia coli (strain K12)
Escherichia coli (strain K12)
Escherichia coli (strain K12)
Escherichia coli (strain K12)
Escherichia coli (strain K12)
Escherichia coli (strain K12)
Escherichia coli (strain K12)
Thermotoga maritima (strain ATCC 43589 / MSB8 / DSM 3109 / JCM 10099)
MOLECULAR WEIGHT
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
22147
x * 22147, calculated from the deduced amino acid sequence
22307
x * 22307, calculated from the deduced amino acid sequence
22320
x * 22320, calculated from the deduced amino acid sequence
22358
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x * 22358, calculated from the deduced amino acid sequence
22506
x * 22506, calculated from the deduced amino acid sequence
25000
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4 * 25000 at pH 2.5, oligomerization at acidic pH
27600
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Western blotting, Myc-tagged LexA
29300
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recombinant LexA
50000
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gel filtration
100000
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tetramer, pore-limiting Page at pH 2.5
SUBUNITS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
monomer
tetramer
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4 * 25000 at pH 2.5, oligomerization at acidic pH
additional information
POSTTRANSLATIONAL MODIFICATION
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
proteolytic modification
additional information
Crystallization/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
determination of three crystal structures of Escherichia coli LexA in complex with SOS boxes. The DNA-binding domains of the LexA dimer interact with the DNA in the classical fashion of a winged helix-turn-helix motif. The wings of these two DNA binding domains bind to the same minor groove of the DNA. These wing-wing contacts also to fulfill spacer length requirement of its SOS operators
full-length mutant forms show that the LexA linker region, from residues Gln70 to Glu74 is solvent exposed
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mutants G85D, S119A, L89P/Q92W/E152A/K156A, and tryptic fragments of mutants S119A and L89P/Q92W/E152A/K156A
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crystallization of C-terminal domain, space groups P3221 and P31, to 2.9 and 2.75 A resolution, respectively
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pH STABILITY
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
7
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or above, stable
29801
TEMPERATURE STABILITY
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
20
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autoproteolysis of the protein occurs with a half-life of roughly 2 h at pH 9.5
GENERAL STABILITY
ORGANISM
UNIPROT
LITERATURE
At high protein concentrations, at low salt concentrations and at pH values of about 6-7, the protein forms a sticky precipitate that cannot be redissolved, to avoid this, the enzyme is maintained in 200 mM NaCl and the pH is kept at 7 or above
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STORAGE STABILITY
ORGANISM
UNIPROT
LITERATURE
-70°C, stable
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5°C, 10 mM PIPES-NaOH, pH 7.0, 0.1 mM EDTA, 10% v/v glycerol, 200 mM NaCl, stable for long periods
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Purification/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
of the recombinant protein
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of the recombinant protein und its truncated variants by Ni–nitrilotriacetic acid column chromatography
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the amino-terminal DNA binding domain of LexA and full-length LexA
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Cloned/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
cDNAs encoding the LexA DNA-binding domain (residues 1-202; X) and the herpes simplex virus regulatory protein VP16 transactivation domain (residues 413-490; V and Vstop) amplified from pEG202
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expression in Escherichia coli
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LexA repressor is overexpressed using Escherichia coli strain JL652
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overexpression in Escherichia coli
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overexpression in Escherichia coli as wild type, mutants and as truncated proteins
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the amino-terminal DNA binding domain of LexA and full-length LexA ligated into pRSETB vector DNA producing pNLexA which expresses a recombinant 11.4 kDa HIS-LexA polypeptide encoding the N-terminal DNA binding domain. Expression of plasmid constructs in Escherichia coli strains DH5alpha and JM109
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the lexA gene, including its promoter region, cloned into pEJMyc to give pKS04, giving LexA with an in-frame C-terminal Myc tag. Plasmids pKS04, pKS04mut1 (one residue deleted between the possible start codons) and the pEJMyc vector transformed separately into Mycobacterium smegmatis strain mc2155
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transformed into Escherichia coli JL2301
When there is no DNA damage, the LexA repressors ensure that both recA and lexA are expressed at low basal levels. Before and after DNA damage the promoter activity of recA is low, yet it exhibits some fluctuations. These fluctuations are due to the low copy number of LexA, which is an auto-repressor. In case that the DNA damage persists, the negative regulation acting on both recA and lexA is eventually removed, and the promoter activity of both genes increases, genetic regulation mechanism, overview
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wild-type strain ATCC 13032 and mutant strain NJ2114, DNA sequence and genetic structure determination and analysis, and gene expression profiling of the lexA. Detection of 46 potential SOS boxes located upstream of differentially expressed transcription units. Binding of a hexahistidyl-tagged LexA protein to 40 double-stranded oligonucleotides containing the potential SOS boxes. LexA binds not only to SOS boxes in the promoter-operator region of upregulated genes, but also to SOS boxes detected upstream of downregulated genes, overview. Genetic organization of the lexA-divS intergenic region deduced from promoter mapping. LexA expression in Escherichia coli strain BL21(DE3)
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EXPRESSION
ORGANISM
UNIPROT
LITERATURE
exposure to SOS-response inducing stresses, such as UV-B and mitomycin C neither affects the expression of LexA in Anabaena nor induces cleavage of LexA in either Anabaena 7120 or Escherichia coli overexpressing Anabaena LexA protein
LexA is under posttranscriptional control
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ENGINEERING
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
K156A
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site directed mutagenesis
L89P/Q92W/E152A/K156A
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designed to trap protein in conformation required for cleavage. Crystallization data of tryptic fragment containing amino acids 68–202
G94E
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prevents cleavage of the LexA
additional information
APPLICATION
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
drug development
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the LexA repressor plays a key role in the induction of the SOS response and its importance in regulating responses to stress suggests that it may be exploited as a drug target
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