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The DNA‐binding activity of the Neisseria gonorrhoeae LexA orthologue NG1427 is modulated by oxidation
Author(s) -
Schook Paul O. P.,
Stohl Elizabeth A.,
Criss Alison K.,
Seifert H. Steven
Publication year - 2011
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2010.07491.x
Subject(s) - repressor lexa , regulon , biology , neisseria gonorrhoeae , sos response , repressor , escherichia coli , gene , dna , microbiology and biotechnology , operon , neisseria , biochemistry , genetics , bacteria , gene expression
Summary Neisseria gonorrhoeae is a human‐specific organism that is not usually exposed to UV light or chemicals but is likely to encounter reactive oxygen species during infection. Exposure of N. gonorrhoeae to sublethal hydrogen peroxide revealed that the ng1427 gene was upregulated sixfold. N. gonorrhoeae was thought to lack an SOS system, although NG1427 shows amino acid sequence similarity to the SOS response regulator LexA from Escherichia coli . Similar to LexA and other S24 peptidases, NG1427 undergoes autoproteolysis in vitro , which is facilitated by either the gonococcal or E. coli RecA proteins or high pH, and autoproteolysis requires the active and cleavage site residues conserved between LexA and NG1427. NG1427 controls a three gene regulon: itself; ng1428 , a Neisseria ‐specific, putative integral membrane protein; and recN , a DNA repair gene known to be required for oxidative damage survival. Full NG1427 regulon de‐repression requires RecA following methyl methanesulphonate or mitomycin C treatment, but is largely RecA‐independent following hydrogen peroxide treatment. NG1427 binds specifically to the operator regions of the genes it controls, and DNA binding is abolished by oxidation of the single cysteine residue encoded in NG1427. We propose that NG1427 is inactivated independently of RecA by oxidation.