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Suppression of constitutive SOS expression by recA4162 (I298V) and recA4164 (L126V) requires UvrD and RecX in Escherichia coli K‐12
Author(s) -
Long Jarukit E.,
Renzette Nicholas,
Sandler Steven J.
Publication year - 2009
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.1365-2958.2009.06765.x
Subject(s) - repressor lexa , sos response , biology , escherichia coli , mutant , dna repair , repressor , dna damage , genetics , dna , microbiology and biotechnology , protein filament , suppressor , phenotype , gene , gene expression
Summary Sensing DNA damage and initiation of genetic responses to repair DNA damage are critical to cell survival. In Escherichia coli , RecA polymerizes on ssDNA produced by DNA damage creating a RecA–DNA filament that interacts with the LexA repressor inducing the SOS response. RecA filament stability is negatively modulated by RecX and UvrD. recA730 (E38K) and recA4142 (F217Y) constitutively express the SOS response. recA4162 (I298V) and recA4164 (L126V) are intragenic suppressors of the constitutive SOS phenotype of recA730 . Herein, it is shown that these suppressors are not allele specific and can suppress SOS C expression of recA730 and recA4142 in cis and in trans . recA4162 and recA4164 single mutants (and the recA730 and recA4142 derivatives) are Rec + , UV R and are able to induce the SOS response after UV treatment like wild‐type. UvrD and RecX are required for the suppression in two ( recA730,4164 and recA4142,4162 ) of the four double mutants tested. To explain the data, one model suggests that recA C alleles promote SOS C expression by mimicking RecA filament structures that induce SOS and the suppressor alleles mimic RecA filament at end of SOS. UvrD and RecX are attracted to these latter structures to help dismantle or destabilize the RecA filament.