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Reconstitution of an SOS response pathway: derepression of transcription in response to DNA breaks.

Authors
Type
Published Article
Journal
Cell
Publisher
Elsevier
Volume
95
Issue
7
Pages
975–979
Source
Kowalczykowski Lab
License
Unknown

Abstract

E. coli responds to DNA damage by derepressing the transcription of about 20 genes that make up the SOS pathway. Genetic analyses have shown that SOS induction in response to double-stranded DNA (dsDNA) breaks requires LexA repressor, and the RecA and RecBCD enzymes—proteins best known for their role as initiators of dsDNA break repair and homologous recombination. Here we demonstrate that purified RecA protein, RecBCD enzyme, single-stranded DNA-binding (SSB) protein, and LexA repressor respond to dsDNA breaks in vitro by derepressing transcription from an SOS promoter. Interestingly, derepression is more rapid if the DNA containing the dsDNA break has a chi recombination hot spot (5 -GCTGGTGG-3 ), suggesting a novel regulatory role for one of the most overrepresented octamers in the E. coli genome.

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