Skip to main content
. Author manuscript; available in PMC: 2010 Apr 19.
Published in final edited form as: Nat Genet. 2007 May 27;39(6):797–802. doi: 10.1038/ng2051

Figure 3.

Figure 3

Induction of the LexA regulon of the SOS response is required for survival of cells (as determined by colony formation) with induced DSBs. (a) Irreparable DSBs. (b) Reparable DSBs. Note the much greater survival with homologous DNA present for repair (b). The fraction of cells surviving I-SceI induction in the presence of a single chromosomal I-SceI site is reduced in cells unable to induce expression of SOS genes, carrying the lexA3(Ind−) allele, and in cells lacking RecA and RecB proteins required for DSB repair (in addition to their roles in SOS induction). When irreparable DSBs are induced with I-SceI (a), constitutive high expression of LexA and SOS genes in lexA(Def) repressor-null mutant cells also improves survival (to 13% ± 1%) relative to wild-type (4% ± 0.4%). Data represent mean ± s.e.m. from four or five experiments. Stars indicate statistical significance calculated as in Figure 1 but versus wild-type cells only. In addition, the surviving fraction of wild-type cells with both I-SceI and cut site differs significantly from the surviving fraction of I-SceI-only cells and the surviving fraction of cut site–only cells, in both a and b. CFU, colony-forming units.