Function and regulation of the cyanobacterial genes lexA, recA and ruvB: LexA is critical to the survival of cells facing inorganic carbon starvation.

摘要: Summary The cyanobacterial genes lexA , recA and ruvB were analysed in Synechocystis PCC6803, which is shown here to be more radiation resistant than the other unicellular model strain Synechococcus PCC7942. We found that cyanobacteria do not have an Escherichia coli -type SOS regulon. promoters strong UV insen- sitive, unlike promoter, weak UV-C inducible. Yet, are regulated by UV-C, but control negative occurs at post-transcriptional level. Two novel conserved ele- ments characterized promoter: (i) unusually long crucial box 5 ¢¢ -TAAAATTTTGTATCTTTT- 3 ( - 64, 47); (ii) a negatively acting motif -TAT GAT-3 42, 37). These elements appeared simple harbouring only single element (i.e. canonical 10 box). RuvB, operating recombi- nation-dependent cellular processes, was dispensable cell growth, whereas LexA RecA critical viability. Using DNA microarrays, we identified 57 with expres- sion altered, least twofold, response depletion. None of these predicted operate metabolism, arguing against involvement regulation repair. Instead, most LexA-responsive known involved carbon assimilation or con- trolled availability. Consistently, growth LexA-depleted strongly dependent on availability inorganic carbon.