Indexed on: 25 May '21Published on: 25 May '21Published in: Journal of microbiology and biotechnology
SOS response is a conserved response to DNA damage in prokaryotes and negatively regulated by LexA protein which recognizes speciﬁcally a "SOS-box" motif present in the promoter region of SOS genes. DK1622 possess a gene, and the deletion had no significant effect on bacterial morphology, UV-C resistance, and sporulation, but delayed growth. UV-C radiation resulted in 651 up-regulated genes in , including the typical SOS genes , , , and so on, mostly enriched in the pathways of DNA replication and repair, secondary metabolism and signal transduction. The UV-irradiated mutant also showed the induced expression of SOS genes and these SOS genes enriched into a similar pathway profile to that of wild type strain. Without irradiation treatment, the absence of LexA enhanced the expression of 122 genes that were not enriched in any pathway. Further analysis of promoter sequence revealed that in the 122 genes, only the promoters of , and an operon composed of three genes (, and ) had SOS box sequence to which the LexA protein is bound directly. These results provide an update on our current understanding of SOS response in that UV induces more genes involved in secondary metabolism and signal transduction in addition to DNA replication and repair; and the canonical LexA-dependent regulation on SOS response has shrunk, only 5 SOS genes are directly repressed by LexA.