Computational analysis of LexA regulons in Proteus species

To gain a general understanding of the SOS system in Proteus species, in this study LexA-binding sites and the LexA regulons in 23 Proteus genomes were first predicted by phylogenetic footprinting server, then with Proteus vulgaris as an example, the expression of LexA regulon in iron limitation was investigated by proteomic analysis and quantitative reverse transcription polymerase chain reaction (RT-qPCR) method. The results showed that LexA proteins were highly conserved in Proteus species, and were in a close phylogenetic relationship with those in Gram-negative bacteria; the core SOS response genes lexA and recA were found in all the 23 genomes, indicating that this system was widely distributed in this genus; besides that, putative LexA-binding sites were also found in the upstream sequences of some genes involved in other biological processes such as biosynthesis, drug resistance, and stress response. Proteomic and RT-qPCR analyses showed that under iron deficient condition, the expression of lexA , recA and sulA was transcriptionally upregulated ( p