Balanced cell division is secured by two different regulatory sites in OxyS RNA

By interfering with cell division, the Escherichia coli oxidative stress-induced OxyS small RNA brings about cell cycle arrest thus allowing DNA damage repair. Cell division and cell elongation are opposing functions to the extent that inhibition of cell division requires a parallel inhibition of cell elongation for the cells to survive. In this study, we report that in addition to cell division OxyS inhibits mepS encoding an essential peptidoglycan endopeptidase responsible for cell elongation. Furthermore, a phylogenetic evolutionary target conservation analysis of OxyS homologs to identify OxyS most common function revealed that the majority of OxyS targets belong to the category of "cell cycle" followed by "peptidoglycan metabolism", especially cell elongation. mepS is the most frequent target of this category, predicted to be regulated by OxyS in 64 % of the 146 organisms studied. We suggest that cell cycle arrest and balancing between cell division and cell elongation are important and conserved functions of the oxidative stress induced sRNA OxyS.