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

Abstract

The hydrogen peroxide-induced small RNA OxyS has been proposed to originate from the 3’ UTR of a peroxide mRNA. Unexpectedly, phylogenetic OxyS targetome predictions indicate that most OxyS targets belong to the category of “cell cycle” including cell division and cell elongation. Previously, we reported that E. coli OxyS inhibits cell division by repressing expression of the essential transcription termination factor nusG, thereby leading to expression of KilR protein which interferes with the function of the major cell division protein FtsZ. By interfering with cell division OxyS 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. Our study indicates that cell cycle arrest and balancing between cell division and cell elongation are important and conserved functions of the oxidative stress-induced sRNA OxyS.