GSE137185
An XRE-superfamily transcriptional regulator XrpA controls low pH tolerance of Serratia marcescens
The acid tolerance of industrial strains is a significant challenge in the fermentation process. The bacterium Serratia marcescens is part of the Enterobacteriaceae family of eubacteria, which is a potential industrial microorganism. However, the molecular mechanism behind S. marcescens acid resistance is not properly understood. In this study, we screened for novel regulators that respond to acidic conditions by a Tn5G transposon insertion mutagenesis of S. marcescens and found mutations in a gene encoding for the HTH_XRE super-family regulatory protein member, here named xrpA. Using transcriptomics and further experiments, we showed that the xrpA disruption conferred pleiotropic phenotype changes, including highly decreased biomass, altered cell shape, H+-ATPase activity, and deficiency of cell membrane permeability and integrity, compared with those of the parent (JNB5-1) strain at low pH. These data revealed that the molecular mechanism by which xrpA affects acid resistance of S. marcescens is through positive regulation of cell membrane permeability, integrity, and H+-ATPase activity to maintain intracellular homeostasis at low pH. Finally, we constructed an acidic resistant strain JNB5-1/pSX1314 by overexpression of xrpA in S. marcescens and found that its ability to produce prodigiosin by fermentation increased by 21.74% compared with that of parent strain at pH4.0. These results indicated that xrpA regulates tolerance to low pH by transcriptional regulation of acid stress response genes to maintain cell membrane function in S. marcescens. Overall design: Global transcription level of S. marcescens parent strain (JNB5-1) and mutant strant (SX1-25)