Quorum sensing regulator LsrR modulates resistance to oxidative stress by interfering with sulfate assimilation in avian pathogenic Escherichia coli

Prokaryotes and eukaryotes endogenously generate the gaseous molecule hydrogen sulfide (H2S), which has been identified as a novel signaling molecule. Bacterial H2S plays a protective role against reactive oxygen species (ROS) and antibiotic-induced cellular damage. Endogenous H2S can be produced by the assimilation pathway of sulfate and thiosulfate in Escherichia coli. The transcription regulator LsrR influences various bacterial characteristics. The results of the present study revealed that avian pathogenic E. coli (APEC) lacking LsrR exhibited increased H2S production and enhanced tolerance to oxidative stress. Transcriptome sequencing revealed the upregulation of genes related to the sulfate assimilation pathway after the deletion of lsrR. Further investigation demonstrated that LsrR, acts as a transcriptional repressor, binds directly to the promoter region of cysPUWAM and interacts with both CysJ and CysN, thereby inhibiting exogenous sulfate assimilation and decreasing the oxidative stress resistance of APEC. Additionally, the absence of lsrR facilitated the survival of APEC94 in macrophage RAW264.7 cells. Our findings suggest that LsrR represses resistance to oxidative stress in APEC by interfering with the sulfate assimilation pathway and provide valuable insights into host-pathogen interactions. Overall design: RNA-seg profiling of wild type APEC94 cells and lsrR deletion mutant(APEC94?lsrR) at the stable mid-exponential (mid-log) phase.