Molecular Mechanisms of Master Regulator VqsM mediating Quorum-sensing and Antibiotic Resistance in Pseudomonas aeruginosa

The Pseudomonas aeruginosa quorum-sensing (QS) systems contribute to bacterial homeostasis and pathogenicity. Although the AraC family transcription factor VqsM has been characterized to control the production of virulence factors and QS signaling molecules, its detailed regulatory mechanisms still remain elusive. Here, we report that VqsM directly binds to the lasI promoter region, and thus regulates its expression. To identify additional targets of VqsM in P. aeruginosa PAO1, we performed chromatin immunoprecipitation followed by high-throughput DNA sequencing (ChIP-seq) which detected 48 enriched loci harboring VqsM-binding peaks in P. aeruginosa genome. The direct regulation of these genes by VqsM has been confirmed by Electrophoretic mobility shift assays (EMSAs) and quantitative real-time polymerase chain reactions (qRT-PCR). A VqsM-binding motif is found by using MEME suite and verified by footprint assays in vitro. In addition, VqsM directly binds to the promoter regions of antibiotic resistance regulator NfxB and the master type III system regulator ExsA. Notably, the vqsM mutant displayed more resistance to two types of antibiotics and promoted bacterial survival in a mouse model, compared to the wild type PAO1 strain. Collectively, this work provides new cues to better understand the detailed regulatory networks of QS systems, T3SS, and antibiotic resistance. Overall design: Pseudomonas aeruginosa MAPO1 containing empty pAK1900 or pAK1900-VqsM-VSV