PqsRMvfR

PqsRMvfR is a transcriptional regulator in the bacterium Pseudomonas aeruginosa. The name combines two well-known aliases for this regulator: PqsR, also called MvfR (Multiple Virulence Factor Regulator). The mvfR gene encodes the protein that governs the Pseudomonas quinolone signal (PQS) quorum sensing system and coordinates expression of virulence-associated genes.

Role and function

PqsRMvfR acts as a transcriptional activator of the pqsABCDE operon and regulates multiple virulence-related genes, including those involved in phenazine production (such as pyocyanin), elastase, rhamnolipids, and biofilm development. It responds to PQS and related quinolone signals, creating a positive feedback loop that ties signal accumulation to increased production of PQS and downstream virulence factors as cell density rises.

Regulatory network

PqsR/MvfR integrates inputs from the PQS circuit and interacts with other quorum sensing systems in P. aeruginosa, notably Las and Rhl. Upon binding ligands such as PQS or HHQ, the regulator binds promoter regions to activate transcription of its target genes, coordinating virulence factor expression with population density.

Structure and localization

The protein is a cytoplasmic transcriptional regulator with a ligand-binding domain that recognizes PQS-family molecules and a DNA-binding domain that modulates transcription of target genes.

Clinical relevance and research

Because of its central role in virulence regulation and quorum sensing, PqsR/MvfR is a target for anti-virulence strategies. Small-molecule inhibitors of PqsR have been explored to reduce virulence, biofilm formation, and antibiotic tolerance in experimental models of P. aeruginosa infection.