Inhibitor Mimetic Mutations in the Pseudomonas aeruginosa PqsE Enzyme Reveal a Protein-Protein Interaction with the...

Area of Science:

• Microbiology and Infectious Diseases
• Drug Discovery and Development
• Structural Biology

Background:

• Pseudomonas aeruginosa is an opportunistic pathogen causing severe human infections.
• There is a critical need for novel antimicrobial strategies against P. aeruginosa.
• The PqsE protein is a key regulator of P. aeruginosa virulence.

Purpose of the Study:

• To identify molecules that inhibit the PqsE protein.
• To elucidate the mechanism by which PqsE promotes virulence.
• To explore PqsE as a novel drug target for combating P. aeruginosa infections.

Main Methods:

• Screening for small molecules that bind to PqsE.
• Biochemical characterization of PqsE enzymatic activity.
• X-ray crystallography to determine inhibitor-bound structures.
• Site-directed mutagenesis to mimic inhibitor binding and assess PqsE function.

Main Results:

• Two inhibitory molecules, BB391 and BB393, were identified.
• Crystallography revealed inhibitor binding sites on PqsE.
• Mutations mimicking inhibitor binding (E182W, S285W) showed PqsE's virulence role is independent of its enzymatic activity.
• The E182W mutation disrupted the interaction between PqsE and the quorum-sensing receptor RhlR.

Conclusions:

• PqsE's role in promoting P. aeruginosa virulence is mediated by its interaction with RhlR, not its enzymatic activity.
• Disruption of the PqsE-RhlR interaction offers a promising strategy for developing new anti-pseudomonas drugs.
• These findings open a new avenue for antimicrobial drug discovery targeting PqsE.