Structural Basis for Native Agonist and Synthetic Inhibitor Recognition by the Pseudomonas aeruginosa Quorum Sensing Regulator PqsR (MvfR)

PLoS Pathogens

Alex Truman¹  Aravindan Ilangovan¹  Christian Pustelny¹  Stephan Heeb¹  Paul Williams¹  Jonas Emsley²  Siri Ram Chhabra³  Kendra Rumbaugh³  Matthew Fletcher³  Miguel Cámara³  Giordano Rampioni⁴ 

[1] Centre for Biomolecular Sciences, University of Nottingham, University Park, Nottingham, United Kingdom;Department of Surgery, University of Texas, Lubbock, Texas, United States of America;School of Molecular Medical Sciences, University of Nottingham, University Park, Nottingham, United Kingdom;School of Pharmacy, University of Nottingham, University Park, Nottingham, United Kingdom

关键词: Pseudomonas aeruginosa;    Crystal structure;    Dimers (Chemical physics);    Bacterial biofilms;    Hydrogen bonding;    Electron density;    Gene expression;    Biosynthesis;   

DOI  :  10.1371/journal.ppat.1003508

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

Bacterial populations co-ordinate gene expression collectively through quorum sensing (QS), a cell-to-cell communication mechanism employing diffusible signal molecules. The LysR-type transcriptional regulator (LTTR) protein PqsR (MvfR) is a key component of alkyl-quinolone (AQ)-dependent QS in Pseudomonas aeruginosa. PqsR is activated by 2-alkyl-4-quinolones including the Pseudomonas quinolone signal (PQS; 2-heptyl-3-hydroxy-4(1H)-quinolone), its precursor 2-heptyl-4-hydroxyquinoline (HHQ) and their C9 congeners, 2-nonyl-3-hydroxy-4(1H)-quinolone (C9-PQS) and 2-nonyl-4-hydroxyquinoline (NHQ). These drive the autoinduction of AQ biosynthesis and the up-regulation of key virulence determinants as a function of bacterial population density. Consequently, PqsR constitutes a potential target for novel antibacterial agents which attenuate infection through the blockade of virulence. Here we present the crystal structures of the PqsR co-inducer binding domain (CBD) and a complex with the native agonist NHQ. We show that the structure of the PqsR CBD has an unusually large ligand-binding pocket in which a native AQ agonist is stabilized entirely by hydrophobic interactions. Through a ligand-based design strategy we synthesized and evaluated a series of 50 AQ and novel quinazolinone (QZN) analogues and measured the impact on AQ biosynthesis, virulence gene expression and biofilm development. The simple exchange of two isosteres (OH for NH2) switches a QZN agonist to an antagonist with a concomitant impact on the induction of bacterial virulence factor production. We also determined the complex crystal structure of a QZN antagonist bound to PqsR revealing a similar orientation in the ligand binding pocket to the native agonist NHQ. This structure represents the first description of an LTTR-antagonist complex. Overall these studies present novel insights into LTTR ligand binding and ligand-based drug design and provide a chemical scaffold for further anti-P. aeruginosa virulence drug development by targeting the AQ receptor PqsR.

【 授权许可】

CC BY