Identification of Small Molecules Blocking the Pseudomonas aeruginosa type III Secretion System Protein PcrV.

Charlotta Sundin,Sara Spjut,Liena Qin,Mikael Elofsson,Michael Saleeb

doi:10.3390/biom11010055

Abstract

Pseudomonas aeruginosa is an opportunistic bacterial pathogen that employs its type III secretion system (T3SS) during the acute phase of infection to translocate cytotoxins into the host cell cytoplasm to evade the immune system. The PcrV protein is located at the tip of the T3SS, facilitates the integration of pore-forming proteins into the eukaryotic cell membrane, and is required for translocation of cytotoxins into the host cell. In this study, we used surface plasmon resonance screening to identify small molecule binders of PcrV. A follow-up structure-activity relationship analysis resulted in PcrV binders that protect macrophages in a P. aeruginosa cell-based infection assay. Treatment of P. aeruginosa infections is challenging due to acquired, intrinsic, and adaptive resistance in addition to a broad arsenal of virulence systems such as the T3SS. Virulence blocking molecules targeting PcrV constitute valuable starting points for development of next generation antibacterials to treat infections caused by P. aeruginosa.

Highlights

Infectious diseases continue to constitute a threat to public health and a serious cause of morbidity and mortality worldwide
We describe surface plasmon resonance (SPR) screening of a library of 7600 diverse small molecules to identify nontoxic PcrV binders with efficacy in a cell-based P. aeruginosa infection model at μM concentrations that can potentially be used as starting points for the development of a virulence blocking molecule
Overnight culture of the P. aeruginosa strain PAK was diluted in LB (Luria Broth) to an

Summary

Introduction

Infectious diseases continue to constitute a threat to public health and a serious cause of morbidity and mortality worldwide. P. aeruginosa is a “superbug” with a unique capacity to develop resistance [3] This is due to a combination of acquired, intrinsic, and adaptive resistance. Adaptive resistance is the result of triggering factors such as antibiotics, biocides, polyamines, pH, anaerobiosis, cations, and carbon sources as well as social behavior in biofilm formation. These factors modulate the expression of genes that lead to increased resistance. Infections caused by antibiotic-resistant P. aeruginosa are associated with increased rates of morbidity and mortality, in critically ill and immunocompromised individuals such as cystic fibrosis and cancer patients [2].

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