Silver binding proteins in S. aureus

ABSTRACT: The rapid emergence of drug resistant Staphylococcus aureus (S. aureus), in particular, methicillin-resistant S. aureus (MRSA) poses a serious threat to public health globally. Reuse of metal-based antimicrobials stands for one of the most promising strategies to resensitize drug resistant bacteria to conventional antibiotics. Silver (Ag) has been used as an antimicrobial agent since antiquity, yet its molecular mechanism of action is elusive largely owing to technical challenges to identify the direct silver-binding protein targets accountable for its action. Herein, using an in-house developed hyphenated technique LC-GE-ICP-MS, we successfully separated and identified 38 authentic Ag+-binding proteins (Ag+-proteome) in S. aureus at the whole-cell scale for the first time. By integration with bioinformatic analysis and systematic biochemical characterizations, we captured the first snapshot on the dynamic action of Ag+ against S. aureus at the molecular level, i.e., Ag+ primarily targets glycolysis via inhibiting multiple enzymes and induces the elevation of ROS through functional disruption of redox homeostasis system at the late stage, leading to an upregulation of oxidative pentose phosphate pathway (oxPPP) to alleviate Ag+ stress. However, the activation of oxPPP is ultimately futile due to key oxPPP enzymes being inhibited by Ag+. We further validated that Ag+ could inhibit 6-phosphogluconate dehydrogenase, a key target from oxPPP through binding to His185 at the active site and morphing the shape of catalytic pocket by X-ray crystallography. Significantly, the multi-target mode of action of silver is accountable for its suppression of antibiotic selection effects towards S. aureus as well as its sustainable antimicrobial activity. Such a unique mode of action of Ag+ (and silver nanoparticles) led to enhanced efficacy of a broad range of antibiotics and resensitization of MRSA to antibiotics. Our study resolves the long-standing question of the molecular targets of silver in S. aureus and offers a novel insight into the sustainable bacterial susceptibility of silver, providing a potential approach for combating antimicrobial resistance.

INSTRUMENT(S): 4800 Proteomics Analyzer

ORGANISM(S): Staphylococcus Aureus

SUBMITTER: Haibo Wang  

LAB HEAD: Prof. Hongzhe Sun

PROVIDER: PXD025106 | Pride | 2021-09-10

REPOSITORIES: Pride