Phage-Encoded Virulence Factor, Gp05, Alters Membrane Phospholipids and Reduces Antimicrobial Susceptibility in Methicillin-Resistant Staphylococcus aureus

Yi Li; Nagendra N Mishra; Liang Chen; Adhar C Manna; Ambrose L Cheung; Richard A Proctor; Yan Q Xiong

doi:10.1093/infdis/jiae640

Phage-Encoded Virulence Factor, Gp05, Alters Membrane Phospholipids and Reduces Antimicrobial Susceptibility in Methicillin-Resistant Staphylococcus aureus

J Infect Dis. 2024 Dec 31:jiae640. doi: 10.1093/infdis/jiae640. Online ahead of print.

Authors

Yi Li¹, Nagendra N Mishra^{1

2}, Liang Chen³, Adhar C Manna⁴, Ambrose L Cheung⁴, Richard A Proctor⁵, Yan Q Xiong^{1

2}

Affiliations

¹ The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, CA, USA.
² David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
³ School of Pharmacy and Pharmaceutical Sciences, University at Buffalo, Buffalo, NY, USA.
⁴ Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, NH, USA.
⁵ University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA.

PMID: 39739874
DOI: 10.1093/infdis/jiae640

Abstract

Background: Methicillin-resistant Staphylococcus aureus (MRSA) is a leading pathogen causing severe endovascular infections. The prophage-encoded protein Gp05 has been identified as a critical virulence factor that contributes to MRSA persistence during vancomycin (VAN) treatment in an experimental endocarditis model. However, the underlining mechanisms driving this persistence phenotype remain poorly understood.

Methods: The current study aimed to elucidate the genetic factors contributing to Gp05-associated MRSA persistence by utilizing RNA sequencing (RNA-seq) on an isogenic MRSA strain set, including a clinical persistent bacteremia isolate (PB 300-169), its isogenic chromosomal gp05 deletion mutant, and gp05-complemented strains.

Results: RNA-seq analysis revealed significantly downregulation of the graSR-vraFG regulatory system and its downstream genes, mprF and dltABCD, in the gp05 deletion mutant compared to the wild-type and gp05-complemented strains. Notably, this downregulation led to a substantial shift in cell membrane composition, with a marked increase in negatively charged phosphatidylglycerol (PG) and a concomitant decrease in positively charged lysyl-PG (LPG). These changes in membrane lipid composition resulted in increased susceptibility of the gp05 deletion mutant to human cationic antimicrobial peptide (CAMP) LL-37, polymorphonuclear neutrophil (PMN) and VAN. Similar findings were observed in an isogenic gp05 overexpression strain set with different genetic background (MRSA USA300 JE2).

Conclusions: These findings suggest that Gp05 plays a pivotal role in MRSA persistence by modulating cell surface components and surface charge. This study provides new insights into the molecular mechanisms underlying Gp05-mediated persistence in MRSA endovascular infections and highlights potential therapeutic targets to combat persistent MRSA infections.

Keywords: MRSA; phage-encoded virulence factor; phospholipids; surface charge; two-component regulatory systems; vancomycin persistence.

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