Acetylation of MsrA at K117 and K153 Regulates Florfenicol Resistance in Vibrio alginolyticus

Vibrio alginolyticus is an important pathogen affecting both aquatic animals and humans, causing substantial economic losses. The rising incidence of antibiotic-resistant V. alginolyticus poses significant challenges for clinical treatment. Although lysine acetylation has gained increasing attention as a regulatory mechanism in bacteria, its role in antibiotic resistance in V. alginolyticus remains unclear. Here, we demonstrate that protein acetylation is dynamically regulated in V. alginolyticus, with global acetylation levels elevated upon acquisition of florfenicol resistance. Acetylproteomic analysis revealed that differentially acetylated proteins were primarily enriched in key pathways such as the two-component system and biofilm formation. Notably, methionine sulfoxide reductase A (MsrA) showed significantly elevated acetylation in resistant strains. We further established that acetylation at K117 and K153 enhances MsrA enzymatic activity by inducing localized conformational changes, thereby strengthening antioxidant capacity and promoting florfenicol resistance. Moreover, acetylation at K117 suppressed adenosine monophosphate (AMP) synthesis, while exogenous AMP supplementation reduced K117 acetylation and enhanced the bactericidal activity of florfenicol on V. alginolyticus. Our study reveals that MsrA acetylation critically regulates antibiotic resistance and identifies AMP as a potential adjuvant to potentiate florfenicol, providing both mechanistic insights and a translational strategy for combating resistant bacterial infections.