γ Irradiation Alters the Staphylococcus aureus Proteome and Enhances Pathogenicity

Staphylococcus aureus (S. aureus) infection has become one of the most common and severe complications among cancer patients. The impact of γ radiation from radiotherapy on S. aureus’s growth and virulence is not yet fully understood. In this study, S. aureus was exposed to γ radiation at a dose of 100 Gy, and its descendants were cultured under normal conditions. Proteome alternations of unirradiated, irradiated, and descendants of irradiated S. aureus were identified by using data-independent acquisition (DIA) proteomic technology. To investigate the consequences of proteome alternations induced by γ irradiation in S. aureus, functional enrichment analysis, pathway enrichment analysis, and protein–protein interaction network analysis were performed. Differentially expressed proteins (DEPs) in the irradiated S. aureus and its descendants were primarily enriched in lipoteichoic acid biosynthesis, S. aureus infection, two-component system, and cationic antimicrobial peptide resistance, suggesting an enhanced infection ability. A strong infection ability is typically associated with increased biofilm formation. Both the proteome study and the biofilm assay indicate that γ irradiation enhances the infection ability of S. aureus, likely resulting in increased pathogenicity.