Structure-dependent cellular mechanisms of PFAS regulating antibiotic resistance genes conjugation through membrane...

Per- and polyfluoroalkyl substances (PFAS) widely coexist with antibiotic resistance genes (ARGs) in aquatic systems, posing ecological risks. However, how environmentally relevant concentrations and structural differences of PFAS regulate ARGs dissemination remains unclear, limiting structure-informed management of PFAS substitutes. Here, conjugation assays, transcriptomics, molecular dynamics simulations, and molecular docking were integrated to systematically investigate the structure-dependent effects of four representative PFAS (PFOA, PFBA, PFOS, and PFBS) on RP4 plasmid conjunction. At 0.01-10 μg·L^-1, short-chain PFAS significantly enhanced RP4 plasmid conjunction, with PFBS showing the strongest promotion (up to 5.8-fold), followed by PFBA（3.8-fold）, whereas long-chain PFAS showed minor effects (PFOA, 1.4-fold; PFOS, 1.1-fold). Notably, PFBS exhibited relatively weak yet dynamic interactions with membrane proteins, facilitating porin accessibility and intracellular transport. Mechanistic analyses revealed that PFAS, especially PFBS, promote ARGs conjunction through coordinated modulation of membrane properties and cellular energy metabolism at environmentally relevant concentrations. Integrated molecular simulations and transcriptomic analyses suggested a structure-dependent mechanism, highlighting the overlooked risk of short-chain sulfonate PFBS. Overall, these findings demonstrated that PFAS-induced ARGs transfer was strongly structure-dependent and identify PFBS as a higher-risk short-chain substitute, with implications for targeted environmental regulation.