
bioRxiv (Cold Spring Harbor Laboratory), Journal Year: 2025, Volume and Issue: unknown
Published: April 10, 2025
Abstract Multidrug efflux pumps are dynamic molecular machines that drive antibiotic resistance by harnessing ion gradients to export chemically diverse substrates. Despite their clinical importance, the principles underlying multidrug promiscuity and energy efficiency remain poorly understood. Using multiparametric deep mutational scanning across eight substrates two conditions, we deconvolute contributions of substrate recognition, energetic coupling, protein stability, providing an integrated, high-resolution view transport. We find specificity arises from a distributed network residues extending beyond binding site, with mutations reshape binding, conformational flexibility, membrane interactions. Further, apply pH-based selection scheme measure effect mutation on pH-dependent transport efficiency. By integrating these data, reveal fundamental relationship between promiscuity: highly efficient variants exhibit broad profiles, while inefficient narrower. These findings establish direct link coupling polyspecificity, uncovering biochemical logic
Language: Английский