Gram-negative bacteria exhibit higher intrinsic resistance to antimicrobial agents than Gram-positive bacteria, largely attributable to their efficient multidrug efflux pumps. Among these, tripartite pumps spanning the inner membrane, periplasm, and outer membrane are central to both intrinsic and acquired resistance. Periplasmic adaptor proteins (PAPs) serve as the core connectors of these systems. Once regarded merely as passive scaffolds, PAPs are now confirmed to function as dynamic alloster