On the function of TRAP substrate-binding proteins: Conformational variation of the sialic acid binding protein SiaP.

ABSTRACT: Tripartite ATP-independent periplasmic (TRAP) transporters are analogous to ABC transporters in that they use a substrate-binding protein to scavenge metabolites (e.g., N-acetylneuraminate) and deliver them to the membrane components for import. TRAP substrate-binding proteins are thought to bind the substrate using a two-state (open and closed) induced-fit mechanism. We solved the structure of the TRAP N-acetylneuraminate substrate-binding protein from Aggregatibacter actinomycetemcomitans (AaSiaP) in both the open ligand-free and closed liganded conformations. Surprisingly, we also observed an intermediate conformation, where AaSiaP is mostly closed and is bound to a non-cognate ligand, acetate, which hints at how N-acetylneuraminate binding stabilizes a fully closed state. AaSiaP prefer

SUBMITTER: King-Hudson TJ 

PROVIDER: S-EPMC11550005 | biostudies-literature | 2024 Nov

REPOSITORIES: biostudies-literature