Mechanistic snapshots of lipid-linked sugar transfer #MMPMID41353435
Morgan RT; Motta S; Gil-Iturbe E; Bhattacharjee B; Anwar MT; Di Muccio G; Romagnoli A; Mishra B; Ashraf KU; Bang I; Di Marino D; Lowary TL; Quick M; Petrou VI; Stowell MHB; Nygaard R; Mancia F
Nat Commun 2025[Dec]; ? (?): ? PMID41353435show ga
Enzymes undergo dynamic conformational changes during catalysis, yet conventional high-resolution structural methods typically capture only the most stable states. Here, we address this gap using rapid UV photolysis of a chemically caged substrate with cryogenic time-resolved electron microscopy (cryo-TREM). We elucidate the catalytic mechanism of GtrB, a membrane-bound glycosyltransferase that transfers glucose from UDP-glucose to the lipid carrier undecaprenyl phosphate. We visualized how GtrB, which has an active site ~15 A from the membrane, transitions during the catalytic cycle to move each substrate in proximity for catalysis. From a single dataset, we resolved distinct conformational states: the initial substrate-bound state, a catalytically poised intermediate, and the product-bound state. Through molecular dynamics simulations and biochemical analyses, we identify coordinated movements within the active site that drive catalysis. These findings provide a molecular framework for understanding how glycosyltransferases function and highlight a broadly applicable strategy for capturing dynamic enzymatic states in native-like environments.
Nat+Commun 2025 ; ? (?): ?
