The Essential Role of Waters in the Reaction Mechanism of Protein O-Fucosyl Transferase 2
Sanz-Martínez I, García-García A, Tejero T, Hurtado-Guerrero R*, Merino P*. The Essential Role of Waters in the Reaction Mechanism of Protein O-Fucosyl Transferase 2. Angew Chem Int Ed Engl. 2022 Oct 19. doi: 10.1002/anie.202213610. Online ahead of print. PMID: 36260536. *joint corresponding authorship
Protein O -fucosyl transferase 2 (PoFUT2) is an inverting glycosyltransferase (GT) that fucosylates thrombospondin repeats (TSRs) from group 1 and 2. PoFUT2 recognizes a large and diverse number of TSRs through a dynamic network of water-mediated interactions. Here, by X-ray structural studies of C. elegans PoFUT2 complexed to a TSR of group 2, we demonstrate that this GT recognizes similarly both the 3D-structure of TSRs from groups 1 and 2. In addition, its active site is highly exposed to the solvent, suggesting that water molecules might also play an essential role in the fucosylation mechanism. We applied QM/MM methods using the human PoFUT2 as a model, finding that Hs PoFUT2 follows a classical S N 2 reaction mechanism in which waters contribute to a great extent in facilitating the release of the leaving pyrophosphate unit, causing the H- transfer from the acceptor nucleophile (Thr/Ser) to the catalytic base, being this the last event in the reaction. This evidences the importance of water molecules not only in recognition of the ligands but also in catalysis.
Protein O -fucosyl transferase 2 (PoFUT2) is an inverting glycosyltransferase (GT) that fucosylates thrombospondin repeats (TSRs) from group 1 and 2. PoFUT2 recognizes a large and diverse number of TSRs through a dynamic network of water-mediated interactions. Here, by X-ray structural studies of C. elegans PoFUT2 complexed to a TSR of group 2, we demonstrate that this GT recognizes similarly both the 3D-structure of TSRs from groups 1 and 2. In addition, its active site is highly exposed to the solvent, suggesting that water molecules might also play an essential role in the fucosylation mechanism. We applied QM/MM methods using the human PoFUT2 as a model, finding that Hs PoFUT2 follows a classical S N 2 reaction mechanism in which waters contribute to a great extent in facilitating the release of the leaving pyrophosphate unit, causing the H- transfer from the acceptor nucleophile (Thr/Ser) to the catalytic base, being this the last event in the reaction. This evidences the importance of water molecules not only in recognition of the ligands but also in catalysis.