title: Substrate-guided front-face reaction revealed by combined structural snapshots and metadynamics for the polypeptide N-acetylgalactosaminyltransferase 2.
abstract: The retaining glycosyltransferase GalNAc-T2 is a member of a large family of human polypeptide GalNAc-transferases that is responsible for the post-translational modification of many cell-surface proteins. By the use of combined structural and computational approaches, we provide the first set of structural snapshots of the enzyme during the catalytic cycle and combine these with quantum-mechanics/molecular-mechanics (QM/MM) metadynamics to unravel the catalytic mechanism of this retaining enzyme at the atomic-electronic level of detail. Our study provides a detailed structural rationale for an ordered bi-bi kinetic mechanism and reveals critical aspects of substrate recognition, which dictate the specificity for acceptor Thr versus Ser residues and enforce a front-face SN i-type reaction in which the substrate N-acetyl sugar substituent coordinates efficient glycosyl transfer.
authors: Institute of Biocomputation and Physics of Complex Systems (BIFI), University of Zaragoza, BIFI-IQFR (CSIC) Joint Unit, Mariano Esquillor s/n, Campus Rio Ebro, Edificio I+D, Fundacion ARAID, Edificio Pignatelli 36 (Spain).
authors: Erandi
authors: E
authors: Lira-Navarrete
authors: Javier
authors: J
authors: Iglesias-Fernández
authors: Wesley F
authors: WF
authors: Zandberg
authors: Ismael
authors: I
authors: Compañón
authors: Yun
authors: Y
authors: Kong
authors: Francisco
authors: F
authors: Corzana
authors: B Mario
authors: BM
authors: Pinto
authors: Henrik
authors: H
authors: Clausen
authors: Jesús M
authors: JM
authors: Peregrina
authors: David J
authors: DJ
authors: Vocadlo
authors: Carme
authors: C
authors: Rovira
authors: Ramon
authors: R
authors: Hurtado-Guerrero
mesh_terms: D017350:N-Acetylgalactosaminyltransferases / Q000737:chemistry*; D011487:Protein Conformation; D013379:Substrate Specificity; D000097763:Polypeptide N-acetylgalactosaminyltransferase
chemical_list: D017350:N-Acetylgalactosaminyltransferases; D000097763:Polypeptide N-acetylgalactosaminyltransferase
keywords: SNi-type reactions; X-ray diffraction; acetamido groups; proteins; quantum mechanics/molecular mechanics