Evidence for a Boat Conformation at the Transition State of GH76 α-1,6-Mannanases-Key Enzymes in Bacterial and Fungal Mannoprotein Metabolism

DOI: 10.1002/ange.201410502

Authors: Andrew J. Thompson (University of York) , Gaetano Speciale (University of Melbourne) , Javier Iglesias-fernández (University of Melbourne) , Zalihe Hakki (University of York; University of Melbourne) , Tyson Belz (University of Melbourne) , Alan Cartmell (University of Melbourne) , Richard J. Spears (University of York) , Emily Chandler (University of York) , Max J. Temple (Newcastle University) , Judith Stepper (University of York) , Harry J. Gilbert (Newcastle University) , Carme Rovira (Universitat de Barcelona) , Spencer J. Williams (University of Melbourne) , Gideon J. Davies (University of York)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Angewandte Chemie , VOL 127 (18) , PAGES 5468 - 5472

State: Published (Approved)
Published: April 2015

Abstract: α-Mannosidases and α-mannanases have attracted attention for the insight they provide into nucleophilic substitution at the hindered anomeric center of α-mannosides, and the potential of mannosidase inhibitors as cellular probes and therapeutic agents. We report the conformational itinerary of the family GH76 α-mannanases studied through structural analysis of the Michaelis complex and synthesis and evaluation of novel aza/imino sugar inhibitors. A Michaelis complex in an OS2 conformation, coupled with distortion of an azasugar in an inhibitor complex to a high energy B2,5 conformation are rationalized through ab initio QM/MM metadynamics that show how the enzyme surface restricts the conformational landscape of the substrate, rendering the B2,5 conformation the most energetically stable on-enzyme. We conclude that GH76 enzymes perform catalysis using an itinerary that passes through OS2 and B2,5≠ conformations, information that should inspire the development of new antifungal agents.

Journal Keywords: Computerchemie;Enzymatische Mechanismen;Glycosidaseinhibitoren;Kohlenhydrate;Konformationsanalyse

Subject Areas: Chemistry


Instruments: I03-Macromolecular Crystallography , I04-1-Macromolecular Crystallography (fixed wavelength) , I04-Macromolecular Crystallography