A Parsimonious Mechanism of Sugar Dehydration by Human GDP-Mannose-4,6-dehydratase.

ABSTRACT: Biosynthesis of 6-deoxy sugars, including l-fucose, involves a mechanistically complex, enzymatic 4,6-dehydration of hexose nucleotide precursors as the first committed step. Here, we determined pre- and postcatalytic complex structures of the human GDP-mannose 4,6-dehydratase at atomic resolution. These structures together with results of molecular dynamics simulation and biochemical characterization of wildtype and mutant enzymes reveal elusive mechanistic details of water elimination from GDP-mannose C5″ and C6″, coupled to NADP-mediated hydride transfer from C4″ to C6″. We show that concerted acid-base catalysis from only two active-site groups, Tyr₁₇₉ and Glu₁₅₇, promotes a syn 1,4-elimination from an enol (not an enolate) intermediate. We also show that t

SUBMITTER: Pfeiffer M 

PROVIDER: S-EPMC6454399 | biostudies-literature | 2019 Apr

REPOSITORIES: biostudies-literature