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

Martin Pfeiffer, Catrine Johansson, Tobias Krojer, Kathryn L. Kavanagh, Udo Oppermann, Bernd Nidetzky

Research output: Contribution to journalArticleResearchpeer-review

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, Tyr 179 and Glu 157 , promotes a syn 1,4-elimination from an enol (not an enolate) intermediate. We also show that the overall multistep catalytic reaction involves the fewest position changes of enzyme and substrate groups and that it proceeds under conserved exploitation of the basic (minimal) catalytic machinery of short-chain dehydrogenase/reductases.

Original languageEnglish
Pages (from-to)2962-2968
Number of pages7
JournalACS Catalysis
Volume9
Issue number4
DOIs
Publication statusPublished - 5 Apr 2019

    Fingerprint

Keywords

  • carbohydrates
  • enzyme catalysis
  • reaction mechanism
  • short-chain dehydrogenase/reductase
  • sugar dehydratase
  • β-elimination

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)

Cite this