Structural studies of the beta-glycosidase from Sulfolobus solfataricus in complex with covalently and noncovalently bound inhibitors

T M Gloster, S Roberts, V M A Ducros, G Perugino, M Rossi, R Hoos, M Moracci, A Vasella, G J Davies

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61 Citations (Scopus)

Abstract

Transition-state mimicry is increasingly important both to understand enzyme mechanism and to direct the synthesis of putative therapeutic agents. X-ray crystallography is able to provide vital information on the interactions between an enzyme and the potential inhibitor. Here we report the structures, at approximately 2 Angstrom resolution, of a family GH1 beta-glycosidase from the hyperthermophilic archaeon Sulfolobus solfataricus, in complex with both covalently (derived from 2-fluoro-glycosides) and noncovalently (hydroximolactam) bound inhibitors. The enzyme has broad specificity, accommodating both gluco- and galacto-configured substrates, and the crystallographic data demonstrate that the only difference in the way these ligands bind lies in the interactions between Gln18, Glu432, and Trp433, and the hydroxyl group at the O3 and O4 positions. Inhibition by the differently configured ligands was also shown to be extremely similar, with K-i values of 1.04 and 1.08 muM for the gluco and galacto epimers, respectively. The noncovalently bound inhibitors have a trigonal anomeric carbon, adopt a H-4(3) (halfchair) conformation, and an interaction is formed between O2 and the catalytic nucleophile, all of which contribute to (partial) mimicry of the oxocarbenium-ion-like transition state. The inhibition of the beta-glycosidase from S. solfataricus by hydroximolactams is discussed in light of the emerging work on family GH1 glycosidase inhibition by a spectrum of putative transition-state mimics.

Original languageEnglish
Pages (from-to)6101-6109
Number of pages9
JournalBiochemistry
Volume43
Issue number20
DOIs
Publication statusPublished - 25 May 2004

Keywords

  • GLYCOSYL-ENZYME INTERMEDIATE
  • X-RAY CRYSTALLOGRAPHY
  • ACTIVE-SITE MUTANTS
  • CRYSTAL-STRUCTURE
  • TRANSITION-STATE
  • GLUCOSIDASE
  • FAMILY
  • HYDROLASES
  • MECHANISM
  • CATALYSIS

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