A novel variant of the catalytic triad in the Streptomyces scabies esterase

Nat Struct Biol. 1995 Mar;2(3):218-23. doi: 10.1038/nsb0395-218.


The crystal structure of a novel esterase from Streptomyces scabies, a causal agent of the potato scab disease, was solved at 2.1 A resolution. The tertiary fold of the enzyme is substantially different from that of the alpha/beta hydrolase family and unique among all known hydrolases. The active site contains a dyad of Ser 14 and His 283, closely resembling two of the three components of typical Ser-His-Asp(Glu) triads from other serine hydrolases. Proper orientation of the active site imidazol is maintained by a hydrogen bond between the N delta-H group and a main chain oxygen. Thus, the enzyme constitutes the first known natural variation of the chymotrypsin-like triad in which a carboxylic acid is replaced by a neutral hydrogen-bond acceptor.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Antibodies, Catalytic / chemistry
  • Binding Sites
  • Esterases / chemistry*
  • Esterases / genetics
  • Esterases / immunology
  • Genetic Variation
  • Hydrogen Bonding
  • Models, Molecular
  • Molecular Sequence Data
  • Protein Structure, Tertiary
  • Streptomyces / enzymology*
  • Streptomyces / genetics
  • Streptomyces / immunology
  • Water / chemistry


  • Antibodies, Catalytic
  • Water
  • Esterases