Biochemical characterization and homology modeling of a purine-specific ribonucleoside hydrolase from the archaeon Sulfolobus solfataricus: insights into mechanisms of protein stabilization

Arch Biochem Biophys. 2009 Mar 1;483(1):55-65. doi: 10.1016/j.abb.2008.12.005. Epub 2008 Dec 24.

Abstract

We report the biochemical and structural characterization of the purine-specific ribonucleoside hydrolase from the archaeon Sulfolobus solfataricus (SsIAG-NH). SsIAG-NH is a homodimer of 70kDa specific for adenosine, guanosine and inosine. SsIAG-NH is highly thermophilic and is characterized by extreme thermodynamic stability (T(m), 107 degrees C), kinetic stability and remarkable resistance to guanidinium chloride-induced unfolding. A disulfide bond that, on the basis of SDS-PAGE is positioned intersubunits, plays an important role in thermal stability. SsIAG-NH shares 43% sequence identity with the homologous pyrimidine-specific nucleoside hydrolase from S. solfataricus (SsCU-NH). The comparative sequence alignment of SsIAG-NH, SsCU-NH, purine non-specific nucleoside hydrolase from Crithidia fasciculata and purine-specific nucleoside hydrolase from Trypanosoma vivax shows that, only few changes in the base pocket are responsible for different substrate specificity of two S. solfataricus enzymes. The structure of SsIAG-NH predicted by homology modeling allows us to infer the role of specific residues in substrate specificity and thermostability.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Catalytic Domain
  • Cloning, Molecular
  • DNA Primers / genetics
  • Enzyme Stability
  • Genes, Archaeal
  • Kinetics
  • Models, Molecular
  • Molecular Sequence Data
  • N-Glycosyl Hydrolases / chemistry*
  • N-Glycosyl Hydrolases / genetics
  • N-Glycosyl Hydrolases / metabolism*
  • Purine Nucleosides / metabolism
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Sequence Homology, Amino Acid
  • Substrate Specificity
  • Sulfolobus solfataricus / enzymology*
  • Sulfolobus solfataricus / genetics
  • Thermodynamics

Substances

  • DNA Primers
  • Purine Nucleosides
  • Recombinant Proteins
  • N-Glycosyl Hydrolases