Characterization of a novel thermostable O-acetylserine sulfhydrylase from Aeropyrum pernix K1

J Bacteriol. 2003 Apr;185(7):2277-84. doi: 10.1128/JB.185.7.2277-2284.2003.

Abstract

An O-acetylserine sulfhydrylase (OASS) from the hyperthermophilic archaeon Aeropyrum pernix K1, which shares the pyridoxal 5'-phosphate binding motif with both OASS and cystathionine beta-synthase (CBS), was cloned and expressed by using Escherichia coli Rosetta(DE3). The purified protein was a dimer and contained pyridoxal 5'-phosphate. It was shown to be an enzyme with CBS activity as well as OASS activity in vitro. The enzyme retained 90% of its activity after a 6-h incubation at 100 degrees C. In the O-acetyl-L-serine sulfhydrylation reaction, it had a pH optimum of 6.7, apparent K(m) values for O-acetyl-L-serine and sulfide of 28 and below 0.2 mM, respectively, and a rate constant of 202 s(-1). In the L-cystathionine synthetic reaction, it showed a broad pH optimum in the range of 8.1 to 8.8, apparent K(m) values for L-serine and L-homocysteine of 8 and 0.51 mM, respectively, and a rate constant of 0.7 s(-1). A. pernix OASS has a high activity in the L-cysteine desulfurization reaction, which produces sulfide and S-(2,3-hydroxy-4-thiobutyl)-L-cysteine from L-cysteine and dithiothreitol.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Archaeal Proteins / chemistry*
  • Archaeal Proteins / genetics
  • Archaeal Proteins / metabolism*
  • Binding Sites
  • Cystathionine / chemistry
  • Cystathionine / metabolism
  • Cysteine / analogs & derivatives
  • Cysteine / biosynthesis
  • Cysteine / chemistry
  • Cysteine / metabolism
  • Cysteine Synthase / chemistry*
  • Cysteine Synthase / genetics
  • Cysteine Synthase / metabolism*
  • Desulfurococcaceae / enzymology*
  • Desulfurococcaceae / genetics
  • Dithiothreitol / chemistry
  • Dithiothreitol / metabolism
  • Enzyme Activation / physiology
  • Enzyme Stability / physiology
  • Homocysteine / chemistry
  • Homocysteine / metabolism
  • Hydrogen-Ion Concentration
  • Kinetics
  • Molecular Sequence Data
  • Sequence Homology, Amino Acid
  • Serine / analogs & derivatives*
  • Serine / chemistry
  • Serine / metabolism
  • Substrate Specificity
  • Sulfides / chemistry
  • Temperature

Substances

  • Archaeal Proteins
  • S-(2,3-dihydroxy-4-thiobutyl)cysteine
  • Sulfides
  • Homocysteine
  • Cystathionine
  • Serine
  • Cysteine Synthase
  • O-acetylserine
  • Cysteine
  • Dithiothreitol