The active site of O-acetylserine sulfhydrylase is the anchor point for bienzyme complex formation with serine acetyltransferase

Bin Huang, Matthew W. Vetting, Steven L. Roderick

Research output: Contribution to journalArticle

65 Scopus citations


The biosynthesis of cysteine in bacteria and plants is carried out by a two-step pathway, catalyzed by serine acetyltransferase (SAT) and O-acetylserine sulfhydrylase (OASS; O-acetylserine [thiol] lyase). The aerobic form of OASS forms a tight bienzyme complex with SAT in vivo, termed cysteine synthase. We have determined the crystal structure of OASS in complex with a C-terminal peptide of SAT required for bienzyme complex formation. The binding site of the peptide is at the active site of OASS, and its C-terminal carboxyl group occupies the same anion binding pocket as the α-carboxylate of the O-acetylserine substrate of OASS. These results explain the partial inhibition of OASS by SAT on complex formation as well as the competitive dissociation of the complex by O-acetylserine.

Original languageEnglish (US)
Pages (from-to)3201-3205
Number of pages5
JournalJournal of Bacteriology
Issue number9
StatePublished - May 1 2005


ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology

Cite this