Cysteine synthesis in plants: protein-protein interactions of serine acetyltransferase from Arabidopsis thaliana

Plant J. 1997 Feb;11(2):251-62. doi: 10.1046/j.1365-313x.1997.11020251.x.


The biosynthesis of cysteine represents the final step of sulfate assimilation in bacteria and plants. It is catalyzed by the sequential action of serine acetyltransferase (SAT) and O-acetylserine (thiol) lyase (OAS-TL) which form a cysteine synthase (CS) complex in vitro. SAT and OAS-TL from Arabidopsis thaliana have previously been cloned, and now the first evidence is presented for the CS complex and SAT self-interaction in vivo employing the yeast two-hybrid system. Application of this method proved to be an efficient tool for the analysis of protein-protein interactions within a plant metabolic protein complex. Mapping of SAT domain structure revealed two new, independent domains with specific functions in protein-protein interaction. Analysis using truncated proteins proved the C-terminus of SAT to be sufficient for association with OAS-TL and to correlate with the putative transferase activity domain. SAT/SAT interaction was localized in the central region of the protein and occurred also between SAT isoforms. Both protein interaction domains coincided with distinct alpha-helical and beta-sheet clusters and together correlated with the minimal protein structure required for SAT catalysis as shown by functional complementation of an Escherichia coli mutant. The homo- and hetero-oligomerization properties are discussed with respect to the assumed function of the CS complex in metabolic channeling and activation of SAT by interaction with OAS-TL.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetyltransferases / chemistry
  • Acetyltransferases / genetics
  • Acetyltransferases / metabolism*
  • Amino Acid Sequence
  • Arabidopsis / enzymology
  • Carbon-Oxygen Lyases*
  • Cysteine / biosynthesis*
  • Cysteine Synthase / metabolism
  • Escherichia coli / genetics
  • Lyases / metabolism*
  • Molecular Sequence Data
  • Multienzyme Complexes*
  • Protein Binding
  • Protein Structure, Secondary
  • Recombinant Fusion Proteins
  • Saccharomyces cerevisiae Proteins*
  • Sequence Deletion
  • Serine O-Acetyltransferase
  • Yeasts / genetics


  • Multienzyme Complexes
  • Recombinant Fusion Proteins
  • Saccharomyces cerevisiae Proteins
  • Acetyltransferases
  • Serine O-Acetyltransferase
  • Cysteine Synthase
  • MET17 protein, S cerevisiae
  • O-acetylhomoserine (thiol)-lyase
  • Lyases
  • Carbon-Oxygen Lyases
  • Cysteine

Associated data

  • GENBANK/A00198