title: Cysteine synthesis in plants: protein-protein interactions of serine acetyltransferase from Arabidopsis thaliana.
abstract: 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.
authors.affiliation: Lehrstuhl für Pflanzenphysiologie, Ruhr-Universität Bochum, Germany.
authors.forename: N
authors.initials: N
authors.lastname: Bogdanova
authors.forename: R
authors.initials: R
authors.lastname: Hell
mesh_terms: D000123:Acetyltransferases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology; D019757:Carbon-Oxygen Lyases; D003545:Cysteine / Q000096:biosynthesis*; D003547:Cysteine Synthase / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics; D008190:Lyases / Q000378:metabolism*; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes; D011485:Protein Binding; D017433:Protein Structure, Secondary; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D017384:Sequence Deletion; D051050:Serine O-Acetyltransferase; D015003:Yeasts / Q000235:genetics
chemical_list: D009097:Multienzyme Complexes; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D000123:Acetyltransferases; D051050:Serine O-Acetyltransferase; D003547:Cysteine Synthase; C103381:MET17 protein, S cerevisiae; C018725:O-acetylhomoserine (thiol)-lyase; D008190:Lyases; D019757:Carbon-Oxygen Lyases; D003545:Cysteine