title: Cloning and characterization of the CYS3 (CYI1) gene of Saccharomyces cerevisiae.
abstract: A DNA fragment containing the Saccharomyces cerevisiae CYS3 (CYI1) gene was cloned. The clone had a single open reading frame of 1,182 bp (394 amino acid residues). By comparison of the deduced amino acid sequence with the N-terminal amino acid sequence of cystathionine gamma-lyase, CYS3 (CYI1) was concluded to be the structural gene for this enzyme. In addition, the deduced sequence showed homology with the following enzymes: rat cystathionine gamma-lyase (41%), Escherichia coli cystathionine gamma-synthase (36%), and cystathionine beta-lyase (25%). The N-terminal half of it was homologous (39%) with the N-terminal half of S. cerevisiae O-acetylserine and O-acetylhomoserine sulfhydrylase. The cloned CYS3 (CYI1) gene marginally complemented the E. coli metB mutation (cystathionine gamma-synthase deficiency) and conferred cystathionine gamma-synthase activity as well as cystathionine gamma-lyase activity to E. coli; cystathionine gamma-synthase activity was detected when O-succinylhomoserine but not O-acetylhomoserine was used as substrate. We therefore conclude that S. cerevisiae cystathionine gamma-lyase and E. coli cystathionine gamma-synthase are homologous in both structure and in vitro function and propose that their different in vivo functions are due to the unavailability of O-succinylhomoserine in S. cerevisiae and the scarceness of cystathionine in E. coli.
authors.affiliation: Laboratory of Environmental Hygiene Chemistry, Faculty of Pharmaceutical Sciences, Okayama University, Japan.
authors.forename: B
authors.initials: B
authors.lastname: Ono
authors.forename: K
authors.initials: K
authors.lastname: Tanaka
authors.forename: K
authors.initials: K
authors.lastname: Naito
authors.forename: C
authors.initials: C
authors.lastname: Heike
authors.forename: S
authors.initials: S
authors.lastname: Shinoda
authors.forename: S
authors.initials: S
authors.lastname: Yamamoto
authors.forename: S
authors.initials: S
authors.lastname: Ohmori
authors.forename: T
authors.initials: T
authors.lastname: Oshima
authors.forename: A
authors.initials: A
authors.lastname: Toh-e
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D019757:Carbon-Oxygen Lyases; D003001:Cloning, Molecular; D003513:Cycloheximide / Q000494:pharmacology; D003542:Cystathionine gamma-Lyase / Q000235:genetics*; D003545:Cysteine / Q000096:biosynthesis*; D004790:Enzyme Induction / Q000187:drug effects; D004926:Escherichia coli / Q000235:genetics; D006714:Homoserine / Q000031:analogs & derivatives / Q000378:metabolism; D008190:Lyases / Q000235:genetics; D008969:Molecular Sequence Data; D015183:Restriction Mapping; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D012689:Sequence Homology, Nucleic Acid
chemical_list: C014196:O-succinylhomoserine; D006714:Homoserine; D003513:Cycloheximide; C022696:O-succinylhomoserine (thiol)-lyase; D008190:Lyases; D019757:Carbon-Oxygen Lyases; D003542:Cystathionine gamma-Lyase; D003545:Cysteine