title: Methionine biosynthesis and its regulation in Corynebacterium glutamicum: parallel pathways of transsulfuration and direct sulfhydrylation.
abstract: There are two alternative pathways leading to methionine synthesis in microorganisms: The transsulfuration pathway involves cystathionine as the intermediate and utilizes cysteine as the sulfur source, but the direct sulfhydrylation pathway bypasses cystathionine and uses inorganic sulfur instead. While most microorganisms synthesize methionine via either one of these pathways, Corynebacterium glutamicum utilizes both pathways, which appear to be fully functional. In C. glutamicum, each pathway is catalyzed by independent enzymes and is tightly regulated by methionine. Although the physiological significance of parallel pathways remains to be elucidated, their presence suggests metabolic flexibility and efficient adaptation of the organism to its environment.
authors.affiliation: Department of Biotechnology, Korea University, Jochiwon, Choongnam 339-700, Korea. hlee@korea.ac.kr
authors.forename: H-S
authors.initials: HS
authors.lastname: Lee
authors.forename: B-J
authors.initials: BJ
authors.lastname: Hwang
mesh_terms: D019757:Carbon-Oxygen Lyases / Q000235:genetics / Q000378:metabolism; D003352:Corynebacterium / Q000378:metabolism*; D003540:Cystathionine / Q000378:metabolism; D003547:Cysteine Synthase; D015964:Gene Expression Regulation, Bacterial; D008190:Lyases / Q000235:genetics / Q000378:metabolism; D008715:Methionine / Q000096:biosynthesis* / Q000235:genetics; D009097:Multienzyme Complexes; D029701:Saccharomyces cerevisiae Proteins; D013431:Sulfates / Q000378:metabolism
chemical_list: D009097:Multienzyme Complexes; D029701:Saccharomyces cerevisiae Proteins; D013431:Sulfates; D003540:Cystathionine; D008715:Methionine; D003547:Cysteine Synthase; C103381:MET17 protein, S cerevisiae; C018725:O-acetylhomoserine (thiol)-lyase; C022696:O-succinylhomoserine (thiol)-lyase; D008190:Lyases; D019757:Carbon-Oxygen Lyases; C019965:cystathionine beta-lyase