title: Bacillus subtilis cysteine synthetase is a global regulator of the expression of genes involved in sulfur assimilation.
abstract: The synthesis of L-cysteine, the major mechanism by which sulfur is incorporated into organic compounds in microorganisms, occupies a significant fraction of bacterial metabolism. In Bacillus subtilis the cysH operon, encoding several proteins involved in cysteine biosynthesis, is induced by sulfur starvation and tightly repressed by cysteine. We show that a null mutation in the cysK gene encoding an O-acetylserine-(thiol)lyase, the enzyme that catalyzes the final step in cysteine biosynthesis, results in constitutive expression of the cysH operon. Using DNA microarrays we found that, in addition to cysH, almost all of the genes required for sulfate assimilation are constitutively expressed in cysK mutants. These results indicate that CysK, besides its enzymatic role in cysteine biosynthesis, is a global negative regulator of genes involved in sulfur metabolism.
authors.affiliation: Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET) and Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Argentina.
authors.forename: Daniela
authors.initials: D
authors.lastname: Albanesi
authors.forename: Maria Cecilia
authors.initials: MC
authors.lastname: Mansilla
authors.forename: Gustavo E
authors.initials: GE
authors.lastname: Schujman
authors.forename: Diego
authors.initials: D
authors.lastname: de Mendoza
mesh_terms: D001412:Bacillus subtilis / Q000201:enzymology* / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D019757:Carbon-Oxygen Lyases / Q000235:genetics / Q000378:metabolism; D003545:Cysteine / Q000096:biosynthesis; D003547:Cysteine Synthase / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli; D015964:Gene Expression Regulation, Bacterial; D050939:Gene Fusion; D017930:Genes, Reporter; D020411:Oligonucleotide Array Sequence Analysis; D009876:Operon; D013455:Sulfur / Q000378:metabolism*; D001616:beta-Galactosidase / Q000032:analysis / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D013455:Sulfur; D003547:Cysteine Synthase; C018725:O-acetylhomoserine (thiol)-lyase; D001616:beta-Galactosidase; D019757:Carbon-Oxygen Lyases; D003545:Cysteine