title: Kinetics of cobalamin repression of the cob operon in Salmonella typhimurium.
abstract: The cob operon in Salmonella typhimurium encodes 25 proteins involved in the biosynthesis of cobalamin. Expression of the cob operon is negatively feedback regulated by cobalamin via a translational control mechanism. The concentration of cobalamin required to repress cob expression to half-maximal was determined in vivo and in vitro to 0.4 microM and 0.6 microM, respectively. These results suggest that cob expression in wild-type cells is partially repressed by de novo synthesized cobalamin.
authors.affiliation: Uppsala University, Department of Microbiology, Sweden.
authors.forename: D
authors.initials: D
authors.lastname: Andersson
mesh_terms: D003001:Cloning, Molecular; D003038:Cobamides / Q000378:metabolism; D005246:Feedback; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects*; D009876:Operon / Q000187:drug effects*; D014176:Protein Biosynthesis / Q000187:drug effects; D012486:Salmonella typhimurium / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic; D014805:Vitamin B 12 / Q000096:biosynthesis* / Q000378:metabolism / Q000494:pharmacology*; D001616:beta-Galactosidase / Q000096:biosynthesis
chemical_list: D003038:Cobamides; D001616:beta-Galactosidase; C000913:cobamamide; D014805:Vitamin B 12