title: Cobalamin (vitamin B12) biosynthesis: identification and characterization of a Bacillus megaterium cobI operon.
abstract: A 16 kb DNA fragment has been isolated from a Bacillus megaterium genomic library and fully sequenced. The fragment contains 15 open reading frames, 14 of which are thought to constitute a B. megaterium cobalamin biosynthetic (cob) operon. Within the operon, 11 genes display similarity to previously identified Salmonella typhimurium cobalamin biosynthetic genes (cbiH60, -J, -C, -D, -ET, -L, -F, -G, -A, cysGA and btuR), whereas three do not (cbiW, -X and -Y). The genes of the B. megaterium cob operon were compared with the cobalamin biosynthetic genes of Pseudomonas denitrificans, Methanococcus jannaschii and Synechocystis sp. Taking into account the presence of cbiD and cbiG, the absence of a cobF, cobG and cobN, -S and -T, it was concluded that B. megaterium, M. jannaschii and Synechocystis sp., like S. typhimurium, synthesize cobalamin by an anaerobic pathway, in which cobalt is added at an early stage and molecular oxygen is not required.
authors.affiliation: Department of Molecular Genetics, Institute of Ophthalmology, UCL, 11-43 Bath Street, London EC1V 9EL, UK. e.raux@ucl.ac.uk
authors.forename: E
authors.initials: E
authors.lastname: Raux
authors.forename: A
authors.initials: A
authors.lastname: Lanois
authors.forename: M J
authors.initials: MJ
authors.lastname: Warren
authors.forename: A
authors.initials: A
authors.lastname: Rambach
authors.forename: C
authors.initials: C
authors.lastname: Thermes
mesh_terms: D001410:Bacillus megaterium / Q000235:genetics*; D018387:Codon, Initiator; D004269:DNA, Bacterial / Q000737:chemistry / Q000302:isolation & purification; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D009876:Operon; D017422:Sequence Analysis, DNA; D014805:Vitamin B 12 / Q000096:biosynthesis* / Q000235:genetics*
chemical_list: D018387:Codon, Initiator; D004269:DNA, Bacterial; D014805:Vitamin B 12