title: Biosynthesis of vitamin B12. Discovery of the enzymes for oxidative ring contraction and insertion of the fourth methyl group.
abstract: In the vitamin B12 biosynthetic pathway the enzymes responsible for the conversion of precorrin-3 to precorrin-4 have been identified as the gene products of cobG and cobJ from Pseudomonas denitrificans. CobG catalyzes the oxidation of precorrin-3 to precorrin-3x (a hydroxy lactone) whereas CobJ is a SAM-dependent C-17 methyl transferase and is necessary for ring contraction. A mechanism for ring contraction is proposed.
authors.affiliation: Department of Chemistry, Texas A&M University, College Station 77843-3255.
authors.forename: A I
authors.initials: AI
authors.lastname: Scott
authors.forename: C A
authors.initials: CA
authors.lastname: Roessner
authors.forename: N J
authors.initials: NJ
authors.lastname: Stolowich
authors.forename: J B
authors.initials: JB
authors.lastname: Spencer
authors.forename: C
authors.initials: C
authors.lastname: Min
authors.forename: S I
authors.initials: SI
authors.lastname: Ozaki
mesh_terms: D001426:Bacterial Proteins; D001483:Base Sequence; D004277:DNA, Single-Stranded; D008745:Methylation; D008780:Methyltransferases / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D010105:Oxygenases / Q000235:genetics / Q000378:metabolism*; D011549:Pseudomonas / Q000201:enzymology; D012436:S-Adenosylmethionine / Q000378:metabolism; D014578:Uroporphyrins / Q000096:biosynthesis; D014805:Vitamin B 12 / Q000096:biosynthesis*
chemical_list: D001426:Bacterial Proteins; D004277:DNA, Single-Stranded; D014578:Uroporphyrins; C078447:precorrin 3; D012436:S-Adenosylmethionine; D010105:Oxygenases; C083406:CobG protein, Pseudomonas denitrificans; C083407:CobJ protein, Pseudomonas denitrificans; D008780:Methyltransferases; D014805:Vitamin B 12