Characterization of the cobalamin (vitamin B12) biosynthetic genes of Salmonella typhimurium.

摘要: Salmonella typhimurium synthesizes cobalamin (vitamin B12) de novo under anaerobic conditions. Of the 30 synthetic genes, 25 are clustered in one operon, cob, and arranged three groups, each group encoding enzymes for a biochemically distinct portion of biosynthetic pathway. We have determined DNA sequence promoter region proximal 17.1 kb cob operon. This includes 20 translationally coupled genes that encode involved parts I III A comparison these with from Pseudomonas denitrificans allows assignment likely functions to 12 sequenced genes. Three additional proteins be transport cobalt, component vitamin B12. However, not all apparent homologs other species. These differences suggest pathways differ between two organisms. The evolution their chromosomal positions is discussed.