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

J. R. Roth, J. G. Lawrence, M. Rubenfield, S. Kieffer-Higgins, G. M. Church

Research output: Contribution to journalArticlepeer-review

195 Scopus citations

Abstract

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

Original languageEnglish (US)
Pages (from-to)3303-3316
Number of pages14
JournalJournal of Bacteriology
Volume175
Issue number11
StatePublished - 1993
Externally publishedYes

ASJC Scopus subject areas

  • Applied Microbiology and Biotechnology
  • Immunology

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