Genetic Analysis, Nucleotide Sequence, and Products of Two Pseudomonas Denitrificans Cob Genes Encoding Nicotinate-Nucleotide: Dimethylbenzimidazole Phosphoribosyltransferase and Cobalamin (5'-phosphate) Synthase

J Bacteriol. 1991 Oct;173(19):6066-73. doi: 10.1128/jb.173.19.6066-6073.1991.


Tn5 Sp(r) transposons have been inserted into the 8-kb Pseudomonas denitrificans DNA fragment from complementation group D, which carries cob genes. Genetic analysis and the nucleotide sequence revealed that only two cob genes (cobU and cobV) were found on this cob genomic locus. Nicotinate-nucleotide: dimethylbenzimidazole phosphoribosyltransferase (EC was assayed and purified to homogeneity from a P. denitrificans strain in which cobU and cobV were amplified. The purified enzyme was identified as the cobU gene product on the basis of identical molecular weights and N-terminal sequences. Cobalamin (5'-phosphate) synthase activity was increased when cobV was amplified in P. denitrificans. The partially purified enzyme catalyzed not only the synthesis of cobalamin 5'-phosphate from GDP-cobinamide and alpha-ribazole 5'-phosphate but also the one-step synthesis of cobalamin from GDP-cobinamide and alpha-ribazole. Biochemical data provided evidence that cobV encodes cobalamin (5'-phosphate) synthase.

MeSH terms

  • Amino Acid Sequence
  • Bacterial Proteins*
  • Base Composition
  • Base Sequence
  • Cobamides / biosynthesis
  • Cobamides / genetics*
  • DNA, Bacterial / chemistry
  • DNA, Bacterial / isolation & purification
  • Deoxyribonuclease EcoRI
  • Deoxyribonuclease HindIII
  • Gene Amplification
  • Genes, Bacterial*
  • Genetic Complementation Test
  • Kinetics
  • Molecular Sequence Data
  • Molecular Weight
  • Multienzyme Complexes*
  • Nitrogenous Group Transferases*
  • Nucleotidyltransferases*
  • Pentosyltransferases / genetics*
  • Pseudomonas / enzymology
  • Pseudomonas / genetics*
  • Transferases / genetics*


  • Bacterial Proteins
  • Cobamides
  • DNA, Bacterial
  • Multienzyme Complexes
  • Transferases
  • Pentosyltransferases
  • nicotinate-nucleotide-dimethylbenzimidazole phosphoribosyltransferase
  • Nitrogenous Group Transferases
  • CobV protein, Pseudomonas denitrificans
  • Nucleotidyltransferases
  • Deoxyribonuclease EcoRI
  • Deoxyribonuclease HindIII

Associated data

  • GENBANK/M62868
  • GENBANK/M64126
  • GENBANK/M64127
  • GENBANK/M64128
  • GENBANK/M64129
  • GENBANK/S52988
  • GENBANK/S52991
  • GENBANK/S53821
  • GENBANK/S57155
  • GENBANK/X61007