A new pathway for the synthesis of α-ribazole-phosphate in Listeria innocua

Mol Microbiol. 2010 Sep;77(6):1429-38. doi: 10.1111/j.1365-2958.2010.07294.x. Epub 2010 Aug 5.


The genomes of Listeria spp. encode all but one of 25 enzymes required for the biosynthesis of adenosylcobalamin (AdoCbl; coenzyme B(12) ). Notably, all Listeria genomes lack CobT, the nicotinamide mononucleotide:5,6-dimethylbenzimidazole (DMB) phosphoribosyltransferase (EC enzyme that synthesizes the unique α-linked nucleotide N(1) -(5-phospho-α-D-ribosyl)-DMB (α-ribazole-5'-P, α-RP), a precursor of AdoCbl. We have uncovered a new pathway for the synthesis of α-RP in Listeria innocua that circumvents the lack of CobT. The cblT and cblS genes (locus tags lin1153 and lin1110) of L. innocua encode an α-ribazole (α-R) transporter and an α-R kinase respectively. Results from in vivo experiments indicate that L. innocua depends on CblT and CblS activities to salvage exogenous α-R, allowing conversion of the incomplete corrinoid cobinamide (Cbi) into AdoCbl. Expression of the L. innocua cblT and cblS genes restored AdoCbl synthesis from Cbi and α-R in a Salmonella enterica cobT strain. LinCblT transported α-R across the cell membrane, but not α-RP or DMB. UV-visible spectroscopy and mass spectrometry data identified α-RP as the product of the ATP-dependent α-R kinase activity of LinCblS. Bioinformatics analyses suggest that α-R salvaging occurs in important Gram-positive human pathogens.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • Benzimidazoles
  • Cloning, Molecular
  • Cobamides / metabolism
  • Computational Biology
  • DNA, Bacterial / genetics
  • Listeria / enzymology*
  • Listeria / genetics
  • Multienzyme Complexes / genetics
  • Multienzyme Complexes / metabolism*
  • Nucleotidyltransferases / genetics
  • Nucleotidyltransferases / metabolism*
  • Pentosyltransferases / genetics
  • Pentosyltransferases / metabolism*
  • Phosphorylation
  • Plasmids
  • Protein Kinases / genetics
  • Protein Kinases / metabolism*
  • Ribonucleosides / biosynthesis*
  • Ribonucleotides / biosynthesis*
  • Salmonella enterica / metabolism


  • Bacterial Proteins
  • Benzimidazoles
  • Cobamides
  • DNA, Bacterial
  • Multienzyme Complexes
  • Ribonucleosides
  • Ribonucleotides
  • alpha-ribazole
  • cobinamide
  • N(1)-(5-phosphoribosyl)-5,6-dimethylbenzimidazole
  • Pentosyltransferases
  • nicotinate-nucleotide-dimethylbenzimidazole phosphoribosyltransferase
  • Protein Kinases
  • Nucleotidyltransferases