title: A new pathway for the synthesis of α-ribazole-phosphate in Listeria innocua.
abstract: 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 2.4.2.21) 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.
authors.affiliation: Department of Bacteriology, University of Wisconsin, 6478 Microbial Sciences Building, 1550 Linden Drive, Madison, WI 53706, USA.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Gray
authors.forename: Jorge C
authors.initials: JC
authors.lastname: Escalante-Semerena
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001562:Benzimidazoles; D003001:Cloning, Molecular; D003038:Cobamides / Q000378:metabolism; D019295:Computational Biology; D004269:DNA, Bacterial / Q000235:genetics; D008087:Listeria / Q000201:enzymology* / Q000235:genetics; D009097:Multienzyme Complexes / Q000235:genetics / Q000378:metabolism*; D009713:Nucleotidyltransferases / Q000235:genetics / Q000378:metabolism*; D010430:Pentosyltransferases / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D010957:Plasmids; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D012263:Ribonucleosides / Q000096:biosynthesis*; D012265:Ribonucleotides / Q000096:biosynthesis*; D019779:Salmonella enterica / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D001562:Benzimidazoles; D003038:Cobamides; D004269:DNA, Bacterial; D009097:Multienzyme Complexes; D012263:Ribonucleosides; D012265:Ribonucleotides; C015491:alpha-ribazole; C017142:cobinamide; C087731:N(1)-(5-phosphoribosyl)-5,6-dimethylbenzimidazole; D010430:Pentosyltransferases; C028015:nicotinate-nucleotide-dimethylbenzimidazole phosphoribosyltransferase; D011494:Protein Kinases; D009713:Nucleotidyltransferases