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A new pathway for the synthesis of α‐ribazole‐phosphate in Listeria innocua
Author(s) -
Gray Michael J.,
EscalanteSemerena Jorge C.
Publication year - 2010
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2010.07294.x
Subject(s) - biology , listeria , adenosylcobalamin , biochemistry , nicotinamide mononucleotide , enzyme , auxotrophy , biosynthesis , operon , nucleotide , gene , genetics , escherichia coli , listeria monocytogenes , cofactor , bacteria , nad+ kinase , nicotinamide adenine dinucleotide
Summary 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. Lin CblT 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 Lin CblS. Bioinformatics analyses suggest that α‐R salvaging occurs in important Gram‐positive human pathogens.