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- Title
Salmonella enterica synthesizes 5,6-dimethylbenzimidazolyl-(DMB)-α-riboside. Why some Firmicutes do not require the canonical DMB activation system to synthesize adenosylcobalamin.
- Authors
Mattes, Theodoric A.; Escalante ‐ Semerena, Jorge C.
- Abstract
5,6-Dimethylbenzimidazolyl-(DMB)- α-ribotide [ α-ribazole-5′-phosphate ( α-RP)] is an intermediate in the biosynthesis of adenosylcobalamin (AdoCbl) in many prokaryotes. In such microbes, α-RP is synthesized by nicotinate mononucleotide (NaMN):DMB phosphoribosyltransferases (CobT in Salmonella enterica), in a reaction that is considered to be the canonical step for the activation of the base of the nucleotide present in adenosylcobamides. Some Firmicutes lack CobT-type enzymes but have a two-protein system comprised of a transporter ( i.e., CblT) and a kinase ( i.e., CblS) that can salvage exogenous α-ribazole ( α-R) from the environment using CblT to take up α-R, followed by α-R phosphorylation by CblS. We report that Geobacillus kaustophilus CblT and CblS proteins restore α-RP synthesis in S. enterica lacking the CobT enzyme. We also show that a S. enterica cobT strain that synthesizes GkCblS ectopically makes only AdoCbl, even under growth conditions where the synthesis of pseudoCbl is favored. Our results indicate that S. enterica synthesizes α-R, a metabolite that had not been detected in this bacterium and that GkCblS has a strong preference for DMB-ribose over adenine-ribose as substrate. We propose that in some Firmicutes DMB is activated to α-RP via α-R using an as-yet-unknown route to convert DMB to α-R and CblS to convert α-R to α-RP.
- Subjects
SALMONELLA enterica; MICROBIOLOGICAL synthesis; BIOSYNTHESIS; RIBOSIDES; GLYCOSIDES
- Publication
Molecular Microbiology, 2017, Vol 103, Issue 2, p269
- ISSN
0950-382X
- Publication type
Article
- DOI
10.1111/mmi.13555