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Vitamin B, cobalamin, belongs to the broader cobamide family whose members are characterized by the presence of a cobalt-containing corrinoid ring. The ability to detect, isolate and characterize cobamides and their biosynthetic intermediates is an important prerequisite when attempting to study the synthesis of this remarkable group of compounds that play diverse roles across the three kingdoms of life. The synthesis of cobamides is restricted to only certain prokaryotes and their structural complexity entails an equally complex synthesis orchestrated through a multi-step biochemical pathway. In this chapter, we have outlined methods that we have found extremely helpful in the characterization of the biochemical pathway, including a plate microbiological assay, a corrinoid affinity extraction method, LCMS characterization and a multigene cloning strategy.
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http://dx.doi.org/10.1016/bs.mie.2022.01.013 | DOI Listing |
mSystems
April 2025
Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, California, USA.
Cobamides, the vitamin B (cobalamin) family of cofactors, are used by most organisms but produced by only a fraction of prokaryotes, and are thus considered key shared nutrients among microbes. Cobamides are structurally diverse, with multiple different cobamides found in most microbial communities. The ability to use different cobamides has been tested for several bacteria and microalgae, and nearly all show preferences for certain cobamides.
View Article and Find Full Text PDFNat Chem Biol
June 2025
Luxembourg Centre for Systems Biomedicine, University of Luxembourg, Esch-sur-Alzette, Luxembourg.
Citrate lyase beta-like protein (CLYBL) is a ubiquitously expressed mammalian enzyme known for its role in the degradation of itaconate, a bactericidal immunometabolite produced in activated macrophages. The association of CLYBL loss of function with reduced circulating vitamin B levels was proposed to result from inhibition of the B-dependent enzyme methylmalonyl-CoA mutase by itaconyl-CoA. The discrepancy between the highly inducible and locally confined production of itaconate and the broad expression profile of CLYBL across tissues suggested a role for this enzyme beyond itaconate catabolism.
View Article and Find Full Text PDFJ Bacteriol
February 2025
Department of Plant & Microbial Biology, University of California Berkeley, Berkeley, California, USA.
Bacteria encounter chemically similar nutrients in their environment, which impact their growth in distinct ways. Among such nutrients are cobamides, the structurally diverse family of cofactors related to vitamin B (cobalamin), which function as cofactors for diverse metabolic processes. Given that different environments contain varying abundances of different cobamides, bacteria are likely to encounter cobamides that enable them to grow robustly and also those that do not function efficiently for their metabolism.
View Article and Find Full Text PDFJ Am Chem Soc
January 2025
Department of Chemistry, University of Wisconsin─Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States.
The adenosylcobalamin (AdoCbl)-dependent enzyme ethanolamine ammonia-lyase (EAL) catalyzes the conversion of ethanolamine to acetaldehyde and ammonia. As is the case for all AdoCbl-dependent isomerases, the catalytic cycle of EAL is initiated by homolytic cleavage of the cofactor's Co-C bond, producing Cocobalamin (CoCbl) and an adenosyl radical that serves to abstract a hydrogen atom from the substrate. Remarkably, in the presence of substrate, the rate of Co-C bond homolysis of enzyme-bound AdoCbl is increased by 12 orders of magnitude.
View Article and Find Full Text PDFFEBS J
February 2025
Department of Functional and Evolutionary Ecology, University of Vienna, Austria.
Corrinoids are cobalt-containing tetrapyrroles. They include adenosylcobalamin (vitamin B) and cobamides that function as cofactors and coenzymes for methyl transfer, radical-dependent and redox reactions. Though cobamides are the most complex cofactors in nature, they are essential in the acetyl-CoA pathway, thought to be the most ancient CO-fixation pathway, where they perform a pterin-to-cobalt-to-nickel methyl transfer reaction catalyzed by the corrinoid iron-sulphur protein (CoFeS).
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