Jun Yan, Meng Bi, Allen K. Bourdon, Abigail T. Farmer, Po-Hsiang Wang, Olivia Molenda, Andrew T. Qualie, Nannan Jiang, Yi Yang, Yongchao Yin, Burcu Şimşir, Shawn R. Campagna, Elizabeth A. Edwards, Frank E. Löffler
Cobamides such as vitamin B12 are structurally conserved, cobalt-containing tetrapyrrole biomolecules that have essential biochemical functions in all domains of life. In organohalide respiration, a vital biological process for the global cycling of natural and anthropogenic organohalogens, cobamides are the requisite prosthetic groups for carbon–halogen bond-cleaving reductive dehalogenases. This study reports the biosynthesis of a new cobamide with unsubstituted purine as the lower base and assigns unsubstituted purine a biological function by demonstrating that Coα-purinyl-cobamide (purinyl-Cba) is the native prosthetic group in catalytically active tetrachloroethene reductive dehalogenases of Desulfitobacterium hafniense. Cobamides featuring different lower bases are not functionally equivalent, and purinyl-Cba elicits different physiological responses in corrinoid-auxotrophic, organohalide-respiring bacteria. Given that cobamide-dependent enzymes catalyze key steps in essential metabolic pathways, the discovery of a novel cobamide structure and the realization that lower bases can effectively modulate enzyme activities generate opportunities to manipulate functionalities of microbiomes.
Yan J, Bi M, Bourdon AK, Farmer AT, Wang P-H, Molenda O, Quaile AT, Jiang N, Yang Y, Yin Y, Şimşir B, Campagna SR, Edwards EA, Löffler FE. 2017. Purinyl-cobamide is a native prosthetic group of reductive dehalogenases. Nature Chemical Biology, 10.1038/nchembio.2512.