Cobalamin Cobalamin in Which Adenine Substitutes for DMB As the Α Ligand
Two distinct pools of B12 analogs reveal community interdependencies in the ocean Katherine R. Heala, Wei Qinb, Francois Ribaleta, Anthony D. Bertagnollib,1, Willow Coyote-Maestasa,2, Laura R. Hmeloa, James W. Moffettc,d, Allan H. Devola, E. Virginia Armbrusta, David A. Stahlb, and Anitra E. Ingallsa,3 aSchool of Oceanography, University of Washington, Seattle, WA 98195; bDepartment of Civil and Environmental Engineering, University of Washington, Seattle, WA 98195; cDepartment of Biological Sciences, University of Southern California, Los Angeles, CA 90089-0894; and dDepartment of Civil and Environmental Engineering, University of Southern California, Los Angeles, CA 90089-0894 Edited by David M. Karl, University of Hawaii, Honolulu, HI, and approved November 28, 2016 (received for review May 25, 2016) Organisms within all domains of life require the cofactor cobalamin cobalamin in which adenine substitutes for DMB as the α ligand (vitamin B12), which is produced only by a subset of bacteria and (12) (Fig. 1). Production of pseudocobalamin in a natural marine archaea. On the basis of genomic analyses, cobalamin biosynthesis environment has not been shown, nor have reasons for the pro- in marine systems has been inferred in three main groups: select duction of this compound in place of cobalamin been elucidated. heterotrophic Proteobacteria, chemoautotrophic Thaumarchaeota, To explore the pervasiveness of cobalamin and pseudocobala- and photoautotrophic Cyanobacteria. Culture work demonstrates min supply and demand in marine systems, we determined the that many Cyanobacteria do not synthesize cobalamin but rather standing stocks of these compounds in microbial communities produce pseudocobalamin, challenging the connection between the from surface waters across the North Pacific Ocean using liquid occurrence of cobalamin biosynthesis genes and production of the chromatography mass spectrometry (LC-MS).
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