New Insights Into the Biosynthesis of Cobamides and Their Use

Metal-containing tetrapyrroles, appropriately referred to as “the pigments of life” include members from four families of compounds, namely cobalt-containing cobamides (Cba), magnesium-containing chlorophylls, iron-containing hemes, and nickel-containing F430. The cobamides are structurally the most complex because they have an upper and lower ligand. Cobamides are synthesized only by some archaea and bacteria, and the organisms that can assemble this molecule de novo have invested substantial genetic information to accomplish this task (~ 30 genes). Here we review different aspects of cobamide biosynthesis to provide the reader with the latest information in the field. We also discuss the diversity of cobamide-dependent reactions and their importance to cell physiology. Over the last thirty years, our understanding of the biosynthesis and use of cobamides has advanced dramatically. Despite this progress, substantial gaps of knowledge remain.