Biosynthesis of Coenzyme F ₄₃₀ , A Nickel Porphinoid Involved in Methanogenesis

Coenzyme F430 is the prosthetic group of methyl-coenzyme-M reductase, which catalyses the final step of methane formation in methanogenic bacteria. The coenzyme is a nickel-containing macrocyclic tetrapyrrole of unique structure. We describe the biosynthesis of this nickel porphinoid from L-glutamate via 5-aminolaevulinic acid, uroporphyrinogen III and dihydrosirohydrochlorin, the binding of the coenzyme to methyl-coenzyme-M reductase and the regulation of coenzyme F430 biosynthesis. We end with some evolutionary considerations on the biosynthesis of macrocyclic tetrapyrroles and remarks on the degradation of these compounds under anaerobic conditions.