Identification of the gene encoding sulfopyruvate decarboxylase, an enzymeinvolved in biosynthesis of coenzyme M

The products of two adjacent genes in the chromosome of Methanococcus janna schii are similar to the amino and carboxyl halves of phosphonopyruvate dec arboxylase, the enzyme that catalyzes the second step of fosfomycin biosynt hesis in Streptomyces wedmorensis. These two M, jannaschii genes were recom binantly expressed in Escherichia coli, and their gene products were tested for the ability to catalyze the decarboxylation of a series of or-ketoacid s, Both subunits are required to form an alpha(6)beta(6) dodecamer that spe cifically catalyzes the decarboxylation of sulfopyruvic acid to sulfoacetal dehyde. This transformation is the fourth step in the biosynthesis of coenz yme M, a crucial cofactor in methanogenesis and aliphatic alkene metabolism . The M. jannaschii sulfopyruvate decarboxylase was found to be inactivated by oxygen and reactivated by reduction with dithionite, The two subunits, designated ComD and ComE, comprise the first enzyme for the biosynthesis of coenzyme M to be described.