EC Explorer

2.1.1.308

cytidylyl-2-hydroxyethylphosphonate methyltransferase

2 S-adenosyl-L-methionine + cytidine 5′-{[hydroxy(2-hydroxyethyl)phosphonoyl]phosphate} + reduced acceptor = S-adenosyl-L-homocysteine + 5′-deoxyadenosine + L-methionine + cytidine 5′-{[hydroxy(2-hydroxypropyl)phosphonoyl]phosphate} + oxidized acceptor

Fom3, S-adenosyl-L-methionine:methylcob(III)alamin:2-hydroxyethylphosphonate methyltransferase (incorrect), 2-hydroxyethylphosphonate methyltransferase (incorrect)

S-adenosyl-L-methionine:cytidine 5′-{[hydroxy(2-hydroxyethyl)phosphonoyl]phosphate} C-methyltransferase

Requires cobalamin. The enzyme, isolated from the bacterium Streptomyces wedmorensis, is involved in fosfomycin biosynthesis. It is a radical S-adenosyl-L-methionine (SAM) enzyme that contains a [4Fe-4S] center and a methylcob(III)alamin cofactor. The enzyme uses two molecues of SAM for the reaction. One molecule forms a 5′-deoxyadenosyl radical, while the other is used to methylate the cobalamin cofactor. The 5′-deoxyadenosyl radical abstracts a hydrogen from the C₂ position of cytidine 5′-{[(2-hydroxyethyl)phosphonoyl]phosphate} forming a free radical that reacts with the methyl group on methylcob(III)alamin at the opposite side from SAM and the [4Fe-4S] cluster to produce a racemic mix of methylated products and cob(II)alamin. Both the [4Fe-4S] cluster and the cob(II)alamin need to be reduced by an unknown factor(s) before the enzyme could catalyse another cycle.

created 2014, modified 2019