2.1.1.196 | homotetrameric apo form of CbiT crystallized in several space groups, to about 2.5 A resolution, and in complex with S-adenosyl-L-homocysteine, to 1.9 A resolution. The protein shows structural similarity to Rossmann-like S-adenosyl-methionine-dependent methyltransferases, and the cocrystal structure shows that it binds S-adenosyl-methionine in standard geometry near a binding pocket that can accommodate a precorrin substrate. CbiT probably functions as a precorrin methyltransferase |