Cl. Drennan et al., COBALAMIN-DEPENDENT METHIONINE SYNTHASE - THE STRUCTURE OF A METHYLCOBALAMIN-BINDING FRAGMENT AND IMPLICATIONS FOR OTHER B-12-DEPENDENT ENZYMES, Current opinion in structural biology, 4(6), 1994, pp. 919-929
Cobalamin-dependent methionine synthase is a large enzyme composed of
structurally and functionally distinct regions. Recent studies have be
gun to define the roles of several regions of the protein. In particul
ar, the structure of a 27 kDa cobalamin-binding fragment of the enzyme
from Escherichia coli has been determined by X-ray crystallography, a
nd has revealed the motifs and interactions responsible for recognitio
n of the cofactor. The amino acid sequences of several adenosylcobalam
in-dependent enzymes, the methylmalonyl coenzyme A mutases and glutama
te mutases, show homology with the cobalamin-binding region of methion
ine synthase and retain conserved residues that are determinants for t
he binding of the prosthetic group, suggesting that these mutases and
methionine synthase share common three-dimensional structures.