1BMT

HOW A PROTEIN BINDS B12: A 3.O ANGSTROM X-RAY STRUCTURE OF THE B12-BINDING DOMAINS OF METHIONINE SYNTHASE

Summary for 1BMT

• Entry DOI: 10.2210/pdb1bmt/pdb
• Descriptor: METHIONINE SYNTHASE, CO-METHYLCOBALAMIN (3 entities in total)
• Functional Keywords: methyltransferase
• Biological source: Escherichia coli
• Total number of polymer chains: 2
• Total formula weight: 57107.07

Authors

Drennan, C.L.,Huang, S.,Drummond, J.T.,Matthews, R.G.,Ludwig, M.L. (deposition date: 1994-09-02, release date: 1995-06-03, Last modification date: 2024-02-07)

Primary citation

Drennan, C.L.,Huang, S.,Drummond, J.T.,Matthews, R.G.,Ludwig, M.L.
How a protein binds B12: A 3.0 A X-ray structure of B12-binding domains of methionine synthase.
Science, 266:1669-1674, 1994

PubMed Abstract: The crystal structure of a 27-kilodalton methylcobalamin-containing fragment of methionine synthase from Escherichia coli was determined at 3.0 A resolution. This structure depicts cobalamin-protein interactions and reveals that the corrin macrocycle lies between a helical amino-terminal domain and an alpha/beta carboxyl-terminal domain that is a variant of the Rossmann fold. Methylcobalamin undergoes a conformational change on binding the protein; the dimethylbenzimidazole group, which is coordinated to the cobalt in the free cofactor, moves away from the corrin and is replaced by a histidine contributed by the protein. The sequence Asp-X-His-X-X-Gly, which contains this histidine ligand, is conserved in the adenosylcobalamin-dependent enzymes methylmalonyl-coenzyme A mutase and glutamate mutase, suggesting that displacement of the dimethylbenzimidazole will be a feature common to many cobalamin-binding proteins. Thus the cobalt ligand, His759, and the neighboring residues Asp757 and Ser810, may form a catalytic quartet, Co-His-Asp-Ser, that modulates the reactivity of the B12 prosthetic group in methionine synthase.

PubMed: 7992050
DOI: 10.1126/science.7992050

Experimental method

X-RAY DIFFRACTION (3 Å)