tailieunhanh - Báo cáo khoa học: Crystal structure and solution characterization of the activation domain of human methionine synthase

Human methionine synthase (hMS) is a multidomain cobalamin-dependent enzyme that catalyses the conversion of homocysteine to methionine by methyl group transfer. We report here the A˚ crystal structure of the C-terminal activation domain of hMS. | ễFEBS Journal Crystal structure and solution characterization of the activation domain of human methionine synthase Kirsten R. Wolthers1 Helen S. Toogood1 Thomas A. Jowitt1 Ker R. Marshall2 David Leys1 and Nigel S. Scrutton1 1 Faculty of Life Sciences University of Manchester UK 2 Department of Biochemistry University of Leicester UK Keywords activation domain cobalamin-dependent enzyme methionine synthase methionine synthase reductase S-adenosyl-methionine Correspondence N. S. Scrutton Manchester Interdisciplinary Biocentre and Faculty of Life Sciences University of Manchester 131 Princess Street Manchester M1 7ND UK Fax 44 161 306 8918 Tel 44 161 306 5152 E-mail Database The atomic coordinates and structure factors 202K have been deposited in the Protein Data Bank Research Collaborator for StructuralBioinformatics Rutgers University New Brunswick NJ USA http These authors contributed equally to this work Received 3 October 2006 revised 22 November 2006 accepted 28 November 2006 doi Human methionine synthase hMS is a multidomain cobalamin-dependent enzyme that catalyses the conversion of homocysteine to methionine by methyl group transfer. We report here the A crystal structure of the C-terminal activation domain of hMS. The structure is C-shaped with the core comprising mixed a and b regions dominated by a twisted antiparallel b sheet with a b-meander region. These features including the positions of the active-site residues are similar to the activation domain of Escherichia coli cobalamin-dependent MS MetH . Structural and solution studies suggest a small proportion of hMS activation domain exists in a dimeric form which contrasts with the monomeric form of the E. coli homologue. Fluorescence studies show that human activation domain interacts with the FMN-binding domain of human methionine synthase reductase hMSR . This interaction is enhanced in the presence of .