title: The crystal structure of a bacterial, bifunctional 5,10 methylene-tetrahydrofolate dehydrogenase/cyclohydrolase.
abstract: The structure of a bifunctional 5,10-methylene-tetrahydrofolate dehydrogenase/cyclohydrolase from Escherichia coli has been determined at 2.5 A resolution in the absence of bound substrates and compared to the NADP-bound structure of the homologous enzyme domains from a trifunctional human synthetase enzyme. Superposition of these structures allows the identification of a highly conserved cluster of basic residues that are appropriately positioned to serve as a binding site for the poly-gamma-glutamyl tail of the tetrahydrofolate substrate. Modeling studies and molecular dynamic simulations of bound methylene-tetrahydrofolate and NADP shows that this binding site would allow interaction of the nicotinamide and pterin rings in the dehydrogenase active site. Comparison of these enzymes also indicates differences between their active sites that might allow the development of inhibitors specific to the bacterial target.
authors.affiliation: Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA.
authors.forename: B W
authors.initials: BW
authors.lastname: Shen
authors.forename: D H
authors.initials: DH
authors.lastname: Dyer
authors.forename: J Y
authors.initials: JY
authors.lastname: Huang
authors.forename: L
authors.initials: L
authors.lastname: D'Ari
authors.forename: J
authors.initials: J
authors.lastname: Rabinowitz
authors.forename: B L
authors.initials: BL
authors.lastname: Stoddard
mesh_terms: D000619:Aminohydrolases / Q000737:chemistry* / Q000378:metabolism; D001665:Binding Sites; D018360:Crystallography, X-Ray; D019281:Dimerization; D004926:Escherichia coli / Q000201:enzymology*; D006801:Humans; D008754:Methylenetetrahydrofolate Dehydrogenase (NADP) / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D009097:Multienzyme Complexes / Q000737:chemistry* / Q000378:metabolism; D011487:Protein Conformation; D013763:Tetrahydrofolates / Q000378:metabolism
chemical_list: D009097:Multienzyme Complexes; D013763:Tetrahydrofolates; C055342:methylene tetrahydrofolate dehydrogenase-methenyltetrahydrofolate cyclohydrolase; C013123:5,10-methylenetetrahydrofolic acid; D008754:Methylenetetrahydrofolate Dehydrogenase (NADP); D000619:Aminohydrolases