title: The crystal structure of the hydrolase domain of 10-formyltetrahydrofolate dehydrogenase: mechanism of hydrolysis and its interplay with the dehydrogenase domain.
abstract: 10-Formyltetrahydrofolate dehydrogenase (FDH) converts 10-formyltetrahydrofolate, a precursor for nucleotide biosynthesis, to tetrahydrofolate. The protein comprises two functional domains: a hydrolase domain that removes a formyl group from 10-formyltetrahydrofolate and a NADP(+)-dependent dehydrogenase domain that reduces the formyl to carbon dioxide. As a first step toward deciphering the catalytic mechanism of the enzyme, we have determined the crystal structure of the hydrolase domain of FDH from rat, solved to 2.3-A resolution. The structure comprises two domains. As expected, domain 1 shares the same Rossmann fold as the related enzymes, methionyl-tRNA-formyltransferase and glycinamide ribonucleotide formyltransferase, but, unexpectedly, the structural similarity between the amino-terminal domain of 10-formyltetrahydrofolate dehydrogenase and methionyl-tRNA-formyltransferase extends to the C terminus of both proteins. The active site contains a molecule of beta-mercaptoethanol that is positioned between His-106 and Asp-142 and that appears to mimic the formate product. We propose a catalytic mechanism for the hydrolase reaction in which Asp-142 polarizes the catalytic water molecule and His-106 orients the carbonyl group of formyl. The structure also provides clues as to how, in the native enzyme, the hydrolase domain transfers its product to the dehydrogenase domain.
authors.affiliation: Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, South Carolina 29425, USA.
authors.forename: Alexander A
authors.initials: AA
authors.lastname: Chumanevich
authors.forename: Sergey A
authors.initials: SA
authors.lastname: Krupenko
authors.forename: Christopher
authors.initials: C
authors.lastname: Davies
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002245:Carbon Dioxide / Q000378:metabolism; D003461:Crystallography; D003545:Cysteine / Q000235:genetics; D006867:Hydrolases / Q000737:chemistry*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D000587:Oxidoreductases Acting on CH-NH Group Donors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D051381:Rats; D013329:Structure-Activity Relationship; D000099295:Formyltetrahydrofolate Dehydrogenase
chemical_list: D002245:Carbon Dioxide; D003545:Cysteine; D006867:Hydrolases; D000587:Oxidoreductases Acting on CH-NH Group Donors; D000099295:Formyltetrahydrofolate Dehydrogenase