The crystal structure of Leishmania major N(5),N(10)-methylenetetrahydrofolate dehydrogenase/cyclohydrolase and assessment of a potential drug target.
Bottom Line: Here, we present the 2.7 Å resolution crystal structure of the bifunctional apo-DHCH from L. major, which is a potential drug target.Sequence alignments show that the cytosolic enzymes found in trypanosomatids share a high level of identity of approximately 60%.Additionally, residues that interact and participate in catalysis in the human homologue are conserved amongst trypanosomatid sequences and this may complicate attempts to derive potent, parasite specific DHCH inhibitors.
Affiliation: Division of Biological Chemistry and Drug Discovery, College of Life Sciences, University of Dundee, Dundee DD1 5EH, UK.Show MeSH
Related in: MedlinePlus
Mentions: The LmDHCH subunit consists of 298 residues displaying a high level of secondary structure; 11 α-helices and 11 β-strands (Fig. 2). The polypeptide folds into N- and C-terminal domains comprising residues 5–147 and 148–298, respectively. A cleft is formed between the two domains and at one end an NADP+ binding site, typical of a Rossmann fold (βαβαβ), is formed. The substrate-binding site is at the other end of the cleft. Analysis of the domains of LmDHCH from the crystallographically independent chains shows a significant pivot around a hinge (residues 150–152 and 274–280) with a rotation of almost 14° evident (Fig. 3). The hinge involves α6 and the loop leading into α11. A similar observation has been made in HsDHCH structures [19,20]. The subunits appear in distinct states, with the active site slightly more compressed in one than the other and this may represent a feature of DHCH activity.
Affiliation: Division of Biological Chemistry and Drug Discovery, College of Life Sciences, University of Dundee, Dundee DD1 5EH, UK.