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
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Mentions: The crystal structure of LmDHCH has been determined at 2.7 Å resolution. The asymmetric unit is a homodimer and subunits are labeled A and B (Fig. 2). There was no evidence of a monomer in solution and the presence of a stable dimer is consistent with gel filtration data and in common with all other DHCH orthologues [19,42]. The first and last few residues (1–2 and 1–3, 297–298 in chains A and B, respectively) are disordered and an additional three residues are disordered in chain B (248–250). Superposition of subunit A onto subunit B gives an RMSD of 1.7 Å over 286 main chain Cα atoms. This high value reflects differences in domain positions, which will be discussed, and in a loop adjacent to the active site (residues 240–255; RMSD 4.1 Å over 13 Cα). This loop is disordered and absent in other DHCH structures and in LmDHCH, although modelled satisfactorily, elevated thermal parameters are noted.
Affiliation: Division of Biological Chemistry and Drug Discovery, College of Life Sciences, University of Dundee, Dundee DD1 5EH, UK.