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The crystal structure of Leishmania major N(5),N(10)-methylenetetrahydrofolate dehydrogenase/cyclohydrolase and assessment of a potential drug target.

Eadsforth TC, Cameron S, Hunter WN - Mol. Biochem. Parasitol. (2011)

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.

View Article: PubMed Central - PubMed

Affiliation: Division of Biological Chemistry and Drug Discovery, College of Life Sciences, University of Dundee, Dundee DD1 5EH, UK.

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Related in: MedlinePlus

An overview of the folate metabolism pathway in formation of essential intermediates in Leishmania. (a) Dihydrofolate (DHF) is converted to tetrahydrofolate (THF) by the actions of dihydrofolate reductase (DHFR) and/or pteridine reductase (PTR1). THF is modified by serine hydroxymethyl transferase (SHMT) or formyltetrahydrofolate ligase (FTL) and the interplay between three substituted intermediates of THF is controlled by the bifunctional dehydrogenase cyclohydrolase (DHCH). Intermediates generated at each stage are utilized by other pathways, for example N5,N10-methylenetetrahydrofolate is used by thymidylate synthase (TS). (b) The action of DHCH maintains the required levels of methenyl-, methylene-, formyl-tetrahydrofolate molecules, first by an NADP+ dependent oxidation from N5,N10-methylenetetrahydrofolate to form N5,N10-methenyltetrahydrofolate, then to N10-formyltetrahydrofolate by the cyclohydrolase activity. The inhibitor LY354899 is also shown. Figure produced using ChemDraw.
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fig0010: An overview of the folate metabolism pathway in formation of essential intermediates in Leishmania. (a) Dihydrofolate (DHF) is converted to tetrahydrofolate (THF) by the actions of dihydrofolate reductase (DHFR) and/or pteridine reductase (PTR1). THF is modified by serine hydroxymethyl transferase (SHMT) or formyltetrahydrofolate ligase (FTL) and the interplay between three substituted intermediates of THF is controlled by the bifunctional dehydrogenase cyclohydrolase (DHCH). Intermediates generated at each stage are utilized by other pathways, for example N5,N10-methylenetetrahydrofolate is used by thymidylate synthase (TS). (b) The action of DHCH maintains the required levels of methenyl-, methylene-, formyl-tetrahydrofolate molecules, first by an NADP+ dependent oxidation from N5,N10-methylenetetrahydrofolate to form N5,N10-methenyltetrahydrofolate, then to N10-formyltetrahydrofolate by the cyclohydrolase activity. The inhibitor LY354899 is also shown. Figure produced using ChemDraw.

Mentions: Folate and derivatives are essential cofactors in the biosynthesis of thymidine, purines, glycine, methionine, initiator fMet-tRNA and also in the metabolism of histidine and serine (Fig. 1a) [6]. It is not surprising that enzymes involved in folate-dependent pathways, e.g. dihydrofolate reductase (DHFR), are important antimicrobial and anticancer drug targets [7,8]. Trypanosomatids are auxotrophic for folates and pterins [9] and reliant on uptake and salvage mechanisms to maintain the required level of these important compounds. Inhibition of DHFR should, in principle, provide a route to treat trypanosomatid infections. However, the presence of a pteridine reductase (PTR1) able to reduce dihydrofolate (DHF) to tetrahydrofolate (THF), i.e. catalyze the same reaction as DHFR, helps to compromise the use of such inhibitors [10]. Promising PTR1 inhibitors have been identified [11–15] in support of a strategy to develop a combination treatment with known DHFR inhibitors to cut-off the supply of reduced pterins/folates. The use of drug combinations might also serve to alleviate the development of drug resistance [13,15]. Here, we turn our attention onto enzymes that maintain the required levels of N10-formyltetrahydrofolate, a key intermediate supporting protein synthesis.


The crystal structure of Leishmania major N(5),N(10)-methylenetetrahydrofolate dehydrogenase/cyclohydrolase and assessment of a potential drug target.

Eadsforth TC, Cameron S, Hunter WN - Mol. Biochem. Parasitol. (2011)

An overview of the folate metabolism pathway in formation of essential intermediates in Leishmania. (a) Dihydrofolate (DHF) is converted to tetrahydrofolate (THF) by the actions of dihydrofolate reductase (DHFR) and/or pteridine reductase (PTR1). THF is modified by serine hydroxymethyl transferase (SHMT) or formyltetrahydrofolate ligase (FTL) and the interplay between three substituted intermediates of THF is controlled by the bifunctional dehydrogenase cyclohydrolase (DHCH). Intermediates generated at each stage are utilized by other pathways, for example N5,N10-methylenetetrahydrofolate is used by thymidylate synthase (TS). (b) The action of DHCH maintains the required levels of methenyl-, methylene-, formyl-tetrahydrofolate molecules, first by an NADP+ dependent oxidation from N5,N10-methylenetetrahydrofolate to form N5,N10-methenyltetrahydrofolate, then to N10-formyltetrahydrofolate by the cyclohydrolase activity. The inhibitor LY354899 is also shown. Figure produced using ChemDraw.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3368264&req=5

fig0010: An overview of the folate metabolism pathway in formation of essential intermediates in Leishmania. (a) Dihydrofolate (DHF) is converted to tetrahydrofolate (THF) by the actions of dihydrofolate reductase (DHFR) and/or pteridine reductase (PTR1). THF is modified by serine hydroxymethyl transferase (SHMT) or formyltetrahydrofolate ligase (FTL) and the interplay between three substituted intermediates of THF is controlled by the bifunctional dehydrogenase cyclohydrolase (DHCH). Intermediates generated at each stage are utilized by other pathways, for example N5,N10-methylenetetrahydrofolate is used by thymidylate synthase (TS). (b) The action of DHCH maintains the required levels of methenyl-, methylene-, formyl-tetrahydrofolate molecules, first by an NADP+ dependent oxidation from N5,N10-methylenetetrahydrofolate to form N5,N10-methenyltetrahydrofolate, then to N10-formyltetrahydrofolate by the cyclohydrolase activity. The inhibitor LY354899 is also shown. Figure produced using ChemDraw.
Mentions: Folate and derivatives are essential cofactors in the biosynthesis of thymidine, purines, glycine, methionine, initiator fMet-tRNA and also in the metabolism of histidine and serine (Fig. 1a) [6]. It is not surprising that enzymes involved in folate-dependent pathways, e.g. dihydrofolate reductase (DHFR), are important antimicrobial and anticancer drug targets [7,8]. Trypanosomatids are auxotrophic for folates and pterins [9] and reliant on uptake and salvage mechanisms to maintain the required level of these important compounds. Inhibition of DHFR should, in principle, provide a route to treat trypanosomatid infections. However, the presence of a pteridine reductase (PTR1) able to reduce dihydrofolate (DHF) to tetrahydrofolate (THF), i.e. catalyze the same reaction as DHFR, helps to compromise the use of such inhibitors [10]. Promising PTR1 inhibitors have been identified [11–15] in support of a strategy to develop a combination treatment with known DHFR inhibitors to cut-off the supply of reduced pterins/folates. The use of drug combinations might also serve to alleviate the development of drug resistance [13,15]. Here, we turn our attention onto enzymes that maintain the required levels of N10-formyltetrahydrofolate, a key intermediate supporting protein synthesis.

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.

View Article: PubMed Central - PubMed

Affiliation: Division of Biological Chemistry and Drug Discovery, College of Life Sciences, University of Dundee, Dundee DD1 5EH, UK.

Show MeSH
Related in: MedlinePlus