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Bioorg Med Chem Lett. 2014 Sep 1;24(17):4158-61. doi: 10.1016/j.bmcl.2014.07.049. Epub 2014 Jul 24.

Structural studies provide clues for analog design of specific inhibitors of Cryptosporidium hominis thymidylate synthase-dihydrofolate reductase.

Author information

1
Department of Pharmacology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA.
2
Department of Chemistry, Yale University, 225 Prospect Street, PO Box 208107, New Haven, CT 06520-8107, USA.
3
Infectious Disease Division, Department of Internal Medicine, University of Texas Medical Branch, Galveston, USA.
4
Division of Medicinal Chemistry, Graduate School of Pharmaceutical Sciences, Duquesne University, Pittsburgh, PA 15282, USA.
5
Division of Medicinal Chemistry, Graduate School of Pharmaceutical Sciences, Duquesne University, Pittsburgh, PA 15282, USA. Electronic address: gangjee@duq.edu.
6
Department of Chemistry, Yale University, 225 Prospect Street, PO Box 208107, New Haven, CT 06520-8107, USA. Electronic address: william.jorgensen@yale.edu.
7
Department of Pharmacology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA. Electronic address: karen.anderson@yale.edu.

Abstract

Cryptosporidium is the causative agent of a gastrointestinal disease, cryptosporidiosis, which is often fatal in immunocompromised individuals and children. Thymidylate synthase (TS) and dihydrofolate reductase (DHFR) are essential enzymes in the folate biosynthesis pathway and are well established as drug targets in cancer, bacterial infections, and malaria. Cryptosporidium hominis has a bifunctional thymidylate synthase and dihydrofolate reductase enzyme, compared to separate enzymes in the host. We evaluated lead compound 1 from a novel series of antifolates, 2-amino-4-oxo-5-substituted pyrrolo[2,3-d]pyrimidines as an inhibitor of Cryptosporidium hominis thymidylate synthase with selectivity over the human enzyme. Complementing the enzyme inhibition compound 1 also has anti-cryptosporidial activity in cell culture. A crystal structure with compound 1 bound to the TS active site is discussed in terms of several van der Waals, hydrophobic and hydrogen bond interactions with the protein residues and the substrate analog 5-fluorodeoxyuridine monophosphate (TS), cofactor NADPH and inhibitor methotrexate (DHFR). Another crystal structure in complex with compound 1 bound in both the TS and DHFR active sites is also reported here. The crystal structures provide clues for analog design and for the design of ChTS-DHFR specific inhibitors.

KEYWORDS:

Cryptosporidium; Crystal structure; Dihydrofolate reductase; Inhibitor; Thymidylate synthase

PMID:
25127103
PMCID:
PMC4427026
DOI:
10.1016/j.bmcl.2014.07.049
[Indexed for MEDLINE]
Free PMC Article

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