Dataset Information

Discovery of Potent and Selective Leads against Toxoplasma gondii Dihydrofolate Reductase via Structure-Based Design.

ABSTRACT: Current treatment of toxoplasmosis targets the parasite's folate metabolism through inhibition of dihydrofolate reductase (DHFR). The most widely used DHFR antagonist, pyrimethamine, was introduced over 60 years ago and is associated with toxicity that can be largely attributed to a similar affinity for parasite and human DHFR. Computational analysis of biochemical differences between Toxoplasma gondii and human DHFR enabled the design of inhibitors with both improved potency and selectivity. The approach described herein yielded TRC-19, a promising lead with an IC50 of 9 nM and 89-fold selectivity in favor of Toxoplasma gondii DHFR, as well as crystallographic data to substantiate in silico methodology. Overall, 50% of synthesized in silico designs met hit threshold criteria of IC50 < 10 ?M and >2-fold selectivity favoring Toxoplasma gondii, further demonstrating the efficiency of our structure-based drug design approach.

SUBMITTER: Welsch ME

PROVIDER: S-EPMC5150685 | biostudies-literature | 2016 Dec

REPOSITORIES: biostudies-literature

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Publications

Discovery of Potent and Selective Leads against <i>Toxoplasma gondii</i> Dihydrofolate Reductase via Structure-Based Design.

Welsch Matthew E ME Zhou Jian J Gao Yueqiang Y Yan Yunqing Y Porter Gene G Agnihotri Gautam G Li Yingjie Y Lu Henry H Chen Zhongguo Z Thomas Stephen B SB

ACS medicinal chemistry letters 20160917 12

Current treatment of toxoplasmosis targets the parasite's folate metabolism through inhibition of dihydrofolate reductase (DHFR). The most widely used DHFR antagonist, pyrimethamine, was introduced over 60 years ago and is associated with toxicity that can be largely attributed to a similar affinity for parasite and human DHFR. Computational analysis of biochemical differences between <i>Toxoplasma gondii</i> and human DHFR enabled the design of inhibitors with both improved potency and selectiv ...[more]

PMID: 27994750

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Project description:Most species, such as humans, have monofunctional forms of thymidylate synthase (TS) and dihydrofolate reductase (DHFR) that are key folate metabolism enzymes making critical folate components required for DNA synthesis. In contrast, several parasitic protozoa, including Toxoplasma gondii , contain a unique bifunctional thymidylate synthase-dihydrofolate reductase (TS-DHFR) having the catalytic activities contained on a single polypeptide chain. The prevalence of T. gondii infections across the world, especially for those immunocompromised, underscores the need to understand TS-DHFR enzyme function and to find new avenues to exploit for the design of novel antiparasitic drugs. As a first step, we have solved the first three-dimensional structures of T. gondii TS-DHFR at 3.7 Å and of a loop truncated TS-DHFR, removing several flexible surface loops in the DHFR domain, improving resolution to 2.2 Å. Distinct structural features of the TS-DHFR homodimer include a junctional region containing a kinked crossover helix between the DHFR domains of the two adjacent monomers, a long linker connecting the TS and DHFR domains, and a DHFR domain that is positively charged. The roles of these unique structural features were probed by site-directed mutagenesis coupled with presteady state and steady state kinetics. Mutational analysis of the crossover helix region combined with kinetic characterization established the importance of this region not only in DHFR catalysis but also in modulating the distal TS activity, suggesting a role for TS-DHFR interdomain interactions. Additional kinetic studies revealed that substrate channeling occurs in which dihydrofolate is directly transferred from the TS to DHFR active site without entering bulk solution. The crystal structure suggests that the positively charged DHFR domain governs this electrostatically mediated movement of dihydrofolate, preventing release from the enzyme. Taken together, these structural and kinetic studies reveal unique, functional regions on the T. gondii TS-DHFR enzyme that may be targeted for inhibition, thus paving the way for designing species specific inhibitors.

Dataset Information

Discovery of Potent and Selective Leads against Toxoplasma gondii Dihydrofolate Reductase via Structure-Based Design.

Publications

Discovery of Potent and Selective Leads against <i>Toxoplasma gondii</i> Dihydrofolate Reductase via Structure-Based Design.

Similar Datasets

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