A Molecular Docking Strategy Identifies Eosin B as a Non-active Site Inhibitor of Protozoal Bifunctional Thymidylate Synthase-Dihydrofolate Reductase

Protozoal parasites are unusual in that their thymidylate synthase (TS) and dihydrofolate reductase (DHFR) enzymes exist on a single polypeptide. In an effort to probe the possibility of substrate channeling between the TS and DHFR active sites and to identify inhibitors specific for bifunctional TS...

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Veröffentlicht in:The Journal of biological chemistry 2003-04, Vol.278 (16), p.14092-14100
Hauptverfasser: Atreya, Chloé E., Johnson, Eric F., Irwin, John J., Dow, Antonia, Massimine, Kristen M., Coppens, Isabelle, Stempliuk, Valeska, Beverley, Stephen, Joiner, Keith A., Shoichet, Brian K., Anderson, Karen S.
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Sprache:eng
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Zusammenfassung:Protozoal parasites are unusual in that their thymidylate synthase (TS) and dihydrofolate reductase (DHFR) enzymes exist on a single polypeptide. In an effort to probe the possibility of substrate channeling between the TS and DHFR active sites and to identify inhibitors specific for bifunctional TS-DHFR, we used molecular docking to screen for inhibitors targeting the shallow groove connecting the two active sites. Eosin B is a 100 μm non-active site inhibitor of Leishmania major TS-DHFR identified by molecular docking. Eosin B slows both the TS and DHFR reaction rates. When Arg-283, a key residue to which eosin B is predicted to bind, is mutated to glutamate, however, eosin B only minimally inhibits the TS-DHFR reaction. Additionally, eosin B was found to be a 180 μm inhibitor of Toxoplasma gondii in both biochemical and cell culture assays.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.M212690200