A molecular docking strategy identifies eosin B as a non-active site inhibitor of protozoal bifunctional thymidylate synthase-dihydrofolate reductase

Chloé E. Atreya, Eric F. Johnson, John J. Irwin, Antonia Dow, Kristen M. Massimine, Isabelle Coppens, Valeska Stempliuk, Stephen Beverley, Keith A Joiner, Brian K. Shoichet, Karen S. Anderson

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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.

Original languageEnglish (US)
Pages (from-to)14092-14100
Number of pages9
JournalJournal of Biological Chemistry
Issue number16
Publication statusPublished - Apr 18 2003
Externally publishedYes


ASJC Scopus subject areas

  • Biochemistry

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