Hypothemycin, a fungal natural product, identifies therapeutic targets in Trypanosoma brucei

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Abstract
Protein kinases are potentially attractive therapeutic targets for neglected parasitic diseases, including African trypanosomiasis caused by the protozoan, Trypanosoma brucei. How to prioritize T. brucei kinases and quantify their intracellular engagement by small-molecule inhibitors remain unsolved problems. Here, we combine chemoproteomics and RNA interference to interrogate trypanosome kinases bearing a Cys-Asp-Xaa-Gly motif (CDXG kinases). We discovered that hypothemycin, a fungal polyketide previously shown to covalently inactivate a subset of human CDXG kinases, kills T. brucei in culture and in infected mice. Quantitative chemoproteomic analysis with a hypothemycin-based probe revealed the relative sensitivity of endogenous CDXG kinases, including TbGSK3short and a previously uncharacterized kinase, TbCLK1. RNAi-mediated knockdown demonstrated that both kinases are essential, but only TbCLK1 is fully engaged by cytotoxic concentrations of hypothemycin in intact cells. Our study identifies TbCLK1 as a therapeutic target for African trypanosomiasis and establishes a new chemoproteomic tool for interrogating CDXG kinases in their native context.
Funding Information
  • Howard Hughes Medical Institute
  • National Institutes of Health (GM071434)
  • Sandler Foundation
  • National Science Foundation
  • Achievement Rewards for College Students Wells Fargo Scholarship
  • Genentech Predoctoral Fellowship
  • National Institutes of Health (NIGMS 8P41 GM103481)
  • Howard Hughes Medical Institute
  • National Institutes of Health (GM071434)
  • Sandler Foundation
  • National Science Foundation
  • Achievement Rewards for College Students Wells Fargo Scholarship
  • Simons Foundation
  • National Institutes of Health (NIGMS 8P41 GM103481)

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