Small molecule screen for candidate antimalarials targeting Plasmodium Kinesin-5.

Area of Science:

• Parasitology
• Medicinal Chemistry
• Molecular Biology

Background:

• Malaria, caused by Plasmodium falciparum and Plasmodium vivax, results in over a million deaths annually.
• Existing antimalarial drugs face widespread parasite resistance, necessitating the development of novel therapeutic agents.
• The Plasmodium Kinesin-5 mechanoenzyme presents a promising new drug target due to its essential role in parasite proliferation.

Purpose of the Study:

• To identify selective inhibitors of Plasmodium Kinesin-5 ATPase activity.
• To explore the potential of targeting Plasmodium Kinesin-5's unique allosteric site for drug development.
• To validate MMV666693 as a selective allosteric inhibitor of Plasmodium Kinesin-5.

Main Methods:

• A chemical screen of nearly 2000 compounds was conducted to identify inhibitors selective for Plasmodium Kinesin-5 over human Kinesin-5.
• ATPase activity assays were performed in parallel for Plasmodium and human Kinesin-5 to assess inhibitor selectivity.
• Biochemical assays were used to characterize the mechanism of inhibition for candidate compounds.

Main Results:

• The screen successfully identified compounds that selectively inhibit Plasmodium vivax and Plasmodium falciparum Kinesin-5 motor domains without affecting human Kinesin-5.
• A specific compound, MMV666693, was identified as a selective allosteric inhibitor of Plasmodium Kinesin-5.
• MMV666693 does not compete with ATP at the active site or disrupt microtubule binding, indicating a novel allosteric inhibition mechanism.

Conclusions:

• Plasmodium Kinesin-5 can be effectively targeted by small molecules, offering a new avenue for antimalarial drug development.
• MMV666693 is the first identified inhibitor targeting Plasmodium Kinesin-5, validating it as a drug target for the Medicines for Malaria Venture.
• Chemical screening strategies used for human kinesins are adaptable for discovering inhibitors against parasitic homologs, advancing infectious disease research.