Structure- and function-based design of Plasmodium-selective proteasome inhibitors.

Area of Science:

• Biochemistry
• Parasitology
• Drug Discovery

Background:

• The proteasome regulates vital cellular processes, making it a target for pathogen treatment.
• Proteasome inhibitors show toxicity against the malaria parasite Plasmodium falciparum.
• Existing inhibitors lack selectivity, affecting both parasite and host proteasomes, limiting therapeutic use.

Purpose of the Study:

• To define Plasmodium proteasome substrate specificity and structural properties for selective inhibitor development.
• To identify differences between human and Plasmodium falciparum proteasome specificities.
• To develop and validate parasite-selective proteasome inhibitors as anti-malarial agents.

Main Methods:

• Substrate profiling to compare human and Plasmodium proteasome specificities.
• Design of inhibitors targeting Plasmodium-specific amino-acid preferences.
• Cryo-electron microscopy to determine the structure of the Plasmodium proteasome bound to an inhibitor.
• In vitro and in vivo testing of inhibitor efficacy and toxicity.

Main Results:

• Identified distinct substrate specificities between human and Plasmodium proteasomes.
• Developed selective inhibitors targeting the Plasmodium proteasome β2-subunit.
• Determined the 3.6 Å cryo-EM structure of the Plasmodium proteasome, revealing an open β2 active site.
• Demonstrated synergistic growth inhibition with artemisinin and parasite attenuation in vivo without host toxicity.

Conclusions:

• The Plasmodium proteasome is a viable and selective drug target for malaria.
• Parasite-selective inhibitors show potential as next-generation anti-malarial therapies.
• Structural insights into the Plasmodium proteasome facilitate rational inhibitor design.