Purification of functional Plasmodium falciparum tubulin allows for the identification of parasite-specific microtubule inhibitors

Cytoskeletal proteins are essential for parasite proliferation, growth, and transmission, and therefore have the potential to serve as drug targets.(1-5) While microtubules and their molecular building block alpha beta-tubulin are established drug targets in a variety of cancers,(6,7) we still lack sufficient knowledge of the biochemistry of parasite tubulins to exploit the structural divergence between parasite and human tubulins. For example, it remains to be determined whether compounds of interest can specifically target parasite microtubules without affecting the host cell cytoskeleton. Such mechanistic insights have been limited by the lack of functional parasite tubulin. In this study, we report the purification and characterization of tubulin from Plasmodium falciparum, the causative agent of malaria. We show that the highly purified tubulin is fully functional, as it efficiently assembles into microtubules with specific parameters of dynamic instability. There is a high degree of amino-acid conservation between human and P. falciparum alpha- and beta-tubulin, sharing approximately 83.7% and 88.5% identity, respectively. However, Plasmodium tubulin is more similar to plant than to mammalian tubulin, raising the possibility of identifying compounds that would selectively disrupt parasite microtubules without affecting the host cell cytoskeleton. As a proof of principle, we describe two compounds that exhibit selective toxicity toward parasite tubulin. Thus, the ability to specifically disrupt protozoan microtubule growth without affecting human microtubules provides an exciting opportunity for the development of novel antimalarials.

Automated summary

Cytoskeletal proteins are crucial for parasite survival and the study of parasite tubulin may lead to the development of novel antimalarials. This study successfully purified and characterized tubulin from Plasmodium falciparum, finding that it shares similarity with plant tubulin rather than mammalian tubulin. This opens up the possibility of finding compounds that can selectively disrupt parasite microtubules without affecting the host cell cytoskeleton.