Tubulin – A novel lead to antimalarial drug discovery

SIMONE REBER (HUB) in partnership with Kevin Saliba (ANU)

The current therapeutic options of microtubule-disruptive drugs as antimalarial agents are limited by their high toxicity to mammalian cells. Often, it is unclear whether the effects of microtubule inhibition are a direct consequence of targeting Plasmodium microtubules or due to defects in cellular processes of the host cell. So far, due to technical limitations, the unavailability of Plasmodium tubulin has limited the search for pathogen-specific microtubule inhibitors.

Based on our understanding of microtubule polymerases [1], we have designed an affinity matrix that binds tubulin in an organism-agnostic manner with very high efficiency [2]. Given the proven pharmacological value of disrupting microtubule function [3], the purification of active Pf tubulin will serve as a promising starting point for investigating new antimalarial therapeutic strategies.

The candidate PhD student will work on the

following objectives:

• Purify active Pf tubulin in the milligram-yield
• Reconstitute Pf microtubules in vitro
• Perform structural studies on Pf microtubules by electron microscopy.
• Study the direct effect of microtubule-disruptive drugs on Pf microtubule dynamics.
• Evaluate the antimalarial blood-stage activity of compounds using Pf whole-cell proliferation assayswith cultured intra-erythrocytic parasites.

Kevin Saliba is trained as a pharmacologist, and his lab's expertise in cellular pharmacology and therapeutics will be indispensable to further advance this project. Upon the identification of compounds that have a stronger affinity and greater microtubule disruptive effect against Plasmodium, we aim to examine the mechanism through which the compounds exert their antiplasmodial activity in whole-cell proliferation assays. To do so, the student will spend time in the Saliba lab to generate resistant parasites, which will be sequenced to gain insight into (1) the mechanism of action or (2) potential mechanisms of drug resistance.

Interlinkages: Christina Spry (ANU), Alexander Maier (ANU), Simon Foote (ANU)

References:

(1) Reber, S. et al. (2013) Nat. Cell Biol. 15:1116-1122.

(2) Widlund, P.O. et al. (2012) Mol. Biol. Cell 23:4393-4401

(3) Kappes, B. and Rohrbach, P. (2007) Future Microbiol. 2:409-423