Parasite Genetics and Adaptations - Project B7

Defining metabolic determinants of drug susceptibility in P. falciparum and T. gondii

Host lab: Martin Blume (Robert Koch-Institute, Berlin)

Partner labs: Kai Matuschewski (Dept. of Biology, Humboldt University Berlin), Kevin Saliba (Department Research School of Biology, ANU, Canberra)

Background and Aim: : The two apicomplexans Toxoplasma gondii and Plasmodium falciparum escape immune responses and antibiotic stress by utilising phenotypic variation in distinct ways. While T. gondii forms professionally persisting tissue cysts containing dormant or slowly proliferating bradyzoites, the drug evasion mechanisms of P. falciparum are less well defined. The modulation of proliferation rates and the metabolic state of intraerythrocytic P. falciparum parasites appears to respond to the nutrient and immune status of the host leading to mild or asymptomatic malaria under certain conditions [1]. Interestingly, the rate of proliferation and the metabolic status via driving an immediate metabolic stress response [2], are important and independent determinants of antibiotic susceptibility for bacteria [3]. For protozoan pathogens this association has not been characterised in detail. However, the long-term metabolic impact of antibiotics on both apicomplexans can be characterized and used to delineate their mode of action [4, 5, unpublished]. In contrast, stress-agnostic short-term responses have not yet been identified and their implications for antibiotic tolerance remain elusive.

The aim of this project is to 

(1) Record short-term immediate metabolic responses to both fatal and sublethal drug exposures of T. gondii and P. falciparum parasites.

(2) Test the impact of these responses by modulating them genetically or pharmacologically

Methods: We use untargeted metabolomics techniques that are based on both liquid and gas chromatography-coupled mass spectrometry to characterize the metabolism of dormant T. gondii and P. falciparum parasites. To this end, both profiling of metabolite levels and stable isotope-resolved flux profiling will be employed. We will use inhibitors and genetic mutants to modulate the activity of metabolic pathways and test their importance to parasites persistence and drug resistance.

References:

[1] Barrett MP et al (2019) Nat Rev Microbiol 17: 607-620.

[2] Zampieri M et al (2017) Cell Rep 19: 1214-1228.

[3] Lopatkin AJ et al (2019) Nature Microbiol 4: 2109-2117.

[4] Allman EL et al (2016) Antimicrob Agents Chemother 60: 6635-6649.

[5] Christiansen et al., BiorXiv, under review, DOI: 10.1101/2021.01.15.426845