Dr. Emma Pietsch (Hamburg / DE), Abhinay Ramaprasad (London / GB), Sabrina Bielfeld (Hamburg / DE), Yvonne Wohlfarter (Innsbruck / AT), Bohumil Maco (Geneva / CH), Louisa Wilcke (Hamburg / DE), Joachim Kloehn (Geneva / CH), Marcus A. Keller (Innsbruck / AT), Dominique Soldati-Favre (Geneva / CH), Michael J. Blackman (London / GB), Prof. Tim Wolf Gilberger (Hamburg / DE), Dr. Paul-Christian Burda (Hamburg / DE)
Abstract text
Introduction: Plasmodium parasites rely on a functional electron transport chain (ETC) within their mitochondrion for proliferation, and compounds targeting mitochondrial functions are validated antimalarials. In other organisms, mitochondrial functions have been shown to be heavily influenced by the phospholipid composition of mitochondrial membranes. However, the importance of phospholipid-modifying enzymes for mitochondrial function in Plasmodium parasites has not been analyzed so far.
Objectives: In this study, we aim to characterize the physiological function of the Plasmodium falciparum patatin-like phospholipase 2 (PfPNPLA2, PF3D7_1358000) during asexual and sexual development of the parasite.
Materials & methods: We endogenously tagged PfPNPLA2 with green fluorescent protein and generated PfPNPLA2-deficient parasites using reverse genetics. Subsequently, we analyzed transgenic parasites using fluorescence microscopy and various cellular assays.
Results: We show that PfPNPLA2 resides in the mitochondrion and its experimental deletion impairs asexual replication. The physiological consequences of this PfPNPLA2 deletion are i) hypersensitivity to proguanil and inhibitors of the mitochondrial ETC including atovaquone, ii) lower mitochondrial respiration measured by quantification of oxygen consumption rates, and iii) a reduced mitochondrial membrane potential. Subsequent lipidomics-based analysis of the mitochondrial phospholipid cardiolipin (CL) reveals that deletion of PfPNPLA2 is associated with an increase of CL with shorter and more saturated acyl-groups, suggesting a potential role of PfPNLA2 in CL remodelling. We finally show that PfPNPLA2-deficient parasites also display profound defects in gametocytogenesis with most parasites only developing to stage III gametocytes, underlining the importance of a functional mitochondrial ETC for sexual development of the parasite.
Conclusion: PfPNPLA2 has a key role for mitochondrial function that is important for asexual replication and sexual development of the parasite.