Malaria remains a major global health concern and the control progress has run into a serious bottleneck in recent years. Each year, more than 3 billion people are living at risk of contracting malaria, 200 million people are infected and half a million people die from malaria. As malaria parasites rapidly develop resistance to available antimalarial drugs, a better understanding of fundamental biology is urgently needed. In the asexual blood stages, malaria parasites mainly reply on glycolysis for energy since the parasite's mitochondrion does not perform oxidative phosphorylation to produce ATP. They also contain membrane bound proton pumping pyrophosphatases (mPPases), which use pyrophosphate, the by-product of over 200 cellular reactions, as the energy source to pump protons across a membrane. We have previously knocked out PfVP2 (PF3D7_1235200) whereas PfVP1 (PF3D7_1456800) has been predicted to be essential. Using a CRISPR/Cas9 mediated genetic tagging/conditional knockdown, we have found that PfVP1 is localized to the parasite plasma membrane and is essential for ring stage development. In this application, we hypothesize that PfVP1 uses pyrophosphate as an alternative energy source to sustain a proton electrochemical gradient in the ring stage development of Plasmodium falciparum. We will test this hypothesis in the following aims.
Aim 1, Assess the activity of PfVP1 as an integral membrane proton-pumping pyrophosphatase.
Aim 2, Define the function of PfVP1 in ring stage parasites. Together, this proposal will uncover important insights of ring stage development and bioenergetics, critical yet understudied aspects of parasite biology. If successful, the studies proposed here will provide direct evidence that an alternative energy source is critical for early stage development of a malaria parasite in RBCs. Finding a critical molecular target at the ring stage will also facilitate target-based drug development in future to better inhibit metabolically less active parasite forms that are often resistant to current antimalarials.
The malaria control and eradication efforts are severely impeded by drug resistance problems, which necessitate an urgent need to deeply understand the parasite biology. We have recently discovered that a membrane integral pyrophosphatase, PfVP1, is essential for ring stage development. We hypothesize that PfVP1 uses an alternative energy source to support parasite development at the time when the RBC host provides limited nutrition.