The role of the Clp protease family in proteostasis regulation in the apicoplast of Plasmodium falciparum

Malaria is a disease that can cause severe health problems such as cyclic fever, brain damage and even death. Human malaria is caused by five species of unicellular organisms, of which Plasmodium falciparum is the deadliest. The parasite has a second endosymbiotic organelle, a non-photosynthetic plastid, known as the apicoplast that plays a central role in cellular metabolism. During evolution, two processes occurred simultaneously – 1. most of the genes in the apicoplast genome were either lost or transferred to the nucleus, including the regulatory factors and 2. the parasite lost is mevalonate pathway and became dependent on the production of IPP and DMAPP by the apicoplast through methyl erythritol 4-phosphate (MEP) pathway. Recent finding from our lab, revealed that the caseinolytic-protease (Clp) system regulates organelle proteostasis. Here, we study the role of the two Clp complex subunits, ClpP and ClpR, and how their knockout affects P. falciparum. We attempted conditional knockout by using a novel Di-Cre recombination system and demonstrated that depletion of ClpP or ClpR negatively affects the phenotype of the parasite. Using these mutants, we aim to examine whether the Clp complex degrades proteins in the apicoplast following the N-end rule of protein degradation and its effect on MEP pathway. Our results demonstrate that ClpP is essential for parasite viability and their knockout leads to the parasite`s death. These findings support that ClpP can be a potential drug targets since they are essential prokaryotic components in a eukaryotic organism and also significantly differ from the human host.