Plasmodium falciparum, a protozoan parasite, is the major causative agent of human malaria. Alarming increase in malaria-related deaths world-wide specially tropical countries calls for novel therapeutic stratgies to overcome this disease. Insights into the signal transduction pathways of malaria parasite in its development may prove useful for devising newer methods to stop its propogation. Our long term goal is to dissect signal transduction pathways at molecular and cellular level to understand their function in the development of this parasite. Recently, we have identified a novel signalling pathway in P. falciparum which involves PfPKB, a protein kinase B (PKB) like enzyme, which is very different from the manner in which host PKB is regulated. PfPKB is activated by calmodulin in a calcium dependent manner and phosphopliase C (PLC) activity is responsible for the required calcium release. These findings suggest that PfPLC, the homologue of PLC, works as an upstream activator of PfPKB in this pathway. We intend to address the following issues to help understand the function of PfPKB, PfPLC and the regulation of this pathway: 1. What is the role of PfPKB in parasite life cycle? Pharmacological and peptide inhibitors of PfPKB will be used to answer these questions. Some of these inhibitors have already been developed by us and preliminary studies using these have suggested that PfPKB may be an important player in parasite life cycle. Genetic studies of PfPKB to disrupt its function will be performed to establish its function. 2. Identification of PfPKB substrates. To understand the role of PfPKB, identity of its target proteins is essential, which will provide crucial information about its function. A proteomics based or a chemical genetics approach will be used for this purpose. 3. Regulation of parasite signalling by PfPKB-substrate interaction. Once the identity of PfPKB targets is known, biochemical and cell biology studies directed at understanding PfPKB-target interplay in the context of parasite signalling will be studied. 4. Role of PfPLC as a regulator of PfPKB and other signaling events. PLC inhibitors attenuate PfPKB activation in the parasite. Understanding of PfPLC regulation will be crucial to follow the upstream events involved in the signaling of PfPKB as well as other pathways. We intend to study i) how PfPLG is regulated in the parasite and what factors infulence its activity; ii) the mechanism of it's targeting to its site-of-action in the parasite. ? ? ? ?
