Molecular characterization and substrate identification of malaria kinase PfCDPK5

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DESCRIPTION (provided by applicant): Malaria is among the leading causes of mortality for children under five years of age worldwide, with most of these deaths resulting from Plasmodium falciparum infection. Resistance to existing anti-malarial medications is an urgent problem and may prevent effective eradication strategies. A molecular understanding of the life cycle of P. falciparum will facilitate the rational design of new therapies. Efficient egress of P. falciparum out of an infected human red blood cell is a fundamental step in the parasite life cycle, and a step that is not targeted by current anti-malarial therapeutics. PfCDPK5 has recently been identified as a kinase that is critical for parasite egress. Using a state-of-the-art inducible protein destabilization system, functional evaluation of this essential gene is now possible. Transgenic parasites with an inducible knockdown in PfCDPK5 are arrested prior to egress. The ability to regulate the level of PfCDPK5 provides a unique resource to study both the mechanism of activation and the downstream effectors of this essential kinase. We hypothesize that PfCDPK5 is a central mediator of the calcium-based egress signaling pathway. The immediate goals of this proposal are to gain a molecular understanding of PfCDPK5 activation and characterize its role in the egress signaling pathway. In the first aim, a molecular genetic analysis of PfCDPK5 activation will be conducted using transgenic parasites that allow inducible regulation of essential protein levels. In the second aim, the downstream substrate(s) of PfCDPK5 will be discovered using both a candidate gene approach as well as advanced proteomic techniques. The long- term objectives and public health implications of these studies are to identify novel targets for new anti- malarial therapeutics. This long-term goal will be achieved as a direct result from the molecular characterization of the essential PfCDPK5 signaling pathway in P. falciparum parasites.