Specific phosphorylation of the PfRh2b invasion ligand of Plasmodium falciparum

Red blood cell invasion by the malaria parasite Plasmodium falciparum relies on a complex protein network that uses low and high affinity receptor-ligand interactions. Signal transduction through the action of specific kinases is a control mechanism for the orchestration of this process. Here we report on the phosphorylation of the cytoplasmic domain (CPD) of P. falciparum reticulocyte homologue protein 2b (Rh2b). First, we identified S3233 as the sole phosphoacceptor site in the CPD for in vitro phosphorylation by parasite extract. We provide several lines of evidence that this phosphorylation is mediated by Plasmodium casein kinase 2 (CK2): phosphorylation is cAMP independent, utilizes ATP as well as GTP as phosphate donors, is inhibited by heparin and tetrabromocinnamic acid, and is mediated by purified PfCK2. We raised a phospho-specific antibody and showed that S3233 phosphorylation occurs in the parasite prior to host cell egress. We analyzed the spatiotemporal aspects of this phosphorylation using immunoprecipitated endogenous Rh2b and minigenes expressing the cytoplasmic domain either at the plasmamembrane or at the rhoptry membrane. Phosphorylation of Rh2b is not spatially restricted to ither plasma or rhoptry membrane and most likely occurs before Rh2b is translocated from the rhoptry neck to the plasma membrane.

Source: BJ Cell - April 2, 2013 Category: Biochemistry Authors: K Engelberg, A S Paul, B Prinz, M Kono, W Ching, D Heincke, T Dobner, T Spielmann, M Duraisingh, T Wolf Gilberger Tags: BJ Disease Source Type: research