Malaria
It is well known that the parasite experiences a temperature shock of over 10°C during its entry in the vertebrate host. Furthermore, during febrile episodes in the patient the parasite is exposed to a heat shock (up to 41°C) due to rise in the body temperature of the host. How does the parasite react to these rapid temperature fluctuations? What are the protective mechanisms employed by the parasite to counter cellular damage? Experiments performed in my group in the last 10 year have shed some light on these mechanisms. Using biochemical, cellular as well as proteomic approaches we have characterized the expression, localization and complexes of abundant chaperones of the class Hsp40, Hsp60, Hsp70, Hsp90 and Hsp100 expressed by the parasite in human red blood cells. Our studies show an essential role for Hsp90 of the parasite and implicate it as a potential drug target against malaria. Pharmacological inhibitors specific to Hsp90 are currently being examined as candidate drugs against malaria. (Pallavi R et al., JBC 2010, Pallavi R et al., Plos One 2011, Acharya P et al., Proteomics CA 2009) The red blood cells undergo extensive remodelling during the course of infection. The cytosol of RBC acquires number of membranous compartments such as Maurers clefts and the cell membrane undergoes modifications to form protrusions know as knobs on its surface. Knobs make erythrocytes rigid and cytoadherent and are largely responsible for the severity of the disease. To bring about these changes parasite exports multiple proteins into the host cell. It is a challenging task for the parasite as it resides in a vacuole inside the RBC and the proteins need to transverse multiple membranes in order to reach their final destinations. It is being speculated that this process of protein trafficking requires an intricate involvement of chaperones owing to their ability to fold, unfold and stabilize proteins. Also, the exported proteins (especially the components of knobs) have a tendency to remain in a disordered conformation due to the presence of homorepeats and prion-like domains in their primary structure. A major group among the class of exported proteins is constituted by chaperones and surprisingly all of them belong to the Hsp40 family. We are interested in understanding the specific roles played by these Hsp40s in the process of host cell remodelling. Towards this, we have generated antisera against some exported Hsp40s and carry out in vivo experiments involving immunofluorescence and immunoprecipitation analysis to determine the localization and interacting partners of the protein respectively.
