Protein domains rich in asparagine and glutamine often form amyloid structures. The malarial parasite Plasmodium falciparum has a genome significantly enriched in asparagine, and almost 25% of P. falciparum proteins have domains predicted to form amyloid conformations. The pathological state of the disease occurs when the parasite infects host erythrocytes. There are a number of asparagine-rich proteins exported out of the vacuole formed by the parasite into the surrounding red blood cell, yet the role of these proteins is not well understood. Additionally, there are a high number of heat shock protein 40 kDa (Hsp40) homologs secreted into the infected erythrocyte, presumably to help fold these low complexity proteins. The goal of this proposal is to understand the contribution of asparagine-rich proteins and Hsp40 homologs in the remodeling of infected erythrocytes. This will be accomplished by (1) characterizing the folding and amyloidogenic nature of exported P. falciparum proteins, (2) establishing the influence of Hsp40 homologs in the folding of characteristic asparagine-rich P. falciparum proteins, and (3) examining the amyloidogenicity of asparagine-rich proteins in vitro and in vivo. Because yeast expressing aggregation-prone proteins display distinct phenotypes, S. cerevisae will be used as an expression platform for much of this proposal. Yeast also provide an excellent system to investigate chaperone activity, and therefore will be used to assess the contribution of Hsp40 homologs to protein folding in infected erythrocytes. Additionally, the ability of asparagine-rich parasite proteins to form fibrils in vitro will be investigated. Infected erythrocytes will also be analyzed to look for the presence of amyloid fibrils.
Infection by P. falciparum, the most deadly malaria parasite, results in approximately two million deaths a year. In order to develop successful vaccines against this parasite, it is important to fully understand the remodeling of infected erythrocytes and the proteins involved in this process, which leads to the clinical symptoms and mortality of the disease.
| Herman, Jonathan D; Pepper, Lauren R; Cortese, Joseph F et al. (2015) The cytoplasmic prolyl-tRNA synthetase of the malaria parasite is a dual-stage target of febrifugine and its analogs. Sci Transl Med 7:288ra77 |
