Poster Presentation The 45th Lorne Conference on Protein Structure and Function 2020

Cryo-EM studies of the AAA+ ATPase p97 in Plasmodium falciparum (#147)

George Kobakhidze 1 , Ashish Sethi 1 , Sepideh Valimehr 1 , Nazanin Mohebali 1 , Isabelle Rouiller 1
  1. Bio21 Institute, University of Melbourne, Parkville, VICTORIA, Australia

In 2017, the World Health Organisation estimated over 435,000 deaths caused by malaria. One of the major culprits, Plasmodium falciparum, is responsible for 93% of malaria deaths in Africa. We propose to study the structure of the protein p97 and its viability as a target to treat malaria. The hexameric AAA+ ATPase p97 is a highly conserved essential protein involved in various activities related to protein homeostasis. It is also an important component of the endoplasmic reticulum-associated degradation (ERAD) pathway. p97 has been recognized as an emerging viable target against cancer and viral infections. The main principle involves inhibiting p97 to cause proteotoxic stress to a cell resulting in apoptosis. Our research aims to extend this principle to malaria. We believe it would be a viable target as the ERAD pathway in protozoans is more sensitive compared to higher eukaryotes. The aim of this study is to characterise the structure of homologous p97 proteins found in P. falciparum using cryo-electron microscopy (cryo-EM). Structural analysis can then allow for discovering inhibitors specific to P. falciparum p97. Two genes were identified in P. falciparum using a BLAST query with 65.7% and 54.1% sequence identity to human p97. Using I-TASSER, we obtained putative structural models of the two Plasmodium proteins. So far, the project has involved optimizing the expression and purification of the proteins. Differences in key amino acid residues and structural features between human and P. falciparum p97 can allow us to design inhibitors specific to the latter. The selective targeting of the p97 protein is a novel concept with promising applications. The success of the project could be met with future studies in antiparasitic drug design in an effort to combat malaria and other serious diseases.