Biophysical analysis of Plasmodium falciparum Hsp70-Hsp90 organising protein (PfHop) reveals a monomer that is characterised by folded segments connected by flexible linkers

PLoS One. 2020 Apr 28;15(4):e0226657. doi: 10.1371/journal.pone.0226657. eCollection 2020.

Abstract

Plasmodium falciparum causes the most lethal form of malaria. The cooperation of heat shock protein (Hsp) 70 and 90 is thought to facilitate folding of select group of cellular proteins that are crucial for cyto-protection and development of the parasites. Hsp70 and Hsp90 are brought into a functional complex that allows substrate exchange by stress inducible protein 1 (STI1), also known as Hsp70-Hsp90 organising protein (Hop). P. falciparum Hop (PfHop) co-localises and occurs in complex with the parasite cytosolic chaperones, PfHsp70-1 and PfHsp90. Here, we characterised the structure of recombinant PfHop using synchrotron radiation circular dichroism (SRCD) and small-angle X-ray scattering. Structurally, PfHop is a monomeric, elongated but folded protein, in agreement with its predicted TPR domain structure. Using SRCD, we established that PfHop is unstable at temperatures higher than 40°C. This suggests that PfHop is less stable at elevated temperatures compared to its functional partner, PfHsp70-1, that is reportedly stable at temperatures as high as 80°C. These findings contribute towards our understanding of the role of the Hop-mediated functional partnership between Hsp70 and Hsp90.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Crystallography, X-Ray
  • Heat-Shock Proteins / chemistry*
  • Humans
  • Malaria, Falciparum / parasitology
  • Models, Molecular
  • Plasmodium falciparum / chemistry*
  • Protein Folding
  • Protein Multimerization
  • Protein Structure, Secondary
  • Protozoan Proteins / chemistry*
  • Recombinant Proteins / chemistry

Substances

  • Heat-Shock Proteins
  • PfHop protein, Plasmodium falciparum
  • Protozoan Proteins
  • Recombinant Proteins

Grants and funding

1. IK, Sigrid Jusélius Foundation; https://sigridjuselius.fi/en/ 2. AS, L1/402/14–1; Deutsche Forchungsgemeinshaft; https://www.validate-network.org/event/german-african-cooperation-projects-in-infectiology-dfg 3. AS; 75464; 92598; National Research Foundation/Department of Science & Innovation of South Africa; https://www.nrf.ac.za/ 3. TZ; 111989; National Research Foundation of South Africa; www.nrf.ac.za