Plasmodium falciparum Hep1 Is Required to Prevent the Self Aggregation of PfHsp70-3

PLoS One. 2016 Jun 2;11(6):e0156446. doi: 10.1371/journal.pone.0156446. eCollection 2016.

Abstract

The majority of mitochondrial proteins are encoded in the nucleus and need to be imported from the cytosol into the mitochondria, and molecular chaperones play a key role in the efficient translocation and proper folding of these proteins in the matrix. One such molecular chaperone is the eukaryotic mitochondrial heat shock protein 70 (Hsp70); however, it is prone to self-aggregation and requires the presence of an essential zinc-finger protein, Hsp70-escort protein 1 (Hep1), to maintain its structure and function. PfHsp70-3, the only Hsp70 predicted to localize in the mitochondria of P. falciparum, may also rely on a Hep1 orthologue to prevent self-aggregation. In this study, we identified a putative Hep1 orthologue in P. falciparum and co-expression of PfHsp70-3 and PfHep1 enhanced the solubility of PfHsp70-3. PfHep1 suppressed the thermally induced aggregation of PfHsp70-3 but not the aggregation of malate dehydrogenase or citrate synthase, thus showing specificity for PfHsp70-3. Zinc ions were indeed essential for maintaining the function of PfHep1, as EDTA chelation abrogated its abilities to suppress the aggregation of PfHsp70-3. Soluble and functional PfHsp70-3, acquired by co-expression with PfHep-1, will facilitate the biochemical characterisation of this particular Hsp70 protein and its evaluation as a drug target for the treatment of malaria.

MeSH terms

  • Cytosol
  • HSP70 Heat-Shock Proteins / genetics*
  • HSP70 Heat-Shock Proteins / metabolism
  • Humans
  • Malaria, Falciparum / genetics*
  • Malaria, Falciparum / parasitology
  • Mitochondria / genetics
  • Molecular Chaperones / genetics*
  • Molecular Chaperones / metabolism
  • Plasmodium falciparum / genetics*
  • Plasmodium falciparum / pathogenicity
  • Protein Aggregation, Pathological / genetics
  • Protein Binding
  • Protozoan Proteins / genetics*

Substances

  • HSP70 Heat-Shock Proteins
  • Molecular Chaperones
  • Protozoan Proteins

Grants and funding

This work was funded by grants from the National Research Foundation (NRF); grant number 87663 and Deutsche Forschungsgemeinschaft (DFG); grant number LI 402/14-1. D.O.N. is the recipient of academic development and training funds from Mwenge Catholic University, Moshi, Tanzania. S.J.B. is the recipient of an NRF Doctoral Innovation Scholarship.