Comparative Characterization of Plasmodium falciparum Hsp70-1 Relative to E. coli DnaK Reveals the Functional Specificity of the Parasite Chaperone

Publication year: 2020
Authors: Lebepe C. 1, Matambanadzo P. 1, Makhoba X. 2, Achilonu I. 3, Zininga T. 1,4, Shonhai A. 1,*

1 - Department of Biochemistry, School of Mathematical & Natural Sciences, University of Venda, Thohoyandou 0950, South Africa

2 - Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria 0028, South Africa
3 - Protein Structure-Function Research Unit, School of Molecular and Cell Biology, University of the Witwatersrand, Johannesburg 2050, South Africa
4 - Department of Biochemistry, Stellenbosch University, Stellenbosch 7602, South Africa
Published in: Biomolecules 2020, Vol. 10(6), p. 856
doi: 10.3390/biom10060856

Hsp70 is a conserved molecular chaperone. How Hsp70 exhibits specialized functions across species remains to be understood. Plasmodium falciparum Hsp70-1 (PfHsp70-1) and Escherichia coli DnaK are cytosol localized molecular chaperones that are important for the survival of these two organisms. In the current study, we investigated comparative structure-function features of PfHsp70-1 relative to DnaK and a chimeric protein, KPf, constituted by the ATPase domain of DnaK and the substrate binding domain (SBD) of PfHsp70-1. Recombinant forms of the three Hsp70s exhibited similar secondary and tertiary structural folds. However, compared to DnaK, both KPf and PfHsp70-1 were more stable to heat stress and exhibited higher basal ATPase activity. In addition, PfHsp70-1 preferentially bound to asparagine rich peptide substrates, as opposed to DnaK. Recombinant P. falciparum adenosylmethionine decarboxylase (PfAdoMetDC) co-expressed in E. coli with either KPf or PfHsp70-1 was produced as a fully folded product. Co-expression of PfAdoMetDC with heterologous DnaK in E. coli did not promote folding of the former. However, a combination of supplementary GroEL plus DnaK improved folding of PfAdoMetDC. These findings demonstrated that the SBD of PfHsp70-1 regulates several functional features of the protein and that this molecular chaperone is tailored to facilitate folding of plasmodial proteins.

MP-SPR keywords: ADP, affinity, ATP, chaperones, interaction, malaria, peptides, protein