Author(s): Matambo TS, Odunuga OO, Boshoff A, Blatch GL
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Abstract Plasmodium falciparum heat shock protein (PfHsp70) has been proposed to be involved in the cytoprotection of the malaria parasite through its action as a molecular chaperone. However, the biochemical and chaperone properties of PfHsp70 have not been elucidated. The heterologous overproduction of P. falciparum proteins in Escherichia coli is problematic because of its AT-rich genome and the usage of codons that are rarely used in E. coli. In this paper, we describe the successful overproduction of (His)(6)-PfHsp70 in E. coli using the pQE30 expression vector system. Initial experiments with E. coli [pQE30/PfHsp70] resulted in the overproduction of the full-length protein and truncated derivatives. The RIG plasmid, which encodes tRNAs for rare codons, was engineered into the E. coli [pQE30/PfHsp70] strain, resulting in significant reduction of the truncated (His)(6)-PfHsp70 derivatives and improved yields of the full-length protein. (His)(6)-PfHsp70 was successfully purified using nickel-chelating Sepharose affinity chromatography and its biochemical properties were determined. The V(max), K(m), and k(cat) for the basal ATPase activity of (His)(6)-PfHsp70 were found to be 14.6 nmol/min/mg, 616.5 microM, and 1.03 min(-1), respectively. Gel filtration studies indicated that (His)(6)-PfHsp70 existed largely as a monomer in solution. This is the first study to biochemically describe PfHsp70 and establishes a foundation for future studies on its chaperone properties.
This article was published in Protein Expr Purif
and referenced in Journal of Proteomics & Bioinformatics