High-efficiency production of Plasmodium falciparum lactate dehydrogenase from bacteria and its functional characterization

Plasmodium falciparum is the pathogen responsible for 90 % of all malaria cases and is associated with severe complications and the highest fatality rate. Plasmodium falciparum lactate dehydrogenase (PfLDH) is a useful biomarker for the treatment and diagnosis of malaria; however, its use is limited by low production yield and functional activity. In this study, using Escherichia coli Rosetta(DE3) strain specialized for eukaryotic protein expression, we successfully expressed and purified PfLDH without a codon optimization process, which has previously been considered essential for protein expression in E. coli strains. The induction temperature and time were optimized for the overexpression of PfLDH using the transformed strain, and 31.3 mg/L of PfLDH protein was successfully purified using immobilized metal affinity chromatography. The physical properties of the purified PfLDH were assessed by verifying tetramer formation, and the functional properties of PfLDH were assessed with a colorimetric assay using a substrate that reacts with PfLDH. Subsequently, the binding of PfLDH with a DNA aptamer, which is known to specifically bind to PfLDH, was verified. These results are expected to provide important suggestions for research on obtaining large amounts of PfLDH from bacteria, thereby facilitating the treatment and diagnosis of malaria.