Identification and characterization of DNA endonucleases in Plasmodium falciparum 3D7 clone

• Published in: Malaria Journal
• Main Authors: Ning Jiang, Zhiwei Tu, Yiwei Zhang, Jianping Li, Ying Feng, Na Yang, Xiaoyu Sang, Qijun Chen
• Format: Article in Journal/Newspaper
• Language: English
• Published: BMC 2018
• Subjects: Malaria; Plasmodium falciparum; DNA endonuclease; Catalysis; Arctic medicine. Tropical medicine; RC955-962; Infectious and parasitic diseases; RC109-216; Arctic
• Online Access: https://doi.org/10.1186/s12936-018-2388-0; https://doaj.org/article/b29ccf6bdbe14d7a981201f920728876

Abstract Background Plasmodium falciparum is the most virulent parasite of the five Plasmodium species that cause human malaria, and biological analysis of the parasite is critical for the development of novel strategies for disease control. DNA endonucleases are important for maintaining the biological activity, gene stability of the parasite and interaction with host immune systems. In this study, ten sequences of DNA endonucleases were found in the genome of P. falciparum 3D7 clone, seven of them were predicted to contain an endonuclease/exonuclease/phosphatase (IPR005135) domain which plays an important role in DNA catalytic activity. The seven DNA endonucleases of P. falciparum were systematically investigated. Methods Plasmodium falciparum 3D7 clone was cultured in human O+ RBCs, RNA was extracted at 8, 16, 24, 32, 40, and 48 h post invasion and real-time quantitative PCR was carried out to analyse the transcription of the seven DNA endonuclease genes in asexual stages. Immunofluorescence assay was carried out to confirm the location of the encoded proteins expressed in the erythrocytic stages. Finally, the catalytic activity of the DNA nucleases were tested. Results Of the seven proteins analysed, two proteins were not soluble. Fragments derived from the rest five endonuclease sequences were successfully expressed as soluble proteins, and which were used to generate antisera for protein localization. The proteins were all located in the nucleus at ring and trophozoite stages. While at schizont stage, proteins encoded by PF3D7_1238600, PF3D7_0107200 and PF3D7_0319200 were in the punctuated forms in the parasite most likely around nuclei of the merozoites. But the proteins encoded by PF3D7_0305600 and PF3D7_1363500 were distributed around the infected erythrocyte membrane. The enzymatic activity of the recombinant GST-PF3D7_1238600 was very efficient without divalent iron, while the activity of the rest four enzymes was iron dependent. Further, divalent irons did not show any specific enhancement on the ...