Plasmodium falciparum XPD translocates in 5′ to 3′ direction, is expressed throughout the blood stages, and interacts with p44

Abstract

XPD helicase, a TFIIH subunit, is essential for several processes including transcription, NER, cell cycle regulation, and apoptosis in eukaryotes. Another component of TFIIH, namely p44, is among the well-known interacting partners of XPD and is vital in regulating the helicase activities of latter. However, none of the above mentioned proteins have been functionally characterized in Plasmodium falciparum. Consequently, in this study, we performed detailed studies on XPD and its interacting partner, p44, from P. falciparum 3D7 strain. Accordingly, we expressed and purified recombinant PfXPD and its fragments and Pfp44 proteins and characterized the enzymatic activities of PfXPD and its fragments. The in vivo stage-specific expression and subcellular localizations of PfXPD and Pfp44 proteins were studied using the specific antibodies in the intraerythrocytic developmental stages of P. falciparum 3D7 strain. Our results suggest that PfXPD displays the characteristic ssDNA-dependent ATPase and 5'-3' DNA helicase activities. We also report the existence of two high molecular weight forms of p44 in P. falciparum 3D7 strain. Both PfXPD and Pfp44 colocalize in the nucleus and interact with each other, which suggest that they are most likely components of the same complex apparently, TFIIH. Furthermore, during trophozoite and schizont stages, both proteins exhibit a distinct cytoplasmic distribution pattern which implies that PfXPD and Pfp44 might also be involved in other functions. These studies will aid in understanding the basic biology of malaria parasite.

Comparative insight into nucleotide excision repair components of Plasmodium falciparum

“…The interacting partner analysis for PfXPD shows that it interacts with a number of proteins such as polymerases, p44, p34 and Rad25 (human XPB homologue) ( Table 2). The interaction of PfXPD and Pfp44 in database is in agreement with our experimental work [36].…”

Plasmodium falciparum specific helicase 3 is nucleocytoplasmic protein and unwinds DNA duplex in 3′ to 5′ direction

“…The characterization of few P . falciparum helicases has been reported previously 30 , 51 – 54 but still the biochemical characterization of other helicases is required for better understanding of the role of these vital enzymes in the parasite. Here we report the biochemical characterization of a novel helicase that is specific to the malaria parasite.…”

Turn of the screw—helicases everywhere

“…The mammalian homologue has been shown to work in splicing and mRNA transport to the cytoplasm. The contribution by Tuteja et al (2015) in the current issue investigates now the rice homologue of the UAP56 helicase type. They show that the transcripts for this protein accumulate in response to salt stress (probably mediated by the phytohormone abscisic acid).…”

“…Two contributions from the current issue highlight the importance of these versatile and somewhat promiscuous proteins in quite different organisms-the parasite Plasmodium and the Angiosperm rice. They also emphasize the impact of helicases for both medical and agricultural applications.The work by Tajedin et al (2015) in the current issue was motivated by the question how Plasmodium falciparum, the causing agent of malaria, can acquire drug resistance. In addition to generic mechanisms such as drug export or degradation, mutations in the DNA repair machinery have been identified as important factor.…”

“…The work by Tajedin et al (2015) in the current issue was motivated by the question how Plasmodium falciparum, the causing agent of malaria, can acquire drug resistance. In addition to generic mechanisms such as drug export or degradation, mutations in the DNA repair machinery have been identified as important factor.…”