title: 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.
authors.affiliation: Malaria Group, International Centre for Genetic Engineering and Biotechnology, P. O. Box 10504, Aruna Asaf Ali Road, New Delhi, 110067, India.
authors.forename: Leila
authors.initials: L
authors.lastname: Tajedin
authors.affiliation: Malaria Group, International Centre for Genetic Engineering and Biotechnology, P. O. Box 10504, Aruna Asaf Ali Road, New Delhi, 110067, India.
authors.forename: Mohammed
authors.initials: M
authors.lastname: Tarique
authors.affiliation: Malaria Group, International Centre for Genetic Engineering and Biotechnology, P. O. Box 10504, Aruna Asaf Ali Road, New Delhi, 110067, India. renu@icgeb.res.in.
authors.forename: Renu
authors.initials: R
authors.lastname: Tuteja
mesh_terms: D021581:Active Transport, Cell Nucleus; D000255:Adenosine Triphosphate / Q000378:metabolism; D002467:Cell Nucleus / Q000201:enzymology; D003001:Cloning, Molecular; D003593:Cytoplasm / Q000201:enzymology; D004247:DNA / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D006868:Hydrolysis; D007700:Kinetics; D008018:Life Cycle Stages; D008970:Molecular Weight; D009690:Nucleic Acid Conformation; D010963:Plasmodium falciparum / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D011485:Protein Binding; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D017422:Sequence Analysis, DNA; D051758:Transcription Factor TFIIH / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D051759:Xeroderma Pigmentosum Group D Protein / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D015800:Protozoan Proteins; D011994:Recombinant Proteins; D051758:Transcription Factor TFIIH; D000255:Adenosine Triphosphate; D004247:DNA; D051759:Xeroderma Pigmentosum Group D Protein
keywords: ATPase activity; Helicase activity; Pfp44; Plasmodium falciparum homologue XPD; TFIIH