Novel RuvB nuclear ATPase is specific to intraerythrocytic mitosis during schizogony of Plasmodium falciparum.
RuvB protein belongs to AAA+ family of enzymes involved in diverse cellular activities. In addition to the annotated two RuvB proteins in Plasmodium falciparum database, we report that a third RuvB protein is also present. The amino acid sequence analysis has revealed that P. falciparum RuvB3 (PfRuvB3) possesses Walker motif A, Walker motif B, sensor I and sensor II conserved motifs similar to yeast and human RuvB like proteins. The phylogenetic analysis revealed that PfRuvB3 is closely related to yeast RuvB like proteins which are essential for the survival of yeast. The biochemical characterization of recombinant PfRuvB3 confirms its ssDNA dependent ATPase activity. Using the truncated derivatives we show that Walker motif A is essential for the enzymatic activity of PfRuvB3. Using the immunodepletion assays we further show that the ATPase activity is attributable to PfRuvB3 protein. The endogenous P. falciparum RuvB3 contains the characteristic ATPase and some DNA helicase activities. The confocal microscopy analysis showed that this protein is mainly expressed during intraerythrocytic schizont stages of the parasite and is localized to the nuclear region. Once merozoite comes out from schizont, PfRuvB3 protein distinctly relocalized to the subnuclear region. The co-localization studies with a nucleolar marker PfNop1 further suggest that in P. falciparum RuvB3 localizes into a discrete nuclear compartment. On the basis of these studies it can be speculated that P. falciparum RuvB3 is most likely required for intraerythrocytic schizogony.
International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, India.
Moaz
M
Ahmad
Shailja
S
Singh
Farhat
F
Afrin
Renu
R
Tuteja
D000251:Adenosine Triphosphatases / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D002467:Cell Nucleus / Q000201:enzymology* / Q000378:metabolism; D004789:Enzyme Activation; D004912:Erythrocytes / Q000469:parasitology*; D005786:Gene Expression Regulation; D018613:Microscopy, Confocal; D008938:Mitosis; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D010802:Phylogeny; D010963:Plasmodium falciparum / Q000201:enzymology* / Q000235:genetics / Q000472:pathogenicity; D021381:Protein Transport; D015800:Protozoan Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism; D052939:Schizonts / Q000166:cytology / Q000201:enzymology; D020539:Sequence Analysis, Protein; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity
D009687:Nuclear Proteins; D015800:Protozoan Proteins; D000251:Adenosine Triphosphatases