Inhibition of unwinding and ATPase activities of Plasmodium falciparum Dbp5/DDX19 homolog.

We have recently reported the isolation and characterization of Plasmodium falciparum Dbp5/DDX19 homolog PfD66 and the results indicate that it contains ATP-dependent bipolar DNA and RNA unwinding activity, intrinsic nucleic acid-dependent ATPase and RNA-binding activities. In the present study we report the effect of a number of compounds such as actinomycin D, aphidicolin, camptothecin, cyclophosphamide, 4',6'-di-amidino-2-phenylindole (DAPI), daunorubicin, distamycin, ethidium bromide, ellipticine, genistein, mitoxantrone, nalidixic acid, netropsin, nogalamycin, novobiocin and VP-16 on the DNA unwinding and ATPase activities of PfD66. The results indicate that DAPI, ethidium bromide, netropsin and nogalamycin efficiently inhibited the helicase and ATPase activities of PfD66. These studies will make an important contribution in understanding the mechanism of DNA unwinding by Plasmodium falciparum helicase PfD66.