Positive and negative effects of deletions and mutations within the 5' flanking sequences of Plasmodium falciparum DNA polymerase delta.

The DNA polymerase delta gene from Plasmodium falciparum is associated with a 1.76 kb 5' untranslated region and a promoter containing long homopolymeric (dA:dT) tracts and intrinsic DNA curvature. Here, a comprehensive deletion and mutational analysis of the DNA Pol(delta) upstream sequences has been undertaken to define functionally important regions. Removal of promoter-proximal DNA was shown to upregulate luciferase reporter gene expression and the ATG-proximal portion of the 5' untranslated region was required in conjunction with the promoter for reporter activity. In contrast to the ATG-proximal 5' untranslated region, deletion of the central part of the untranslated region had a positive effect on expression. Disruption of a homopolymeric (dA:dT) tract adjacent to the main transcription start site both derepressed gene expression and reduced the intrinsic curvature of DNA fragments containing this sequence.