THE GENE ENCODING TOPOISOMERASE-I FROM THE HUMAN MALARIA PARASITE PLASMODIUM-FALCIPARUM

Part of the topoisomerase I (TopoI)-encoding gene from Plasmodium falc iparum (Pf) was isolated by PCR from cDNA using oligodeoxyribonucleoti des modelled on the highly conserved regions of sequence from other sp ecies. The entire TopoI gene was obtained by screening a Pf K1 HindIII -EcoRI genomic library in lambda NM1149 with a random-labeled heterolo gous probe from the Saccharomyces cerevisiae TopoI gene. DNA sequence analysis revealed an open reading frame of 2520 nt encoding a deduced protein of 839 amino acids (aa) with no detectable introns. The Pf Top oI aa sequence has about 40% identity with most eukaryotic TopoI homol ogues. The gene is located as a single copy on chromosome 5 and Northe rn analysis identified a transcript of 3.8 kb.