Analysis of transcriptomes of human malaria parasite Plasmodium falciparum using full-length enriched library: identification of novel genes and diverse transcription start sites of messenger RNAs.

Now that the sequencing of the complete genome of the human malaria parasite Plasmodium falciparum is now underway, importance of analyses of complementary DNAs (cDNAs) is looming up. We constructed a full-length-enriched cDNA library from erythrocytic stage P. falciparum using the 'oligo-capping' method (Nucleic Acids Res. 29 (2001) 70). In this report we describe the novel genes identified using this library and detailed characterization of transcriptional start site of knob-associated histidine rich protein gene. Contrary to the previous report we conclude all the transcripts of plasmodium genes have diverse start sites. Sequence comparisons between the cDNAs and the complete sequences of chromosomes 2 identified three novel genes that had been missed by computational predictions. Moreover, analysis of transcriptional start sites revealed that the average length of the 5' untranslated region was 346 nt, which is much longer than that in humans. The transcriptional start sites of all the genes studied were far more diverse than those of human genes. These observations may reflect unique mechanism(s) of gene expression in this organism, which has an extremely AT-rich genome.