Watanabe Junichi, Sasaki Masahide, Suzuki Yutaka, Sugano Sumio
Department of Parasitology, Institute of Medical Science, The University of Tokyo, 4-6-1 Shirokanedai, Minatoku, Tokyo 108-8639, Japan.
Gene. 2002 May 29;291(1-2):105-13. doi: 10.1016/s0378-1119(02)00552-8.
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.
鉴于人类疟原虫恶性疟原虫的全基因组测序正在进行中，互补DNA（cDNA）分析的重要性日益凸显。我们使用“oligo-capping”方法（《核酸研究》29（2001年）70）构建了来自恶性疟原虫红细胞期的全长富集cDNA文库。在本报告中，我们描述了使用该文库鉴定的新基因以及富含组氨酸的与结节相关蛋白基因转录起始位点的详细特征。与之前的报告相反，我们得出结论，疟原虫基因的所有转录本都有不同的起始位点。cDNA与2号染色体完整序列之间的序列比较鉴定出三个新基因，这些基因在计算预测中被遗漏。此外，转录起始位点分析表明，5'非翻译区的平均长度为346 nt，远长于人类。所有研究基因的转录起始位点比人类基因的转录起始位点更加多样。这些观察结果可能反映了这种基因组富含AT的生物体中独特的基因表达机制。
