Oguariri Raphael M, Dunn Josephine M, Golightly Linnie M
Department of Medicine, Division of International Medicine and Infectious Diseases, Weill Medical College of Cornell University, New York, NY 10021, USA.
Mol Biochem Parasitol. 2006 Apr;146(2):163-72. doi: 10.1016/j.molbiopara.2005.12.004. Epub 2006 Jan 4.
Development of sexual stage parasites within the mosquito vector is a crucial step in the transmission of Plasmodium parasites. The expression of the P25 and P28 proteins on the surface of Plasmodium parasites in the mosquito midgut is required for development and hence disease transmission. 3' gene-flanking sequences are essential for expression of these critical proteins but the nucleotide elements required are poorly defined. Transient gene transfection experiments using constructs containing deletions of the 3' gene-flanking region of the Plasmodium falciparum P25 homologue, pfs25, reveal that elements necessary for protein expression are within 315 nucleotides (nt) of the stop codon. A T-rich region 137-231 nt from the stop codon is required for expression. The nonamer AATAAAATG, 360 nt downstream from the stop codon, enhances expression by 51 percent. Using 3' RACE analysis, multiple polyadenylation sites from endogenous and plasmid-derived pfs25 transcripts were identified. Dissimilarities between the identified elements and those of metazoans support the hypothesis that definition of P25/28 3' gene regulatory processes may eventually permit the development of agents which block malaria transmission but are non-toxic to humans.
疟原虫在蚊媒体内发育成性阶段寄生虫是疟原虫传播过程中的关键一步。疟原虫在蚊中肠的表面表达P25和P28蛋白是其发育以及疾病传播所必需的。3'基因侧翼序列对于这些关键蛋白的表达至关重要，但所需的核苷酸元件尚不明确。使用含有恶性疟原虫P25同源物pfs25的3'基因侧翼区域缺失的构建体进行瞬时基因转染实验，结果表明蛋白质表达所需的元件位于终止密码子的315个核苷酸（nt）范围内。终止密码子下游137 - 231 nt处的富含T的区域是表达所必需的。终止密码子下游360 nt处的九聚体AATAAAATG可使表达提高51%。使用3' RACE分析，鉴定出了内源性和质粒衍生的pfs25转录本的多个聚腺苷酸化位点。所鉴定的元件与后生动物的元件之间的差异支持了这样一种假说，即对P25/28 3'基因调控过程的定义最终可能会促使开发出能够阻断疟疾传播但对人类无毒的药物。
