Regulation of Plasmodium yoelii oocyst development by strain- and stage-specific small-subunit rRNA.
Regulation of Plasmodium yoelii oocyst development by strain- and stage-specific small-subunit rRNA.
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菌株和阶段特异性小亚基 rRNA 对约氏疟原虫卵囊发育的调节
作者：
Qi Y;Zhu F;Eastman RT;Fu Y;Zilversmit M;Pattaradilokrat S;Hong L;Liu S;McCutchan TF;Pan W;Xu W;Li J;Huang F;Su XZ
疟疾寄生虫的一个独特特征是在不同发育阶段结构不同的rRNA（rRNA）基因的差异转录：A型基因主要在无性阶段转录，而S型基因主要在有性阶段或蚊期表达。然而，不同的rRNA在调节阶段特异性寄生虫发育中的决定性功能证据仍然缺乏。在这里，我们进行遗传杂交的约氏疟原虫寄生虫与一个父母有卵囊发育缺陷（ODD）表型和另一个生产正常的卵囊，以确定基因（S）有助于ODD。在将带有绿色荧光蛋白基因的质粒导入寄生虫基因组并在小鼠中传代后，获得了具有ODD的亲本，其特征在于具有小卵囊和缺乏感染性子孢子。对48个将第6号染色体上含有S型基因（D型小亚基rRNA基因[D-ssu]）的片段与ODD连锁的杂交后代的全基因组微卫星基因型进行了数量性状位点分析。质粒整合位点、基因表达模式和基因敲除实验的精细作图表明，D-ssu基因的破坏导致ODD表型。有趣的是，引入D-SSU基因到相同的寄生虫株（自身），但不是到一个不同的亚种，显着影响或完全消融卵囊发育，这表明阶段和亚种（株）特异性调节卵囊发育的D-SSU。这项研究表明，约氏疟原虫D-ssu是正常的卵囊和子孢子发育所必需的，D-ssu序列的变化可以对寄生虫的发育产生显着的影响。疟疾寄生虫是唯一已知的在不同发育阶段表达结构不同的rRNA基因的生物。这些基因的差异表达表明它们在寄生虫复杂的生命周期中发挥着独特的作用。然而，不同rRNA在调节寄生虫发育中的决定性功能证据仍然缺乏或存在争议。在这里，我们首次在功能上证明了一个阶段特异性表达的D型小亚基rRNA基因（D-SSU）是蚊子体内约氏疟原虫卵囊发育所必需的。本研究还表明，D-ssu序列和/或转录时间的变化可能对寄生虫卵囊发育产生深远的影响。结果表明，除了蛋白质翻译，疟疾寄生虫的rRNA也调节寄生虫的发育和分化，在菌株特异性的方式，可以探索控制寄生虫的传播。疟疾寄生虫是唯一已知的在不同发育阶段表达结构不同的rRNA基因的生物体。这些基因的差异表达表明它们在寄生虫复杂的生命周期中发挥着独特的作用。然而，不同rRNA在调节寄生虫发育中的决定性功能证据仍然缺乏或存在争议。在这里，我们首次在功能上证明了一个阶段特异性表达的D型小亚基rRNA基因（D-SSU）是蚊子体内约氏疟原虫卵囊发育所必需的。本研究还表明，D-ssu序列和/或转录时间的变化可能对寄生虫卵囊发育产生深远的影响。结果表明，除了蛋白质翻译，疟疾寄生虫的rRNA也调节寄生虫的发育和分化，在菌株特异性的方式，可以探索控制寄生虫的传播。
ABSTRACT One unique feature of malaria parasites is the differential transcription of structurally distinct rRNA (rRNA) genes at different developmental stages: the A-type genes are transcribed mainly in asexual stages, whereas the S-type genes are expressed mostly in sexual or mosquito stages. Conclusive functional evidence of different rRNAs in regulating stage-specific parasite development, however, is still absent. Here we performed genetic crosses of Plasmodium yoelii parasites with one parent having an oocyst development defect (ODD) phenotype and another producing normal oocysts to identify the gene(s) contributing to the ODD. The parent with ODD—characterized as having small oocysts and lacking infective sporozoites—was obtained after introduction of a plasmid with a green fluorescent protein gene into the parasite genome and subsequent passages in mice. Quantitative trait locus analysis of genome-wide microsatellite genotypes of 48 progeny from the crosses linked an ~200-kb segment on chromosome 6 containing one of the S-type genes (D-type small subunit rRNA gene [D-ssu]) to the ODD. Fine mapping of the plasmid integration site, gene expression pattern, and gene knockout experiments demonstrated that disruption of the D-ssu gene caused the ODD phenotype. Interestingly, introduction of the D-ssu gene into the same parasite strain (self), but not into a different subspecies, significantly affected or completely ablated oocyst development, suggesting a stage- and subspecies (strain)-specific regulation of oocyst development by D-ssu. This study demonstrates that P. yoelii D-ssu is essential for normal oocyst and sporozoite development and that variation in the D-ssu sequence can have dramatic effects on parasite development. IMPORTANCE Malaria parasites are the only known organisms that express structurally distinct rRNA genes at different developmental stages. The differential expression of these genes suggests that they play unique roles during the complex life cycle of the parasites. Conclusive functional proof of different rRNAs in regulating parasite development, however, is still absent or controversial. Here we functionally demonstrate for the first time that a stage-specifically expressed D-type small-subunit rRNA gene (D-ssu) is essential for oocyst development of the malaria parasite Plasmodium yoelii in the mosquito. This study also shows that variations in D-ssu sequence and/or the timing of transcription may have profound effects on parasite oocyst development. The results show that in addition to protein translation, rRNAs of malaria parasites also regulate parasite development and differentiation in a strain-specific manner, which can be explored for controlling parasite transmission. Malaria parasites are the only known organisms that express structurally distinct rRNA genes at different developmental stages. The differential expression of these genes suggests that they play unique roles during the complex life cycle of the parasites. Conclusive functional proof of different rRNAs in regulating parasite development, however, is still absent or controversial. Here we functionally demonstrate for the first time that a stage-specifically expressed D-type small-subunit rRNA gene (D-ssu) is essential for oocyst development of the malaria parasite Plasmodium yoelii in the mosquito. This study also shows that variations in D-ssu sequence and/or the timing of transcription may have profound effects on parasite oocyst development. The results show that in addition to protein translation, rRNAs of malaria parasites also regulate parasite development and differentiation in a strain-specific manner, which can be explored for controlling parasite transmission.