Evolution and phylogeny of the heterogeneous cytosolic SSU rRNA genes in the genus Plasmodium
Evolution and phylogeny of the heterogeneous cytosolic SSU rRNA genes in the genus Plasmodium
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DOI：
10.1016/j.ympev.2008.01.031
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发表时间：
2008-04-01
影响因子：
4.1
通讯作者：
Hashimoto, Tetsuo
中科院分区：
文献类型：
--
作者：
Nishimoto, Yuriko;Arisue, Nobuko;Hashimoto, Tetsuo
与其他真核生物不同，疟原虫属中的疟疾寄生虫具有在不同发育阶段表达的胞质（细胞-）SSU rRNA（18 S rRNA）基因的结构和功能不同的旁系同源拷贝。在恶性疟原虫、间日疟原虫和伯氏疟原虫中，A型细胞型SSU rRNA在无性阶段表达，而S型在子孢子阶段表达。第三种类型（O型）已在间日疟原虫中描述。它只在蚊子的卵囊阶段表达。最近，已经表明疟原虫中异质细胞-SSU rRNA的维持可以被建模为强纯化选择下的出生和死亡过程[Rooney，A. P.，2004.顶复门中功能异质性18 S rRNA基因的进化和维持机制摩尔生物进化21，1704-1711]。在这项研究中，我们进行了详细的系统发育分析疟原虫细胞SSU rRNA，特别强调在猴疟原虫物种的多拷贝基因的进化。我们对来自所有非洲猿类疟原虫物种（刚德氏疟原虫）和亚洲猿类疟原虫物种（脆性疟原虫、Coatneyi疟原虫、Inui疟原虫、Hylobati疟原虫、菲尔德疟原虫、猿卵疟原虫和食蟹猴疟原虫）的细胞-SSU rRNA基因的旁系同源拷贝进行了测序。有趣的是，所有亚洲猿类疟原虫物种都有一个类似S型的基因和几个类似A型的基因。比对分析首次证明，在V7可变区靠近茎43处的大约50个残基的插入仅由亚洲猴疟原虫物种的S型样序列和间日疟原虫的S型和O型序列共享。我们全面分析了目前数据库中疟原虫属的所有细胞-SSU rRNA序列。疟原虫属的所有公开的细胞-SSU rRNA序列的系统发育分析清楚地表明，基因复制事件引起的A型和S型样序列独立地发生至少三次在疟原虫的进化，支持这一假设，这些基因的进化根据出生和死亡的模式。(C)2008年爱思唯尔公司All rights reserved.
Unlike other eukaryotes, malaria parasites in the genus Plasmodium have structurally and functionally different paralogous copies of the cytosolic (cyto-) SSU rRNA (18S rRNA) gene that are expressed at different developmental stages. In P. falciparum, P. vivax, and P. berghei, A-type cyto-SSU rRNA is expressed in asexual stage, while S-type in sporozoite stage. A third type (O-type) has been described in P. vivax. It is expressed only in oocyst stage in the mosquito. Recently, it has been shown that the maintenance of heterogeneous cyto-SSU rRNAs in Plasmodium can be modeled as a birth-and-death process under strong purifying selection [Rooney, A.P., 2004. Mechanisms underlying the evolution and maintenance of functionally heterogeneous 18S rRNA genes in Apicomplexans. Mol. Biol. Evol. 21, 1704-1711]. In this study, we performed detailed phylogenetic analyses of Plasmodium cyto-SSU rRNAs with special emphasis on the evolution of multi-copy genes in simian Plasmodium species. We sequenced paralogous copies of the cyto-SSU rRNA genes from all African simian Plasmodium species, P. gonderi, and Asian simian Plasmodium species, P. fragile, P. coatneyi, P. inui, P. hylobati, P. fieldi, P. simiovale, and P. cynomolgi. Interestingly, all Asian simian Plasmodium species have a single S-type-like gene and several A-type-like genes. Alignment analysis demonstrated for the first time that an approximately 50-residue insertion in the V7 variable region near the stem 43 is shared exclusively by the S-type-like sequences of the Asian simian Plasmodium species and the S- and O-type sequences of P. vivax. We comprehensively analyzed all cyto-SSU rRNA sequences of the genus Plasmodium currently available in the database. Phylogenetic analyses of all publicly available cyto-SSU rRNA sequences for the genus Plasmodium clearly demonstrated that gene duplication events giving rise to A- and S-type-like sequences took place independently at least three times ill the Plasmodium evolution, supporting the hypothesis that these genes evolve according to a birth-and-death model. (C) 2008 Elsevier Inc. All rights reserved.