Unusual molecular evolution of an Adh pseudogene in Drosophila.
Unusual molecular evolution of an Adh pseudogene in Drosophila.
复制标题
果蝇中 Adh 假基因的异常分子进化。
DOI：
10.1093/oxfordjournals.molbev.a040125
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发表时间：
1994
影响因子：
10.7
通讯作者：
Yum,J
中科院分区：
文献类型：
--
作者：
Sullivan,DT;Starmer,WT;Curtiss,SW;Menotti-Raymond,M;Yum,J
果蝇属repleta组的Adh基因座含有一个或两个复制事件的产物。在迄今为止所研究的所有物种中，其中一个Adh基因现在是假基因，因为突变使这些基因不能被翻译成功能性的乙醇脱氢酶。这些假基因在标准Adh基因位置含有内含子;因此，它们的起源不是通过反转录转座。来自repleta组的每个亚组的代表的Adh-psi的序列的比较揭示Adh假基因存在于每个亚组中，并且密码子2处的突变和紧邻Adh-psi的5'区域中的缺失是所有物种共有的。因此，很可能导致假基因的翻译失活事件发生在组成repleta组的物种分化之前。我们研究了D. hydei等人发现，该转录具有与任何已知Adh基因不同的发育特征，不利用Adh启动子，并且起始于上游几乎12 kb的点。repleta组的物种内的Adh-psi的序列差异的比较表明，Adh-psi的外显子的进化速度大大低于基因间区域，只是略快于功能性Adh基因的外显子。第二，保留密码子的偏好性被发现在大多数物种的Adh-psi，和同义编码位置的取代大大超过非同义编码位置的取代。其他假定的假基因与repleta组Adh假基因的进化比较表明，果蝇中至少有一些假基因序列可能是通过目前尚不清楚的机制和/或影响而进化的。
The Adh locus in Drosophila species which are members of the repleta group contains products of one or two duplication events. In all species examined to date one of the Adh genes is now a pseudogene, since mutations have rendered these genes incapable of being translated into a functional alcohol dehydrogenase. These pseudogenes contain introns in the standard Adh gene position; hence, their origin is not by retrotransposition. Comparison of the sequences of the Adh-psi from representatives of each of the subgroups of the repleta group reveal that the Adh pseudogene is present in each subgroup and that mutations at codon 2 and a deletion in the region immediately 5' to Adh-psi are common to all species. Therefore, it is likely that the translational inactivation event that resulted in a pseudogene occurred before the divergence of the species that make up the repleta group. We have investigated the transcription of Adh-psi of D. hydei and have found that the transcription has a developmental profile dissimilar from any known Adh gene, does not utilize an Adh promoter, and is initiated at a point almost 12 kb upstream. Comparison of sequence divergence of Adh-psi within species of the repleta group reveals that rates of evolution of the exons of Adh-psi are substantially slower than intergenic regions and are only slightly faster than those of exons of functional Adh genes. Second, retention of codon bias is found in the Adh-psi of most species, and substitution at synonymous coding positions substantially exceeds substitution at nonsynonymous coding positions. Comparison of the evolution of other putative pseudogenes with repleta group Adh pseudogenes suggests that at least some pseudogene sequences in Drosophila may be evolving through mechanisms and/or under influences not presently understood.