Lyozin G T, Makarova K S, Velikodvorskaja V V, Zelentsova H S, Khechumian R R, Kidwell M G, Koonin E V, Evgen'ev M B
Institute of Cellular Biophysics, Pushino, Russia.
J Mol Evol. 2001 May;52(5):445-56. doi: 10.1007/s002390010174.
The Penelope element is the key element responsible for mobilization of other transposable elements in the course of hybrid dysgenesis in Drosophila virilis. Penelope has an unusually complex, highly variable organization in all studied species of the virlis group. Thc BRIDGE1 element from the fish Fugu rubripes is homologous to Penelope, and database searches detected additional homologous sequences among Expressed Sequence Tags from the flatworm Schistosoma mansonii and the nematode Ancylostoma caninum. Phylogenetic analysis shows that the reverse transcriptase of the Penelope group does not belong to any of the characterized major retroelement lineages, but apparently represents a novel branch of non-LTR retroelements. Sequence profile analysis results in the prediction that the C-terminal domain of the Penelope polyprotein is an active endonuclease related to intron-encoded endonucleases and the bacterial repair endonuclease UvrC, which could function as an integrase. No retroelements containing a predicted endonuclease of this family have been described previously. Phylogenetic analysis of Penelope copies isolated from several species of the virilis group reveals two subfamilies of Penelope elements, one of which includes full-length copies whose nucleotide sequences are almost identical, whereas the other one consists of highly diverged defective copies. Phylogenetic analysis of Penelope suggests both vertical transmission of the element and probable horizontal transfers. These findings support the notion that Penelope invasions occurred repeatedly in the evolution of the virilis group.
佩内洛普元件是在粗壮果蝇杂种不育过程中负责动员其他转座元件的关键元件。在所有已研究的粗壮果蝇组物种中，佩内洛普元件具有异常复杂、高度可变的结构。来自红鳍东方鲀的BRIDGE1元件与佩内洛普元件同源，数据库搜索在曼氏血吸虫和犬钩虫的表达序列标签中检测到了其他同源序列。系统发育分析表明，佩内洛普元件组的逆转录酶不属于任何已鉴定的主要逆转录元件谱系，而是显然代表了非LTR逆转录元件的一个新分支。序列谱分析结果预测，佩内洛普多聚蛋白的C末端结构域是一种与内含子编码的内切核酸酶和细菌修复内切核酸酶UvrC相关的活性内切核酸酶，它可以作为整合酶发挥作用。此前尚未描述过含有该家族预测内切核酸酶的逆转录元件。对从粗壮果蝇组的几个物种中分离出的佩内洛普元件拷贝进行的系统发育分析揭示了佩内洛普元件的两个亚家族，其中一个亚家族包括核苷酸序列几乎相同的全长拷贝，而另一个亚家族则由高度分化的缺陷拷贝组成。对佩内洛普元件的系统发育分析表明该元件既有垂直传播，也可能存在水平转移。这些发现支持了佩内洛普元件在粗壮果蝇组的进化过程中多次入侵的观点。
