R4, A NON-LTR RETROTRANSPOSON SPECIFIC TO THE LARGE SUBUNIT RIBOSOMAL-RNA GENES OF NEMATODES
R4, A NON-LTR RETROTRANSPOSON SPECIFIC TO THE LARGE SUBUNIT RIBOSOMAL-RNA GENES OF NEMATODES
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DOI：
10.1093/nar/23.22.4628
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发表时间：
1995-11-25
影响因子：
14.9
通讯作者：
EICKBUSH, TH
中科院分区：
文献类型：
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作者：
BURKE, WD;MULLER, F;EICKBUSH, TH
在蛔虫26S核糖体RNA基因中有4.7kb的序列特异性插入，命名为R4，是一个非长末端重复(Non-Ltr)反转录转座子元件。R4元件插入在大亚基rRNA基因的一个位置，该位置位于其他两个序列特异性的非LTR逆转录转座元件R1和R2之间，这两个元件在大多数昆虫中发现。根据其开放阅读框的结构和逆转录酶结构域的序列，R4元件似乎不是一个改变了插入位点的R1或R2元件家族，R4在结构和序列上与元件DON最相似，而DON不专用于插入到rDNA单元中。因此，R4代表一个单独的非LTR逆转座子，它已经变得专用于插入到宿主的rRNA基因中。利用针对逆转录酶编码区保守区的寡核苷酸引物，还扩增了马副寄生虫和扭转血吸虫R4位点上的插入片段。讨论了为什么几个非LTR反转录转座子元件变得专用于插入大亚基rRNA基因的短区域(87bp)。
A 4.7 kb sequence-specific insertion in the 26S ribosomal RNA gene of Ascaris lumbricoides, named R4, is shown to be a non-long terminal repeat (non-LTR) retrotransposable element. The R4 element inserts at a site in the large subunit rRNA gene which is midway between two other sequence-specific non-LTR retrotransposable elements, R1 and R2, found in most insect species. Based on the structure of its open reading frame and the sequence of its reverse transcriptase domain, R4 elements do not appear to be a family of R1 or R2 elements that have changed their insertion site, R4 is most similar in structure and in sequence to the element Dong, which is not specialized for insertion into rDNA units. Thus R4 represents a separate non-LTR retrotransposable element that has become specialized for insertion in the rRNA genes of its host. Using oligonucleotide primers directed to a conserved region of the reverse transcriptase encoding domain, insertions in the R4 site were also amplified from Parascaris equorum and Haemon-chus contortus. Why several non-LTR retrotransposable elements have become specialized for insertion into a short (87 bp) region of the large subunit rRNA gene is discussed.