PDF(Pubmed)
Abstract：
Short Interspersed Elements (SINEs) are eukaryotic retrotransposons transcribed by RNA polymerase III (pol III). Many mammalian SINEs (T+ SINEs) contain a polyadenylation signal (AATAAA), a pol III transcription terminator, and an A-rich tail in their 3\'-end. The RNAs of such SINEs have the capacity for AAUAAA-dependent polyadenylation, which is unique to pol III-generated transcripts. The structure, evolution, and polyadenylation of the Ere SINE of ungulates (horses, rhinos, and tapirs) were investigated in this study. A bioinformatics analysis revealed the presence of up to ~4 × 105 Ere copies in representatives of all three families. These copies can be classified into two large subfamilies, EreA and EreB, the former distinguished by an additional 60 bp sequence. The 3\'-end of numerous EreA and all EreB copies exhibit a 50 bp sequence designated as a terminal domain (TD). The Ere family can be further subdivided into subfamilies EreA_0TD, EreA_1TD, EreB_1TD, and EreB_2TD, depending on the presence and number of terminal domains (TDs). Only EreA_0TD copies can be assigned to T+ SINEs as they contain the AATAAA signal and the TCTTT transcription terminator. The analysis of young Ere copies identified by comparison with related perissodactyl genomes revealed that EreA_0TD and, to a much lesser extent, EreB_2TD have retained retrotranspositional activity in the recent evolution of equids and rhinoceroses. The targeted mutagenesis and transfection of HeLa cells were used to identify sequences in equine EreA_0TD that are critical for the polyadenylation of its pol III transcripts. In addition to AATAAA and the transcription terminator, two sites in the 3\' half of EreA, termed the β and τ signals, were found to be essential for this process. The evolution of Ere, with a particular focus on the emergence of T+ SINEs, as well as the polyadenylation signals are discussed in comparison with other T+ SINEs.
摘要：
短散布元件(SINE)是由RNA聚合酶III(polIII)转录的真核反转录转座子。许多哺乳动物SINE（TSINE）含有聚腺苷酸化信号（AATAAA），polIII转录终止子，在他们的三端有一条富含A的尾巴。此类SINE的RNA具有AAUAAA依赖性聚腺苷酸化的能力，这是polIII产生的转录物独有的。结构,进化,和有蹄类动物EreSINE的聚腺苷酸化(马，犀牛,和tapirs)在这项研究中进行了调查。生物信息学分析显示，在所有三个家族的代表中，存在多达〜4×105Ere副本。这些副本可以分为两个大的子家族，EreA和EreB,前者的区别在于一个额外的60bp序列。许多EreA和所有EreB拷贝的3'末端显示50bp序列,指定为末端结构域(TD)。Ere家族可以进一步细分为亚家族EreA_0TD，EreA_1TD,EreB_1TD,和EreB_2TD，取决于末端结构域(TD)的存在和数量。只有EreA_0TD拷贝可以分配给T+SINE,因为它们含有AATAAA信号和TCTTT转录终止子。通过与相关的周枝基因组比较鉴定的年轻Ere拷贝的分析显示，EreA_0TD和，在更小的程度上，EreB_2TD在最近的马和犀牛进化中保留了逆转转位活性。HeLa细胞的靶向诱变和转染用于鉴定马EreA_0TD中对其polIII转录物的聚腺苷酸化至关重要的序列。除了AATAAA和转录终止子，在EreA的三个半区有两个地点，称为β和τ信号，被发现对这个过程至关重要。Ere的进化，特别关注T+犯罪的出现，以及与其他T+SINE相比，讨论了聚腺苷酸化信号。
