Tan M, Heckmann K, Brünen-Nieweler C
Institut für Allgemeine Zoologie und Genetik, Universität Münster, D-48149, Münster, Germany.
Gene. 1999 Jun 11;233(1-2):131-40. doi: 10.1016/s0378-1119(99)00146-8.
The micronuclear gene of the ciliated protozoan Euplotes octocarinatus (Eo) syngen 1 encoding the putative aminoacyl-tRNA synthetase cofactor (ARCE), as well as its macronuclear version and the corresponding cDNA, were amplified and sequenced. Analyses of the sequences revealed that the micronuclear gene contains two sequences (430 and 625bp long) that are missing in the macronuclear version of this gene. These sequences are called 'internal eliminated sequences' (IESs) and appear to occur in all ciliates. The two IESs are located in the coding region of the micronuclear gene. One IES is flanked by a pair of dinucleotide 5'-TA-3' direct repeats and the other one by a pair of hepta-nucleotide 5'-TTACTGA-3' direct repeats. Inside the two IESs, several other sequence repeats were found. The macronuclear DNA molecule carrying this gene is 1517bp long and shows characteristics typical of macronuclear chromosomes of hypotrichous ciliates. Copy number determination revealed that the molecule is amplified to only about 750 copies per macronucleus. The deduced protein is a 441-amino-acid (aa) polypeptide with a molecular mass of 50kDa. It shares a conserved endothelial monocyte-activating polypeptide II (EMAP II)-like carboxyl-terminal domain and a hydrophilic central domain containing a KEKE-motif with a group of proteins associated with aminoacyl-tRNA synthetases and tRNAs.
编码假定氨酰基 - tRNA合成酶辅因子（ARCE）的八肋游仆虫（Euplotes octocarinatus，Eo）同宗群1的微核基因，以及其大核版本和相应的cDNA，被扩增并测序。序列分析表明，微核基因包含两个在该基因的大核版本中缺失的序列（分别长430和625bp）。这些序列被称为“内部消除序列”（IESs），似乎存在于所有纤毛虫中。这两个IESs位于微核基因的编码区域。一个IES两侧是一对二核苷酸5'-TA-3'直接重复序列，另一个两侧是一对七核苷酸5'-TTACTGA-3'直接重复序列。在这两个IESs内部，还发现了其他几个序列重复。携带该基因的大核DNA分子长1517bp，显示出寡毛纲纤毛虫大核染色体的典型特征。拷贝数测定表明，该分子在每个大核中仅扩增到约750个拷贝。推导的蛋白质是一个441个氨基酸（aa）的多肽，分子量为50kDa。它与一组与氨酰基 - tRNA合成酶和tRNA相关的蛋白质共享一个保守的内皮单核细胞激活多肽II（EMAP II）样羧基末端结构域和一个含有KEKE基序的亲水性中央结构域。
