Xu G L, Wieland B, Bindereif A
Max-Planck-Institut für Molekulare Genetik, Otto-Warburg-Laboratorium, Berlin (Dahlem), Germany.
Mol Cell Biol. 1994 Jul;14(7):4565-70. doi: 10.1128/mcb.14.7.4565-4570.1994.
U6 RNA genes from the trypanosomatids Crithidia fasciculata and Leptomonas seymouri have been isolated and sequenced. As in Trypanosoma brucei, the U6 RNA genes in both C. fasciculata and L. seymouri are arranged in close linkage with upstream tRNA genes. The U6 RNA sequences from C. fasciculata and L. seymouri deviate in five and three positions, respectively, from the published T. brucei sequence. Interestingly, both C. fasciculata U6 RNA genes carry a C-->T change at the second position of the ACAGAG hexanucleotide sequence, which is important for splicing function and has been considered phylogenetically invariable. A compensatory base change of the C. fasciculata spliced leader RNA at the highly conserved 5' splice site position +5, G-->A, suggests that an interaction between the 5' splice site region and U6 RNA recently proposed for the yeast cis-splicing system may also occur in trans splicing.
已经分离并测序了来自锥虫科的克氏锥虫和西氏利什曼原虫的U6 RNA基因。与布氏锥虫一样，克氏锥虫和西氏利什曼原虫中的U6 RNA基因都与上游tRNA基因紧密连锁排列。克氏锥虫和西氏利什曼原虫的U6 RNA序列分别与已发表的布氏锥虫序列在五个和三个位置上存在差异。有趣的是，克氏锥虫的两个U6 RNA基因在ACAGAG六核苷酸序列的第二个位置都发生了C→T变化，这对剪接功能很重要，并且在系统发育上被认为是不变的。克氏锥虫剪接前导RNA在高度保守的5'剪接位点位置+5处发生的G→A补偿性碱基变化表明，最近在酵母顺式剪接系统中提出的5'剪接位点区域与U6 RNA之间的相互作用也可能发生在反式剪接中。
