Schneider Claudia, Will Cindy L, Brosius Jürgen, Frilander Mikko J, Lührmann Reinhard
Department of Cellular Biochemistry, Max Planck Institute of Biophysical Chemistry, 37077 Goettingen, Germany.
Proc Natl Acad Sci U S A. 2004 Jun 29;101(26):9584-9. doi: 10.1073/pnas.0403400101. Epub 2004 Jun 21.
Previous reports suggested that U11, in contrast to U12 or other small nuclear (sn)RNAs of the U12-type spliceosome, might be either highly divergent or absent in Drosophila melanogaster. Affinity purification of Drosophila U12-containing complexes has led to the identification of the fly U11 snRNA, which contains a potential U12-type 5' splice-site-interacting sequence, but whose sequence and length differs significantly from vertebrate and plant U11. Analysis of U12-type introns revealed an A-rich region directly downstream of Drosophila, but not human, U12-type 5' splice sites. This finding, coupled with the presence of a highly divergent U11 snRNA, and the apparent absence of Drosophila homologs of human U11 proteins, suggest that U12-type 5' splice site recognition might be different in flies. A comparison of U11 snRNAs that we have identified from vertebrates, plants, and insects, suggests that an evolutionarily divergent U11 snRNA may be unique to Drosophila and not characteristic of insects in general.
先前的报告表明，与U12或U12型剪接体的其他小核（sn）RNA不同，U11在黑腹果蝇中可能高度分化或不存在。对含有果蝇U12的复合物进行亲和纯化，已鉴定出果蝇U11 snRNA，其含有潜在的U12型5'剪接位点相互作用序列，但其序列和长度与脊椎动物和植物的U11有显著差异。对U12型内含子的分析显示，在果蝇而非人类的U12型5'剪接位点直接下游存在一个富含A的区域。这一发现，再加上高度分化的U11 snRNA的存在，以及人类U11蛋白的果蝇同源物明显缺失，表明果蝇中U12型5'剪接位点的识别可能有所不同。我们从脊椎动物、植物和昆虫中鉴定出的U11 snRNA的比较表明，进化上分化的U11 snRNA可能是果蝇特有的，而不是昆虫的普遍特征。
