Melin L, Soldati D, Mital R, Streit A, Schümperli D
Abteilung für Entwicklungsbiologie, Universität Bern, Switzerland.
EMBO J. 1992 Feb;11(2):691-7. doi: 10.1002/j.1460-2075.1992.tb05101.x.
Histone RNA 3' end formation occurs through a specific cleavage reaction that requires, among other things, base-pairing interactions between a conserved spacer element in the pre-mRNA and the minor U7 snRNA present as U7 snRNP. An oligonucleotide complementary to the first 16 nucleotides of U7 RNA can be used to characterize U7 snRNPs from nuclear extracts by native gel electrophoresis. Using similar native gel techniques, we present direct biochemical evidence for a stable association between histone pre-mRNA and U7 snRNPs. Other complexes formed in the nuclear extract are dependent on the 5' cap structure and on the conserved hairpin element of histone pre-mRNA, respectively. However, in contrast to the U7-specific complex, their formation is not required for processing. Comparison of several authentic and mutant histone pre-mRNAs with different spacer sequences demonstrates that the formation and stability of the U7-specific complex closely follows the predicted stability of the potential RNA-RNA hybrid. However, this does not exclude a stabilization of the complex by U7 snRNP structural proteins.
组蛋白RNA 3'末端的形成是通过一种特定的切割反应实现的，该反应除其他因素外，还需要前体mRNA中保守间隔元件与以U7 snRNP形式存在的小U7 snRNA之间的碱基配对相互作用。与U7 RNA的前16个核苷酸互补的寡核苷酸可用于通过天然凝胶电泳从核提取物中鉴定U7 snRNP。使用类似的天然凝胶技术，我们提供了组蛋白前体mRNA与U7 snRNP之间稳定结合的直接生化证据。核提取物中形成的其他复合物分别依赖于5'帽结构和组蛋白前体mRNA的保守发夹元件。然而，与U7特异性复合物不同，它们的形成对于加工过程并非必需。对几种具有不同间隔序列的真实和突变组蛋白前体mRNA的比较表明，U7特异性复合物的形成和稳定性与潜在RNA-RNA杂交体的预测稳定性密切相关。然而，这并不排除U7 snRNP结构蛋白对复合物的稳定作用。
