Du H, Rosbash M
Department of Biology, Howard Hughes Medical Institute, Brandeis University, Waltham, Massachusetts 02454, USA.
RNA. 2001 Jan;7(1):133-42. doi: 10.1017/s1355838201001844.
Base pairing between the 5' end of U1 snRNA and the conserved 5' splice site of pre-mRNA is important for commitment complex formation in vitro. However, the biochemical mechanisms by which pre-mRNA is initially recognized by the splicing machinery is not well understood. To evaluate the role of this base pairing interaction, we truncated U1 snRNA to eliminate the RNA-RNA interaction and surprisingly found that U1 snRNP can still form a nearly normal RNA-protein complex and maintain sequence specificity. We propose that some feature of U1 snRNP, perhaps one or more protein factors, is more important than the base pairing for initial 5' splice site recognition. In addition, at least five sets of interactions contribute to complex formation or stability. Only one of these is base pairing between the 5' splice site and the 5' end of U1 snRNA, without which the U1 snRNP-pre-mRNA complex is less stable and has a somewhat altered conformation.
U1 snRNA的5'端与前体mRNA保守的5'剪接位点之间的碱基配对对于体外形成承诺复合体很重要。然而，剪接机制最初识别前体mRNA的生化机制尚未完全了解。为了评估这种碱基配对相互作用的作用，我们截短了U1 snRNA以消除RNA-RNA相互作用，令人惊讶地发现U1 snRNP仍然可以形成几乎正常的RNA-蛋白质复合体并保持序列特异性。我们提出，U1 snRNP的某些特征，可能是一种或多种蛋白质因子，对于最初的5'剪接位点识别比碱基配对更重要。此外，至少五组相互作用有助于复合体的形成或稳定性。其中只有一组是5'剪接位点与U1 snRNA的5'端之间的碱基配对，没有它，U1 snRNP-前体mRNA复合体的稳定性较低且构象有所改变。
