Krol A, Westhof E, Bach M, Lührmann R, Ebel J P, Carbon P
Laboratoire de Biochimie, Institut de Biologie Moléculaire et Cellulaire du CNRS, Strasbourg, France.
Nucleic Acids Res. 1990 Jul 11;18(13):3803-11. doi: 10.1093/nar/18.13.3803.
The solution structure of human U1 snRNA was investigated by using base-specific chemical probes (dimethylsulfate, carbodiimide, diethylpyrocarbonate) and RNase V1. Chemical reagents were employed under various conditions of salt and temperature and allowed information at the Watson-Crick base-pairing positions to be obtained for 66% of the U1 snRNA bases. Double-stranded or stacked regions were examined with RNase V1. The dat gained from these experiments extend and support the previous 2D model for U1snRNA. However, to elucidate some aspects of the solution data that could not be accounted for by the secondary structure model, the information gathered from structure probing was used to provide the experimental basis required to construct and to test a tertiary structure model by computer graphics modeling. As a result, U1 snRNA is shown to adopt an asymmetrical X-shape that is formed by two helical domains, each one being generated by coaxial stacking of helices at the U1 snRNA cruciform. Chemical reactivities and model building show that a few nucleotides, previously proposed to be unpaired, can form A.G and U.U non Watson-Crick base-pairs, notably in stem-loop B. The structural model we propose for regions G12 to A124 integrates stereochemical constraints and is based both on solution structure data and sequence comparisons between U1 snRNAs.
利用碱基特异性化学探针（硫酸二甲酯、碳二亚胺、焦碳酸二乙酯）和核糖核酸酶V1对人U1小核核糖核酸（snRNA）的溶液结构进行了研究。在不同的盐浓度和温度条件下使用化学试剂，从而获得了U1 snRNA 66%碱基在沃森-克里克碱基配对位置的信息。用核糖核酸酶V1检测双链或堆积区域。从这些实验中获得的数据扩展并支持了先前关于U1 snRNA的二维模型。然而，为了阐明二级结构模型无法解释的溶液数据的某些方面，利用从结构探测收集到的信息，为通过计算机图形建模构建和测试三级结构模型提供所需的实验基础。结果表明，U1 snRNA呈现出一种不对称的X形，由两个螺旋结构域形成，每个结构域由U1 snRNA十字形处螺旋的同轴堆积产生。化学反应性和模型构建表明，一些先前认为未配对的核苷酸可以形成A·G和U·U非沃森-克里克碱基对，特别是在茎环B中。我们为G12至A124区域提出的结构模型整合了立体化学限制，并且基于溶液结构数据和U1 snRNAs之间的序列比较。
