Branch A D, Benenfeld B J, Robertson H D
Proc Natl Acad Sci U S A. 1985 Oct;82(19):6590-4. doi: 10.1073/pnas.82.19.6590.
The positions of intramolecular crosslinks induced by irradiation with ultraviolet light were mapped into potato spindle tuber viroid RNA and HeLa 5S rRNA. Crosslinking in each of these molecules occurred at a single major site, which was located by RNA fingerprinting and secondary analysis (and additional primer extension studies in the case of the viroid). Various lines of evidence suggest that these crosslinks identify a previously undescribed element of local tertiary structure common to these two widely divergent RNA molecules: (i) both crosslinks occur in an identical eight-base context, with the sequence 5' GGGAA 3' on one side and the sequence 5' UAC 3' on the other; (ii) both crosslinks connect bases that are not thought to be involved in conventional hydrogen bonding, within regions usually depicted as single-stranded loops flanked by short helical segments; and (iii) both crosslinks connect a purine and a pyrimidine residue, and both may generate the same G-U dimer. Furthermore, it is likely that the crosslinking site is of functional significance because it is located within the most highly conserved region of the viroid sequence and involves bases that are essentially invariant among eukaryotic 5S rRNA molecules.
用紫外线照射诱导的分子内交联位置被定位到马铃薯纺锤块茎类病毒RNA和HeLa 5S rRNA中。这些分子中的每一个的交联都发生在一个主要位点，该位点通过RNA指纹图谱和二级分析（对于类病毒还进行了额外的引物延伸研究）来定位。各种证据表明，这些交联确定了这两个差异很大的RNA分子共有的一种以前未描述的局部三级结构元件：（i）两个交联都发生在相同的八个碱基的背景下，一侧是序列5'GGGAA 3'，另一侧是序列5'UAC 3'；（ii）两个交联连接的碱基被认为不参与传统的氢键形成，在通常被描绘为两侧有短螺旋段的单链环的区域内；（iii）两个交联都连接一个嘌呤和一个嘧啶残基，并且两者都可能产生相同的G-U二聚体。此外，交联位点可能具有功能意义，因为它位于类病毒序列中最保守的区域内，并且涉及在真核5S rRNA分子中基本不变的碱基。
