Murphy F L, Wang Y H, Griffith J D, Cech T R
Howard Hughes Medical Institute, Department of Chemistry and Biochemistry, University of Colorado, Boulder 80309.
Science. 1994 Sep 16;265(5179):1709-12. doi: 10.1126/science.8085157.
Coaxial stacking of helical elements is a determinant of three-dimensional structure in RNA. In the catalytic center of the Tetrahymena group I intron, helices P4 and P6 are part of a tertiary structural domain that folds independently of the remainder of the intron. When P4 and P6 were fused with a phosphodiester linkage, the resulting RNA retained the detailed tertiary interactions characteristic of the native P4-P6 domain and even required lower magnesium ion concentrations for folding. These results indicate that P4 and P6 are coaxial in the P4-P6 domain and, therefore, in the native ribozyme. Helix fusion could provide a general method for identifying pairs of coaxially stacked helices in biological RNA molecules.
螺旋元件的同轴堆积是RNA三维结构的一个决定因素。在嗜热四膜虫I组内含子的催化中心，螺旋P4和P6是一个三级结构域的一部分，该结构域独立于内含子的其余部分折叠。当P4和P6通过磷酸二酯键连接时，所得RNA保留了天然P4-P6结构域特有的详细三级相互作用，甚至折叠时所需的镁离子浓度更低。这些结果表明，P4和P6在P4-P6结构域中是同轴的，因此在天然核酶中也是同轴的。螺旋融合可为鉴定生物RNA分子中同轴堆积的螺旋对提供一种通用方法。
