Lipfert Jan, Ouellet Jonathan, Norman David G, Doniach Sebastian, Lilley David M J
Department of Physics, Geballe Laboratory of Advanced Materials, Stanford University, Stanford, CA 94305, USA.
Structure. 2008 Sep 10;16(9):1357-67. doi: 10.1016/j.str.2008.07.007.
We have used small-angle X-ray solution scattering to obtain ab initio shape reconstructions of the complete VS ribozyme. The ribozyme occupies an electron density envelope with an irregular shape, into which helical sections have been fitted. The ribozyme is built around a core comprising a near-coaxial stack of three helices, organized by two three-way helical junctions. An additional three-way junction formed by an auxiliary helix directs the substrate stem-loop, juxtaposing the cleavage site with an internal loop to create the active complex. This is consistent with the current view of the probable mechanism of trans-esterification in which adenine and guanine nucleobases contributed by the interacting loops combine in general acid-base catalysis.
我们利用小角X射线溶液散射技术对完整的VS核酶进行了从头形状重建。该核酶占据了一个形状不规则的电子密度包络,其中已拟合了螺旋片段。核酶围绕着一个由三个螺旋近同轴堆叠组成的核心构建,由两个三向螺旋连接点组织。由一个辅助螺旋形成的另一个三向连接点引导底物茎环,将切割位点与一个内环并列以形成活性复合物。这与目前关于转酯反应可能机制的观点一致,即相互作用环贡献的腺嘌呤和鸟嘌呤核碱基在一般酸碱催化中结合。