Diprose J M, Burroughs J N, Sutton G C, Goldsmith A, Gouet P, Malby R, Overton I, Ziéntara S, Mertens P P, Stuart D I, Grimes J M
Division of Structural Biology, The Henry Wellcome Building for Genomic Medicine, Oxford University, Roosevelt Drive, Headington, Oxford OX3 7BN, UK.
EMBO J. 2001 Dec 17;20(24):7229-39. doi: 10.1093/emboj/20.24.7229.
The bluetongue virus core is a molecular machine that simultaneously and repeatedly transcribes mRNA from 10 segments of viral double-stranded RNA, packaged in a liquid crystalline array. To determine how the logistical problems of transcription within a sealed shell are solved, core crystals were soaked with various ligands and analysed by X-ray crystallography. Mg(2+) ions produce a slight expansion of the capsid around the 5-fold axes. Oligonucleotide soaks demonstrate that the 5-fold pore, opened up by this expansion, is the exit site for mRNA, whilst nucleotide soaks pinpoint a separate binding site that appears to be a selective channel for the entry and exit of substrates and by-products. Finally, nucleotides also bind to the outer core layer, providing a substrate sink.
蓝舌病毒核心是一种分子机器，它能同时且反复地从10条病毒双链RNA片段转录信使核糖核酸（mRNA），这些片段包装成液晶阵列。为了确定在密封外壳内转录的后勤问题是如何解决的，核心晶体用各种配体浸泡并用X射线晶体学进行分析。镁离子（Mg²⁺）使衣壳在五重轴周围略有扩张。寡核苷酸浸泡实验表明，这种扩张打开的五重孔是mRNA的出口位点，而核苷酸浸泡实验则确定了一个单独的结合位点，该位点似乎是底物和副产物进出的选择性通道。最后，核苷酸也与核心外层结合，形成一个底物库。
