Baratova L A, Efimov A V, Dobrov E N, Fedorova N V, Hunt R, Badun G A, Ksenofontov A L, Torrance L, Järvekülg L
N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119899, Russia.
J Virol. 2001 Oct;75(20):9696-702. doi: 10.1128/JVI.75.20.9696-9702.2001.
Potato virus A (PVA) particles were bombarded with thermally activated tritium atoms, and the intramolecular distribution of the label in the amino acids of the coat protein was determined to assess their in situ steric accessibility. This method revealed that the N-terminal 15 amino acids of the PVA coat protein and a region comprising amino acids 27 to 50 are the most accessible at the particle surface to labeling with tritium atoms. A model of the spatial arrangement of the PVA coat protein polypeptide chain within the virus particle was derived from the experimental data obtained by tritium bombardment combined with predictions of secondary-structure elements and the principles of packing alpha-helices and beta-structures in proteins. The model predicts three regions of tertiary structure: (i) the surface-exposed N-terminal region, comprising an unstructured N terminus of 8 amino acids and two beta-strands, (ii) a C-terminal region including two alpha-helices, as well as three beta-strands that form a two-layer structure called an abCd unit, and (iii) a central region comprising a bundle of four alpha-helices in a fold similar to that found in tobacco mosaic virus coat protein. This is the first model of the three-dimensional structure of a potyvirus coat protein.
用热激活的氚原子轰击马铃薯A病毒（PVA）颗粒，并测定标记物在衣壳蛋白氨基酸中的分子内分布，以评估其原位空间可及性。该方法表明，PVA衣壳蛋白的N端15个氨基酸以及包含27至50位氨基酸的区域在颗粒表面最容易被氚原子标记。通过氚轰击获得的实验数据，结合二级结构元件的预测以及蛋白质中α螺旋和β结构堆积的原理，推导出了病毒颗粒内PVA衣壳蛋白多肽链的空间排列模型。该模型预测了三个三级结构区域：（i）表面暴露的N端区域，包括8个氨基酸的无结构N端和两条β链；（ii）C端区域，包括两条α螺旋以及形成称为abCd单元的两层结构的三条β链；（iii）中心区域，由一束四个α螺旋组成，其折叠方式与烟草花叶病毒衣壳蛋白中的相似。这是第一个马铃薯Y病毒属病毒衣壳蛋白三维结构的模型。
