Mayo M A, Brierley K M, Goodman B A
Scottish Crop Research Institute, Invergowrie, Dundee, UK.
Biochimie. 1993;75(8):639-44. doi: 10.1016/0300-9084(93)90093-8.
Particles of tobraviruses resemble those of tobacco mosaic tobramovirus (TMV) in having helical symmetry and in being rod-shaped. However, isolated tobravirus coat protein and TMV coat protein respond to changes in the ionic strength and pH of the solute in contrasting ways. The types of aggregate formed in solutions of coat protein also differ which may be related to differences in the apparent mechanism of reconstitution of virus particles from isolated protein and RNA. The amino acid sequences of tobravirus and tobramovirus coat proteins have been shown to be similar in some regions known to be important for the structure of TMV particles. These alignments also show that tobravirus proteins are larger than tobramoviral proteins in part because of extra residues at the C-terminus. Tobravirus particles give a signal in proton NMR spectroscopy but TMV particles do not. The signal is caused by segmental mobility of the C-terminal peptide. This difference between TMV and tobraviruses may be related to a property not shared by tobraviruses and TMV and it is therefore speculated that the mobile C-terminal peptide of tobravirus coat proteins may be important in the transmission of tobravirus particles by nematode vectors.
烟草脆裂病毒粒子在具有螺旋对称结构和呈杆状方面与烟草花叶烟草脆裂病毒（TMV）粒子相似。然而，分离出的烟草脆裂病毒外壳蛋白和TMV外壳蛋白对溶质离子强度和pH值变化的反应方式截然不同。在外壳蛋白溶液中形成的聚集体类型也有所不同，这可能与从分离的蛋白质和RNA重构病毒粒子的明显机制差异有关。烟草脆裂病毒和烟草花叶病毒外壳蛋白的氨基酸序列在已知对TMV粒子结构重要的一些区域显示出相似性。这些比对还表明，烟草脆裂病毒蛋白比烟草花叶病毒蛋白更大，部分原因是C末端有额外的残基。烟草脆裂病毒粒子在质子核磁共振光谱中产生信号，但TMV粒子则不会。该信号是由C末端肽段的片段流动性引起的。TMV和烟草脆裂病毒之间的这种差异可能与烟草脆裂病毒和TMV不共有的一种特性有关，因此推测烟草脆裂病毒外壳蛋白的可移动C末端肽段在通过线虫载体传播烟草脆裂病毒粒子过程中可能很重要。
