Salánki Katalin, Gellért Akos, Náray-Szabó Gábor, Balázs Ervin
Agricultural Biotechnology Center, Szent-Györgyi Albert u. 4, H-2100 Gödöllo, Hungary.
Virology. 2007 Feb 5;358(1):109-18. doi: 10.1016/j.virol.2006.08.014. Epub 2006 Sep 20.
The Ns strain of Cucumber mosaic virus (CMV) induces hypersensitive response (HR) on Nicotiana tabacum cv. Xanthi-nc and on Nicotiana glutinosa. The genetic determinant of the HR induction was localized earlier to amino acid 461 of the 1a protein. The 3D structure of the 1a protein is still unknown and building a homology model is impossible. Nevertheless, on the basis of secondary structure predictions we have created partial protein models for the region surrounding residue 461 which can account structurally for the effect of aa 461 on elicitor function. Seven different amino acid mutations were designed and introduced to the position 461 of the 1a protein in RNA 1. Three of the mutations (proline, glutamic acid, asparagine) inhibited virus replication. Two of the mutants caused systemic symptom development (lysine and arginine). Two mutants (alanine and serine) resulted in localization of the virus, but strong necrosis similar to the original Ns-CMV strain was not observed. Inoculation of purified Ns-CMV virions at extremely high concentration provoked systemic symptoms.
黄瓜花叶病毒（CMV）的Ns株系可在烟草品种Xanthi-nc和粘毛烟草上诱导过敏反应（HR）。HR诱导的遗传决定因素先前已定位到1a蛋白的第461位氨基酸。1a蛋白的三维结构仍然未知，构建同源模型也不可能。然而，基于二级结构预测，我们为第461位残基周围的区域创建了部分蛋白质模型，这些模型可以从结构上解释第461位氨基酸对激发子功能的影响。设计了七种不同的氨基酸突变，并将其引入RNA 1中1a蛋白的第461位。其中三种突变（脯氨酸、谷氨酸、天冬酰胺）抑制病毒复制。两种突变体导致系统症状发展（赖氨酸和精氨酸）。两种突变体（丙氨酸和丝氨酸）导致病毒定位，但未观察到与原始Ns-CMV株系相似的强烈坏死。以极高浓度接种纯化的Ns-CMV病毒粒子会引发系统症状。
