Makarova S S, Makhotenko A V, Khromov A V, Skurat E V, Solovyev A G, Makarov V V, Kalinina N O
Lomonosov Moscow State University, Biological Faculty, Moscow, 119991, Russia.
Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119991, Russia.
Biochemistry (Mosc). 2018 Dec;83(12):1543-1551. doi: 10.1134/S000629791812012X.
Capsid proteins (CPs) of (+)RNA-containing plant viruses are multifunctional proteins involved in many stages of viral infection cycle, in addition to their main function of virus capsid formation. For example, the tobamoviral CP ensures virus systemic transport in plants and defines the virus-host interactions, thereby influencing the virus host range, virus infectivity, pathogenicity, and manifestation of infection symptoms. Hordeiviruses and tobamoviruses belong to the Virgaviridae family and have rod-shaped virions with a helical symmetry; their CPs are similar in structure. However, no non-structural functions of hordeiviral CPs have been described so far. In this study, we assayed possible non-structural functions of CP from the barley stripe mosaic virus (BSMV) (hordeivirus). To do this, the genome of turnip vein clearing virus (TVCV) (tobamovirus) was modified by substituting the TVCV CP gene with the BSMV CP gene or its mutants. We found that BSMV CP efficiently replaced TVCV CP at all stages of viral infection. In particular, BSMV CP performed the role of tobamoviral CP in the long-distance transport of the chimeric virus, acted as a hypersensitive response elicitor, and served as a pathogenicity determinant that influenced the symptoms of the viral infection. The chimeric tobamovirus coding for the C-terminally truncated BSMV CP displayed an increased infectivity and was transported in plants in a form of atypical virions (ribonucleoprotein complexes).
含正链RNA的植物病毒的衣壳蛋白（CPs）是多功能蛋白，除了形成病毒衣壳的主要功能外，还参与病毒感染周期的许多阶段。例如，烟草花叶病毒属病毒的CP可确保病毒在植物中的系统运输，并决定病毒与宿主的相互作用，从而影响病毒宿主范围、病毒感染性、致病性以及感染症状的表现。大麦病毒属病毒和烟草花叶病毒属病毒属于病毒科，具有螺旋对称的杆状病毒粒子；它们的CP在结构上相似。然而，迄今为止尚未描述过大麦病毒属病毒CP的非结构功能。在本研究中，我们检测了大麦条纹花叶病毒（BSMV）（大麦病毒属病毒）CP可能的非结构功能。为此，通过用BSMV CP基因或其突变体替换芜菁脉明病毒（TVCV）（烟草花叶病毒属病毒）的CP基因，对TVCV基因组进行了修饰。我们发现，BSMV CP在病毒感染的各个阶段都能有效地替代TVCV CP。特别是，BSMV CP在嵌合病毒的长距离运输中发挥了烟草花叶病毒属病毒CP的作用，充当过敏反应激发子，并作为影响病毒感染症状的致病性决定因素。编码C末端截短的BSMV CP的嵌合烟草花叶病毒表现出增强的感染性，并以非典型病毒粒子（核糖核蛋白复合物）的形式在植物中运输。
