Bean common mosaic virus (BCMV) causes severe disease in Phaseolus vulgaris plants. One of its non structural protein, the helper-component proteinase (HcPro) involves in multiple roles in aphid transmission, RNA binding, suppression of gene silencing and protease activity. The multifunctional role of HcPro hint towards its regulation at multiple host cellular sites. The mechanisms of these regulatory activities are poorly understood. Therefore, it is very important to study the molecular level interaction of HcPro with different cellular components. In this study, we demonstrate that the HcPro interacts with RuBisCo, an enzyme of chloroplast origin which might plays a crucial role in virus infection. A further line of experiments were carried out with factors of nuclear origin. Due to nucleic acid binding activity of HcPro, it showed interaction with dsDNA of nucleosome, as ascertained through electrophoretic mobility shift assay (EMSA). Interestingly, HcPro interacts with host nucleoprotein histones, H3 and H4. The gel-overlay assay and native electrophoresis-western blot analysis (NEWeB) revealed a direct interaction of BCMV HcPro with host nucleosome and with histones. These findings suggest that the BCMV through HcPro, not only utilize the host cytoplasmic components but also use host nuclear factors for its propagation and disease development.

中文翻译：

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杯状病毒辅助成分蛋白酶（HcPro）与RuBisCO和核小体在植物病毒感染中的相互作用。

菜豆普通花叶病毒（BCMV）在菜豆植物中引起严重的病害。辅助成分蛋白酶（HcPro）是其非结构蛋白之一，在蚜虫传播，RNA结合，基因沉默抑制和蛋白酶活性中起多种作用。HcPro的多功能作用暗示了其在多个宿主细胞部位的调控。这些监管活动的机制了解甚少。因此，研究HcPro与不同细胞组分的分子水平相互作用非常重要。在这项研究中，我们证明了HcPro与RuBisCo相互作用，RuBisCo是一种叶绿体起源的酶，可能在病毒感染中起关键作用。用核起源因子进行了进一步的实验。由于HcPro的核酸结合活性，通过电泳迁移率迁移分析（EMSA）可以确定它与核小体的dsDNA有相互作用。有趣的是，HcPro与宿主核蛋白组蛋白H3和H4相互作用。凝胶覆盖分析和天然电泳-western印迹分析（NEWeB）显示BCMV HcPro与宿主核小体和组蛋白直接相互作用。这些发现表明，通过HcPro的BCMV，不仅利用宿主细胞质成分，而且利用宿主核因子进行其繁殖和疾病发展。凝胶覆盖分析和天然电泳-western印迹分析（NEWeB）显示BCMV HcPro与宿主核小体和组蛋白直接相互作用。这些发现表明，通过HcPro的BCMV，不仅利用宿主细胞质成分，而且利用宿主核因子进行其繁殖和疾病发展。凝胶覆盖分析和天然电泳-western印迹分析（NEWeB）显示BCMV HcPro与宿主核小体和组蛋白直接相互作用。这些发现表明，通过HcPro的BCMV，不仅利用宿主细胞质成分，而且利用宿主核因子进行其繁殖和疾病发展。