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.