Sesbania mosaic virus (SeMV) is a single‐stranded positive‐sense RNA plant virus belonging to the genus Sobemovirus. The movement protein (MP) encoded by SeMV ORF1 showed no significant sequence similarity with MPs of other genera, but showed 32% identity with the MP of Southern bean mosaic virus within the Sobemovirus genus. With a view to understanding the mechanism of cell‐to‐cell movement in sobemoviruses, the SeMV MP gene was cloned, over‐expressed in Escherichia coli and purified. Interaction of the recombinant MP with the native virus (NV) was investigated by ELISA and pull‐down assays. It was observed that SeMV MP interacted with NV in a concentration‐ and pH‐dependent manner. Analysis of N‐ and C‐terminal deletion mutants of the MP showed that SeMV MP interacts with the NV through the N‐terminal 49 amino acid segment. Yeast two‐hybrid assays confirmed the in vitro observations, and suggested that SeMV might belong to the class of viruses that require MP and NV/coat protein for cell‐to‐cell movement. Structured digital abstract http://mint.bio.uniroma2.it/mint/search/interaction.do?interactionAc=MINT-8050243: p53 (uniprotkb:http://www.uniprot.org/uniprot/P02340) physically interacts (http://www.ebi.ac.uk/ontology-lookup/?termId=MI:0915) with T‐Ag (uniprotkb:http://www.uniprot.org/uniprot/P03070) by two hybrid (http://www.ebi.ac.uk/ontology-lookup/?termId=MI:0018) http://mint.bio.uniroma2.it/mint/search/interaction.do?interactionAc=MINT-8050226: MP (uniprotkb:http://www.uniprot.org/uniprot/Q9EB09) physically interacts (http://www.ebi.ac.uk/ontology-lookup/?termId=MI:0915) with CP (uniprotkb:http://www.uniprot.org/uniprot/Q9EB06) by two hybrid (http://www.ebi.ac.uk/ontology-lookup/?termId=MI:0018)

Sesbania mosaic virus (SeMV) is a single strand positive-sense RNA plant virus that belongs to the genus Sobemovirus. The mechanism of cell-to-cell movement in sobemoviruses has not been well studied. With a view to identify the viral encoded ancillary proteins of SeMV that may assist in cell-to-cell movement of the virus, all the proteins encoded by SeMV genome were cloned into yeast Matchmaker system 3 and interaction studies were performed. Two proteins namely, viral protein genome linked (VPg) and a 10-kDa protein (P10) c v gft encoded by OFR 2a, were identified as possible interacting partners in addition to the viral coat protein (CP). Further characterization of these interactions revealed that the movement protein (MP) recognizes cognate RNA through interaction with VPg, which is covalently linked to the 5′ end of the RNA. Analysis of the deletion mutants delineated the domains of MP involved in the interaction with VPg and P10. This study implicates for the first time that VPg might play an important role in specific recognition of viral genome by MP in SeMV and shed light on the possible role of P10 in the viral movement.