P4 Protein Encoded By Pepper Vein Yellows Virus Facilitates Virus Cell-to-cell Movent

For systematical infecting host,plant viruses have to overcome the bottleneck of plasmodesmata(PD)of the host cell.Indeed,plant viruses encode movement protein to guide virus cell-to-cell movement through PD of the host cell.Pepper vein yellows virus(Pe VYV)is positive single strand RNA virus belonging to genus Polerovirus,family Luteoviridae.Pe VYV can transmit by aphid or grafting,and causes vein yellowing,clustering nascent leaves in infected host,results in severe yield and commodity loss to some Solanaceae crops.The results of unveiling of movement protein and its functions would be contributed to uncover the pathogenecity of Pe VYV,and also benefited to scientifically evaluate its potentail threat to some Solanaceae crops.The ORF4 of Pe VYV encodes the 17.5 k Da protein,named P4.The conserved domain analysis shown the transmembrane region exists in 117-138 aa.The subcellular localization results shown P4 protein colocalizates with PDLP8 protein,a PD mark protein,and presences the discrete fluorescent points.The P4 protein mutants,which are deleting or replacing of 117-138 aa with alanine(A),lost colocalizating with PDLP8 protein.These results demonstrated the transmembrane region of 117-138 aa is critical for P4 localizating to PD.The rescuing cell-to-cell movement capacity of Cucumber mosaic virus(CMV)?3a,which CMV movement protein 3a was replaced by GFP reporter protein,shown P4 protein possesses the capacity of rescuing the cell-to-cell movement of CMV ?3a,upto 92% virions move to neighbour cells.?P4 AAA 117-138 protein could drive 16%of virions to neighbour cells.Otherwise,?P4 117-138 protein lost the capacity of driving CMV ?3a cell-to-cell movement.The host proteins interacting with P4 protein and its mutants were screened and identified by co-immunoprecipiation tandem mass/mass(LC-MS/MS).There were 16 proteins involving in ER binding,energy metabolism,mitogen acitivated protein kinase,autophagy and DNA methylation etc,interacted with P4 protein.There were14 proteins excepting that involving in mitogen acitivated protein kinase,autophagy,interacted with two mutants of P4 protein.The results hinted P4 protein possesses multifunction of regulating viral replication and host resistance besides of driving virus cell-to-cell movement.