Specificity of Plant Rhabdovirus Cell-to-Cell Movement

Abstract

Positive-stranded RNA virus movement proteins (MPs) generally lack sequence-specific nucleic acid-binding activities and display cross-family movement complementarity with related and unrelated viruses. Negative-stranded RNA plant rhabdoviruses encode MPs with limited structural and functional relatedness with other plant virus counterparts, but the precise mechanisms of intercellular transport are obscure. In this study, we first analyzed the abilities of MPs encoded by five distinct rhabdoviruses to support cell-to-cell movement of two positive-stranded RNA viruses by using trans-complementation assays. Each of the five rhabdovirus MPs complemented the movement of MP-defective mutants of tomato mosaic virus and potato X virus. In contrast, movement of recombinant MP deletion mutants of sonchus yellow net nucleorhabdovirus (SYNV) and tomato yellow mottle-associated cytorhabdovirus (TYMaV) was rescued only by their corresponding MPs, i.e., SYNV sc4 and TYMaV P3. Subcellular fractionation analyses revealed that SYNV sc4 and TYMaV P3 were peripherally associated with cell membranes. A split-ubiquitin membrane yeast two-hybrid assay demonstrated specific interactions of the membraneassociated rhabdovirus MPs only with their cognate nucleoproteins (N) and phosphoproteins (P). More importantly, SYNV sc4-N and sc4-P interactions directed a proportion of the N-P complexes from nuclear sites of replication to punctate loci at the cell periphery that partially colocalized with the plasmodesmata. Our data show that cell-to-cell movement of plant rhabdoviruses is highly specific and suggest that cognate MP-nucleocapsid core protein interactions are required for intra-and intercellular trafficking. IMPORTANCE Local transport of plant rhabdoviruses likely involves the passage of viral nucleocapsids through MP-gated plasmodesmata, but the molecular mechanisms are not fully understood. We have conducted complementation assays with MPs encoded by five distinct rhabdoviruses to assess their movement specificity. Each of the rhabdovirus MPs complemented the movement of MP-defective mutants of two positive-stranded RNA viruses that have different movement strategies. In marked contrast, cell-to-cell movement of two recombinant plant rhabdoviruses was highly specific in requiring their cognate MPs. We have shown that these rhabdovirus MPs are localized to the cell periphery and associate with cellular membranes, and that they interact only with their cognate nucleocapsid core proteins. These interactions are able to redirect viral nucleocapsid core proteins from their sites of replication to the cell periphery. Our study provides a model for the specific interand intracellular trafficking of plant rhabdoviruses that may be applicable to other negative-stranded RNA viruses. Downloaded fromN atural infections of plant viruses are initiated from one or a few primary infected cells, followed by cell-to-cell spread to adjacent cells and then to distal tissues via vascular networks. To accomplish systemic infections, plant viruses must ci...

Dichorhaviruses Movement Protein and Nucleoprotein Form a Protein Complex That May Be Required for Virus Spread and Interacts in vivo With Viral Movement-Related Cilevirus Proteins

“…Previous studies with the CoRSV MP localized the protein predominantly at the cell periphery when ectopically expressed in plant cells ( Ramalho et al, 2014 ). MP nuclear localization has also been reported for the lettuce necrotic yellows cytorhabdovirus (LNYV), alfalfa dwarf cytorhabdovirus (ADV), and SYNV betanucleorhabdovirus ( Goodin et al, 2002 , 2007 ; Martin et al, 2012 ; Bejerman et al, 2015 ; Zhou et al, 2019 ). For the LNYV MP (4b protein), its nuclear localization was supported by the presence of a predicted NLS domain, whereas no canonical NLS was predicted for ADV MP (P3 protein).…”

“…Our findings reveal that dichorhavirus MPs do not display cross-movement complementation with distinct (+) RNA viruses, suggesting either that these MPs mediate virus transport with a mechanism distinct from those viruses used in the transport complementation assay or the requirement of specific interactions and/or proteins playing a role in virus transport. For plant rhabdoviruses and others (-)ssRNA viruses, their MPs were able to rescue the cell-to-cell movement of potexvirus, tobamovirus, or alfamovirus defective-movement mutants ( Huang et al, 2005 ; Peiro et al, 2014a ; Mann et al, 2016 ; Leastro et al, 2017b ; Zhou et al, 2019 ). On the other hand, defective nucleo- and cytorhabdovirus movement mutants were rescued only by their cognate MPs ( Zhou et al, 2019 ).…”

“…For plant rhabdoviruses and others (-)ssRNA viruses, their MPs were able to rescue the cell-to-cell movement of potexvirus, tobamovirus, or alfamovirus defective-movement mutants ( Huang et al, 2005 ; Peiro et al, 2014a ; Mann et al, 2016 ; Leastro et al, 2017b ; Zhou et al, 2019 ). On the other hand, defective nucleo- and cytorhabdovirus movement mutants were rescued only by their cognate MPs ( Zhou et al, 2019 ). Thus, we speculate that the movement mechanism mediated by the dichorhavirus MP could be specific, requiring cognate viral proteins as shown for other plant rhabdoviruses.…”

Rice yellow stunt virus activates polyamine biosynthesis to promote viral propagation in insect vectors by disrupting ornithine decarboxylase antienzyme function

“…Furthermore, both RYSV M and ODC1 interact with the same ODC-binding domain at the C-terminus of OAZ1. During the propagation of the nucleorhabdoviruses in the nuclei of insect vectors and plant hosts, the RNP cores are assembled within the viroplasm matrix in the nucleic, and then M proteins recognize and condense RNP cores to assemble the bullet-shaped or ba- cilliform non-enveloped virions at the nuclear membrane (Wang et al, 2018;Jackson and Li, 2016;Jackson et al, 2018;Zhou et al, 2019). Our electron microscopic observation has shown that abundant non-enveloped bulletshaped virions of RYSV budded from the nuclear membrane into the cytoplasm in the CNS of N. cincticeps (Wang et al, 2019).…”

A Versatile Plant Rhabdovirus-Based Vector for Gene Silencing, miRNA Expression and Depletion, and Antibody Production

“…The genome of SYNV contains six open reading frames (ORFs) in the order 3’-N-P-sc4-M-G-L-5’ that are conserved among plant rhabdoviruses ( Jackson et al, 2005 ). The N, P, L proteins form a ribonucleoprotein complex with the viral genomic RNA that is essential for replication and transcription ( Ganesan et al, 2013 ; Wang et al, 2015 ), and the M and G proteins are involved in virus budding and morphogenesis ( Sun et al, 2018 ), whereas the sc4 protein is the cell-to-cell movement protein ( Zhou et al, 2019 ). Several genetic features of rhabdovirus make their genomes highly amenable for vector engineering.…”