RT Journal Article
SR Electronic
T1 A new plant-specific syntaxin-6 protein may define an intracytoplasmic route for begomoviruses
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2020.01.10.901496
DO 10.1101/2020.01.10.901496
A1 Bianca Castro Gouveia-Mageste
A1 Laura Gonçalves Costa Martins
A1 Maximiller Dal-Bianco
A1 João Paulo Batista Machado
A1 José Cleydson Ferreira da Silva
A1 Anésia Aparecida dos Santos
A1 Joseph R Ecker
A1 Elizabeth Pacheco Batista Fontes
YR 2020
UL http://biorxiv.org/content/early/2020/01/10/2020.01.10.901496.abstract
AB Due to limited free diffusion in the cytoplasm, viruses must use active transport mechanisms to move intracellularly. Nevertheless, how the plant ssDNA begomovirus hijacks the host intracytoplasmic transport machinery to move from the nucleus to the plasmodesma remains enigmatic. Here, we identified nuclear shuttle protein (NSP)-interacting proteins by probing a protein microarray and demonstrated that viral NSP, a facilitator of the nucleocytoplasmic trafficking of viral (v)DNA, interacts with a new endosomal vesicle-localized plant-specific syntaxin-6 protein, designated NISP in planta. We also showed that begomovirus infection requires the NISP-NSP interaction; NISP displays a pro-viral function, but not the syntaxin-6 paralog AT2G18860 that failed to interact with NSP. Consistent with these findings, nisp-1 mutant plants were less susceptible to begomovirus infection, a phenotype reversed by NISP complementation, whereas overexpressing lines accumulated higher levels of viral DNA than wild-type. Furthermore, NISP interacts with NIG, another pro-viral factor that accessorizes the NSP-vDNA nucleocytoplasmic translocation. Additionally, the NISP-NIG interaction is enhanced by NSP. We also showed that NISP associates with vDNA and might assemble a NISP-NIG-NSP-vDNA- complex. NISP may function as a docking site for recruiting NIG and NSP into trafficking vesicles, providing a mechanism for the intracytoplasmic translocation of the NSP-vDNA complex towards the cell periphery.Author Summary As viruses must use an active and directed intracellular movement, they hijack the intracellular host transport system for their benefit. Therefore, the identification of interactions between host proteins and begomovirus movement proteins should target the intracellular transport machinery. This work focused on the identification of these protein-protein interactions; it addressed the molecular bases for the intracellular transport of begomoviruses. We used a protein microarray to identify cellular partners for the movement protein (MP) and the viral nuclear shuttle protein (NSP), which is a facilitator of the nucleocytoplasmic trafficking of viral (v)DNA. We identified relevant protein-protein interaction (PPI) hubs connecting host and viral proteins. We revealed a novel NSP-interacting protein, which functions in the intracytoplasmic transport of proteins and DNA from begomoviruses and was designated NSP-interacting syntaxin domain-containing protein (NISP). Our data suggest an intracellular route connecting the release of newly-synthesized begomoviral DNA in the cytosol with the cell surface. Resolving viral DNA-host protein complexes led to the identification of a novel class of components of the cell machinery and a representative member, NISP, that functions as a susceptibility gene against begomoviruses. As geminiviruses pose a severe threat to agriculture and food security, this recessive gene can now be exploited as a target for engineering resistance by gene editing in crops.