A plant-specific syntaxin-6 protein contributes to the intracytoplasmic route for the begomovirus CabLCV

• Published in: Plant physiology (Bethesda) Vol. 187; no. 1; pp. 158 - 173
• Main Authors: Gouveia-Mageste, Bianca Castro, Martins, Laura Gonçalves Costa, Dal-Bianco, Maximiller, Machado, João Paulo Batista, da Silva, José Cleydson Ferreira, Kim, Alice Y, Yazaki, Junshi, Dos Santos, Anésia Aparecida, Ecker, Joseph R, Fontes, Elizabeth Pacheco Batista
• Format: Journal Article
• Language: English
• Published: United States Oxford University Press 04.09.2021
• Subjects: Arabidopsis - genetics; Arabidopsis - metabolism; Arabidopsis - virology; Begomovirus - physiology; Cell Nucleus - metabolism
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1093/plphys/kiab252

Because of limited free diffusion in the cytoplasm, viruses must use active transport mechanisms to move intracellularly. Nevertheless, how the plant single-stranded DNA begomoviruses hijack the host intracytoplasmic transport machinery to move from the nucleus to the plasmodesmata remains enigmatic. Here, we identified nuclear shuttle protein (NSP)-interacting proteins from Arabidopsis (Arabidopsis thaliana) by probing a protein microarray and demonstrated that the cabbage leaf curl virus NSP, a facilitator of the nucleocytoplasmic trafficking of viral (v)DNA, interacts in planta with an endosomal vesicle-localized, plant-specific syntaxin-6 protein, designated NSP-interacting syntaxin domain-containing protein (NISP). NISP displays a proviral function, unlike 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. NISP-overexpressing lines accumulated higher levels of vDNA than wild-type. Furthermore, NISP interacted with an NSP-interacting GTPase (NIG) involved in NSP-vDNA nucleocytoplasmic translocation. The NISP-NIG interaction was enhanced by NSP. We also showed that endosomal NISP associates with vDNA. NISP may function as a docking site for recruiting NIG and NSP into endosomes, providing a mechanism for the intracytoplasmic translocation of the NSP-vDNA complex toward and from the cell periphery.