title: The TGB1 movement protein of Potato virus X reorganizes actin and endomembranes into the X-body, a viral replication factory.
abstract: Potato virus X (PVX) requires three virally encoded proteins, the triple gene block (TGB), for movement between cells. TGB1 is a multifunctional protein that suppresses host gene silencing and moves from cell to cell through plasmodesmata, while TGB2 and TGB3 are membrane-spanning proteins associated with endoplasmic reticulum-derived granular vesicles. Here, we show that TGB1 organizes the PVX "X-body," a virally induced inclusion structure, by remodeling host actin and endomembranes (endoplasmic reticulum and Golgi). Within the X-body, TGB1 forms helically arranged aggregates surrounded by a reservoir of the recruited host endomembranes. The TGB2/3 proteins reside in granular vesicles within this reservoir, in the same region as nonencapsidated viral RNA, while encapsidated virions accumulate at the outer (cytoplasmic) face of the X-body, which comprises a highly organized virus "factory." TGB1 is both necessary and sufficient to remodel host actin and endomembranes and to recruit TGB2/3 to the X-body, thus emerging as the central orchestrator of the X-body. Our results indicate that the actin/endomembrane-reorganizing properties of TGB1 function to compartmentalize the viral gene products of PVX infection.
authors.affiliation: Institute of Molecular Plant Sciences, University of Edinburgh, Edinburgh EH9 3JR, United Kingdom.
authors.forename: Jens
authors.initials: J
authors.lastname: Tilsner
authors.forename: Olga
authors.initials: O
authors.lastname: Linnik
authors.forename: Kathryn M
authors.initials: KM
authors.lastname: Wright
authors.forename: Karen
authors.initials: K
authors.lastname: Bell
authors.forename: Alison G
authors.initials: AG
authors.lastname: Roberts
authors.forename: Christophe
authors.initials: C
authors.lastname: Lacomme
authors.forename: Simon
authors.initials: S
authors.lastname: Santa Cruz
authors.forename: Karl J
authors.initials: KJ
authors.lastname: Oparka
mesh_terms: D000199:Actins / Q000378:metabolism*; D016960:Agrobacterium tumefaciens / Q000235:genetics / Q000378:metabolism; D022162:Cytoplasmic Vesicles / Q000378:metabolism / Q000821:virology; D004721:Endoplasmic Reticulum / Q000378:metabolism / Q000821:virology; D005455:Fluorescent Antibody Technique / Q000379:methods; D005814:Genes, Viral; D006056:Golgi Apparatus / Q000378:metabolism / Q000821:virology; D007425:Intracellular Membranes / Q000378:metabolism* / Q000821:virology; D008854:Microscopy, Electron; D010935:Plant Diseases / Q000821:virology; D018515:Plant Leaves / Q000378:metabolism / Q000648:ultrastructure / Q000821:virology; D053830:Plant Viral Movement Proteins / Q000235:genetics / Q000378:metabolism*; D031425:Plasmodesmata / Q000378:metabolism / Q000821:virology; D017863:Potexvirus / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity / Q000502:physiology; D021381:Protein Transport; D014026:Nicotiana / Q000033:anatomy & histology / Q000235:genetics / Q000378:metabolism / Q000821:virology; D014779:Virus Replication
chemical_list: D000199:Actins; D053830:Plant Viral Movement Proteins