title: Myosins VIII and XI play distinct roles in reproduction and transport of tobacco mosaic virus.
abstract: Viruses are obligatory parasites that depend on host cellular factors for their replication as well as for their local and systemic movement to establish infection. Although myosin motors are thought to contribute to plant virus infection, their exact roles in the specific infection steps have not been addressed. Here we investigated the replication, cell-to-cell and systemic spread of Tobacco mosaic virus (TMV) using dominant negative inhibition of myosin activity. We found that interference with the functions of three class VIII myosins and two class XI myosins significantly reduced the local and long-distance transport of the virus. We further determined that the inactivation of myosins XI-2 and XI-K affected the structure and dynamic behavior of the ER leading to aggregation of the viral movement protein (MP) and to a delay in the MP accumulation in plasmodesmata (PD). The inactivation of myosin XI-2 but not of myosin XI-K affected the localization pattern of the 126k replicase subunit and the level of TMV accumulation. The inhibition of myosins VIII-1, VIII-2 and VIII-B abolished MP localization to PD and caused its retention at the plasma membrane. These results suggest that class XI myosins contribute to the viral propagation and intracellular trafficking, whereas myosins VIII are specifically required for the MP targeting to and virus movement through the PD. Thus, TMV appears to recruit distinct myosins for different steps in the cell-to-cell spread of the infection.
authors.affiliation: Zürich-Basel Plant Science Center, Botany, Department of Environmental Sciences, University of Basel, Basel, Switzerland.
authors.forename: Khalid
authors.initials: K
authors.lastname: Amari
authors.affiliation: Zürich-Basel Plant Science Center, Botany, Department of Environmental Sciences, University of Basel, Basel, Switzerland.
authors.forename: Martin
authors.initials: M
authors.lastname: Di Donato
authors.affiliation: Department of Botany and Plant Pathology and Center for Genome Research and Biocomputing, Oregon State University, Corvallis, Oregon, United States of America.
authors.forename: Valerian V
authors.initials: VV
authors.lastname: Dolja
authors.affiliation: Zürich-Basel Plant Science Center, Botany, Department of Environmental Sciences, University of Basel, Basel, Switzerland; Institut de Biologie Moléculaire des Plantes du CNRS, Université de Strasbourg, Strasbourg, France.
authors.forename: Manfred
authors.initials: M
authors.lastname: Heinlein
mesh_terms: D009218:Myosins / Q000378:metabolism*; D053830:Plant Viral Movement Proteins / Q000378:metabolism*; D031425:Plasmodesmata / Q000378:metabolism / Q000821:virology*; D014026:Nicotiana / Q000821:virology*; D014027:Tobacco Mosaic Virus / Q000502:physiology; D014779:Virus Replication / Q000502:physiology
chemical_list: D053830:Plant Viral Movement Proteins; D009218:Myosins