title: Functional analysis of a DNA-shuffled movement protein reveals that microtubules are dispensable for the cell-to-cell movement of tobacco mosaic virus.
abstract: Microtubules interact strongly with the viral movement protein (MP) of Tobacco mosaic virus (TMV) and are thought to transport the viral genome between plant cells. We describe a functionally enhanced DNA-shuffled movement protein (MP(R3)) that remained bound to the vertices of the cortical endoplasmic reticulum, showing limited affinity for microtubules. A single amino acid change was shown to confer the MP(R3) phenotype. Disruption of the microtubule cytoskeleton in situ with pharmacological agents, or by silencing of the alpha-tubulin gene, had no significant effect on the spread of TMV vectors expressing wild-type MP (MP(WT)) and did not prevent the accumulation of MP(WT) in plasmodesmata. Thus, cell-to-cell trafficking of TMV can occur independently of microtubules. The MP(R3) phenotype was reproduced when infection sites expressing MP(WT) were treated with a specific proteasome inhibitor, indicating that the degradation of MP(R3) is impaired. We suggest that the improved viral transport functions of MP(R3) arise from evasion of a host degradation pathway.
authors.affiliation: Unit of Cell Biology, Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, Scotland, United Kingdom.
authors.forename: Trudi
authors.initials: T
authors.lastname: Gillespie
authors.forename: Petra
authors.initials: P
authors.lastname: Boevink
authors.forename: Sophie
authors.initials: S
authors.lastname: Haupt
authors.forename: Alison G
authors.initials: AG
authors.lastname: Roberts
authors.forename: Rachel
authors.initials: R
authors.lastname: Toth
authors.forename: Tracy
authors.initials: T
authors.lastname: Valentine
authors.forename: Sean
authors.initials: S
authors.lastname: Chapman
authors.forename: Karl J
authors.initials: KJ
authors.lastname: Oparka
mesh_terms: D004279:DNA, Viral / Q000378:metabolism*; D005822:Genetic Vectors; D008870:Microtubules / Q000502:physiology* / Q000821:virology; D009068:Movement; D011523:Protoplasts / Q000502:physiology / Q000821:virology; D014026:Nicotiana / Q000502:physiology* / Q000821:virology; D014027:Tobacco Mosaic Virus / Q000235:genetics / Q000502:physiology*; D014162:Transfection
chemical_list: D004279:DNA, Viral