title: Leader proteinase of beet yellows virus functions in long-distance transport.
abstract: The 66-kDa leader proteinase (L-Pro) of the Beet yellows virus (BYV) possesses a nonconserved N-terminal domain and a conserved, papain-like C-terminal domain. Previous work revealed that the N-terminal domain functions in RNA amplification, whereas the C-terminal domain is required for autoproteolysis. Alanine-scanning mutagenesis was applied to complete the functional analysis of L-Pro throughout the virus life cycle. This analysis indicated that the C-terminal domain of L-Pro, in addition to being required for proteolysis, also functions in RNA amplification and that these two functions are genetically separable. Examination of the role of L-Pro in BYV cell-to-cell movement revealed that none of the 20 examined replication-competent mutants was movement defective. In contrast, six of the L-Pro mutations affected the long-distance transport of BYV to various degrees, whereas three mutations completely abolished the transport. Because these mutations were located throughout the protein molecule, both domains of L-Pro function in virus transport. We conclude that in addition to previously identified functions of L-Pro, it also serves as the BYV long-distance transport factor.
authors.affiliation: Department of Botany and Plant Pathology and Center for Gene Research and Biotechnology, Oregon State University, Corvallis, Oregon 97331, USA.
authors.forename: Chih-Wen
authors.initials: CW
authors.lastname: Peng
authors.forename: Alberto J
authors.initials: AJ
authors.lastname: Napuli
authors.forename: Valerian V
authors.initials: VV
authors.lastname: Dolja
mesh_terms: D017790:Closterovirus / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D010450:Endopeptidases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D010935:Plant Diseases / Q000821:virology; D018515:Plant Leaves / Q000821:virology; D029622:Portulacaceae / Q000821:virology*; D014026:Nicotiana / Q000821:virology; D014779:Virus Replication
chemical_list: D008164:Luminescent Proteins; D049452:Green Fluorescent Proteins; D010450:Endopeptidases