title: Long-distance movement factor: a transport function of the potyvirus helper component proteinase.
abstract: Transport of viruses from cell to cell in plants typically involves one or more viral proteins that supply dedicated movement functions. Transport from leaf to leaf through phloem, or long-distance transport, is a poorly understood process with requirements differing from those of cell-to-cell movement. Through genetic analysis of tobacco etch virus (TEV; potyvirus group), a novel long-distance movement factor was identified that facilitates vascular-associated movement in tobacco. A mutation in the central region of the helper component proteinase (HC-Pro), a TEV-encoded protein with previously described activities in aphid-mediated transmission and polyprotein processing, inactivated long-distance movement. This mutant virus exhibited only minor defects in genome amplification and cell-to-cell movement functions. In situ histochemical analysis revealed that the mutant was capable of infecting mesophyll, bundle sheath, and phloem cells within inoculated leaves, suggesting that the long-distance movement block was associated with entry into or exit from sieve elements. The long-distance movement defect was specifically complemented by HC-Pro supplied in trans by a transgenic host. The data indicate that HC-Pro functions in one or more steps unique to long-distance transport.
authors.affiliation: Department of Biology, Texas A & M University, College Station 77843, USA.
authors.forename: S
authors.initials: S
authors.lastname: Cronin
authors.forename: J
authors.initials: J
authors.lastname: Verchot
authors.forename: R
authors.initials: R
authors.lastname: Haldeman-Cahill
authors.forename: M C
authors.initials: MC
authors.lastname: Schaad
authors.forename: J C
authors.initials: JC
authors.lastname: Carrington
mesh_terms: D001692:Biological Transport; D003546:Cysteine Endopeptidases / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D004252:DNA Mutational Analysis; D017930:Genes, Reporter; D005966:Glucuronidase / Q000235:genetics; D016297:Mutagenesis, Site-Directed; D053830:Plant Viral Movement Proteins; D030821:Plants, Genetically Modified; D010947:Plants, Toxic; D017800:Potyvirus / Q000235:genetics / Q000254:growth & development* / Q000472:pathogenicity; D014176:Protein Biosynthesis; D011499:Protein Processing, Post-Translational; D011523:Protoplasts / Q000821:virology; D014026:Nicotiana / Q000166:cytology / Q000821:virology*; D014158:Transcription, Genetic; D014764:Viral Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D014774:Virulence / Q000235:genetics
chemical_list: D053830:Plant Viral Movement Proteins; D014764:Viral Proteins; D005966:Glucuronidase; D003546:Cysteine Endopeptidases; C072775:HC-Pro protein, potyvirus