Intracellular targeting of a hordeiviral membrane-spanning movement protein: sequence requirements and involvement of an unconventional mechanism.
The membrane-spanning protein TGBp3 is one of the three movement proteins (MPs) of Poa semilatent virus. TGBp3 is thought to direct other viral MPs and genomic RNA to peripheral bodies located in close proximity to plasmodesmata. We used the ectopic expression of green fluorescent protein-fused TGBp3 in epidermal cells of Nicotiana benthamiana leaves to study the TGBp3 intracellular trafficking pathway. Treatment with inhibitors was used to reveal that the targeting of TGBp3 to plasmodesmata does not require a functional cytoskeleton or secretory system. In addition, the suppression of endoplasmic reticulum-derived vesicle formation by a dominant negative mutant of small GTPase Sar1 had no detectable effect on TGBp3 trafficking to peripheral bodies. Collectively, these results suggested the involvement of an unconventional pathway in the intracellular transport of TGBp3. The determinants of targeting to plasmodesmata were localized to the C-terminal region of TGBp3, including the conserved hydrophilic and terminal membrane-spanning domains.
Schepetilnikov
Mikhail V
MV
Department of Botany and Plant Pathology, Oregon State University, Cordley Hall 2082, Corvallis, OR 97331, USA.
Solovyev
Andrey G
AG
Gorshkova
Elena N
EN
Schiemann
Joachim
J
Prokhnevsky
Alexey I
AI
Dolja
Valerian V
VV
Morozov
Sergey Y
SY
D000595:Amino Acid Sequence; D019677:Artificial Gene Fusion; D003598:Cytoskeletal Proteins / Q000037:antagonists & inhibitors; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D020559:Monomeric GTP-Binding Proteins / Q000172:deficiency / Q000235:genetics; D053830:Plant Viral Movement Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010942:Plant Viruses / Q000378:metabolism*; D031425:Plasmodesmata / Q000737:chemistry; D021382:Protein Sorting Signals / Q000235:genetics; D012328:RNA Viruses / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D014026:Nicotiana / Q000821:virology
D003598:Cytoskeletal Proteins; D053830:Plant Viral Movement Proteins; D021382:Protein Sorting Signals; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D020559:Monomeric GTP-Binding Proteins