Double-spanning plant viral movement protein integration into the endoplasmic reticulum membrane is signal recognition particle-dependent, translocon-mediated, and concerted.
The current model for cell-to-cell movement of plant viruses holds that transport requires virus-encoded movement proteins that intimately associate with endoplasmic reticulum membranes. We have examined the early stages of the integration into endoplasmic reticulum membranes of a double-spanning viral movement protein using photocross-linking. We have discovered that this process is cotranslational and proceeds in a signal recognition particle-dependent manner. In addition, nascent chain photocross-linking to Sec61alpha and translocating chain-associated membrane protein reveal that viral membrane protein insertion takes place via the translocon, as with most eukaryotic membrane proteins, but that the two transmembrane segments of the viral protein leave the translocon and enter the lipid bilayer together.
Saurí
Ana
A
Departament de Bioquímica i Biologia Molecular, Universitat de València E-46 100 Burjassot, Spain.
Saksena
Suraj
S
Salgado
Jesús
J
Johnson
Arthur E
AE
Mingarro
Ismael
I
D002135:Calcium-Binding Proteins / Q000378:metabolism*; D019184:Carmovirus / Q000502:physiology*; D003432:Cross-Linking Reagents; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D004926:Escherichia coli; D008051:Lipid Bilayers / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism; D016296:Mutagenesis; D053830:Plant Viral Movement Proteins; D012367:RNA, Viral; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism*; D018000:Receptors, Peptide / Q000378:metabolism*; D000069816:SEC Translocation Channels; D018271:Signal Recognition Particle / Q000378:metabolism*; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*
D002135:Calcium-Binding Proteins; D003432:Cross-Linking Reagents; D008051:Lipid Bilayers; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D053830:Plant Viral Movement Proteins; D012367:RNA, Viral; D018160:Receptors, Cytoplasmic and Nuclear; D018000:Receptors, Peptide; D000069816:SEC Translocation Channels; D018271:Signal Recognition Particle; D014764:Viral Proteins; C066973:signal sequence receptor; C074282:translocating chain-associating membrane protein (TRAM)