Linear remodeling of helical virus by movement protein binding.
Previously we have shown that encapsidated potato virus X (PVX) RNA was nontranslatable in vitro, but could be converted into a translatable form by binding of the PVX-coded movement protein (termed TGBp1) to one end of a polar helical PVX virion. We reported that binding of TGBp1 to coat protein (CP) subunits located at one extremity of the helical particles induced a linear destabilization of the CP helix, which was transmitted along the whole particle. Two model structures were used: (i) native PVX and (ii) artificial polar helical PVX-like particles lacking intact RNA (PVX(RNA-DEG)). Binding of TGBp1 to the end of either of these particles led to their destabilization, but no disassembly of the CP helix occurred. Influence of additional factors was required to trigger rapid disassembly of TGBp1-PVX and TGBp1-PVX(RNA-DEG) complexes. Thus: (i) no disassembly was observed unless TGBp1-PVX complex was translated. A novel phenomenon of TGBp1-dependent, ribosome-triggered disassembly of PVX was described: initiation of translation and few translocation steps were needed to trigger rapid (and presumably cooperative) disassembly of TGBp1-PVX into protein subunits and RNA. Importantly, the whole of the RNA molecule (including its 3'-terminal region) was released. The TGBp1-induced linear destabilization of CP helix was reversible, suggesting that PVX in TGBp1-PVX complex was metastable; (ii) entire disassembly of the TGBp1-PVX(RNA-DEG) complex (but not of the TGBp1-free PVX(RNA-DEG) particles) into 2.8S subunits was triggered under influence of a centrifugal field. To our knowledge, transmission of the linear destabilization along the polar helical protein array induced by a foreign protein binding to the end of the helix represents a novel phenomenon. It is tempting to suggest that binding of TGBp1 to the end of the PVX CP helix induced conformational changes in terminal CP subunits that can be linearly transferred along the whole helical particle, i.e. that intersubunit conformational changes may be transferred along the CP helix.
Rodionova
Nina P
NP
Department of Virology of Moscow State University, Moscow 119992, Russia.
Karpova
Olga V
OV
Kozlovsky
Stanislav V
SV
Zayakina
Olga V
OV
Arkhipenko
Marina V
MV
Atabekov
Joseph G
JG
D036022:Capsid Proteins / Q000378:metabolism; D008854:Microscopy, Electron; D053830:Plant Viral Movement Proteins; D017863:Potexvirus / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D011485:Protein Binding; D014176:Protein Biosynthesis; D017433:Protein Structure, Secondary; D012367:RNA, Viral / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000378:metabolism; D017361:Viral Nonstructural Proteins / Q000378:metabolism; D014764:Viral Proteins / Q000378:metabolism*; D019065:Virus Assembly
D036022:Capsid Proteins; D053830:Plant Viral Movement Proteins; D012367:RNA, Viral; D016601:RNA-Binding Proteins; D017361:Viral Nonstructural Proteins; D014764:Viral Proteins; C103801:betab protein, barley stripe mosaic virus