EMD-5376

Single-particle
4.1 Å
EMD-5376 Deposition: 25/12/2011
Map released: 26/03/2012
Last modified: 24/10/2012
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links

EMD-5376

Structure of a transcribing cypovirus by cryo-electron microscopy

EMD-5376

Single-particle
4.1 Å
EMD-5376 Deposition: 25/12/2011
Map released: 26/03/2012
Last modified: 24/10/2012
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links
Sample Organism: Bombyx mori cypovirus 1
Sample: transcribing cypovirus
Fitted models: 3j17 (Avg. Q-score: 0.355)

Deposition Authors: Yang C, Ji G, Liu H, Zhang K , Liu G, Sun F, Zhu P, Cheng L
Cryo-EM structure of a transcribing cypovirus.
Yang C, Ji G, Liu H, Zhang K , Liu G, Sun F, Zhu P, Cheng L
(2012) PNAS , 109 , 6118 - 6123
Abstract:
Double-stranded RNA viruses in the family Reoviridae are capable of transcribing and capping nascent mRNA within an icosahedral viral capsid that remains intact throughout repeated transcription cycles. However, how the highly coordinated mRNA transcription and capping process is facilitated by viral capsid proteins is still unknown. Cypovirus provides a good model system for studying the mRNA transcription and capping mechanism of viruses in the family Reoviridae. Here, we report a full backbone model of a transcribing cypovirus built from a near-atomic-resolution density map by cryoelectron microscopy. Compared with the structure of a nontranscribing cypovirus, the major capsid proteins of transcribing cypovirus undergo a series of conformational changes, giving rise to structural changes in the capsid shell: (i) an enlarged capsid chamber, which provides genomic RNA with more flexibility to move within the densely packed capsid, and (ii) a widened peripentonal channel in the capsid shell, which we confirmed to be a pathway for nascent mRNA. A rod-like structure attributable to a partially resolved nascent mRNA was observed in this channel. In addition, conformational change in the turret protein results in a relatively open turret at each fivefold axis. A GMP moiety, which is transferred to 5'-diphosphorylated mRNA during the mRNA capping reaction, was identified in the pocket-like guanylyltransferase domain of the turret protein.