Cryo-EM structure of a transcribing cypovirus
| Autor: | Chongwen Yang, Lingpeng Cheng, Guangqiao Liu, Ping Zhu, Kai Zhang, Fei Sun, Hongrong Liu, Gang Ji |
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| Rok vydání: | 2012 |
| Předmět: |
Models
Molecular Guanylyltransferase Multidisciplinary Transcription Genetic biology Protein Conformation Cryo-electron microscopy viruses Cryoelectron Microscopy RNA Reoviridae Biological Sciences biology.organism_classification Molecular biology Protein Structure Tertiary Cell biology Capsid Protein structure Icosahedral viral capsid RNA Viral Capsid Proteins RNA Messenger Cypovirus |
| Zdroj: | Proceedings of the National Academy of Sciences. 109:6118-6123 |
| ISSN: | 1091-6490 0027-8424 |
| DOI: | 10.1073/pnas.1200206109 |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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