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Published on: August 9, 2011
Structural plasticity of mumps virus nucleocapsids with cryo-EM structures
Hong Shan1,2, Xin Su1, Tianhao Li1
1iHuman Institute and School of Life Science and Technology, ShanghaiTech University, Shanghai, China.
Abstract:
Mumps virus (MuV) is a highly contagious human pathogen and frequently causes worldwide outbreaks despite available vaccines. Similar to other mononegaviruses such as Ebola and rabies, MuV uses a single-stranded negative-sense RNA as its genome, which is enwrapped by viral nucleoproteins into the helical nucleocapsid. The nucleocapsid acts as a scaffold for genome condensation and as a template for RNA replication and transcription. Conformational changes in the MuV nucleocapsid are required to switch between different activities, but the underlying mechanism remains elusive due to the absence of high-resolution structures. Here, we report two MuV nucleoprotein-RNA rings with 13 and 14 protomers, one stacked-ring filament and two nucleocapsids with distinct helical pitches, in dense and hyperdense states, at near-atomic resolutions using cryo-electron microscopy. Structural analysis of these in vitro assemblies indicates that the C-terminal tail of MuV nucleoprotein likely regulates the assembly of helical nucleocapsids, and the C-terminal arm may be relevant for the transition between the dense and hyperdense states of helical nucleocapsids. Our results provide the molecular mechanism for structural plasticity among different MuV nucleocapsids and create a possible link between structural plasticity and genome condensation.
Insights
Mumps virus nucleocapsid structures reveal how its RNA genome condenses. These findings explain the virus
Area of Science:
- Virology
- Structural Biology
- Molecular Biology
Background:
- Mumps virus (MuV) is a contagious pathogen causing global outbreaks.
- MuV, like other mononegaviruses, has a single-stranded negative-sense RNA genome.
- The viral nucleocapsid, formed by nucleoproteins, is crucial for genome management and viral replication.
Purpose of the Study:
- To elucidate the molecular mechanisms behind Mumps virus nucleocapsid structural plasticity.
- To understand how Mumps virus nucleocapsid conformational changes facilitate different viral activities.
- To provide high-resolution structural insights into Mumps virus nucleocapsid assembly and genome condensation.
Main Methods:
- Cryo-electron microscopy was employed to determine near-atomic resolution structures.
- In vitro assembly of Mumps virus nucleoprotein-RNA complexes was analyzed.
- Structural analysis focused on nucleocapsid states, including rings, filaments, and helical structures.
Main Results:
- Two Mumps virus nucleoprotein-RNA rings (13 and 14 protomers), a stacked-ring filament, and two distinct helical nucleocapsids were resolved.
- Structures revealed dense and hyperdense states of the Mumps virus nucleocapsid.
- The C-terminal tail of the nucleoprotein appears to regulate helical nucleocapsid assembly and transitions between states.
Conclusions:
- The study provides a molecular mechanism for the structural plasticity observed in Mumps virus nucleocapsids.
- Findings suggest a link between nucleocapsid structural plasticity and efficient genome condensation.
- These insights are critical for understanding Mumps virus replication and for developing antiviral strategies.
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