Cryo-EM Structure of a Begomovirus Geminate Particle

Area of Science:

• Plant virology
• Structural biology
• Molecular biology

Background:

• Tobacco curly shoot virus (TbCSV), a monopartite begomovirus, causes significant leaf curl diseases in tomato and tobacco plants.
• TbCSV is often associated with betasatellite molecules, exacerbating disease severity.

Purpose of the Study:

• To elucidate the structural basis of TbCSV particle formation.
• To understand the role of the viral DNA genome in the assembly of the geminate structure.

Main Methods:

• Single-particle cryo-electron microscopy (cryo-EM) was employed to determine the TbCSV particle structure.
• High-resolution (3.57 Å) structural analysis was performed to visualize molecular interactions.

Main Results:

• The characteristic geminate architecture of the TbCSV particle was confirmed.
• Single-stranded DNA was observed to be bound to each coat protein (CP).
• Interactions between coat proteins (CP⁻CP) and between DNA and coat proteins (DNA⁻CP) were partially resolved, showing a CP⁻DNA⁻CP pattern.

Conclusions:

• The genomic DNA is crucial for mediating stable CP⁻CP and DNA⁻CP interactions.
• This DNA-mediated interface is essential for the proper assembly of the geminate TbCSV particle.