Structure of an insect virus at 3.0 A resolution

Area of Science:

• Structural biology
• Virology
• Biochemistry

Background:

• Black beetle virus (BBV) is an insect virus with a bipartite RNA genome.
• Understanding viral structure is crucial for virology and evolutionary studies.
• Previous studies have solved structures of plant and animal viruses, but not insect viruses at atomic resolution.

Purpose of the Study:

• To determine the first atomic resolution structure of an insect virus, specifically black beetle virus (BBV).
• To investigate the structural organization and evolutionary implications of BBV's capsid.
• To compare BBV's structure with known plant and animal viruses.

Main Methods:

• Single crystal X-ray diffraction was used to determine the atomic structure.
• Analysis of the capsid protomer composition and quaternary organization.
• Comparison of BBV structural motifs with other spherical viruses.

Main Results:

• The atomic resolution structure of BBV was determined, revealing 180 protomers on a T=3 lattice.
• BBV protomers feature a beta-barrel, an outer beta-sheet protrusion, and internal helices.
• The conserved structural motif of BBV's shell is shared with other spherical viruses.

Conclusions:

• BBV's structure is similar to T=3 plant viruses, indicating conserved quaternary organization.
• The conserved shell architecture suggests a common evolutionary origin for spherical viruses.
• BBV's primitive genome structure implies it represents an early stage in viral evolution from cellular genes.