Higher-order structures of the foot-and-mouth disease virus RNA-dependent RNA polymerase required for genome...

Area of Science:

• Virology
• Structural Biology
• Molecular Biology

Background:

• Positive-sense RNA virus replication occurs in membrane-associated compartments, concentrating viral components and evading host immunity.
• The molecular mechanisms and dynamics within these replication compartments are not well understood.
• RNA-dependent RNA polymerase (RdRp) is a key enzyme in viral RNA replication and can form higher-order structures in vitro.

Purpose of the Study:

• To investigate the structure and function of higher-order RNA-dependent RNA polymerase (RdRp) complexes.
• To elucidate the role of these complexes in viral RNA replication.

Main Methods:

• Cryo-electron microscopy (cryo-EM) was used to determine the structure of foot-and-mouth disease virus 3Dpol fibrils at ~7-9 Å resolution.
• High-resolution coordinates were fitted to define intermolecular interactions.
• Mutagenesis studies using a sub-genomic replicon system were employed to assess the functional importance of identified interactions.

Main Results:

• Cryo-EM revealed multiple conformations of flexible higher-order 3Dpol assemblies.
• Potential intermolecular interactions within these fibrils were identified.
• Mutagenesis data confirmed the importance of these interactions for viral replication.

Conclusions:

• Higher-order 3Dpol complexes form dynamic scaffolds essential for RNA replication.
• These structures likely play a crucial role in concentrating replication machinery and facilitating efficient viral RNA synthesis within host cells.