Surface for catalysis by poliovirus RNA-dependent RNA polymerase

Area of Science:

• Virology
• Structural Biology
• Molecular Biology

Background:

• Poliovirus RNA-dependent RNA polymerase (3Dpol) is crucial for viral genome replication.
• Replication occurs on intracellular membranes, involving complex polymerase assemblies.
• Previous studies revealed 3Dpol forms linear arrays via interface-I interactions.

Purpose of the Study:

• To investigate the structural organization and assembly dynamics of poliovirus 3Dpol.
• To understand how polymerase structure facilitates RNA replication.
• To explore the role of protein-protein interactions in polymerase lattice formation.

Main Methods:

• Analysis of crystal structures of wild-type poliovirus polymerase.
• Electron cryomicroscopy of helical polymerase arrays.
• Computational analysis of diffraction patterns, including ghost reflections.
• Investigation of enzymatically inactive polymerase oligomerization.

Main Results:

• 3Dpol assembles into filaments, sheets, and helical tubes through specific protein-protein interactions (interface-I and others).
• Helical tubes are composed of bundled filaments, with variations in subunit orientation and inter-bundle interactions.
• Inactive polymerase forms thinner tubes lacking interface-I, suggesting allosteric regulation.
• A positively charged groove in polymerase arrays may stabilize the RNA template.

Conclusions:

• Poliovirus polymerase utilizes flexible interactions for adaptable lattice formation, crucial for efficient RNA replication.
• The structural adaptability of polymerase assemblies likely enhances RNA template positioning and stabilization.
• Allosteric mechanisms may influence polymerase conformation and function during replication.