Subnanometer structure of medusavirus capsid during maturation using cryo-electron microscopy

Area of Science:

• Virology
• Structural Biology
• Microscopy

Background:

• Medusavirus, a giant virus from the Mamonoviridae family, releases immature particles alongside mature virions.
• The structural dynamics of medusavirus capsids during maturation remain largely uncharacterized.

Purpose of the Study:

• To elucidate the structural changes in medusavirus capsids during maturation using cryo-electron microscopy.
• To understand the role of minor capsid proteins (mCPs) and major capsid proteins (MCPs) in the virus maturation process.

Main Methods:

• Cryo-electron microscopy (cryo-EM) single particle analysis with block-based reconstruction.
• High-resolution (7-10 Å) structural mapping of immature and mature medusavirus particles.
• Molecular modeling to define protein boundaries and interactions within the capsid.

Main Results:

• A novel network of mCPs supporting MCPs was identified in medusavirus capsids.
• Dynamic conformational changes in mCPs were observed, influenced by the internal membrane's presence or absence in immature particles.
• The lower portion of penton proteins was absent in mature virions, indicating structural alterations during maturation.

Conclusions:

• The study provides the first detailed structural insights into the maturation process of giant viruses.
• Dynamic conformational changes in mCPs are crucial for medusavirus maturation.
• Structural differences between immature and mature medusavirus particles highlight key events in viral development.