Local microenvironments of capsomer variants in the PBCV-1

Area of Science:

• Virology
• Structural Biology
• Biophysics

Background:

• The giant virus PBCV-1, classified within Nucleocytoviricota virus (NCV), possesses a capsid structure resolved to near atomic resolution.
• PBCV-1 capsids are primarily composed of Type I capsomers, with five other variant types identified.
• The specific roles of certain variant capsomers, like Type V found at unique locations, remain largely unknown.

Purpose of the Study:

• To investigate the functional roles of Type V capsomers within the PBCV-1 capsid.
• To compare the interactions of Type V and Type I capsomers with their local capsid microenvironment.
• To elucidate the mechanisms governing viral capsid assembly through understanding capsomer interactions.

Main Methods:

• Experimental replacement of Type V capsomers with Type I capsomers in the PBCV-1 capsid.
• Analysis of interactions between capsomer variants and their surrounding capsid structures.
• Identification of salt bridges and electrostatic interactions using computational methods.

Main Results:

• Significant differences in binding forces were observed between Type V and Type I capsomers.
• Type V capsomers exhibited a stronger binding affinity to neighboring capsomers compared to Type I.
• Identified salt bridges and electrostatic calculations confirmed key residue interactions.

Conclusions:

• Type V capsomers play a distinct role in PBCV-1 capsid stability due to stronger interactions.
• Understanding local capsid microenvironments and capsomer interactions is crucial for viral assembly.
• This research provides foundational knowledge for future studies on giant virus structure and assembly.