Exploring the Effects of Intersubunit Interface Mutations on Virus-Like Particle Structure and Stability

Area of Science:

• Biophysics
• Structural Biology
• Nanotechnology

Background:

• Bacteriophage MS2 virus-like particles (VLPs) are utilized for studying protein self-assembly and engineered drug delivery systems.
• Previous research identified supercharged mutants (T71K/G73R) enhancing mammalian cell uptake.
• A single point mutation (S37P) was known to alter particle geometry from T=3 to T=1 symmetry.

Purpose of the Study:

• To investigate the impact of intersubunit interface mutations on the structure and function of MS2-based VLPs.
• To explore how combining mutations affects VLP size, morphology, and cellular internalization.
• To understand the relationship between VLP assembly dynamics, particle properties, and drug delivery efficacy.

Main Methods:

• Site-directed mutagenesis to create engineered MS2 VLPs with combined mutations (T71K/G73R and S37P).
• Characterization of VLP assembly states using transmission electron microscopy (TEM).
• In silico molecular dynamics simulations to analyze structural rationale and assembly preferences.

Main Results:

• Engineered triple mutants exhibited increased thermostability and unexpected T=3 assembly, not the predicted T=1.
• TEM revealed diverse assembly states including T=3, T=1, and rod-like particles depending on mutation combinations.
• Molecular dynamics simulations supported the T=1 formation for S37P alone but not with rod-favoring mutations.

Conclusions:

• Interdimer interface dynamics significantly influence VLP size and morphology.
• Engineered MS2 VLPs retain drug delivery functionality despite altered assembly states.
• Understanding these structure-function relationships is crucial for designing advanced VLP-based nanocarriers.