Solid-state NMR studies of HIV-1 capsid protein assemblies

Area of Science:

• Structural Biology
• Virology
• Biophysics

Background:

• Mature HIV-1 virions contain a 26.6 kDa CA protein forming a cone-shaped capsid enclosing the viral genome.
• The capsid structure is modeled as a fullerene cone composed of hexameric and pentameric CA units, enabling tubular or conical formations.

Purpose of the Study:

• To analyze the structure of wild-type HIV-1 CA protein assemblies using solid-state NMR.
• To investigate the conformational homogeneity and structural characteristics of CA protein in different assembly forms (conical and spherical).

Main Methods:

• Solid-state NMR spectroscopy was employed on uniformly (13)C,(15)N-labeled wild-type HIV-1 CA protein.
• Conical and spherical CA assemblies were prepared and analyzed, withstanding magic angle spinning frequencies of 10-25 kHz.
• Multidimensional homo- and heteronuclear correlation spectra were recorded to assess protein structure and conformational homogeneity.

Main Results:

• CA protein assemblies exhibited narrow spectral lines, indicating conformational homogeneity.
• Partial residue-specific resonance assignments were achieved for conical CA assemblies.
• Structural analysis revealed no significant differences in CA protein structure between conical and spherical morphologies.

Conclusions:

• Solid-state NMR is a viable technique for detailed structural analysis of HIV-1 CA protein assemblies.
• The CA protein maintains structural integrity and homogeneity across different assembly forms.
• This study provides insights into the structural basis of HIV-1 capsid formation.