Figure 3.

Solid-state NMR studies on the HIV and HBV capsids. (a) Illustration of the mature HIV-1 capsid (PDB: 3J3Y [99]); and the CA protein in (b), with a zoom on the backbone ¹⁵N^H CSA tensor and its orientation in the protein molecular frame. (c) Transmission EM image of CA and (d) the corresponding 2D NCA spectrum recorded at 14 kHz MAS. (e) HBV capsid structure (PDB: 1QGT [7]) showing the pentamers formed by A subunits and hexamers formed by B, C and D subunits. (f) Negative-staining EM picture of HBV capsids and (g) corresponding 2D Dipolar Assisted Rotational Resonance (DARR) spectrum recorded at 17.5 kHz MAS. Residues with NMR peak splitting due to the asymmetric subunits are highlighted in yellow and are shown as spheres in (h) on the capsid structure. Pictures from panels (a–d) were reprinted with permission from reference [94], Copyright (2016) American Chemical Society. Pictures from panels (e–h) were taken with permissions from reference [55].