Cryo-electron microscopy analysis of E. coli- produced tandem core particles.

a) Surface-rendered views of the reconstructions. Red—hetero-tandem core, contoured at 1σ. Green—homo-tandem core, contoured at 1σ. Blue—difference map, hetero-minus-homo, contoured at 4σ. b) Transverse view across 5-fold axis of the He core with co-ordinates from the HBc crystal structure (Wynne et al., 1999) fitted into the EM density. c) Density profiles of the He (red) and Ho (green) cores generated from translationally-aligned rotational averages. For comparison central sections of the He (upper panel) and Ho (lower panel) maps are shown to the right. A ring of density under the main capsid surface and at a radius of ~90 Å derives from the protamine-like region in He.