Fig. 2: Structure of HML2 CA^rec monomer and assembled particles.

a (Left) Cartoon representation of the HML2 CA^rec monomer from the T = 1 particle. The CA^rec-NTD, residues P1 to S153, and CA^rec-CTD, residues A154 to Q246, are coloured in pink and cyan, respectively. (Right) Experimental electron potential map (grey mesh) and model for the region indicated between α6 and α6′. Residues G152 to P156 in the linker region were built de novo into the density. b (Left) Surface representation of the T = 1 particle (60 monomers arranged as 12 pentamers) viewed along the five-fold symmetry axis with the NTDs and CTDs coloured as in a. (Right) The inner CTD “cage” viewed along the five-fold (upper) and the two-fold (lower). c (Left) D5 particle (90 monomers arranged as 12 pentamers and 5 hexamers) viewed along an equatorial pseudo-hexamer at the two-fold symmetry axis. Pentamer NTDs and CTDs are coloured as in a, and hexamer NTDs and CTDs are coloured in red and teal, respectively. (Right) Central slab of the D5 density map (grey surface) with the T = 1 particle aligned on the D5 polar pentamer. d D6 particle (108 monomers arranged as 12 pentamers and 8 hexamers) viewed along an equatorial pseudo-hexamer at the two-fold symmetry axis. Pentamers and hexamers are coloured as in c. e T = 3 particle (180 monomers arranged as 12 pentamers and 20 hexamers) viewed along an icosahedral two-fold symmetry axis. Pentamers and hexamers are coloured as in c.