Extended Data Fig. 1: Full capsid atomic model of the dArc2.
From: Structures of virus-like capsids formed by the Drosophila neuronal Arc proteins
The views and color scheme are similar to those shown in Fig. 2. a, The 12 five-fold capsomeres are coloured in green (CANTD), and yellow (CACTD). The 30 two-fold capsomeres are coloured in cyan to blue (CANTD) and orange to red (CACTD). b, The asymmetric unit containing four CA molecules. 60 asymmetric units including 240 individual CA molecules make up the T=4 capsid. c, Close-up of the five-fold capsomere (outlined in a) i) Cut-away showing three out of five N-termini in the centre of the capsomeres. The N-termini extend into and form the capsid spikes. The N-termini are stabilized by docking into an extended hydrophobic groove adjacent to α1. d, External view of the five-fold capsomere i) The CANTD:CANTD interaction between α1, and α2 and α3 of the neighbouring CA molecule in the capsomere. Electronegative charged residues on the outside of α1 interact with electropositive charges in α2 and α3. ii) The CANTD:CACTD interface which involves α6 in the CACTD and α3 and α4 in the neighbouring CANTD. This interface relies on both hydrophobic and electrostatic interactions. Residues R43, I80, W84, F106, C135 and D131 are depicted in the figure. e, External view of the two and three-fold CACTD interfaces. i) The two-fold CACTD interface connects two adjacent capsomeres and is dominated by hydrophobic π-stacking interactions. The interface involves residues from α5 and α. Residues Y113, Y116, F120, R148, T153, F157 and Y159 are depicted in figure. EM density is shown only for the contact site. All CACTD interfaces are highly similar (Supplementary Fig. 7). ii) The three-fold CACTD axis. At this position, instead of the histidine present in dArc1, E168 and S169 from α8 surround the largest gap in the capsid. The corresponding views for dArc1 are shown in Fig. 2.
