D8 oligomeric interface is secluded to the C-terminal region 235–262.

A. From top to bottom: selected class averages of (i) unliganded D8 oligomer, (ii) oligomeric D8+JE11-Fab, and (iii) oligomeric D8+JE11-Fab+LA5-Fab. Despite the monodispersity of unliganded D8 oligomeric sample, particles showed a varying number of drupelets, because of their orientation on the EM grid. The class averages with the highest number of drupelets always show six drupelets surrounding a central one (red arrows). B. SEC profiles of recombinant D8 Δ235, Δ262, and Δ263 suggest that D8 oligomerises through the C-terminal domain. SEC markers as grey curve with MW given in kDa. C. Putative D8 hexameric model based on EM data and SEC-MALS using biochemical constraints relative to the dimer and oligomer interfaces. The black circle highlights the putative seventh and central drupelet, arising from all six SU C-terminal extremities, converging toward the IMV envelope. D. CS-E microarray indicating that D8 hexamer (0.33 µM) binds more effectively to CS-E compared to 6-times molar excess of D8 monomer (2 µM) E. GAG microarray obtained with D8 oligomer (0.1 µM). D8 oligomer binds CS-E with higher affinity than the monomer, and also weakly binds to other CS species but not to DS, HA, heparin and HS. Micro array binding experiment was performed in triplicate, and the data represent the average of 10 spots per concentration averaged from the three experiments (±SEM, error bars).