FIG 4 .

Atomic model of the XcpQ_N012 dodecameric complex. (A) Model of XcpQ_N012 dodecamer generated by SymmDock by imposing a C6 symmetry. The six XcpQ_N012 dimers are shown in cartoon form with a specific color. (B) The residues Thr54 and Gln86 in the N0ⁿ⁺²-N0ⁿ⁺³ interface are shown in stick and mesh presentations. (C) Top, side, and bottom views of the dodecameric XcpQ_N012 model docked into the EM map of the complex. (D) The dodecameric XcpQ_N012 model is organized into two peripheral and internal rings. The peripheral ring is colored in blue and presents the denoted subunits of each of the six dimers. The inner ring is colored in pink and presents the un-stranded subunits of each of the six dimers. (E) Model of vHH04-XcpQ_N012 complex. The crystal structure of the vHH04-XcpQ_N012 complex is overlaid with the dodecameric model of XcpQ_N012. Only six vHH04s presented in hot pink are able to bind the XcpQ_N012 complex. (F) Side view of the 6:12 vHH04-XcpQ_N012 complex docked into the EM map.