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. Author manuscript; available in PMC: 2018 May 18.
Published in final edited form as: Science. 2018 Apr 5;360(6384):eaao7298. doi: 10.1126/science.aao7298

Fig. 3. Structure of the triplex.

Fig. 3

(A) Distribution of triplexes in the MCP network. (B) Magnified view of a triplex Tb as viewed from the outside of the capsid. (C to F) Detailed structures of triplex Tb (C) and its components Tri1 (D), Tri2A (E), and Tri2B (F). Dotted curves in (C) and (D) denote the N-terminal region of Tri1 that was not modeled because of its flexibility. (G) Superposition of Tri2A and Tri2B showing constant trunk domains and conformational differences in their embracing-arm domains. (H) Tri2A and Tri2B embrace each other with their embracing-arm domains to form a dimer. (I) The Tri1 insertional arm binding on top of the Tri2 dimer and the Tri1-Tri2B intermolecular disulfide bond (shown in magnified view) stabilize the triplex structure. (J) Architectural similarities between HSV-1 triplex (top) and the gpD trimer of phage λ (bottom, PDB 1C5E) (26). Both are viewed from the inside of the capsid. (K) Same topology of β strands among gpD, Tri1, and Tri2. Corresponding β strands are colored in the same way and numbered one to eight, from Nʹ to Cʹ. (L) Cryo-EM density of triplex Tb in the same orientation as (J), showing the tri-lobed density of the flexible Tri1 N anchor (gray), which penetrates through the capsid floor and anchors the entire triplex to the capsid shell, as depicted in (C).