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Figure 1
(a) Schematic figures of sections along the long axis of a diffocin (left) and contractile bacteriophage such as ΦCD508 (right). (b) Surface-rendered model showing three layers from the extended tail of ΦCD508 determined by Wilson et al. (2025View full citation). Sheath subunits are differentially coloured. (c) Three layers of the ΦCD508 tail tube (left), which has a similar architecture to that of an engineered diffocin, Av-CD291.2 (right). Individual subunits are differentially coloured. (d) Superposition of the main trunk sheath protein structures determined from pre-contracted forms of an engineered diffocin, Av-CD291.2 (grey, PDB ID 8v3x; Cai et al., 2024View full citation), and phage ΦCD508 (rainbow coloured, N-terminus blue, C-terminus red). The ΦCD508 structure is a refined version of that originally described by Wilson et al. (2025View full citation), with additional residues at the N-terminus modelled in. Domains are labelled with Roman numerals; note that domain III in the phage sheath appears very disordered in the helical reconstruction, so the precise chain fold is poorly determined in this region. (e) Superposition of the tail tube subunit structures from pre-contracted forms of an engineered diffocin, Av-CD291.2 (grey, PDB ID 8v3x; Cai et al., 2024View full citation), and phage ΦCD508 (rainbow, N-terminus blue, C-terminus red). The ΦCD508 structure is a refined version of that originally described by Wilson et al. (2025View full citation), with better fit of residues at the N- and C-termini. Figures made within ChimeraX (Meng et al., 2023View full citation).

IUCrJ
Volume 13| Part 4| July 2026|
ISSN: 2052-2525
https://doi.org/10.1107/S2052252526005105