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. Author manuscript; available in PMC: 2020 Oct 13.
Published in final edited form as: Nat Microbiol. 2020 Apr 13;5(7):966–975. doi: 10.1038/s41564-020-0703-3

Figure 4. Comparison to structurally or functionally homologous assemblies.

Figure 4

a, The closest structural homologue to the RBM3 portion of the FliF ring is the 30-mer B. subtilis protein SpoIIIAG (PDB-5wc3). A view from the outer-membrane side is shown above and from the side below, with a cartoon representation of a single, extracted, monomer also shown. A small beta-insertion structure is indicated (arrow on monomer structures). b, The virulence T3SS basal body is constructed from two protein chains in the MS-ring equivalent region, which both form 24-mer rings consisting of multiple RBM domains. Central sections of the Salmonella SPI-1 injectisome basal body (PDB-5tcr, LH panel) and the FliF ring (RH panel) show the striking similarity in overall shape despite fundamental differences in the chains and domain types used. They also show the 21-fold RBM2inner domains are very similarly arranged to the PrgK/SctJ-RBM2 24-fold ring, whilst the FliF-RBM1 and PrgK/SctJ-RBM1 domains are very differently arranged with respect to these.