Supplementary Figure 9: Comparison of several core complexes in secretion systems and several β-barrel structures.
From: Structural insights into the secretin translocation channel in the type II secretion system
(a) Cap gate structures. The cap gate of Vc_GspD is composed of 30 β-strands, forming a small β-barrel (left, orange). The cap of T4SS core complex (PDB code 3JQO) is composed of 28 α-helixes (right, orange), different from that of Vc_GspD. (b) Domain architectures of secretins. Shown here are domain architectures of Vc_GspD (Vibrio cholerae), K12_GspD (Escherichia coli K12), Pa_XcpQ (Pseudomonas aeruginosa) and Ko_PulD (Klebsiella oxytoca), St_InvG (Salmonella typhimurium) and Nm_PilQ (Neisseria meningitidis). They all shared similar N terminal domains, C terminal secretin domain and S domain. (c) CryoEM structures of secretin channels. Shown here from left to right are T3SS St_InvG (EMD-1224), T2SS K12_GspD, T2SS Vc_GspD, T2SS Ko_PulD (EMD-2628) and T4PBS Nm_PilQ (EMD-2105). They all shared cylindrical structures. (d) Comparison of several β-barrel structures. Vc_GspD exhibits more complicated β-barrel structure than those of OmpF (PDB code 1PHO), BamA (PDB code 4K3B), CsgG (PDB code 4UV3) and TolC (PDB code 1EK9), including much larger size, partial β-barrel transmembrane and novel double-β-barrel architecture.
