Biogenesis, Regulation, and Targeting of the Type III Secretion System Thierry Izoré, Viviana Job, Andréa Dessen  Structure  Volume 19, Issue 5, Pages 603-612 (May 2011) DOI: 10.1016/j.str.2011.03.015 Copyright © 2011 Elsevier Ltd Terms and Conditions

Figure 1 Schematic Diagram of the T3SS of Yersinia spp The basal body is a multi-ring structure that anchors the system to the two bacterial membranes. Upon its formation the needle protein potentially travels through the rings (step 1) and self-polymerizes on the outside of the bacterium. Subsequently, translocon proteins (step 2) are secreted, and finally, toxins/effectors are injected into the eukaryotic cytoplasm (step 3) (see Movie S1). The table includes homologous proteins in Pseudomonas, Shigella, Salmonella, and pathogenic E. coli spp. n.i., molecules that were not yet identified. Structure 2011 19, 603-612DOI: (10.1016/j.str.2011.03.015) Copyright © 2011 Elsevier Ltd Terms and Conditions

Figure 2 Organization of T3SS Operons in Different Bacterial Species Only operons containing transcriptional regulators, basal body, and needle formation genes are shown. Strains include Yersinia pestis CO29 (NC_003143), P. aeruginosa PAO1 (NC_002516), S. flexneri 301 (NC_004851), Salmonella enterica serovar Typhimurium LT2 (NC_003197), and E. coli (enteropathogenic) O127:H6 E2348/69 (NC_011601). Homologous genes are highlighted in the same color. Structure 2011 19, 603-612DOI: (10.1016/j.str.2011.03.015) Copyright © 2011 Elsevier Ltd Terms and Conditions

Figure 3 Structural Overview of the T3SS Base-Forming Proteins Top left shows OMR-forming proteins: EscC (Protein Data Bank ID code 3GR5) and MxiM (1Y9T). Top right illustrates IMR-forming proteins: PrgH (3GR1) and EscJ (1YJ7). Bottom shows export apparatus: HrcQb (YscQ-homolog; 1O9Y); EscN (2OBL); EscU (3BZL); YscU (2JLH); SpaS (3CO1); Spa40 (2VT1); and InvA (2X49). Structure 2011 19, 603-612DOI: (10.1016/j.str.2011.03.015) Copyright © 2011 Elsevier Ltd Terms and Conditions

Figure 4 A Gallery of T3SS Chaperones Class IA and IB chaperones share a common overall heart-shaped structure, whereas class II and class III chaperones display TPR-like folds. In the latter class a smaller partner protein (blue) is required to stabilize the main chaperone (green). Depicted molecules in the gallery include SycT (2BSJ), SycE (1JYA), SicP (1JYO), SycH (1TTW), SigE (1K3S), SrcA, (3EPU), AvrPphF (1S28), ExsC (3KXY), Spa15 (1RY9), InvB (2FM8), PcrH (2XCB), IpgC (4GZ2), SycD (2VGX), PscG-PscE (2UWJ), and YscG-YscE (2P58). Structure 2011 19, 603-612DOI: (10.1016/j.str.2011.03.015) Copyright © 2011 Elsevier Ltd Terms and Conditions

Figure 5 TPR Folds Recognize Helical and Stretched Peptides (A) A prototypical class III chaperone, PscG (light blue), is shown in complex with PscE (light brown) and the C-terminal region of PscF (red). The interaction between PscF and PscG is mediated by an amphipathic helix located within the concave region of the PscG TPR fold (Quinaud et al., 2007); hydrophobic residues are shown in green, hydrophilic in yellow. (B) PcrH, a class II chaperone, in complex with a peptide from PopD (yellow), which also occupies the concave region of the TPR fold of PcrH but in outstretched form (Job et al., 2010). (C) Eukaryotic TPR-containing HOP in complex with a peptide from Hsp90; here, the concave region of the TPR is also recognized by an outstretched peptide (Scheufler et al., 2000). Hsp90 interacts with HOP in an elongated fashion, highly similar to PcrH:PopD. Structures on the right are rotated axially by 90° in relation to the ones on the left. Structure 2011 19, 603-612DOI: (10.1016/j.str.2011.03.015) Copyright © 2011 Elsevier Ltd Terms and Conditions

Figure 6 Representative Structures of Small Molecules that Inhibit the T3SS The right side of the figure describes inhibition effects observed mostly through the employment of cellular-based assays. Structure 2011 19, 603-612DOI: (10.1016/j.str.2011.03.015) Copyright © 2011 Elsevier Ltd Terms and Conditions