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The type III secretion injectisome

Nature Reviews Microbiologyvolume 4pages811825 (2006) | Download Citation

Subjects

Abstract

The type III secretion injectisome is a complex nanomachine that allows bacteria to deliver protein effectors across eukaryotic cellular membranes. In recent years, significant progress has been made in our understanding of its structure, assembly and mode of operation. The principal structural components of the injectisome, from the base located in the bacterial cytosol to the tip of the needle protruding from the cell surface, have been investigated in detail. The structures of several constituent proteins were solved at the atomic level and important insights into the assembly process have been gained. However, despite the ongoing concerted efforts of molecular and structural biologists, the role of many of the constituent components of this nanomachine remain unknown.

Key Points

  • The type III secretion injectisome is a nanomachine that delivers bacterial proteins into the cytosol of eukaryotic target cells. It is evolutionarily related to the flagellum, with which it shares structural and functional similarities.

  • It consists of a basal structure made of several rings spanning the inner and the outer membranes, connected by a central tube. A dodecameric ATPase forms a ring structure at the cytoplasmic side of this basal structure.

  • On top of the basal body is a short, stiff needle or a needle and a filament (animal pathogens) or a pilus (plant pathogens). This distal structure allows bacteria to reach the plasma membrane of the target cell.

  • The needle terminates with a specific tip structure. This structure functions as a scaffold for the formation of the translocation pore.

  • The length of the needle is controlled and adapted to match the length of various macromolecules at the surface of the bacterium and the host cell.

  • The export apparatus, localized in the basal structure, exports the protein subunits that form the external elements of the injectisome. When assembly is complete, the export apparatus changes its substrate specificity and is ready to export the pore formers and the effector proteins. Export of the proteins will only occur on contact with a target cell.

  • Contact to a eukaryotic cell membrane triggers export, by a complex mechanism that is not understood. In some cases, the presence of cholesterol in the target membrane is required. Delivery of proteins by the T3SS is a fast process.

  • The assembly and operation requires the presence of specific cytosolic chaperones dedicated either to effector proteins (class I), to the pore formers (class II) or to substructures subunits (class III). The common main function could be to hide polymerization or aggregation-prone domains in the bacterial cytosol.

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References

  1. 1

    Cornelis, G. R. & Wolf-Watz, H. The Yersinia Yop virulon: a bacterial system for subverting eukaryotic cells. Mol. Microbiol. 23, 861–867 (1997).

  2. 2

    Galan, J. E. & Collmer, A. Type III secretion machines: bacterial devices for protein delivery into host cells. Science 284, 1322–1328 (1999).

  3. 3

    Cornelis, G. R. & Van Gijsegem, F. Assembly and function of type III secretory systems. Annu. Rev. Microbiol. 54, 735–774 (2000).

  4. 4

    Mota, L. J. & Cornelis, G. R. The bacterial injection kit: type III secretion systems. Ann. Med. 37, 234–249 (2005).

  5. 5

    Alfano, J. R. & Collmer, A. Type III secretion system effector proteins: double agents in bacterial disease and plant defense. Annu. Rev. Phytopathol. 42, 385–414 (2004).

  6. 6

    Grant, S. R., Fisher, E. J., Chang, J. H., Mole, B. M. & Dangl, J. L. Subterfuge and manipulation: type III effector proteins of phytopathogenic bacteria. Annu. Rev. Microbiol. 5 June 2006 [epub ahead of print].

  7. 7

    Yip, C. K. & Strynadka, N. C. New structural insights into the bacterial type III secretion system. Trends Biochem. Sci. 31, 223–230 (2006).

  8. 8

    Van Gijsegem, F. et al. The hrp gene locus of Pseudomonas solanacearum, which controls the production of a type III secretion system, encodes eight proteins related to components of the bacterial flagellar biogenesis complex. Mol. Microbiol. 15, 1095–1114 (1995).

  9. 9

    Fields, K. A., Plano, G. V. & Straley, S. C. A low-Ca2+ response (LCR) secretion (ysc) locus lies within the lcrB region of the LCR plasmid in Yersinia pestis. J. Bacteriol. 176, 569–579 (1994).

  10. 10

    Woestyn, S., Allaoui, A., Wattiau, P. & Cornelis, G. R. YscN, the putative energizer of the Yersinia Yop secretion machinery. J. Bacteriol. 176, 1561–1569 (1994).

  11. 11

    Macnab, R. M. How bacteria assemble flagella. Annu. Rev. Microbiol. 57, 77–100 (2003).

  12. 12

    Young, G. M., Schmiel, D. H. & Miller, V. L. A new pathway for the secretion of virulence factors by bacteria: the flagellar export apparatus functions as a protein-secretion system. Proc. Natl Acad. Sci. USA 96, 6456–6461 (1999).

  13. 13

    Kubori, T. et al. Supramolecular structure of the Salmonella typhimurium type III protein secretion system. Science 280, 602–605 (1998).

  14. 14

    Gophna, U., Ron, E. Z. & Graur, D. Bacterial type III secretion systems are ancient and evolved by multiple horizontal-transfer events. Gene 312, 151–163 (2003).

  15. 15

    Pallen, M. J., Beatson, S. A. & Bailey, C. M. Bioinformatics, genomics and evolution of non-flagellar type III secretion systems: a Darwinian perspective. FEMS Microbiol. Rev. 29, 201–229 (2005).

  16. 16

    Troisfontaines, P. & Cornelis, G. R. Type III secretion: more systems than you think. Physiology (Bethesda) 20, 326–339 (2005).

  17. 17

    Roy-Burman, A. et al. Type III protein secretion is associated with death in lower respiratory and systemic Pseudomonas aeruginosa infections. J. Infect. Dis. 183, 1767–1774 (2001).

  18. 18

    Burr, S. E., Wahli, T., Segner, H., Pugovkin, D. & Frey, J. Association of type III secretion genes with virulence of Aeromonas salmonicida subsp. salmonicida. Dis. Aquat. Organ. 57, 167–171 (2003).

  19. 19

    Zhou, D. & Galan, J. Salmonella entry into host cells: the work in concert of type III secreted effector proteins. Microbes Infect. 3, 1293–1298 (2001).

  20. 20

    Waterman, S. R. & Holden, D. W. Functions and effectors of the Salmonella pathogenicity island 2 type III secretion system. Cell Microbiol. 5, 501–511 (2003).

  21. 21

    Sekiya, K. et al. Supermolecular structure of the enteropathogenic Escherichia coli type III secretion system and its direct interaction with the EspA-sheath-like structure. Proc. Natl Acad. Sci. USA 98, 11638–11643 (2001).

  22. 22

    Tamano, K. et al. Supramolecular structure of the Shigella type III secretion machinery: the needle part is changeable in length and essential for delivery of effectors. EMBO J. 19, 3876–3887 (2000).

  23. 23

    Blocker, A. et al. The tripartite type III secreton of Shigella flexneri inserts IpaB and IpaC into host membranes. J. Cell Biol. 147, 683–693. (1999).

  24. 24

    Kimbrough, T. G. & Miller, S. I. Contribution of Salmonella typhimurium type III secretion components to needle complex formation. Proc. Natl Acad. Sci. USA 97, 11008–11013 (2000).

  25. 25

    Daniell, S. J. et al. The filamentous type III secretion translocon of enteropathogenic Escherichia coli. Cell Microbiol. 3, 865–871 (2001).

  26. 26

    Ogino, T. et al. Assembly of the type III secretion apparatus of enteropathogenic Escherichia coli. J. Bacteriol. 188, 2801–2811 (2006).

  27. 27

    Morita-Ishihara, T. et al. Shigella Spa33 is an essential C-ring component of type III secretion machinery. J. Biol. Chem. 281, 599–607 (2006).

  28. 28

    Blocker, A. et al. Structure and composition of the Shigella flexneri 'needle complex', a part of its type III secreton. Mol. Microbiol. 39, 652–663 (2001).

  29. 29

    Feldman, M. F., Muller, S., Wuest, E. & Cornelis, G. R. SycE allows secretion of YopE-DHFR hybrids by the Yersinia enterocolitica type III Ysc system. Mol. Microbiol. 46, 1183–1197 (2002).

  30. 30

    Marlovits, T. C. et al. Structural insights into the assembly of the type III secretion needle complex. Science 306, 1040–1042 (2004).

  31. 31

    Young, H. S., Dang, H., Lai, Y., DeRosier, D. J. & Khan, S. Variable symmetry in Salmonella typhimurium flagellar motors. Biophys. J. 84, 571–577 (2003).

  32. 32

    Bogdanove, A. J. et al. Unified nomenclature for broadly conserved hrp genes of phytopathogenic bacteria. Mol. Microbiol. 20, 681–683 (1996).

  33. 33

    Kubori, T., Sukhan, A., Aizawa, S. I. & Galan, J. E. Molecular characterization and assembly of the needle complex of the Salmonella typhimurium type III protein secretion system. Proc. Natl Acad. Sci. USA 97, 10225–10230 (2000).

  34. 34

    Koster, M. et al. The outer membrane component, YscC, of the Yop secretion machinery of Yersinia enterocolitica forms a ring-shaped multimeric complex. Mol. Microbiol. 26, 789–797 (1997).

  35. 35

    Burghout, P. et al. Structure and electrophysiological properties of the YscC secretin from the type III secretion system of Yersinia enterocolitica J. Bacteriol. 186, 4645–4654 (2004).

  36. 36

    Chami, M. et al. Structural insights into the secretin PulD and its trypsin-resistant core. J. Biol. Chem. 280, 37732–37741 (2005).

  37. 37

    Collins, R. F. et al. Structure of the Neisseria meningitidis outer membrane PilQ secretin complex at 12 A resolution. J. Biol. Chem. 279, 39750–39756 (2004).

  38. 38

    Russel, M. Phage assembly: a paradigm for bacterial virulence factor export? Science 265, 612–614 (1994).

  39. 39

    Burghout, P. et al. Role of the pilot protein YscW in the biogenesis of the YscC secretin in Yersinia enterocolitica. J. Bacteriol. 186, 5366–5375 (2004).

  40. 40

    Daefler, S. & Russel, M. The Salmonella typhimurium InvH protein is an outer membrane lipoprotein required for the proper localization of InvG. Mol. Microbiol. 28, 1367–1380 (1998).

  41. 41

    Crago, A. M. & Koronakis, V. Salmonella InvG forms a ring-like multimer that requires the InvH lipoprotein for outer membrane localization. Mol. Microbiol. 30, 47–56 (1998).

  42. 42

    Crepin, V. F. et al. Structural and functional studies of the enteropathogenic Escherichia coli type III needle complex protein EscJ. Mol. Microbiol. 55, 1658–1670 (2005).

  43. 43

    Yip, C. K. et al. Structural characterization of the molecular platform for type III secretion system assembly. Nature 435, 702–707 (2005).

  44. 44

    Sukhan, A., Kubori, T. & Galan, J. E. Synthesis and localization of the Salmonella SPI-1 type III secretion needle complex proteins PrgI and PrgJ. J. Bacteriol. 185, 3480–3483 (2003).

  45. 45

    Fadouloglou, V. E. et al. Structure of HrcQB-C, a conserved component of the bacterial type III secretion systems. Proc. Natl Acad. Sci. USA 101, 70–75 (2004).

  46. 46

    Gonzalez-Pedrajo, B., Fraser, G. M., Minamino, T. & Macnab, R. M. Molecular dissection of Salmonella FliH, a regulator of the ATPase FliI and the type III flagellar protein export pathway. Mol. Microbiol. 45, 967–982 (2002).

  47. 47

    Jackson, M. W. & Plano, G. V. Interactions between type III secretion apparatus components from Yersinia pestis detected using the yeast two-hybrid system. FEMS Microbiol. Lett. 186, 85–90 (2000).

  48. 48

    Blaylock, B., Riordan, K. E., Missiakas, D. M. & Schneewind, O. Characterization of the Yersinia enterocolitica type III secretion ATPase YscN and its regulator, YscL. J. Bacteriol. 188, 3525–3534 (2006).

  49. 49

    Jouihri, N. et al. MxiK and MxiN interact with the Spa47 ATPase and are required for transit of the needle components MxiH and MxiI, but not of Ipa proteins, through the type III secretion apparatus of Shigella flexneri. Mol. Microbiol. 49, 755–767 (2003).

  50. 50

    Minamino, T. & MacNab, R. M. Interactions among components of the Salmonella flagellar export apparatus and its substrates. Mol. Microbiol. 35, 1052–1064 (2000).

  51. 51

    Pozidis, C. et al. Type III protein translocase: HrcN is a peripheral ATPase that is activated by oligomerization. J. Biol. Chem. 278, 25816–25824 (2003).

  52. 52

    Muller, S. A. et al. Double hexameric ring assembly of the type III protein translocase ATPase HrcN. Mol. Microbiol. 61, 119–125 (2006).

  53. 53

    Claret, L., Calder, S. R., Higgins, M. & Hughes, C. Oligomerization and activation of the FliI ATPase central to bacterial flagellum assembly. Mol. Microbiol. 48, 1349–1355 (2003).

  54. 54

    Akeda, Y. & Galan, J. E. Chaperone release and unfolding of substrates in type III secretion. Nature 437, 911–915 (2005).

  55. 55

    Hoiczyk, E. & Blobel, G. Polymerization of a single protein of the pathogen Yersinia enterocolitica into needles punctures eukaryotic cells. Proc. Natl Acad. Sci. USA 98, 4669–4674 (2001).

  56. 56

    Cordes, F. S. et al. Helical structure of the needle of the type III secretion system of Shigella flexneri. J Biol Chem 278, 17103–7 (2003).

  57. 57

    Deane, J. E. et al. Molecular model of a type III secretion system needle: implications for host-cell sensing. Proc. Natl Acad. Sci. USA (2006).

  58. 58

    Yonekura, K., Maki-Yonekura, S. & Namba, K. Complete atomic model of the bacterial flagellar filament by electron cryomicroscopy. Nature 424, 643–650 (2003).

  59. 59

    Mueller, C. A. et al. The V-antigen of Yersinia forms a distinct structure at the tip of injectisome needles. Science 310, 674–676 (2005).

  60. 60

    Derewenda, U. et al. The structure of Yersinia pestis V-antigen, an essential virulence factor and mediator of immunity against plague. Structure (Camb) 12, 301–306 (2004).

  61. 61

    Jin, Q. & He, S. Y. Role of the Hrp pilus in type III protein secretion in Pseudomonas syringae. Science 294, 2556–2558 (2001).

  62. 62

    Hakansson, S., Galyov, E. E., Rosqvist, R. & Wolf-Watz, H. The Yersinia YpkA Ser/Thr kinase is translocated and subsequently targeted to the inner surface of the HeLa cell plasma membrane. Mol. Microbiol. 20, 593–603. (1996).

  63. 63

    Neyt, C. & Cornelis, G. R. Insertion of a Yop translocation pore into the macrophage plasma membrane by Yersinia enterocolitica: requirement for translocators YopB and YopD, but not LcrG. Mol. Microbiol. 33, 971–981 (1999).

  64. 64

    Rosqvist, R., Magnusson, K. E. & Wolf-Watz, H. Target cell contact triggers expression and polarized transfer of Yersinia YopE cytotoxin into mammalian cells. EMBO J. 13, 964–972 (1994).

  65. 65

    Sory, M. P. & Cornelis, G. R. Translocation of a hybrid YopE-adenylate cyclase from Yersinia enterocolitica into HeLa cells. Mol. Microbiol. 14, 583–594 (1994).

  66. 66

    Pettersson, J. et al. The V-antigen of Yersinia is surface exposed before target cell contact and involved in virulence protein translocation. Mol. Microbiol. 32, 961–976 (1999).

  67. 67

    Boland, A. et al. Status of YopM and YopN in the Yersinia Yop virulon: YopM of Y. enterocolitica is internalized inside the cytosol of PU5–1. 8 macrophages by the YopB, D, N delivery apparatus. EMBO J. 15, 5191–5201 (1996).

  68. 68

    Sarker, M. R., Neyt, C., Stainier, I. & Cornelis, G. R. The Yersinia Yop virulon: LcrV is required for extrusion of the translocators YopB and YopD. J. Bacteriol. 180, 1207–1214 (1998).

  69. 69

    Menard, R., Sansonetti, P., Parsot, C. & Vasselon, T. Extracellular association and cytoplasmic partitioning of the IpaB and IpaC invasins of S. flexneri. Cell 79, 515–525 (1994).

  70. 70

    Harrington, A. et al. Characterization of the interaction of single tryptophan containing mutants of IpaC from Shigella flexneri with phospholipid membranes. Biochemistry 45, 626–636 (2006).

  71. 71

    Hume, P. J., McGhie, E. J., Hayward, R. D. & Koronakis, V. The purified Shigella IpaB and Salmonella SipB translocators share biochemical properties and membrane topology. Mol. Microbiol. 49, 425–439 (2003).

  72. 72

    Schoehn, G. et al. Oligomerization of type III secretion proteins PopB and PopD precedes pore formation in Pseudomonas. EMBO J. 22, 4957–4967 (2003).

  73. 73

    Faudry, E., Vernier, G., Neumann, E., Forge, V. & Attree, I. Synergistic pore formation by type III toxin translocators of Pseudomonas aeruginosa. Biochemistry 45, 8117–8123 (2006).

  74. 74

    Fields, K. A., Nilles, M. L., Cowan, C. & Straley, S. C. Virulence role of V antigen of Yersinia pestis at the bacterial surface. Infect. Immun. 67, 5395–5408 (1999).

  75. 75

    Marenne, M. N., Journet, L., Mota, L. J. & Cornelis, G. R. Genetic analysis of the formation of the Ysc-Yop translocation pore in macrophages by Yersinia enterocolitica: role of LcrV, yscF and YopN. Microb. Pathogen. 35, 243–258 (2003).

  76. 76

    Hakansson, S. et al. The YopB protein of Yersinia pseudotuberculosis is essential for the translocation of Yop effector proteins across the target cell plasma membrane and displays a contact-dependent membrane disrupting activity. EMBO J. 15, 5812–5823. (1996).

  77. 77

    Goure, J. et al. The V antigen of Pseudomonas aeruginosa is required for assembly of the functional PopB/PopD translocation pore in host cell membranes. Infect. Immun. 72, 4741–4750 (2004).

  78. 78

    Goure, J., Broz, P., Attree, O., Cornelis, G. R. & Attree, I. Protective anti-V antibodies inhibit Pseudomonas and Yersinia translocon assembly within host membranes. J. Infect. Dis. 192, 218–225 (2005).

  79. 79

    Picking, W. L. et al. IpaD of Shigella flexneri is independently required for regulation of Ipa protein secretion and efficient insertion of IpaB and IpaC into host membranes. Infect. Immun. 73, 1432–1440 (2005).

  80. 80

    Espina, M. et al. IpaD localizes to the tip of the type III secretion system needle of Shigella flexneri. Infect. Immun. 74, 4391–4400 (2006).

  81. 81

    Warawa, J., Finlay, B. B. & Kenny, B. Type III secretion-dependent hemolytic activity of enteropathogenic Escherichia coli. Infect. Immun. 67, 5538–5540 (1999).

  82. 82

    Yonekura, K. et al. The bacterial flagellar cap as the rotary promoter of flagellin self-assembly. Science 290, 2148–2152 (2000).

  83. 83

    Li, C. M. et al. The Hrp pilus of Pseudomonas syringae elongates from its tip and acts as a conduit for translocation of the effector protein HrpZ. EMBO J. 21, 1909–1915 (2002).

  84. 84

    Crepin, V. F., Shaw, R., Abe, C. M., Knutton, S. & Frankel, G. Polarity of enteropathogenic Escherichia coli EspA filament assembly and protein secretion. J. Bacteriol. 187, 2881–2889 (2005).

  85. 85

    Marlovits, T. C. et al. Assembly of the inner rod determines needle length in the type III secretion injectisome. Nature 441, 637–640 (2006).

  86. 86

    Ikeda, T., Asakura, S. & Kamiya, R. 'Cap' on the tip of Salmonella flagella. J. Mol. Biol. 184, 735–737 (1985).

  87. 87

    Quinaud, M. et al. The PscE-PscF-PscG complex controls type III secretion needle biogenesis in Pseudomonas aeruginosa. J. Biol. Chem. 280, 36293–36300 (2005).

  88. 88

    Journet, L., Agrain, C., Broz, P. & Cornelis, G. R. The needle length of bacterial injectisomes is determined by a molecular ruler. Science 302, 1757–1760 (2003).

  89. 89

    Williams, A. W. et al. Mutations in fliK and flhB affecting flagellar hook and filament assembly in Salmonella typhimurium. J. Bacteriol. 178, 2960–2970 (1996).

  90. 90

    Magdalena, J. et al. Spa32 regulates a switch in substrate specificity of the type III secreton of Shigella flexneri from needle components to Ipa proteins. J. Bacteriol. 184, 3433–3441 (2002).

  91. 91

    Makishima, S., Komoriya, K., Yamaguchi, S. & Aizawa, S. I. Length of the flagellar hook and the capacity of the type III export apparatus. Science 291, 2411–2413 (2001).

  92. 92

    Agrain, C. et al. Characterization of a type III secretion substrate specificity switch (T3S4) domain in YscP from Yersinia enterocolitica. Mol. Microbiol. 56, 54–67 (2005).

  93. 93

    Agrain, C., Sorg, I., Paroz, C. & Cornelis, G. R. Secretion of YscP from Yersinia enterocolitica is essential to control the length of the injectisome needle but not to change the type III secretion substrate specificity. Mol. Microbiol. 57, 1415–1427 (2005).

  94. 94

    Creighton, T. E. Proteins: structures and molecular properties 2nd edn (W. H. Freeman, New York, 1992).

  95. 95

    Kutsukake, K., Minamino, T. & Yokoseki, T. Isolation and characterization of FliK-independent flagellation mutants from Salmonella typhimurium. J. Bacteriol. 176, 7625–7629 (1994).

  96. 96

    Hirano, T., Yamaguchi, S., Oosawa, K. & Aizawa, S. Roles of FliK and FlhB in determination of flagellar hook length in Salmonella typhimurium. J. Bacteriol. 176, 5439–5449 (1994).

  97. 97

    Edqvist, P. J. et al. YscP and YscU regulate substrate specificity of the Yersinia type III secretion system. J. Bacteriol. 185, 2259–2266 (2003).

  98. 98

    Minamino, T. et al. Domain organization and function of Salmonella FliK, a flagellar hook-length control protein. J. Mol. Biol. 341, 491–502 (2004).

  99. 99

    Minamino, T. & Macnab, R. M. Domain structure of Salmonella FlhB, a flagellar export component responsible for substrate specificity switching. J. Bacteriol. 182, 4906–4914 (2000).

  100. 100

    Moriya, N., Minamino, T., Hughes, K. T., Macnab, R. M. & Namba, K. The type III flagellar export specificity switch is dependent on FliK ruler and a molecular clock. J. Mol. Biol. 359, 466–477 (2006).

  101. 101

    Tamano, K., Katayama, E., Toyotome, T. & Sasakawa, C. Shigella Spa32 is an essential secretory protein for functional type III secretion machinery and uniformity of its needle length. J. Bacteriol. 184, 1244–1252 (2002).

  102. 102

    Chakravortty, D., Rohde, M., Jager, L., Deiwick, J. & Hensel, M. Formation of a novel surface structure encoded by Salmonella pathogenicity island 2. EMBO J. 24, 2043–2052 (2005).

  103. 103

    Mota, L. J., Journet, L., Sorg, I., Agrain, C. & Cornelis, G. R. Bacterial injectisomes: needle length does matter. Science 307, 1278 (2005).

  104. 104

    West, N. P. et al. Optimization of virulence functions through glucosylation of Shigella LPS. Science 307, 1313–1317 (2005).

  105. 105

    Pettersson, J. et al. Modulation of virulence factor expression by pathogen target cell contact. Science 273, 1231–1233 (1996).

  106. 106

    Forsberg, A., Viitanen, A. M., Skurnik, M. & Wolf-Watz, H. The surface-located YopN protein is involved in calcium signal transduction in Yersinia pseudotuberculosis. Mol. Microbiol. 5, 977–986 (1991).

  107. 107

    Day, J. B. & Plano, G. V. A complex composed of SycN and YscB functions as a specific chaperone for YopN in Yersinia pestis. Mol. Microbiol. 30, 777–788 (1998).

  108. 108

    Iriarte, M. & Cornelis, G. R. YopT, a new Yersinia Yop effector protein, affects the cytoskeleton of host cells. Mol. Microbiol. 29, 915–929 (1998).

  109. 109

    Skryzpek, E. & Straley, S. C. LcrG, a secreted protein involved in negative regulation of the low-calcium response in Yersinia pestis. J. Bacteriol. 175, 3520–3528 (1993).

  110. 110

    Schubot, F. D. et al. Three-dimensional structure of a macromolecular assembly that regulates type III secretion in Yersinia pestis. J. Mol. Biol. 346, 1147–1161 (2005).

  111. 111

    Nilles, M. L., Williams, A. W., Skrzypek, E. & Straley, S. C. Yersinia pestis LcrV forms a stable complex with LcrG and may have a secretion-related regulatory role in the low-Ca2+ response. J. Bacteriol. 179, 1307–1316 (1997).

  112. 112

    van der Goot, F. G., Tran van Nhieu, G., Allaoui, A., Sansonetti, P. & Lafont, F. Rafts can trigger contact-mediated secretion of bacterial effectors via a lipid-based mechanism. J. Biol. Chem. 279, 47792–47798 (2004).

  113. 113

    Hayward, R. D. et al. Cholesterol binding by the bacterial type III translocon is essential for virulence effector delivery into mammalian cells. Mol. Microbiol. 56, 590–603 (2005).

  114. 114

    Kenjale, R. et al. The needle component of the type III secreton of Shigella regulates the activity of the secretion apparatus. J. Biol. Chem. 280, 42929–42937 (2005).

  115. 115

    Andersson, K. et al. YopH of Yersinia pseudotuberculosis interrupts early phosphotyrosine signalling associated with phagocytosis. Mol. Microbiol. 20, 1057–10569 (1996).

  116. 116

    Schlumberger, M. C. et al. Real-time imaging of type III secretion: Salmonella SipA injection into host cells. Proc. Natl Acad. Sci. USA 102, 12548–12553 (2005).

  117. 117

    Enninga, J., Mounier, J., Sansonetti, P. & Tran Van Nhieu, G. Secretion of type III effectors into host cells in real time. Nature Methods 2, 959–965 (2005).

  118. 118

    Cornelis, G. R., Agrain, C. & Sorg, I. Length control of extended protein structures in bacteria and bacteriophages. Curr. Opin. Microbiol. 9, 201–206 (2006).

  119. 119

    Evdokimov, A. G. et al. Similar modes of polypeptide recognition by export chaperones in flagellar biosynthesis and type III secretion. Nature Struct. Biol. 10, 789–793 (2003).

  120. 120

    Birtalan, S. & Ghosh, P. Structure of the Yersinia type III secretory system chaperone SycE. Nature Struct. Biol. 8, 974–978 (2001).

  121. 121

    Birtalan, S. C., Phillips, R. M. & Ghosh, P. Three-dimensional secretion signals in chaperone-effector complexes of bacterial pathogens. Mol. Cell. 9, 971–980 (2002).

  122. 122

    Stebbins, C. E. & Galan, J. E. Maintenance of an unfolded polypeptide by a cognate chaperone in bacterial type III secretion. Nature 414, 77–81 (2001).

  123. 123

    Fraser, G. M., Bennett, J. C. & Hughes, C. Substrate-specific binding of hook-associated proteins by FlgN and FliT, putative chaperones for flagellum assembly. Mol. Microbiol. 32, 569–580 (1999).

  124. 124

    Auvray, F., Thomas, J., Fraser, G. M. & Hughes, C. Flagellin polymerisation control by a cytosolic export chaperone. J. Mol. Biol. 308, 221–229 (2001).

  125. 125

    Bennett, J. C. & Hughes, C. From flagellum assembly to virulence: the extended family of type III export chaperones. Trends Microbiol. 8, 202–204 (2000).

  126. 126

    Neyt, C. & Cornelis, G. R. Role of SycD, the chaperone of the Yersinia Yop translocators YopB and YopD. Mol. Microbiol. 31, 143–156 (1999).

  127. 127

    Wattiau, P., Bernier, B., Deslee, P., Michiels, T. & Cornelis, G. R. Individual chaperones required for Yop secretion by Yersinia. Proc. Natl Acad. Sci. USA 91, 10493–10497 (1994).

  128. 128

    Darwin, K. H. & Miller, V. L. Type III secretion chaperone-dependent regulation: activation of virulence genes by SicA and InvF in Salmonella typhimurium. EMBO J. 20, 1850–1862 (2001).

  129. 129

    Page, A. L. & Parsot, C. Chaperones of the type III secretion pathway: jacks of all trades. Mol. Microbiol. 46, 1–11 (2002).

  130. 130

    Feldman, M. F. & Cornelis, G. R. The multitalented type III chaperones: all you can do with 15 kDa. FEMS Microbiol. Lett. 219, 151–158 (2003).

  131. 131

    Ghosh, P. Process of protein transport by the type III secretion system. Microbiol. Mol. Biol. Rev. 68, 771–795 (2004).

  132. 132

    Parsot, C., Hamiaux, C. & Page, A. L. The various and varying roles of specific chaperones in type III secretion systems. Curr. Opin. Microbiol. 6, 7–14 (2003).

  133. 133

    Wattiau, P. & Cornelis, G. R. SycE, a chaperone-like protein of Yersinia enterocolitica involved in the secretion of YopE. Mol. Microbiol. 8, 123–131 (1993).

  134. 134

    Luo, Y. et al. Structural and biochemical characterization of the type III secretion chaperones CesT and SigE. Nature Struct. Biol. 8, 1031–1036 (2001).

  135. 135

    Evdokimov, A. G., Tropea, J. E., Routzahn, K. M. & Waugh, D. S. Three-dimensional structure of the type III secretion chaperone SycE from Yersinia pestis. Acta Crystallogr. D Biol. Crystallogr. 58, 398–406 (2002).

  136. 136

    Locher, M. et al. Crystal Structure of the Yersinia enterocolitica type III secretion chaperone SycT. J. Biol. Chem. 280, 31149–31155 (2005).

  137. 137

    Trame, C. B. & McKay, D. B. Structure of the Yersinia enterocolitica molecular-chaperone protein SycE. Acta Crystallogr. D Biol. Crystallogr. 59, 389–392 (2003).

  138. 138

    Phan, J., Tropea, J. E. & Waugh, D. S. Structure of the Yersinia pestis type III secretion chaperone SycH in complex with a stable fragment of YscM2. Acta Crystallogr. D Biol. Crystallogr. 60, 1591–1599 (2004).

  139. 139

    van Eerde, A., Hamiaux, C., Perez, J., Parsot, C. & Dijkstra, B. W. Structure of Spa15, a type III secretion chaperone from Shigella flexneri with broad specificity. EMBO Rep. 5, 477–483 (2004).

  140. 140

    Buttner, C. R., Cornelis, G. R., Heinz, D. W. & Niemann, H. H. Crystal structure of Yersinia enterocolitica type III secretion chaperone SycT. Protein Sci. 14, 1993–2002 (2005).

  141. 141

    Boyd, A. P., Lambermont, I. & Cornelis, G. R. Competition between the Yops of Yersinia enterocolitica for delivery into eukaryotic cells: role of the SycE chaperone binding domain of YopE. J. Bacteriol. 182, 4811–4821 (2000).

  142. 142

    Page, A. L., Sansonetti, P. & Parsot, C. Spa15 of Shigella flexneri, a third type of chaperone in the type III secretion pathway. Mol. Microbiol. 43, 1533–1542 (2002).

  143. 143

    Letzelter, M. et al. The discovery of SycO highlights a new function for type III secretion effector chaperones. EMBO J. 25, 3223–3233 (2006).

  144. 144

    Swietnicki, W. et al. Novel protein-protein interactions of the Yersinia pestis type III secretion system elucidated with a matrix analysis by surface plasmon resonance and mass spectrometry. J. Biol. Chem. 279, 38693–38700 (2004).

  145. 145

    Krall, R., Zhang, Y. & Barbieri, J. T. Intracellular membrane localization of pseudomonas ExoS and Yersinia YopE in mammalian cells. J. Biol. Chem. 279, 2747–2753 (2004).

  146. 146

    Ehrbar, K., Hapfelmeier, S., Stecher, B. & Hardt, W. D. InvB is required for type III-dependent secretion of SopA in Salmonella enterica serovar Typhimurium. J. Bacteriol. 186, 1215–1219 (2004).

  147. 147

    Creasey, E. A. et al. CesT is a bivalent enteropathogenic Escherichia coli chaperone required for translocation of both Tir and Map. Mol. Microbiol. 47, 209–221 (2003).

  148. 148

    Lee, S. H. & Galan, J. E. Salmonella type III secretion-associated chaperones confer secretion-pathway specificity. Mol. Microbiol. 51, 483–495 (2004).

  149. 149

    Wulff-Strobel, C. R., Williams, A. W. & Straley, S. C. LcrQ and SycH function together at the Ysc type III secretion system in Yersinia pestis to impose a hierarchy of secretion. Mol. Microbiol. 43, 411–423 (2002).

  150. 150

    Parsot, C. et al. A secreted anti-activator, OspD1, and its chaperone, Spa15, are involved in the control of transcription by the type III secretion apparatus activity in Shigella flexneri. Mol. Microbiol. 56, 1627–1635 (2005).

  151. 151

    Hanson, P. I. & Whiteheart, S. W. AAA+ proteins: have engine, will work. Nature Rev. Mol. Cell Biol. 6, 519–529 (2005).

  152. 152

    Yip, C.K., Finlay, B.B. & Strynadka, N.C. Structural characterization of a type III secretion system filament protein in complex with its chaperone. Nature Struct. Mol. Biol. 12, 75–81 (2005).

  153. 153

    Kauppi, A. M., Nordfelth, R., Uvell, H., Wolf-Watz, H. & Elofsson, M. Targeting bacterial virulence: inhibitors of type III secretion in Yersinia. Chem. Biol. 10, 241–249 (2003).

  154. 154

    Wolf, K. et al. Treatment of Chlamydia trachomatis with a small molecule inhibitor of the Yersinia type III secretion system disrupts progression of the chlamydial developmental cycle. Mol. Microbiol. 61, 1543–1555 (2006).

  155. 155

    Muschiol, S. et al. A small-molecule inhibitor of type III secretion inhibits different stages of the infectious cycle of Chlamydia trachomatis. Proc. Natl Acad. Sci. USA 103, 14566–14571 (2006).

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Acknowledgements

This review does not claim to be comprehensive. For the sake of coherence, the Yersinia Ysc archetype was taken as a unifying thread, which means that there is a bias in favour of work on this organism. I apologize to colleagues whose work could not be cited for these two reasons. I sincerely thank P. Broz and M. Letzelter for help in the conception of the illustrations and for challenging discussions. I am grateful to P. Broz, M. Letzelter and I. Sorg for discussions, information and critical assessment of the manuscript. I also thank J. Galan for exchange of information. Work in my laboratory is supported by the Swiss National Science Foundation.

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  1. Biozentrum der Universität Basel, Klingelbergstrasse 50, Basel, CH-4056, Switzerland

    • Guy R. Cornelis

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The author declares no competing financial interests.

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Glossary

Injectisome

The injectisome is a nanomachine that evolved for the delivery of bacterial proteins, by type III secretion, across eukaryotic cell membranes. In the present stage of knowledge, it consists of a basal structure, which resembles the basal structure of the flagellum, surmounted by either a needle, a needle and a filament or a long pilus.

Flagellum

The flagellum is a motility organelle consisting of a rotating long filament connected to a rotary motor by a short curved structure called the hook. The motor is powered by the flow of ions down an electrochemical gradient across the cytoplasmic membrane into the cell. The ions are typically H+ (protons) in Escherichia coli and enterobacteria and Na+ in alkalophiles and marine Vibrio species.

Needle complex

The needle complex is the part of the injectisome that was characterized in great detail by cryo-EM28,30,85. This structure contains neither the ATPase nor the putative C ring.

Basal structure

Here, the basal structure is defined as the injectisome without its needle, filament or pilus.

Type II secretion apparatus

The type II secretion apparatus is a complex nanomachine that translocates proteins across the outer membrane. This machine involves a secretin in the outer membrane and a dynamic short pilus that functions as a piston.

Type IV pili

Type IV pili are retractable pili involved in adherence and motility and found on diverse bacteria. They are related to the piston of the type II secretion apparatus.

Lipoprotein

A Lipoprotein (LP) is a protein that is synthesized with a signal peptide followed by a cysteine onto which a diacylglycerol is covalently attached by a thioether bond during export. LPs insert either in the plasma membrane or in the outer membrane.

AAA+

(ATPases associated with various cellular activities) The AAA+ family is a large and functionally diverse group of enzymes that can induce conformational changes in a wide range of substrate proteins. The defining feature of the family is a structurally conserved ATPase domain that assembles into oligomeric rings and undergoes conformational changes during cycles of nucleotide binding and hydrolysis. AAA+ are associated with several ATP-dependent bacterial proteases, including ClpXP and ClpAP. They unfold proteins and translocate the unfolded polypeptide into the proteolytic chamber for degradation. See Ref. 152 for a review.

General secretory pathway

(Sec pathway) The General Secretory pathway is the most essential bacterial export pathway. It is involved in the assembly of inner membrane proteins and it translocates many proteins across the plasma membrane. The Sec machine recognizes its substrates by an amino-terminal signal peptide that is cleaved off during translocation.

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