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  • The EMBO Journal (2000) 19, 3876 - 3887
  • doi:10.1093/emboj/19.15.3876

Supramolecular structure of the Shigella type III secretion machinery: the needle part is changeable in length and essential for delivery of effectors

Koichi Tamano1, Shin-Ichi Aizawa2, Eisaku Katayama3, Takashi Nonaka3, Shinobu Imajoh-Ohmi3, Asaomi Kuwae1, Shinya Nagai4 and Chihiro Sasakawa1,5

  1. Department of Microbiology and Immunology Minato-ku, Institute of Medical Science, University of Tokyo, 4-6-1, Shirokanedai, Minato-ku, Tokyo 108-8639, Japan
  2. Department of Biosciences, Teikyo University, 1-1, Toyosatodai, Utsunomiya 320-8551, Japan
  3. Department of Basic Medical Sciences, Institute of Medical Science, University of Tokyo, 4-6-1, Shirokanedai, Minato-ku, Tokyo 108-8639, Japan
  4. Nippon Institute for Biological Science, 9-2221-1, Shinmachi, Ome, Tokyo 198-0024 Japan
  5. Department of Bacterial Toxicology, Research Institute for Microbial Diseases, Osaka University, 3-1, Yamadaoka, Suita, Osaka 565-0871, Japan

Correspondence to:

Chihiro Sasakawa, E-mail: sasakawa@ims.u-tokyo.ac.jp

Received 9 May 2000; Accepted 12 June 2000; Revised 12 June 2000

We investigated the supramolecular structure of the Shigella type III secretion machinery including its major components. Our results indicated that the machinery was composed of needle and basal parts with respective lengths of 45.4 plusminus 3.3 and 31.6 plusminus 0.3 nm, and contained MxiD, MxiG, MxiJ and MxiH. spa47, encoding a putative F1-type ATPase, was required for the secretion of effector proteins via the type III system and was involved in the formation of the needle. The spa47 mutant produced a defective, needle-less type III structure, which contained MxiD, MxiG and MxiJ but not MxiH. The mxiH mutant produced a defective type III structure lacking the needle and failed to secrete effector proteins. Upon overexpression of MxiH in the mxiH mutant, the bacteria produced type III structures with protruding dramatically long needles, and showed a remarkable increase in invasiveness. Our results suggest that MxiH is the major needle component of the type III machinery and is essential for delivery of the effector proteins, and that the level of MxiH affects the length of the needle.

  • Keywords:

    • MxiH,
    • Shigella invasion,
    • supramolecular structure,
    • type III secretion system