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Journal of Bacteriology, March 2008, p. 1680-1690, Vol. 190, No. 5
0021-9193/08/$08.00+0     doi:10.1128/JB.01671-07
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

Bioinformatic and Biochemical Evidence for the Identification of the Type III Secretion System Needle Protein of Chlamydia trachomatis{triangledown}

H. J. Betts,1 L. E. Twiggs,1 M. S. Sal,2 P. B. Wyrick,2 and K. A. Fields1*

Department of Microbiology and Immunology, University of Miami Miller School of Medicine, Miami, Florida 33101,1 Department of Microbiology, East Tennessee State University, James H. Quillen College of Medicine, Johnson City, Tennessee 376142

Received 16 October 2007/ Accepted 17 December 2007

Chlamydia spp. express a functional type III secretion system (T3SS) necessary for pathogenesis and intracellular growth. However, certain essential components of the secretion apparatus have diverged to such a degree as to preclude their identification by standard homology searches of primary protein sequences. One example is the needle subunit protein. Electron micrographs indicate that chlamydiae possess needle filaments, and yet database searches fail to identify a SctF homologue. We used a bioinformatics approach to identify a likely needle subunit protein for Chlamydia. Experimental evidence indicates that this protein, designated CdsF, has properties consistent with it being the major needle subunit protein. CdsF is concentrated in the outer membrane of elementary bodies and is surface exposed as a component of an extracellular needle-like projection. During infection CdsF is detectible by indirect immunofluorescence in the inclusion membrane with a punctuate distribution adjacent to membrane-associated reticulate bodies. Biochemical cross-linking studies revealed that, like other SctF proteins, CdsF is able to polymerize into multisubunit complexes. Furthermore, we identified two chaperones for CdsF, termed CdsE and CdsG, which have many characteristics of the Pseudomonas spp. needle chaperones PscE and PscG, respectively. In aggregate, our data are consistent with CdsF representing at least one component of the extended Chlamydia T3SS injectisome. The identification of this secretion system component is essential for studies involving ectopic reconstitution of the Chlamydia T3SS. Moreover, we anticipate that CdsF could serve as an efficacious target for anti-Chlamydia neutralizing antibodies.

* Corresponding author. Mailing address: Department of Microbiology and Immunology, University of Miami Miller School of Medicine, Miami, FL 33101. Phone: (305) 243-6711. Fax: (305) 243-4623. E-mail: Kfields{at}med.miami.edu

{triangledown} Published ahead of print on 28 December 2007.

Journal of Bacteriology, March 2008, p. 1680-1690, Vol. 190, No. 5
0021-9193/08/$08.00+0     doi:10.1128/JB.01671-07
Copyright © 2008, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Rao, X., Deighan, P., Hua, Z., Hu, X., Wang, J., Luo, M., Wang, J., Liang, Y., Zhong, G., Hochschild, A., Shen, L. (2009). A regulator from Chlamydia trachomatis modulates the activity of RNA polymerase through direct interaction with the {beta} subunit and the primary {sigma} subunit. Genes Dev. 23: 1818-1829 [Abstract] [Full Text]  
  • Stone, C. B., Johnson, D. L., Bulir, D. C., Gilchrist, J. D., Mahony, J. B. (2008). Characterization of the Putative Type III Secretion ATPase CdsN (Cpn0707) of Chlamydophila pneumoniae. J. Bacteriol. 190: 6580-6588 [Abstract] [Full Text]  


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