Crystal Structure of the Vibrio cholerae Colonization Factor TcpF and Identification of a Functional Immunogenic Site.
Megli, C.J., Yuen, A.S., Kolappan, S., Richardson, M.R., Dharmasena, M.N., Krebs, S.J., Taylor, R.K., Craig, L.(2011) J Mol Biol 409: 146-158
- PubMed: 21440558 
- DOI: https://doi.org/10.1016/j.jmb.2011.03.027
- Primary Citation of Related Structures:  
3OC5, 3OC8 - PubMed Abstract: 
Vibrio cholerae relies on two main virulence factors--toxin-coregulated pilus (TCP) and cholera toxin--to cause the gastrointestinal disease cholera. TCP is a type IV pilus that mediates bacterial autoagglutination and colonization of the intestine. TCP is encoded by the tcp operon, which also encodes TcpF, a protein of unknown function that is secreted by V. cholerae in a TCP-dependent manner. Although TcpF is not required for TCP biogenesis, a tcpF mutant has a colonization defect in the infant mouse cholera model that is as severe as a pilus mutant. Furthermore, TcpF antisera protect against V. cholerae infection. TcpF has no apparent sequence homology to any known protein. Here, we report the de novo X-ray crystal structure of TcpF and the identification of an epitope that is critical for its function as a colonization factor. A monoclonal antibody recognizing this epitope is protective against V. cholerae challenge and adds to the protection provided by an anti-TcpA antibody. These data suggest that TcpF has a novel function in V. cholerae colonization and define a region crucial for this function.
Organizational Affiliation: 
Department of Microbiology and Immunology, Dartmouth Medical School, Hanover, NH 03755, USA.