IAI FigSearch
Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Krishnan, H. H.
Right arrow Articles by Chowdhury, R.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Krishnan, H. H.
Right arrow Articles by Chowdhury, R.

 Previous Article  |  Next Article 

Infection and Immunity, July 2004, p. 3961-3967, Vol. 72, No. 7
0019-9567/04/$08.00+0     DOI: 10.1128/IAI.72.7.3961-3967.2004
Copyright © 2004, American Society for Microbiology. All Rights Reserved.

Effect of Anaerobiosis on Expression of Virulence Factors in Vibrio cholerae

H. H. Krishnan,{dagger} Amalendu Ghosh, Kalidas Paul, and Rukhsana Chowdhury*

Biophysics Division, Indian Institute of Chemical Biology, Calcutta 700 032, India

Received 16 February 2004/ Returned for modification 1 April 2004/ Accepted 3 April 2004

In Vibrio cholerae, the transmembrane DNA binding proteins, ToxR and TcpP, activate expression of the regulatory gene toxT in response to specific environmental signals. The resulting enhanced level of ToxT leads to a coordinated increase in the production of a subset of virulence factors, including cholera toxin (CT) and toxin-coregulated pilus (TCP). The effect of anaerobiosis on expression of the V. cholerae virulence regulatory cascade was examined. The expression of the major regulatory genes, tcpP, toxR, and toxT, in anaerobically grown V. cholerae was comparable to that in cells grown under aerobic conditions, and no significant difference in the ToxT-dependent expression of tcpA was detected when aerobic and anaerobic cultures were compared. However, in spite of the presence of functional ToxT, ctxAB expression was drastically reduced, and practically no CT was detected in cells grown under anaerobic conditions. In a V. cholerae hns mutant, however, high levels of ctxAB expression occurred even under anaerobic conditions. Also, deletion of the H-NS binding site from the ctxAB promoter eliminated anaerobic repression of ctxAB expression. These results suggest that H-NS directly represses ctxAB expression under anaerobic growth conditions. It has been reported that in the first stage of infection of infant mice by V. cholerae, tcpA is expressed but ctxAB expression is shut off (S. H. Lee, D. L. Hava, M. K. Waldor, and A. Camilli, Cell 99: 625-634, 1999). This pattern is similar to the pattern in anaerobic cultures of V. cholerae. Under all other in vitro conditions, ctxAB and tcpA are known to be coordinately expressed.

* Corresponding author. Mailing address: Biophysics Division, Indian Institute of Chemical Biology, 4 Raja S. C. Mullick Road, Calcutta 700 032, India. Phone: 91 33 473 0350. Fax: 91 33 473 5197. E-mail: rukhsana{at}iicb.res.in.

Editor: J. T. Barbieri

{dagger} Present address: Department of Microbiology, Immunology and Molecular Genetics, University of Kansas Medical Center, Kansas City, KS 66160.

Infection and Immunity, July 2004, p. 3961-3967, Vol. 72, No. 7
0019-9567/04/$08.00+0     DOI: 10.1128/IAI.72.7.3961-3967.2004
Copyright © 2004, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:



Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
J. Bacteriol. J. Virol. Eukaryot. Cell
Microbiol. Mol. Biol. Rev. Clin. Vaccine Immunol. All ASM Journals

Copyright © 2004 by the American Society for Microbiology. All rights reserved.