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Infection and Immunity, November 2008, p. 4968-4977, Vol. 76, No. 11
0019-9567/08/$08.00+0 doi:10.1128/IAI.01615-07
Copyright © 2008, American Society for Microbiology. All Rights Reserved.
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National Institute of Cholera and Enteric Diseases, Kolkata, India,1 Infectious Diseases and Immunology Division, Indian Institute of Chemical Biology, Kolkata, India2
Received 6 December 2007/ Returned for modification 28 April 2008/ Accepted 19 August 2008
The chitin-binding protein GbpA of Vibrio cholerae has been recently described as a common adherence factor for chitin and intestinal surface. Using an isogenic in-frame gbpA deletion mutant, we first show that V. cholerae O1 El Tor interacts with mouse intestinal mucus quickly, using GbpA in a specific manner. The gbpA mutant strain showed a significant decrease in intestinal adherence, leading to less colonization and fluid accumulation in a mouse in vivo model. Purified recombinant GbpA (rGbpA) specifically bound to N-acetyl-D-glucosamine residues of intestinal mucin in a dose-dependent, saturable manner with a dissociation constant of 11.2 µM. Histopathology results from infected mouse intestine indicated that GbpA binding resulted in a time-dependent increase in mucus secretion. We found that rGbpA increased the production of intestinal secretory mucins (MUC2, MUC3, and MUC5AC) in HT-29 cells through upregulation of corresponding genes. The upregulation of MUC2 and MUC5AC genes was dependent on NF-
B nuclear translocation. Interestingly, mucin could also increase GbpA expression in V. cholerae in a dose-dependent manner. Thus, we propose that there is a coordinated interaction between GbpA and mucin to upregulate each other in a cooperative manner, leading to increased levels of expression of both of these interactive factors and ultimately allowing successful intestinal colonization and pathogenesis by V. cholerae.
Published ahead of print on 2 September 2008.
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