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 Fleiszig, S. M. J.
Right arrow Articles by Ramphal, R.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Fleiszig, S. M. J.
Right arrow Articles by Ramphal, R.

 Previous Article  |  Next Article 

Infection and Immunity, August 2001, p. 4931-4937, Vol. 69, No. 8
0019-9567/01/$04.00+0   DOI: 10.1128/IAI.69.8.4931-4937.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.

FlhA, a Component of the Flagellum Assembly Apparatus of Pseudomonas aeruginosa, Plays a Role in Internalization by Corneal Epithelial Cells

Suzanne M. J. Fleiszig,1,* Shiwani K. Arora,2 Rajana Van,1 and Reuben Ramphal2

The Morton D. Sarver Laboratory for Cornea and Contact Lens Research, School of Optometry, University of California, Berkeley, California, 94720-2020,1 and Department of Medicine/Infectious Diseases, University of Florida, Gainesville, Florida 326102

Received 22 September 2000/Returned for modification 18 December 2000/Accepted 1 May 2001

Pseudomonas aeruginosa invades various epithelial cell types in vitro and in vivo. The P. aeruginosa genome possesses a gene (flhA) which encodes a protein that is believed to be part of the export apparatus for flagellum assembly and which is homologous to invA of Salmonella spp. Because invA is required for invasion of Salmonella spp., a role for flhA in P. aeruginosa invasion was explored using cultured rabbit corneal epithelial cells. An flhA mutant of P. aeruginosa strain PAO1 was constructed and was shown to be nonmotile. Complementation with flhA in trans restored motility. Corneal cells were infected for 3 h with the wild type (PAO1), the flhA mutant, the flhA mutant complemented with flhA in trans, an flhA mutant containing the plasmid vector control, or an fliC mutant (nonmotile mutant control). Invasion was quantified by amikacin exclusion assays. Both the flhA and the fliC mutants invaded at a lower level than the wild-type strain did, suggesting that both fliC and flhA played roles in invasion. However, loss of motility was not sufficient to explain the reduced invasion by flhA mutants, since centrifugation of bacteria onto cells did not restore invasion to wild-type levels. Unexpectedly, the flhA mutant adhered significantly better to corneal epithelial cells than wild-type bacteria or the fliC mutant did. The percentage of adherent bacteria that invaded was reduced by ~80% for the flhA mutant and ~50% for the fliC mutant, showing that only part of the role of flhA in invasion involves fliC. Invasion was restored by complementing the flhA mutant with flhA in trans but not by the plasmid vector control. Intracellular survival assays, in which intracellular bacteria were enumerated after continued incubation in the presence of antibiotics, showed that although flhA and fliC mutants had a reduced capacity for epithelial cell entry, they were not defective in their ability to survive within those cells after entry. These results suggest that the flagellum assembly type III secretion system plays a role in P. aeruginosa invasion of epithelial cells. Since the flhA mutants were not defective in their ability to adhere to corneal epithelial cells, to retain viability at the cell surface, or to survive inside epithelial cells after entry, the role of flhA in invasion of epithelial cells is likely to occur during the process of bacterial internalization.

* Corresponding author. Mailing address: School of Optometry, University of California, Berkeley, CA 94720-2020. Phone: (510) 643-0990. Fax: (510) 643-5109. E-mail: fleiszig{at}socrates.berkeley.edu.

Infection and Immunity, August 2001, p. 4931-4937, Vol. 69, No. 8
0019-9567/01/$04.00+0   DOI: 10.1128/IAI.69.8.4931-4937.2001
Copyright © 2001, 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 © 2001 by the American Society for Microbiology. All rights reserved.