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Journal of Bacteriology, December 2001, p. 7126-7134, Vol. 183, No. 24
Department of
Genetics1 and Department of
Surgery,3 Harvard Medical School, and
Department of Molecular Biology2 and
Shriner's Burns Institute,4
Massachusetts General Hospital, Boston, Massachusetts 02114
Received 4 June 2001/Accepted 18 September 2001
We cloned the rpoN (ntrA, glnF) gene
encoding the alternate sigma factor
0021-9193/01/$04.00+0 DOI: 10.1128/JB.183.24.7126-7134.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
Differential Roles of the Pseudomonas aeruginosa
PA14 rpoN Gene in Pathogenicity in Plants,
Nematodes, Insects, and Mice


54 from the
opportunistic multihost pathogen Pseudomonas aeruginosa strain PA14. A marker exchange protocol was used to construct the PA14
rpoN insertional mutation
rpoN::Genr. PA14
rpoN::Genr synthesized
reduced levels of pyocyanin and displayed a variety of phenotypes
typical of rpoN mutants, including a lack of motility and the failure to grow on nitrate, glutamate, or histidine as the sole
nitrogen source. Compared to wild-type PA14,
rpoN::Genr was ca. 100-fold less
virulent in a mouse thermal injury model and was significantly impaired
in its ability to kill the nematode Caenorhabditis
elegans. In an Arabidopsis thaliana leaf
infectivity assay, although
rpoN::Genr exhibited significantly
reduced attachment to trichomes, stomata, and the epidermal cell
surface, did not attach perpendicularly to or perforate mesophyll cell
walls, and proliferated less rapidly in Arabidopsis
leaves, it nevertheless elicited similar disease symptoms to wild-type
P. aeruginosa PA14 at later stages of infection. rpoN::Genr was not impaired in
virulence in a Galleria mellonella (greater wax moth)
pathogenicity model. These data indicate that rpoN does not regulate the expression of any genes that encode virulence factors
universally required for P. aeruginosa pathogenicity in diverse hosts.
*
Corresponding author. Mailing address: Department of
Molecular Biology, Wellman 10, Massachusetts General Hospital, Boston, MA 02114. Phone: (617) 726-5969. Fax: (617) 726-5949. E-mail: ausubel{at}molbio.mgh.harvard.edu.
Present address: Department of Microbiology, University of
Washington, Seattle, WA 98195.
Present address: Microbia, Inc., Cambridge, MA 02139.
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