JB
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 Wu, H.
Right arrow Articles by Ohtake, H.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Wu, H.
Right arrow Articles by Ohtake, H.

Journal of Bacteriology, June 2000, p. 3400-3404, Vol. 182, No. 12
0021-9193/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.

Identification and Characterization of Two Chemotactic Transducers for Inorganic Phosphate in Pseudomonas aeruginosa

Hong Wu, Junichi Kato, Akio Kuroda, Tsukasa Ikeda, Noboru Takiguchi, and Hisao Ohtake*

Department of Fermentation Technology, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8527, Japan

Received 18 January 2000/Accepted 23 March 2000

Two chemotactic transducers for inorganic phosphate (Pi), designated CtpH and CtpL, have been identified in Pseudomonas aeruginosa. The corresponding genes (ctpH and ctpL) were inactivated by inserting kanamycin and tetracycline resistance gene cassettes into the wild-type genes in the P. aeruginosa PAO1 genome. Computer-assisted capillary assays showed that the ctpH single mutant failed to exhibit Pi taxis when the concentration of Pi in the capillary was higher than 5 mM. Conversely, the ctpL single mutant could not respond to Pi at the concentration of 0.01 mM. The ctpH ctpL double mutant was defective in Pi taxis at any concentration ranging from 0.01 to 10 mM. To investigate regulation of Pi taxis, the ctpH and ctpL genes were also disrupted individually in the P. aeruginosa phoU and phoB single mutants. The ctpH phoU and ctpH phoB double mutants were defective in Pi taxis, regardless of whether the cells were starved for Pi. The ctpL phoU double mutant was constitutive for Pi taxis, whereas the ctpL phoB double mutant was induced by Pi limitation for Pi taxis. The region upstream of ctpL, but not ctpH, contained a putative pho box sequence. Expression of ctpL::lacZ was induced by Pi limitation in PAO1, while it was constitutive in the phoU mutant. In contrast, the phoB mutant showed only background levels of ctpL::lacZ expression. These results showed that ctpL is involved in the pho regulon genes in P. aeruginosa. The ctpH phoU mutant, which failed to exhibit Pi taxis, was constitutive for ctpL::lacZ expression, suggesting that the Pi detection by CtpL requires PhoU. Like PAO1, the phoB and phoU single mutants were constitutive for expression of ctpH::lacZ. Thus, the evidence that the ctpL phoU mutant, but not the ctpL phoB mutant and PAO1, was constitutive for Pi taxis raised the possibility that PhoU exerts a negative control on Pi detection by CtpH at the posttranscriptional level.

* Corresponding author. Mailing address: Department of Fermentation Technology, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8527, Japan. Phone: 81-824-24-7756. Fax: 81-824-22-3758. E-mail: hohtake{at}ipc.hiroshima-u.ac.jp.

Journal of Bacteriology, June 2000, p. 3400-3404, Vol. 182, No. 12
0021-9193/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.


This article has been cited by other articles:



Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
Appl. Environ. Microbiol. Infect. Immun. Eukaryot. Cell
Mol. Cell. Biol. J. Virol. Microbiol. Mol. Biol. Rev.
ALL ASM JOURNALS

Copyright © 2000 by the American Society for Microbiology. All rights reserved.