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Infect. Immun., Oct 1997, 4061-4067, Vol 65, No. 10
DG Storey, EE Ujack, I Mitchell and HR Rabin
Pseudomonas aeruginosa causes a chronic infection in the lungs of
individuals with cystic fibrosis. The P. aeruginosa isolates from these
infections, when grown under laboratory conditions, characteristically are
mucoid and produce low levels of the more destructive virulence factors,
such as exotoxin A and the proteases. We wanted to determine if during the
chronic lung infections associated with CF, the expression of alginate was
inversely correlated to the expression of exotoxin A, elastase, and the
LasA protease. We measured the transcript accumulation of algD, a marker of
alginate, toxA, the structural gene for exotoxin A, lasB, the structural
gene for elastase, and lasA, the structural gene for LasA protease, from
the sputum bacterial populations of 23 patients. In the 131 samples tested,
we frequently detected transcripts from the four genes. When a Spearman
rank correlation analysis was done on the samples, we found no correlation
between algD transcript accumulation and toxA transcript accumulation. This
result suggested that toxA was regulated independently of algD. Curiously,
we found a positive correlation between algD transcript accumulation and
both lasB and lasA transcript accumulation levels. This correlation may not
indicate a direct association between algD and either lasA or lasB. More
likely, it indicates a common regulatory element in a cascade of regulators
or a common environmental cue that triggers transcription.
Copyright © 1997, American Society for Microbiology
Positive correlation of algD transcription to lasB and lasA transcription by populations of Pseudomonas aeruginosa in the lungs of patients with cystic fibrosis
Department of Biological Sciences, University of Calgary, Alberta, Canada. storey@acs.ucalgary.ca
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