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April 1, 1993Infection and ImmunityOpen Access

LasR of Pseudomonas aeruginosa is a transcriptional activator of the alkaline protease gene (apr) and an enhancer of exotoxin A expression

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Authors

MGMichael J. GambelloEmory UniversitySKS KayeBirmingham City HospitalBIBarbara H. IglewskiTufts University

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Implication

Molecular analysis reveals LasR activates alkaline protease and enhances exotoxin A expression in Pseudomonas aeruginosa, suggesting a global regulatory role in bacterial pathogenesis.

Key Points

  • To determine whether the transcriptional regulator LasR controls the expression of alkaline protease (apr) and exotoxin A (toxA) in Pseudomonas aeruginosa.
  • Assessed alkaline protease mRNA expression in parental strain PAO-SR and lasR mutant PAO-R1, with and without an intact lasR gene supplied in trans, using Northern blot analysis.
  • Measured exotoxin A activity in culture supernatants of parental, mutant, and multicopy lasR-complemented strains.
  • Analyzed transcriptional control using toxA promoter-lacZ reporter fusions and regA promoter-chloramphenicol acetyltransferase (CAT) gene reporter fusions.
  • Alkaline protease mRNA was undetectable in the lasR mutant PAO-R1 but was restored when intact lasR was supplied in trans.
  • Exotoxin A activity in PAO-R1 culture supernatants was 30% lower than in parental PAO-SR, whereas supplying multiple copies of lasR in trans doubled exotoxin A activity relative to parental levels.
  • PAO-R1 displayed an approximate 40% reduction in toxA promoter-driven beta-galactosidase activity compared with PAO-SR, with no observed difference in regA promoter-driven CAT activity.

Cite This Study

Gambello et al. (1993) studied this question.

synapsesocial.com/papers/69d78a87f44a16d01ef31a69https://doi.org/10.1128/iai.61.4.1180-1184.1993
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