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Regulation of exotoxin A synthesis in Pseudomonas aeruginosa : characterization of toxA‐lacZ fusions in wild‐type and mutant strains
Author(s) -
Vasil M. L.,
Grant C. C. R.,
Prince R. W.
Publication year - 1989
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.1989.tb00182.x
Subject(s) - biology , lac operon , plasmid , mutant , pseudomonas exotoxin , pseudomonas aeruginosa , gene , microbiology and biotechnology , wild type , homologous recombination , promoter , genetics , recombinant dna , gene expression , bacteria
Summary A mobilizable plasmid which carries the promoter for the exotoxin A (ETA) structural gene fused to lacZ was integrated into the chromosome of wild‐type and mutant strains of Pseudomonas aeruginosa at the toxA locus by homologous recombination. β‐galactosidase synthesis in the strains (cointegrates) carrying the tox4‐lacZ fusions was regulated like ETA synthesis is in P. aeruginosa . Two multicopy plasmids carrying a positive regulatory gene designated toxR were constructed which are identical except with respect to the orientation of toxR to the lacZ promoter on the plasmid. These plasmids were then introduced into P. aeruginosa cointegrate strains. When toxR was using its own promoter, synthesis of β‐galactosidase in the cointegrate strains was increased but the pattern of iron regulation was not altered. In contrast, when the lacZ promoter was directing synthesis of the toxR product in the cointegrate strains, iron regulation of β‐galacto‐sidase and ETA synthesis were abolished.