TABLE 3.

Effect of the mucA22 mutation on the expression of single-copy lacZ transcriptional fusions to the genes for ClpP, porin F, and DsbA in P. aeruginosa^a

Strain	Genotype	Transcriptional activity of:
		clpP-lacZ	oprF-lacZ	dsbA-lacZ
PAO1 (Alg−)	Wild type	25 ± 6	120 ± 3	30 ± 5
PDO300 (Alg+)	mucA22	23 ± 7	110 ± 5	90 ± 4

^aPAO1 and its mucA22 derivative PDO300 (Alg⁺, alginate overproducing) had derivatives of pMS122 integrated into the chromosome by homologous recombination to form the transcriptional fusions clpP-lacZ, oprF-lacZ, and dsbA-lacZ (Fig. 2). Strains were grown in L broth to an OD₆₀₀ of 1.0, and cell extracts were then subjected to β-galactosidase assays, with transcriptional activity defined as follows: (β-galactosidase activity OD₄₂₀ × 1,000)/(reaction time [min] × vol of cells [ml] × OD₆₀₀) (23). Data are the averages of results from four experiments ± standard errors.