TABLE 2.

Acyl-HSL-dependent expression of a PA1897-lacZ fusion in E. coli containing LasR, QscR, or QscR mutant expression vectorsa

Plasmidβ-Galactosidase activities (U)
No signal3OC12-HSLC4-HSL
pJN10579 ± 3488 ± 4773 ± 34
pJN105-LasR86 ± 2491 ± 3365 ± 16
pJN105-QscR95 ± 4318,500 ± 2,50085 ± 23
pJN105-QscR-Y66H57 ± 2850 ± 26
pJN105-QscR-D75E77 ± 50175 ± 40
pJN105-QscR-P76L89 ± 4075 ± 34
pJN105-QscR-A105V77 ± 40180 ± 90
pJN105-QscR-G113D75 ± 2075 ± 20
  • a All strains carried the PA1897-lacZ reporter pJL101 with the indicated qscR or lasR expression plasmid. The control vector is pJN105; pJN105-LasR, called pJN105L previously by Lee et al. (15) contained lasR; pJN105-QscR contained wild-type qscR; and the other plasmids contained qscR with point mutations coding for substitutions in the amino acid residues indicated. Transcription from the PA1897 promoter was assessed by measuring β-galactosidase activity in cells from cultures at an optical density at 600 nm of 1.8 to 2.0. Values are the means ± standard deviations of three individual experiments.