TABLE 1.

Effects of mutations in conserved amino acids on LasR multimerization and function

Plasmid% sulA expressiona% Changeb% lasI expressionc% Changeb
No 3O-C12-HSLWith 3O-C12-HSLNo 3O-C12-HSLWith 3O-C12-HSL
pSR658100 ± 798 ± 3−2 ± 7.85 ± 16 ± 11 ± 1.4
pLXR87 ± 317 ± 3−70 ± 4.2d6 ± 2100 ± 1294 ± 12.2d
pLXRF7T90 ± 515 ± 2−75 ± 5.4d6 ± 390 ± 584 ± 5d
pLXRW19A79 ± 179 ± 40 ± 4.16 ± 28 ± 22 ± 2.8
pLXRY64H87 ± 492 ± 65 ± 7.26 ± 210 ± 14 ± 2.2
pLXRD73E79 ± 877 ± 4−2 ± 8.97 ± 19 ± 12 ± 1.4
pLXRP74L91 ± 8105 ± 1214 ± 14.49 ± 110 ± 21 ± 1.7
pLXRP74Q94 ± 696 ± 22 ± 6.38 ± 110 ± 12 ± 1.4
pLXRC79S95 ± 515 ± 1−75 ± 5.1d9 ± 190 ± 1781 ± 17d
pLXRW88Y77 ± 479 ± 15 ± 4.17 ± 212 ± 15 ± 2.2
pLXRA105V86 ± 381 ± 10−5 ± 10.48 ± 232 ± 424 ± 4.5d
pLXRL110I90 ± 320 ± 2−70 ± 3.6d9 ± 297 ± 2089 ± 1.4d
pLXRG113V86 ± 582 ± 4−4 ± 6.411 ± 111 ± 20 ± 1.7
pLXRG113D105 ± 5110 ± 105 ± 11.210 ± 110 ± 20 ± 1.7
pLXRP117F88 ± 490 ± 32 ± 59 ± 110 ± 21 ± 1.7
  • a Expression of sulA::lacZ from E. coli SU101 in the absence or presence of 100 nM 3O-C12-HSL when a plasmid was present. Repression of sulA expression indicates multimer formation by mutant LasR expressed from a plasmid. The values are averages ± standard deviations for three individual experiments and were normalized to the value for parent plasmid pSR658, which expressed only the LexA DBD. The value for the parent plasmid was defined as 100%.

  • b Net percent change in sulA::lacZ or lasI::lacZ expression in the presence of 100 nM 3O-C12-HSL. Negative numbers indicate a decrease. The values are averages ± standard deviations for three individual experiments.

  • c Expression of lasI::lacZ in E. coli MG4(λI14), expressed as a percentage relative to the expression with parent plasmid pLXR, which expresses full-length wild-type LasR. An increase in expression indicates that LasR can function as a transcriptional activator in the absence or presence of 100 nM 3O-C12-HSL. The values are averages ± standard deviations for three individual experiments.

  • d The change in expression was significant.