TABLE 2.
AI-2 activities of strains DH5α and TX1 expressing LuxS variants and small peptidesa
| Strain and plasmid(s) | LuxS variant | Level of induction (fold) of AI-2 activityb |
|---|---|---|
| DH5α/pL1 | None | 1 |
| DH5α/pBTES | Wild type | 319 ± 19.14 |
| DH5α/pH54A | H54A | 1 ± 0.02 |
| DH5α/pH58A | H58A | 1 ± 0.04 |
| DH5α/pE122K | E122K | 302 ± 12.08 |
| DH5α/pDC | C site deletion | 1 ± 0.01 |
| DH5α/pDP | P site deletion | 1 ± 0.01 |
| DH5α/pDE122 | E122 deletion | 1 ± 0.02 |
| DH5α/pELS | Wild type | 305 ± 21.35 |
| DH5α/pL1/pELS | Wild type | 308 ± 26.18 |
| DH5α/pH54A/pELS | Wild type + H54A mutant | 289 ± 10.40 |
| DH5α/pDC/pELS | Wild type + C site deletion mutant | 48 ± 1.34 |
| DH5α/pDP/pELS | Wild type + P site deletion mutant | 55 ± 3.16 |
| TX1/pJRA | Wild type | 524 ± 41.92 |
| TX1/pJDC | Wild type + C site deletion mutant | 78 ± 2.63 |
| TX1/pJDP | Wild type + P site deletion mutant | 99 ± 5.78 |
| TX1/p5411 | Wild type + 5411 | 68 ± 4.37 |
| TX1/p5906 | Wild type + 5906 | 104 ± 5.86 |
| TX1/p1026 | Wild type + 1026 | 512 ± 18.94 |
a
Cell-free culture fluids taken from cultures of plasmid-containing DH5α and TX1 grown in LB medium to an OD600 of 0.9 were used for AI-2 assay.
b
AI-2 activities are presented as the change in level of induction over that in the DH5α/pL1 culture. Data are representative of at least three independent experiments and are presented as the means ± SE.