Table 3.
Effect of mutated Ler proteins on LEE5 expression in EPEC strain SE796
The EPEC E2348/69-derived strain SE796 contains an in-frame deletion of ler.
| Fusion plasmid | Protein plasmid | Glucose* | Arabinose* | Fold-induction† |
|---|---|---|---|---|
| – | – | 19 (6) | 8 (3) | – |
| pRS551 | – | 31 (1) | 43 (2) | – |
| pKMTIR3 | pBAD33 | 692 (19) | 731 (26) | 1.1 |
| pKMTIR3 | pKHLB01(Ler) | 526 (13) | 10 218 (185) | 20 |
| pKMTIR3 | pKHB1123 (H-NS) | 439 (23) | 216 (12) | 0.5 |
| pKMTIR3 | pFL08 | 752 (19) | 1588 (196) | 2.1 |
| pKMTIR3 | pFL09 | 717 (74) | 1887 (334) | 2.6 |
| pKMTIR3 | pKHB1527(C1) | 996 (68) | 1067 (41) | 1.1 |
| pKMTIR3 | pKHB1163(C2) | 1139 (63) | 1128 (38) | 1.0 |
| pKMTIR3 | pKHB1047(C4) | 1015 (20) | 891 (13) | 0.9 |
| pKMTIR3 | pKHB1167(C5) | 822 (24) | 3767 (113) | 4.6 |
*
β-Galactosidase activity derived from the pKMTIR3 5–lacZ reporter gene vector in the strain SE796 was monitored in the presence of the listed protein expression and control plasmids under repressing (0.1% glucose) and inducing (0.1% arabinose) conditions. The values are presented in Miller units and represent the mean of representative assays performed in triplicate with SDs in parentheses.
†
Represents the ratio of transcriptional activity in the presence of the inducer (arabinose) to that in the presence of the repressor (glucose) for the indicated strains.