Table II. β-galactosidase synthesis in cells carrying repA–lacZ translational fusion plasmids, alone or in the presence of CopA supplied in trans.
| Plasmidsa | CopA/CopT pairsb | Specific β-gal activityc | Relative β-gal activityd |
|---|---|---|---|
| pGEM2 | –/– | 9 ± 4 | <0.01 |
| pGW177-L | [wt/wt]e | 459 ± 101 | 0.16 |
| pGW177-III-L | –/wt | 2940 ± 992 | 1.00 |
| pGW177-H1-III-L | –/H1 | 3469 ± 198 | 1.18 |
| pGW177-H2-III-L | –/H2 | 3065 ± 406 | 1.04 |
| pGW177-H3-III-L | –/H3 | 3086 ± 278 | 1.05 |
| pGW177-H4-III-L | –/H4 | 3223 ± 765 | 1.10 |
| pGW177-H5-III-L | –/H5 | 3389 ± 885 | 1.15 |
| pGW177-L1-III-L | –/L1 | 3239 ± 641 | 1.10 |
| pGEM2-H1 + pGW177-H1-III-L | H1/H1 | 10 ± 2 | <0.01 |
| pGEM2-H2 + pGW177-H2-III-L | H2/H2 | 12 ± 3 | <0.01 |
| pGEM2-H3 + pGW177-H3-III-L | H3/H3 | 8 ± 0 | <0.01 |
| pGEM2-H4 + pGW177-H4-III-L | H4/H4 | 15 ± 5 | <0.01 |
| pGEM2-H5 + pGW177-H5-III-L | H5/H5 | 3 ± 2 | <0.01 |
| pGEM2-L1 + pGW177-L1-III-L | L1/L1 | 6 ± 2 | <0.01 |
| pGEM2-H1 + pGW177-III-L | H1/wt | 662 ± 300 | 0.23 |
| pGEM2-H2 + pGW177-III-L | H2/wt | 124 ± 62 | 0.04 |
| pGEM2-H3 + pGW177-III-L | H3/wt | 9 ± 2 | <0.01 |
| pGEM2-H4 + pGW177-III-L | H4/wt | 4 ± 1 | <0.01 |
| pGEM2-H5 + pGW177-III-L | H5/wt | 578 ± 24 | 0.20 |
| pGEM2-L1 + pGW177-III-L | L1/wt | 5 ± 1 | <0.01 |
| pGW643 + pGW177-III-L | wt/wt | 8 ± 3 | <0.01 |
| pGW643 + pGW177-H1-III-L | wt/H1 | 1163 ± 411 | 0.40 |
| pGW643 + pGW177-H2-III-L | wt/H2 | 216 ± 69 | 0.07 |
| pGW643 + pGW177-H3-III-L | wt/H3 | 11 ± 6 | <0.01 |
| pGW643 + pGW177-H4-III-L | wt/H4 | 16 ± 2 | <0.01 |
| pGW643 + pGW177-H5-III-L | wt/H5 | 911 ± 342 | 0.31 |
| pGW643 + pGW177-L1-III-L | wt/L1 | 23 ± 5 | <0.01 |
aFusion plasmids and CopA-donor plasmids: pGW63 carries the copA gene in vector plasmid derivative from pSP64 (Persson et al., 1990); pGW177-L plasmid carries the control region of plasmid R1 (Blomberg et al., 1992); pGW177-III-L derivative of pGW177-L contains the mutation III in copA promoter (Blomberg et al., 1994). The mutated plasmids (pGW177-III-L and pGEM2 series) were constructed as described in Materials and methods.
bThe RNAs produced in vivo are indicated as follows: wt, wild-type CopA or CopT; H1, H2, H3, H4, H5 and L1 mutated RNAs; –, no RNA.
cβ-galactosidase (β-gal) activity assays were performed as in Materials and methods, and represent averages of four independent determinations. Values are given in Miller units (Miller, 1972). Standard deviations are indicated.
dMiller units were converted to relative activities. The activity obtained with pGW177-III-L was set to unity.
eCopA encoded from fusion plasmid (the CopA concentration is lower than when encoded in trans).