Table 3.
Effect of rpoB2063 and rpoC2064 on NusA-mediated transcriptional feedback regulation at the terminators between metY and rimP
| Genotype | Readthrougha |
Mean fold repression ± SDb | |||
|---|---|---|---|---|---|
| Expt 1 |
Expt 2 |
||||
| −Ara | +Ara | −Ara | +Ara | ||
| nusA+rpoB+rpoC+/pJML007 (nusA+) | 0.20 | 0.085 | 0.21 | 0.085 | 2.41 ± 0.06 |
| nusA94/pJML007 (nusA+) | 0.36 | 0.13 | 0.40 | 0.13 | 2.92 ± 0.15 |
| rpoB2063/pJML007 (nusA+) | 0.32 | 0.31 | 0.36 | 0.29 | 1.14 ± 0.10 |
| rpoC2064/pJML007 (nusA+) | 0.17 | 0.22 | 0.24 | 0.21 | 0.95 ± 0.18 |
Readthrough was calculated as [(P + T)/P]. The effect of induced expression of nusA on the readthrough of the metY-T1T2 terminators was determined in two independent experiments by comparing the β-galactosidase activity of the PmetY-metY-T1T2-lacZ (P + T) and PmetY-metY-lacZ (P) fusions in strains harboring plasmid pJML007 that carries nusA under the control of the arabinose-inducible PBAD promoter. Readthrough was determined with (+Ara) or without (−Ara) the addition of 0.02% arabinose. Only relevant genotypes are indicated. For complete genotypes. see Table 1. The strains used were GOB906/pJML007, GOB898/pJML007, GOB752/pJML007, GOB750/pJML007, GOB904/pJML007, GOB896/pJML007, GOB908/pJML007, and GOB900/pJML007.
The repression was calculated as the ratio of the readthrough in the absence of arabinose to that in the presence of arabinose.