TABLE 4.
Repression by mutant LexA-Mig1 proteins
| Expressed protein | Invertase activitya | β-Galactosidase activityb with:
|
Fold repression | |
|---|---|---|---|---|
| 0 lexA operators | 4 lexA operators | |||
| LexA87 | 83 | 322 | 151 | 2.1 |
| LexA-Mig1 | 4 | 244 | 8 | 30 |
| LexA-Mig1S278*S311* | 6 | NDc | ND | ND |
| LexA-Mig1S222*S278*S311* | 8 | 547 | 25 | 22 |
| LexA-Mig1S278*S311*S381* | 7 | 431 | 21 | 21 |
YM4738 (mig1Δ mig2Δ) was transformed with plasmids expressing the indicated LexA fusion protein. The double mutant produces higher invertase activity than a mig1Δ single mutant, thereby providing a more sensitive assay for Mig1 repressor function. Transformants were grown to mid-log phase in SC medium plus 5% glucose and assayed for invertase activity (expressed as micromoles of glucose released per minute per 100 mg of cells).
Wild-type strain MCY829 was transformed with plasmids expressing the indicated LexA fusion protein and lexAop-CYC1-lacZ reporters with zero or four lexA operators (pLGΔ312S, JK1621). Transformants were grown in SC medium plus 5% glucose. β-Galactosidase activity (Miller units) was assayed in permeabilized cells. Values represent the averages from at least three transformants. Standard errors were <18%.
ND, not determined.