TABLE 2.
Effects of separately and coexpressed malK fragments on maltose transport and mal gene expressiona
| Plasmid | Protein synthesized | Maltose uptake (% of control) | β-Galactosidase activity (% recovered) |
|---|---|---|---|
| pSE380 | None | ND | 100 |
| pSW7 | MalK | 100 | 6 ± 0.4 |
| pGS94-11 | MalKN1 | n.d. | 96 ± 3.7 |
| pGS94-8 | MalKC1 | n.d. | 46 ± 1.2 |
| pGS94-13 | MalKN2 | n.d. | 82 ± 2.7 |
| pGS94-14 | MalKC2 | n.d. | 102 ± 4.8 |
| pGS94-20 | MalKN3 | n.d. | 100 ± 4.3 |
| pGS95-6 | MalKC3 | n.d. | 95 ± 2.4 |
| pGS95-19 | MalKN1/C1 | 81 ± 1.7 | 49 ± 0.6 |
| pGS95-11 | MalKN2/C2 | ND | 102 ± 5.5 |
| pGS95-9 | MalKN3/C3 | ND | 104 ± 4.2 |
a
The effect of plasmid-encoded truncated MalK fragments on transport activity was measured for S. typhimurium ES25 (malK) (100% = 1.24 ± 0.1 nmol/min/109 cells). The effect on the expression of malK-lacZ was measured for E. coli SK1280 (100% = 148 ± 15 Miller units). Values are means ± standard deviations of three and four independent experiments, respectively. ND, not detectable; n.d., not determined.