TABLE 5.
Steady-state melibiose accumulation
| melB strain | Melibiose accumulation valuea in the presence of:
|
|||
|---|---|---|---|---|
| H+ | 10 mM Na+ | 100 mM Na+ | 10 mM Li+ | |
| Wild-type | 6 ± 1.4 | 153 ± 21 | 51 ± 5 | 87 ± 4 |
| R52K | 4 ± 1 | 127 ± 14 | 97 ± 9 | 115 ± 6 |
| R52Q | 0.4 ± 0.1 | 5 ± 1 | 2 ± 0.2 | 5 ± 1 |
| R52V | 0.2 ± 0.1 | 0.8 ± 0.2 | 1 ± 0.4 | 0.2 ± 0.2 |
| R52S | 0.3 ± 0.1 | 9 ± 1 | 1 ± 0.2 | 2 ± 0.2 |
| R52S W116R | 1 ± 0.4 | 23 ± 4 | 41 ± 5 | 10 ± 2 |
| R52S S247R | 0.6 ± 0.1 | 24 ± 5 | 8 ± 0.5 | 39 ± 6 |
| R52S N248K | 1 ± 0.8 | 69 ± 5 | 28 ± 1 | 66 ± 9 |
| R52V T338R | 0.7 ± 0.2 | 3 ± 0.5 | 10 ± 1 | 4 ± 0.7 |
| R52S D19G | 0.2 ± 0.3 | 2 ± 0.6 | 5 ± 0.6 | 2 ± 0.1 |
| R52S D55N | 0.8 ± 0.2 | 6 ± 1 | 19 ± 2 | 1 ± 0.2 |
| R52S P60Q | 0.5 ± 0.2 | 4 ± 0.3 | 1 ± 0.1 | 2 ± 0.4 |
| R52S N244S | 0.5 ± 0.2 | 8 ± 2 | 2 ± 0.1 | 4 ± 0.8 |
| R52S I352V | 0.4 ± 0.2 | 7 ± 1 | 1 ± 0.1 | 5 ± 0.5 |
a
The concentration of radiolabeled melibiose in transport assays was 0.2 mM, and values given represent transport at 15 min. Each value is given as the ratio of intracellular melibiose concentration to the extracellular melibiose concentration. Transport values were calculated assuming 0.4 μl of intracellular water for every 109 cells. The data are averages of at least two separate experiments with duplicate determinations in each experiment ± standard errors.