TABLE 2.
ATPase activities of membrane vesicles of deletion mutants
ATPase activities of membrane preparations of mutants and controls were measured as described under “Materials and Methods.” The given values represent the average of at least three independent measurements ± S.D. The positive control was strain pTR19-ASDS/DK8, which expresses Bacillus PS3 ATP synthase in E. coli; this strain served as the background for the deletions. The negative control was strain pUC118/DK8, which expresses neither PS3 ATP synthase nor the endogenous E. coli enzyme. Turnover rates were calculated as described in the legend to Table 1.
| Strain/mutation | Membrane ATPase activity | Turnover rate kcat |
|---|---|---|
| units/mg | s−1 | |
| Wild type | 2.4 ± 0.6 | 102 |
| ϵI88stop | 2.5 ± 0.3 | 106 |
| Δγ | 0.051 ± 0.020 | 5 |
| pUC118/DK8 (unc−) | 0.012 ± 0.011 | |
| γQ36stop | 0.075 ± 0.052 | 7 |
| γQ36stop/ϵI88stop | 0.076 ± 0.043 | 7 |
| γP43stop | 0.102 ± 0.020 | 7 |
| γP43stop/ϵI88stop | 0.106 ± 0.012 | 8 |