Table 3. Summary of RelP and RelQ molar specific activities with/without alarmone stimulation.
| Protein | No added alarmone | + 100 μM pppGpp | + 100 μM ppGpp | + 100 μM pGpp | |||
|---|---|---|---|---|---|---|---|
| Reaction rate (μmol.min-1.μmol-1) |
Reaction rate (μmol.min-1.μmol-1) |
Fold-change | Reaction rate (μmol.min-1.μmol-1) |
Fold-change | Reaction rate (μmol.min-1.μmol-1) |
Fold change | |
| GMP + ATP | |||||||
| Sa-RelQ | 0.46 ± 0.25 | 16.3 ± 0.8 | 36 ± 2 | 11.7 ± 0.8 | 26 ± 2 | 2.06 ± 0.53 | 4.5 ± 1.2 |
| Sm-RelQ | 0.43 ± 0.14 | 310 ± 80 | 572 ± 149 | 1.91 ± 0.26 | 3.5 ± 0.5 | 0.85 ± 0.08 | 1.6 ± 0.2 |
| EF-RelQ | 83.3 ± 27.8 | 367 ± 58 | 4.4 ± 1.2 | 271 ± 34 | 3.3 ± 0.6 | 105.6 ± 8.3 | 1.3 ± 0.1 |
| Sa-RelP | 3.69 ± 0.47 | 2.84 ± 0.08 | 0.8 ± 0.1 | 2.65 ± 0.23 | 0.7 ± 0.1 | 3.20 ± 0.07 | 0.9 ± 0.1 |
| Sm-RelP | 2.79 ± 0.50 | 0.78 ± 0.18 | 0.3 ± 0.1 | 1.13 ± 0.30 | 0.4 ± 0.1 | 1.29 ± 0.30 | 0.5 ± 0.1 |
| GDP + ATP | |||||||
| Sa-RelQ | 15.0 ± 4.3 | 22.1 ± 3.3 | 1.5 ± 0.2 | 23.4 ± 3.1 | 1.6 ± 0.1 | 28.8 ± 3.2 | 1.9 ± 0.1 |
| Sm-RelQ | 7.07 ± 2.17 | 123 ± 21 | 18 ± 3 | 36.5 ± 13.3 | 5.2 ± 1.9 | 33.8 ± 16.4 | 4.8 ± 2.4 |
| EF-RelQ | 173 ± 22 | 1014 ± 43 | 5.9 ± 0.4 | 1353 ± 70 | 7.8 ± 0.6 | 960.3 ± 46.7 | 5.5 ± 0.5 |
| Sa-RelP | 99.1 ± 11.6 | 73.9 ± 2.6 | 0.8 ± 0.1 | 82.4 ± 8.0 | 0.8 ± 0.2 | 79.4 ± 7.6 | 0.8 ± 0.2 |
| Sm-RelP | 14.1 ± 3.7 | 6.64 ± 4.25 | 0.5 ± 0.3 | 6.26 ± 1.97 | 0.4 ±0.2 | 8.95 ± 2.31 | 0.6 ± 0.2 |
| GTP + ATP | |||||||
| Sa-RelQ | 8.25 ± 1.53 | 13.7 ± 1.9 | 1.7 ± 0.2 | 14.2 ± 3.1 | 1.7 ± 0.4 | 13.6 ± 1.8 | 1.6 ± 0.1 |
| Sm-RelQ | 242 ± 19 | 185 ± 64 | 0.8 ± 0.3 | 143 ± 51 | 0.6 ± 0.3 | 191 ± 29 | 0.8 ± 0.2 |
| EF-RelQ | 234 ± 14 | 363 ± 18 | 1.6 ± 0.1 | 454 ± 12 | 1.9 ± 0.1 | 371 ± 22 | 1.6 ± 0.2 |
| Sa-RelP | 53.8 ± 18.0 | 38.0 ± 15.5 | 0.7 ± 0.3 | 45.5 ± 23.1 | 0.9 ± 0.5 | 50.2 ± 17.5 | 0.9 ± 0.4 |
| Sm-RelP | 29.1 ± 10.1 | 16.5 ± 5.6 | 0.6 ± 0.2 | 20.2 ± 6.7 | 0.7 ± 0.3 | 23.13 ± 5.62 | 0.8 ± 0.2 |
The table summarizes the molar specific activities (i.e. reaction rates in units of micromoles of alarmone product formed per minute per micromole of protein) for the five SAS RelQ/RelP proteins under standardized conditions in the absence of stimulatory alarmone (no added alarmone), as well as in the presence of 100 μM pppGpp, ppGpp or pGpp. The values are reported as mean ± standard deviation, based on data from 2–4 experimental replicates. The fold-change represents the ratio of alarmone-stimulated rate/non-stimulated rate, for each of the respective (pp)pGpp-synthesizing reactions, for each of the three added (allosteric) alarmones.