TABLE 1.
RbsC-PhoA fusions
| Fusion site | Residue with no.a (PhoA activityb) |
|---|---|
| N terminus | 2T (9.93) |
| TM helix I | 36L (242.84), 39N (168.21) |
| Periplasmic loop I | 48N (109.2),c 50L (251.16) |
| TM helix II | 62G (238.77), 64T (161.9), 65L (191.59), 69T (13.6), 77G (39.2) |
| Cytoplasmic loop I | 93I (28.34),d 100A (62.18), 113A (16.41), 117V (45.42),d 120A (16.72),d 123R (3.87)d |
| TM helix III | 126A (5.45),d 129A (4.52)d |
| Periplasmic loop II | 147G (295.11), 152T (189.24),d 155T (103.26), 159D (204.25), 160L (181.33), 162G (183.52), 163W (154.43), 167G (195.31), 168R (152.01) |
| TM helix IV | 171G (189.72), 173P (229.46), 177W (169.37), 178I (51), 180G (104.08), 181I (113.47), 184L (62.61), 186A (114.86), 187W (93.59) |
| Cytoplasmic loop II | 195L (10.75), 199I (5.77),d 209T (1.5) |
| TM helix V | 222I (1.35), 225S (1.12), 236I (207.12) |
| Periplasmic loop III | 250G (245.89), 255L (355.52), 263L (270.05), 264G (19.7),d 271G (158.61), 287F (156), 288L (279.06) |
| TM helix VI | 297V (248.91), 301Y (243.16), 302Q (199.34), 304I (230.33), 306K (266.89), 307A (254.92), 308V (214.52), 309V (169.66), 310I (231.48), 311L (233.15), 313A (34.12),d 316V (71.46)c |
| C terminus | 317D (16.25),d 320K (74.3), 321Q (8.75)d |
a
The amino acid residue at the fusion joint of RbsC is indicated. Most of the fusions were constructed by serial deletion with exonuclease III unless otherwise indicated.
b
Alkaline phosphatase activities of RbsC-PhoA fusions were measured by the method of Brickman and Beckwith (4). The values are averages of three or four separate experiments. Boldface indicates values of more than 75 U of enzyme activity.
c
The fusions were made by using unique restriction enzyme sites in rbsC.
d
The fusions were obtained at specific sites by PCR.