TABLE 2.
Importance of the core positions; interplay between permanent and transient core residues in Af1503 and Tsr HAMP domains
In vitro adenylyl cyclase activities, maximal inhibition by 10 mm serine, and IC50 serine concentrations of mutants at transient positions of Af1503 HAMP and Tsr are shown.
| Mutation | AC activity | % of inhibition | IC50 |
|---|---|---|---|
| nmol·mg−1min−1 | by 10 mm serine | μm | |
| Tsr receptor1–215 Af1503 HAMP278–331 Rv3645 CHD331–549 | |||
| WT | 19.1 ± 1.6 | No inhibition | |
| x-da from Tsr | 21.2 ± 1.5 | 54 ± 3.5 | 28 ± 12.5 |
| A291I | 3.4 ± 0.3 | No inhibition | |
| S288I | 21.5 ± 2.4 | No inhibition | |
| S288I/A291I | 17.7 ± 1.5 | 59 ± 1.6 | 6.9 ± 5.7 |
| T281I | 13.3 ± 1.0 | No inhibition | — |
| T281I/A291I | 3.1 ± 0.2 | 34 ± 7.8 | 284 ± 383 |
| A295I | 5.6 ± 1.2 | No inhibition | |
| A291I/A295I | 3.8 ± 0.1 | No inhibition | |
| E311I | 4.9 ± 0.4 | No inhibition | |
| A291I/E311I | 0.9 ± 0.1 | No inhibition | |
| S318I | 23.6 ± 2.6 | No inhibition | |
| A291I/S318I | 5.4 ± 0.3 | 52 ± 5.4 | 6.2 ± 1.8 |
| S325I | 13.1 ± 0.4 | No inhibition | |
| A291I/S325I | 4.6 ± 0.4 | 38 ± 4.7 | 7 ± 2.7 |
| Tsr receptor + HAMP1–268 Rv3645 CHD331–549 | |||
| WT | 18.4 ± 0.6 | 82 ± 2.7 | 66 ± 18 |
| x-da from Af1503 | 30.0 ± 2.3 | 36 ± 6.7 | 295 ± 122 |
| I226S | 3.4 ± 0.5 | 65 ± 11 | 123 ± 221 |
| I229A | 20 ± 1 | No inhibition | |
| WT | 18.4 ± 0.6 | 82 ± 2.7 | 66 ± 18 |