TABLE 1.
GlnB* variants identified for their improved interaction with NifA in the yeast two-hybrid systema
| GlnB* variantb | Growth response |
|---|---|
| Wild type | −/+ |
| K12R | +++ |
| E15Ac | ++ |
| E15D | +++ |
| K17T (2)c | ++++ |
| I28L | +++ |
| H42Q (9)c | ++++ |
| L45P (5)c | +++ |
| L45M | ++ |
| R47P (3) | ++++ |
| V52D (3)c | ++++ |
| V52I | +++ |
| F55L (5)c | ++++ |
| V59A | +++ |
| R72C | +++ |
| A95T | +++ |
a
The growth response of the yeast strains expressing each variant is shown. Cells were grown in minimal (SD) medium without histidine and in the presence of 3 mM 3-amino-1,2,4-triazol, a competitive inhibitor of His3 protein (9). A sense of the degree of growth that is represented by the plus signs can be gained by the photographs of the selected variants shown in Fig. 2.
b
The various causative substitutions found in GlnB* variants are shown in the left column, with the number of identical isolates shown in parentheses.
c
These variants are the selected set used in many of the later experiments.