FIGURE 7.

Effect of Tyr²⁷⁵ mutations on GABA uptake and OC8HSL degradation. Left and middle, uptake of 1 μm l-[³H]proline and [³H]GABA (as described in the legend to Fig. 5) was assayed in cultures of mutants atu2422(atu2422-F77A), atu2422(atu2422-Y275K), atu2422(atu2422-Y275A), atu2422(atu2422-Y275F), atu2422(atu2422), and atu2422(6000). Right, the OC8HSL concentration (added at 400 nm) was measured in cultures of these same strains grown in AB medium supplemented with (0.1 mm; gray bars) and without (black bars) GABA in the presence of competing solutes added at a final concentration of 1 mm. Experiments were done in duplicate.