Fig. 5.

In vivo activation profiles of OpuA and derivatives. L. lactis Opu401 cells carrying pNZOpuAHis, pNZOpuA(Δ12)His, or pNZOpuA(Δ61)His were grown in M17 supplemented with 0.5% glucose/5 μg/ml chloramphenicol. For the induction of OpuA (●), OpuAΔ12 (○), and OpuAΔ61 (▴), 1.3·10⁻⁴% (vol/vol) culture supernatant of the nisin A producing strain NZ9700 was used. After induction, the cells were washed twice with ice-cold 50 mM Hepes, pH 7.3. Before initiation of transport, cells at 0.4 mg of total protein/ml were preenergized for 5 min with 10 mM glucose (at 30°C). Uptake of [¹⁴C]glycine betaine was assayed in 50 mM Hepes, pH 7.3, supplemented with 50 μg/ml chloramphenicol and 10 mM glucose, with or without added sucrose as indicated on the x axis.