FIG. 7.

Inhibition of glycerol kinase activity by IIA^LacS. S. typhimurium PP2178 (crr::Tn10 nagE) was transformed with pKK223-3 (control) (A), pKKELE (IIA^LacS) (B), pSKIIAm2his [IIA^LacS-6H(I548E/G556D)] (C), and pSKIIAm1his [IIA^LacS-6H(H552R)] (D). Cells were grown overnight on a minimal salts medium supplemented with 0.4% dl-lactate. After being washed with minimal salts medium, the cells were diluted to an A₆₆₀ of 0.35 in minimal salts medium containing 54 mM glycerol and incubated for 30 min at 37°C; glucose was added to a final concentration of 10 mM; the cells were incubated for 1 h at 37°C and then washed with minimal salts medium. Uptake assays with 0.5 mM [¹⁴C]glycerol were performed in the presence (open symbols) and absence (filled symbols) of 10 mM 2-deoxy-d-glucose; the cells were equilibrated in the presence or absence of 2-deoxy-d-glucose for 5 min prior to the initiation of uptake.