Figure 2.

Heat-induced synthesis of σ³², σ³²-B, and A-LacZ in strain MC4100 carrying λrpoHBAZ or its derivative. (A) Cells were grown in minimal medium at 30°C and shifted to 42°C at t = 0. Samples were taken at the times indicated and pulse labeled with [³⁵S]Met (1,200 Ci/mmol; 100 μCi/ml) for 30 s. The labeled σ³² and σ³²-B were precipitated by σ³²-specific antiserum and analyzed by SDS/PAGE followed by quantification as described in Materials and Methods. Values were normalized to the t = 0 value for each protein and then to σ³² in MC4100. (●) σ³² in MC4100; (■) σ³² in MC4100 (λrpoHBAZ); and (□) σ³²-B in MC4100 (λrpoHBAZ). (B) Cells were grown and treated essentially as in A, except that the pulse labeling with [³⁵S]Met was done at 600 Ci/mmol for 60 s followed by chase with excess unlabeled Met for 60 s. The labeled A-LacZ was precipitated with anti-β-galactosidase antiserum and analyzed by SDS/PAGE. Quantification was done as in A and normalized to t = 0 for each protein and then to rpoHBAZ. The dotted line indicates the expected curve if the heat-induced synthesis from rpoHBAZ was shut off. (○) TLF247; (■) rpoHBAZ; (▴) 123BAZ; (□) rpoHΔC17BAZ; and (▵) 123ΔC17BAZ.