Fig. 3. σ^S(Δ7–35) is present at increased cellular levels that are not altered by mutations affecting RssB or ClpP. (A) Cells of strain MNC10 (lanes 1–3), which carries the rpoS^(Δ7–35) mutation, or W3110Δlac (lanes 4–6), which expresses wild-type σ^S, and rssB or clpP mutations as indicated were grown in LB. During mid-log phase (at an OD₅₇₈ between 0.7 and 0.9), σ^S levels were assayed by immunoblot analysis. Numbers at the left indicate molecular masses (kDa) of size standard proteins. (B) Using the same conditions as those described in the legend to Figure 2, degradation of σ^S and σ^S(Δ7–35) was assayed using strains W3110Δlac (open circles) and MNC10 (closed circles), respectively.