FIG. 2.

lacO(Con) mutants restore SecAΔ11his function by overproduction. (A) Sequence of the lac operator region with the lacO(Con) suppressor mutations indicated below the sequence. The lacO(Con) mutation at position 12 was present in two independent suppressor mutants, whereas the mutation at position 15 and the mutation at position 17 were each present in a single suppressor mutant. The number below each lacO(Con) mutation was obtained from a previous study (2), and these numbers indicate the corresponding repressor affinities for the mutant operator compared to the wild-type operator, which was defined as 100%. The lac repressor-protected fragment is indicated above the sequence, and the axis of dyad symmetry of the sequence is also indicated. (B) Western blot of BL21.19 containing the indicated plasmids. The analysis was performed like the analysis described in the legend to Fig. 1 except that both SecA and OmpA antisera were used to probe the blot. OmpA was utilized as a control protein to verify that equivalent levels of total protein were loaded on the gel.