Fig. 4.

Expression of His₆-nusA from the P_BAD promoter in rpo⁺, rpoB2063, and rpoC2064 strains as determined by Western blot analysis. Total cellular extracts of strains grown in the presence (0.02%) or absence of arabinose were probed on filters with an antibody against the His tag. The strains used (with relevant genetic markers in parentheses) were MW176/pMW498 (rpoB⁺ rpoC⁺/his₆-nusA), MW181/pMW498 (rpoB2063 rpoC⁺/his₆-nusA), and MW177/pMW498 (rpoB⁺ rpoC2064/his₆-nusA). For complete genotypes, see Table 1. MW, molecular mass marker with sizes in kilodaltons. The relative amounts of His₆-NusA shown were obtained by using an unknown protein (*) for which the synthesis did not respond to addition of arabinose as an internal control and normalizing the obtained ratios to that for the rpoB⁺ rpoC⁺ strain.