FIG. 5.

Proteases Lon and ClpP are both involved in HemA turnover. The genetic requirements for proteolysis of HemA in vivo were determined in E. coli because of the poor growth of lon clpP double mutants of S. typhimurium. The wild-type E. coli strain MG1655 and its lon::Tn10 clpP::Cam double mutant derivative (TE6907) were analyzed for HemA turnover by the same methods as those used for previous experiments. (A) Top, pulse-chase analysis of wild type; bottom, pulse-chase analysis of the double mutant; (B) data obtained from PhosphorImager analysis of duplicate gels. HemA was unstable in the wild-type strain (half-life of ≈30 min), while it was stable (half-life of >300 min) in the lon clpP double mutant.