Figure 4.

 Excess HflB compensates for loss of ClpP in the degradation of cI–SsrA. The strains used were JM105 (○), its ΔhflB3::kan derivative (▪), and its clpP::Tn9 derivative carrying either the HflB-overproducing plasmid pULB6234 (▴) or the control plasmid pRK7813 (▵). All strains carried plasmid pλN-SPT, coding for cI–SsrA. Cultures were grown to exponential phase at 37°C in M63 supplemented with glycerol, ampicillin, and chloramphenicol. The cultures were pulse labeled and chased and the amount of labeled cI variant was measured periodically, as described in Materials and Methods.