Figure 4.

Depletion of GroEL/S in vivo increases σ³² activity. Strain CAG48176, whose chromosomal groELS gene is driven by the inducible Para promoter, was grown in exponential phase at 30°C in M9 minimal media containing all amino acids except methionine and cysteine with 0.2% fructose as the main carbon source and 0.1% arabinose to maintain near wild-type levels of GroEL/S. Depletion of GroEL/S was initiated at time 0 by removing arabinose from the media and adding 0.2% glucose. HtpG synthesis and GroEL levels were analyzed as in Figure 2.