Figure 5.

Growth competitions between degP⁺ cells and degP^R207P or degP^Y444A cells. (A) Three independent mixtures with equal initial quantities of a degP⁺ strain and a degP^R207P or degP^Y444A strain were subjected to eight cycles of 10⁴-fold dilution in LB broth and subsequent growth for ∼12 h at 45°C. At the beginning of the experiment and after each cycle, the fraction of each strain in the population was determined by relative CFP or YFP fluorescence. The degP⁺ cells dominated the population after one cycle of competition against degP^R207P cells and after six cycles of competition against degP^Y444A cells when the wild-type strain was marked with CFP and the mutant strain was marked with YFP and vice versa. (B) Micrographs of strains expressing chromosomal DegP, DegP^R207P, or DegP^Y444A at 45°C.