FIG 1.

Sequence changes in ropB. The locations of spontaneous mutations in the two wild-type backgrounds are shown above the DNA sequence. The letters represent base substitutions. The locations of CPR-derived mutations in the wild-type CC107 background and a dinB-deficient strain are shown below. The solid lines are aligned with deleted base pairs; the arrows indicate locations of insertions. The numbers with plus signs in parentheses show the number of additional mutations at any given site that appeared more than once in a sample of four from the same culture. Mutants from three strains are shown in the following colors: green, BW25113 background; black, CC107 background; red, a dinB derivative of BW25113.