Cells with straight filaments have increased DegU-P levels. (A) The nonmotile phenotype of a hagA233V mutant. The wild-type (IS75) and the hagA233V mutant (BD7599) were centrally inoculated on LB fortified with 0.3% agar. After 18 h incubation at 30°C, the plates were photographed against a black background. (B) Fluorescence microscopy of flagella filaments (HagT209C). HagT209C was stained with a maleimide reactive dye (green) in the wild-type strain (BD7816, hagT209C) and the hagA233V mutant (BD7757, hagT209C-A233V). Strains were grown to mid log phase in LB. (C) hagA233V decreases comK expression. Effect of hagA233V (BD7626) on PcomK-luc expression compared to wild-type (BD4773). (D) degUD56N suppresses high aprE expression in hagA233V. Expression from PaprE-luc in hagA233V is higher than wild-type expression. The degUD56N allele bypasses hagA233V for expression from PaprE. Strains used were: wild-type PaprE-luc (BD6904), hagA233V PaprE-luc (BD8007), degUD56N PaprE-luc (BD7423), and hagA233V degUD56N PaprE-luc (BD8011). The vertical arrows in panel C and D indicate T0.