Negative control of flagellum synthesis in Pseudomonas aeruginosa is modulated by the alternative sigma factor AlgT (AlgU)

Many respiratory isolates of Pseudomonas aeruginosa from cystic fibrosis pa tients are mucoid (alginate producing) yet lack flagella. It was hypothesiz ed that an alginate regulator inhibits flagellar gene expression. Mutations in algB, algR, and algT resulted in nonmucoid derivatives, yet algT mutant s expressed flagella. AlgT-dependent control of flagellum synthesis occurre d through inhibition of fliC but not rpoN transcription.