GadE regulates gene transcription and motility in .

BACKGROUND

() express flagella to ascend human urinary tracts. To survive in the acidic pH of human urine, uses the glutamate decarboxylase acid response system, which is regulated by the GadE protein.

AIM

To determine if growth in an acidic pH environment affected transcription and whether GadE regulated that transcription.

METHODS

A reporter fusion was created on a single copy number plasmid to assess the effects of acidic pH on transcription. Further, a Δ mutant strain of a uropathogenic was created and tested for motility compared to the wild-type strain.

RESULTS

cells carrying the fusion displayed significantly less transcription when grown in an acidic pH medium compared to when grown in a neutral pH medium. Transcription of fell further when the was grown in an acidic pH/high osmolarity environment. Since GadE is a critical regulator of one acid response system, transcription was tested in a mutant strain grown under acidic conditions. Expression of was derepressed in the mutant strain grown under acidic conditions compared to that in wild-type bacteria under the same conditions. Furthermore, a mutation in a uropathogenic background exhibited significantly greater motility than the wild-type strain following growth in an acidic medium.

CONCLUSION

Together, our results suggest that GadE may down-regulate transcription and motility in grown under acidic conditions.