Title |
Direct interaction between the transcription factors CadC and OmpR involved in the acid stress response of Salmonella enterica |
Author |
Yong Heon Lee1,2 and Ji Hye Kim1 |
Address |
1School of Life Sciences and Biotechnology, Korea University, Seoul 02841, Republic of Korea, 2Department of Biomedical Laboratory Science, Dongseo University, Busan 47011, Republic of Korea |
Bibliography |
Journal of Microbiology, 55(12),966–972, 2017,
|
DOI |
10.1007/s12275-017-7410-7
|
Key Words |
Salmonella enterica, CadC, OmpR, fliC, acid stress |
Abstract |
In Salmonella enterica serovar Typhimurium, the acid-sensing
regulator CadC activates transcription of the cadBA operon
which contributes to the acid tolerance response. The
DNA-binding response regulator OmpR in two-component
regulatory system with EnvZ binds to its own promoter for
autoinduction. We previously reported that CadC exerts a
negative influence on ompR transcription during acid adaptation.
However, its underlying mechanisms remain to be elucidated.
Here we show that the level of OmpR protein is gradually
reduced by a gradual increase in the CadC level using
an arabinose-inducible expression system, indicating there
exists a negative correlation between the expression levels of
two transcription factors. To explore the molecular basis for
OmpR repression by CadC, we performed in vitro binding assays
and determined that CadC directly interacts with OmpR.
We further show that inactivation of cadC inhibits transcription
of the fliC gene, which encodes the major flagellar subunit,
resulting in impaired flagellar motility under acid-adaptation
conditions. Together, our findings suggest that CadC may
repress autoinduction of the OmpR response regulator through
their direct interaction. |