RpoS recovery from phosphate starvation

Acclimation of E. coli to environmental stress is dependent on changes in gene expression. RpoS is a sigma factor that helps the cell deal with a range of stresses. When cells are not under stress, RpoS is rapidly degraded; however, during stationary phase or under other stresses during growth, RpoS accumulates due to increased translation or decreased proteolysis. Under phosphate starvation, RpoS degradation is inhibited by a small antiadaptor protein, IraP. IraP achieves RpoS stabilization by blocking adaptor protein RssB from delivering RpoS to the ClpXP protease for degradation. While the pathway for RpoS stabilization under phosphate starvation is well defined, recovery from stress is less well understood. Western blot analysis indicates that when phosphate is introduced into phosphate‐deprived cultures, RpoS levels sharply decrease to barely detectable levels within five minutes of exposure, which strongly suggests that rapid degradation is restored when phosphate is restored to cultures. We are examining the mechanism behind this recovery process by monitoring the fate of IraP and control of the adaptor protein RssB in the presence of phosphate. We hope this study will help us better understand how the interplay of stress induction and recovery govern adaptations under nutrient starvation. The lessons learned from the recovery of IraP may also provide insight into the mechanism of recovery of the two other known antiadaptors, IraD and IraM. Support or Funding Information NIH Intramural Funding This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .