Prefolding and quality control of OMPs in periplasmic space (224.1)

The outer membrane proteins (OMPs) of Gram‐negative bacteria have to be translocated through the periplasmic space before reaching their final destination. The aqueous environment of the periplasmic space and high permeability of the outer membrane engender such a translocation process inevitably challenging. In Escherichia coli , although SurA, Skp and DegP have been identified to function in translocating OMPs across the periplasm, their precise roles and their relationship remain to be elucidated. In addition, DegP is said to have protease/chaperone dual function. However, whether DegP truly performs chaperone activity has long been under debate, let alone how this dual function is regulated. Our single molecule detection study has revealed the mechanism on the collaboration among SurA, Skp and DegP. We have also found that DegP indeed processes chaperone‐like activity. The dual function is regulated by both the substrate conformation and oligomerization status of DegP itself. Based on our results, a model on how OMPs are safeguarded and quality controlled in the periplastic space is proposed.