Mechanistic Insights into Diverse Protease Adaptor Functions

Protein degradation is an essential cellular process that helps maintain proper homeostasis. The ClpXP protease broadly regulates bacterial development and quality control during the cell cycle. The range and order of substrates that ClpXP degrades during the cell cycle is dictated by 3 accessory proteins, which are known as adaptors. This thesis will elaborate on how dimerization tightly regulates the stability and activity of the adaptor protein at the center of this hierarchy, RcdA, and show how this affects normal cellular processes in Caulobacter crescentus. I will discuss the mechanism by which dimerization limits RcdA activity and how the dimerization interface contains selective regions that differentiate which substrates can engage with RcdA. Lastly, I will discuss how RcdA and the master regulator of Caulobacter, CtrA, interacts with the third adaptor in the hierarchy, PopA and the various surfaces on the PopA adaptor that are involved in each interaction. The remainder of the thesis will present data that arises from these projects