Protein–protein interactions modulate the docking-dependent E3-ubiquitin ligase activity of Carboxy-terminus of Hsc70-interacting protein (CHIP)

• Main Authors: Narayan, Vikram, Landré, Vivien, Ning, Jia, Hernychova, Lenka, Muller, Petr, Verma, Chandra, Walkinshaw, Malcolm D., Blackburn, Elizabeth A., Ball, Kathryn L.
• Other Authors: School of Biological Sciences
• Format: Article
• Language: English
• Published: 2018
• Subjects: DRNTU::Science::Biological sciences; Ubiquitin Protein Ligase; Protein Structure
• Online Access: https://hdl.handle.net/10356/88869; http://hdl.handle.net/10220/46059
• Institution: Nanyang Technological University

CHIP is a tetratricopeptide repeat (TPR) domain protein that functions as an E3-ubiquitin ligase. As well as linking the molecular chaperones to the ubiquitin proteasome system, CHIP also has a docking-dependent mode where it ubiquitinates native substrates, thereby regulating their steady state levels and/or function. Here we explore the effect of Hsp70 on the docking-dependent E3-ligase activity of CHIP. The TPR-domain is revealed as a binding site for allosteric modulators involved in determining CHIP's dynamic conformation and activity. Biochemical, biophysical and modeling evidence demonstrate that Hsp70-binding to the TPR, or Hsp70-mimetic mutations, regulate CHIP-mediated ubiquitination of p53 and IRF-1 through effects on U-box activity and substrate binding. HDX-MS was used to establish that conformational-inhibition-signals extended from the TPR-domain to the U-box. This underscores inter-domain allosteric regulation of CHIP by the core molecular chaperones. Defining the chaperone-associated TPR-domain of CHIP as a manager of inter-domain communication highlights the potential for scaffolding modules to regulate, as well as assemble, complexes that are fundamental to protein homeostatic control.