Interactions between a subset of substrate side chains and AAA+ motor pore loops determine grip during protein unfolding

eLife

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[1] Department of Biology, Massachusetts Institute of Technology, Cambridge, United States;Department of Biology, Massachusetts Institute of Technology, Cambridge, United States;Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, United States;

关键词: ClpXP;    AAA+ enzymes;    ATP-dependent protein unfolding;    protein degradation;    E. coli;   

DOI  :  10.7554/eLife.46808

来源: publisher

【 摘 要 】

10.7554/eLife.46808.001Most AAA+ remodeling motors denature proteins by pulling on the peptide termini of folded substrates, but it is not well-understood how motors produce grip when resisting a folded domain. Here, at single amino-acid resolution, we identify the determinants of grip by measuring how substrate tail sequences alter the unfolding activity of the unfoldase-protease ClpXP. The seven amino acids abutting a stable substrate domain are key, with residues 2–6 forming a core that contributes most significantly to grip. ClpX grips large hydrophobic and aromatic side chains strongly and small, polar, or charged side chains weakly. Multiple side chains interact with pore loops synergistically to strengthen grip. In combination with recent structures, our results support a mechanism in which unfolding grip is primarily mediated by non-specific van der Waal’s interactions between core side chains of the substrate tail and a subset of YVG loops at the top of the ClpX axial pore.

【 授权许可】

CC BY