Clathrin-coat disassembly illuminates the mechanisms of Hsp70 force generation

• Published in: Nature structural & molecular biology Vol. 23; no. 9; pp. 821 - 829
• Main Authors: Sousa, Rui, Liao, Hsien-Shun, Cuéllar, Jorge, Jin, Suping, Valpuesta, José M, Jin, Albert J, Lafer, Eileen M
• Format: Journal Article
• Language: English
• Published: New York Nature Publishing Group US 01.09.2016; Nature Publishing Group
• Subjects: 101/28; 631/45/173; 631/57/2272/2276; Adenosine triphosphatase; Amino Acid Sequence; Animals; ATP; Binding Sites; Biochemistry; Biological Microscopy; Cell organelles; Cellular control mechanisms; Clathrin Heavy Chains - chemistry; Cryoelectron Microscopy; Entropy; Enzymes; Genetic aspects; Heat shock proteins; HSP72 Heat-Shock Proteins - chemistry; HSP72 Heat-Shock Proteins - physiology; Hydrogen-Ion Concentration; Hydrolysis; Life Sciences; Membrane Biology; Models, Molecular; Observations; Particle Size; Properties; Protein Domains; Protein Multimerization; Protein Stability; Protein Structure; Protein Structure, Quaternary; Protein synthesis; Protein-protein interactions; Rats; Substrates
• ISSN: 1545-9993; 1545-9985
• DOI: 10.1038/nsmb.3272

Light-scattering kinetics and atomic force and electron microscopy analyses show that Hsp70-mediated disassembly of clathrin cages occurs via a collision-pressure mechanism consistent with the entropic pulling model. Hsp70s use ATP hydrolysis to disrupt protein-protein associations and to move macromolecules. One example is the Hsc70- mediated disassembly of the clathrin coats that form on vesicles during endocytosis. Here, we exploited the exceptional features of these coats to test three models—Brownian ratchet, power-stroke and entropic pulling—proposed to explain how Hsp70s transform their substrates. Our data rule out the ratchet and power-stroke models and instead support a collision-pressure mechanism whereby collisions between clathrin-coat walls and Hsc70s drive coats apart. Collision pressure is the complement to the pulling force described in the entropic pulling model. We also found that self-association augments collision pressure, thereby allowing disassembly of clathrin lattices that have been predicted to be resistant to disassembly. These results illuminate how Hsp70s generate the forces that transform their substrates.