title: Clathrin-coat disassembly illuminates the mechanisms of Hsp70 force generation.
abstract: 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.
authors.affiliation: Department of Biochemistry and Center for Biomedical Neuroscience, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA.
authors.forename: Rui
authors.initials: R
authors.lastname: Sousa
authors.affiliation: Laboratory of Cellular Imaging and Macromolecular Biophysics, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, Maryland, USA.
authors.forename: Hsien-Shun
authors.initials: HS
authors.lastname: Liao
authors.affiliation: Department for Macromolecular Structures, Centro Nacional de Biotecnología (CNB-CSIC), Madrid, Spain.
authors.forename: Jorge
authors.initials: J
authors.lastname: Cuéllar
authors.affiliation: Department of Biochemistry and Center for Biomedical Neuroscience, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA.
authors.forename: Suping
authors.initials: S
authors.lastname: Jin
authors.affiliation: Department for Macromolecular Structures, Centro Nacional de Biotecnología (CNB-CSIC), Madrid, Spain.
authors.forename: José M
authors.initials: JM
authors.lastname: Valpuesta
authors.affiliation: Laboratory of Cellular Imaging and Macromolecular Biophysics, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, Maryland, USA.
authors.forename: Albert J
authors.identifier: 0000-0003-3826-1081
authors.initials: AJ
authors.lastname: Jin
authors.affiliation: Department of Biochemistry and Center for Biomedical Neuroscience, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA.
authors.forename: Eileen M
authors.initials: EM
authors.lastname: Lafer
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D033922:Clathrin Heavy Chains / Q000737:chemistry*; D020285:Cryoelectron Microscopy; D019277:Entropy; D050884:HSP72 Heat-Shock Proteins / Q000737:chemistry / Q000502:physiology*; D006863:Hydrogen-Ion Concentration; D008958:Models, Molecular; D010316:Particle Size; D000072417:Protein Domains; D055503:Protein Multimerization; D055550:Protein Stability; D020836:Protein Structure, Quaternary; D051381:Rats
chemical_list: D050884:HSP72 Heat-Shock Proteins; D033922:Clathrin Heavy Chains