title: The quaternary organization and dynamics of the molecular chaperone HSP26 are thermally regulated.
abstract: The function of ScHSP26 is thermally controlled: the heat shock that causes the destabilization of target proteins leads to its activation as a molecular chaperone. We investigate the structural and dynamical properties of ScHSP26 oligomers through a combination of multiangle light scattering, fluorescence spectroscopy, NMR spectroscopy, and mass spectrometry. We show that ScHSP26 exists as a heterogeneous oligomeric ensemble at room temperature. At heat-shock temperatures, two shifts in equilibria are observed: toward dissociation and to larger oligomers. We examine the quaternary dynamics of these oligomers by investigating the rate of exchange of subunits between them and find that this not only increases with temperature but proceeds via two separate processes. This is consistent with a conformational change of the oligomers at elevated temperatures which regulates the disassembly rates of this thermally activated protein.
authors.affiliation: Department of Chemistry, Physical and Theoretical Chemistry Laboratory, Oxford, UK.
authors.forename: Justin L P
authors.initials: JL
authors.lastname: Benesch
authors.forename: J Andrew
authors.initials: JA
authors.lastname: Aquilina
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Baldwin
authors.forename: Agata
authors.initials: A
authors.lastname: Rekas
authors.forename: Florian
authors.initials: F
authors.lastname: Stengel
authors.forename: Robyn A
authors.initials: RA
authors.lastname: Lindner
authors.forename: Eman
authors.initials: E
authors.lastname: Basha
authors.forename: Glyn L
authors.initials: GL
authors.lastname: Devlin
authors.forename: Joseph
authors.initials: J
authors.lastname: Horwitz
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Vierling
authors.forename: John A
authors.initials: JA
authors.lastname: Carver
authors.forename: Carol V
authors.initials: CV
authors.lastname: Robinson
mesh_terms: D002850:Chromatography, Gel; D006360:Heat-Shock Proteins / Q000737:chemistry* / Q000378:metabolism; D008027:Light; D019906:Nuclear Magnetic Resonance, Biomolecular; D020836:Protein Structure, Quaternary; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000378:metabolism; D012542:Scattering, Radiation; D013050:Spectrometry, Fluorescence; D021241:Spectrometry, Mass, Electrospray Ionization; D013696:Temperature
chemical_list: C499528:HSP26 protein, S cerevisiae; D006360:Heat-Shock Proteins; D029701:Saccharomyces cerevisiae Proteins