|Entry||Database: PDB / ID: 7oa6|
|Title||Pseudo-atomic model for Hsp26 residues 63 to 214. Please be advised that the target map is not of sufficient resolution to unambiguously position backbone or side chain atoms. This model represents a likely fit.|
|Components||Heat shock protein 26Heat shock response|
|Keywords||CHAPERONE / small heat shock proteins / Hsp26 S207E mutant|
|Function / homology|
Function and homology information
cytoplasmic stress granule / unfolded protein binding / cellular response to heat / protein folding / mRNA binding / mitochondrion / identical protein binding / nucleus / cytoplasm
Similarity search - Function
: / Hsp20/alpha crystallin family / Small heat shock protein (sHSP) domain profile. / Alpha crystallin/Hsp20 domain / HSP20-like chaperone
Similarity search - Domain/homology
Heat shock protein 26
Similarity search - Component
|Biological species||Saccharomyces cerevisiae (baker's yeast)|
|Method||ELECTRON MICROSCOPY / single particle reconstruction / cryo EM / Resolution: 7.8 Å|
|Authors||Muehlhofer, M. / Peters, C. / Kriehuber, T. / Kreuzeder, M. / Kazman, P. / Rodina, N. / Reif, B. / Haslbeck, M. / Weinkauf, S. / Buchner, J.|
|Funding support|| Germany, 1items |
|Citation||Journal: Nat Commun / Year: 2021|
Title: Phosphorylation activates the yeast small heat shock protein Hsp26 by weakening domain contacts in the oligomer ensemble.
Authors: Moritz Mühlhofer / Carsten Peters / Thomas Kriehuber / Marina Kreuzeder / Pamina Kazman / Natalia Rodina / Bernd Reif / Martin Haslbeck / Sevil Weinkauf / Johannes Buchner /
Abstract: Hsp26 is a small heat shock protein (sHsp) from S. cerevisiae. Its chaperone activity is activated by oligomer dissociation at heat shock temperatures. Hsp26 contains 9 phosphorylation sites in ...Hsp26 is a small heat shock protein (sHsp) from S. cerevisiae. Its chaperone activity is activated by oligomer dissociation at heat shock temperatures. Hsp26 contains 9 phosphorylation sites in different structural elements. Our analysis of phospho-mimetic mutations shows that phosphorylation activates Hsp26 at permissive temperatures. The cryo-EM structure of the Hsp26 40mer revealed contacts between the conserved core domain of Hsp26 and the so-called thermosensor domain in the N-terminal part of the protein, which are targeted by phosphorylation. Furthermore, several phosphorylation sites in the C-terminal extension, which link subunits within the oligomer, are sensitive to the introduction of negative charges. In all cases, the intrinsic inhibition of chaperone activity is relieved and the N-terminal domain becomes accessible for substrate protein binding. The weakening of domain interactions within and between subunits by phosphorylation to activate the chaperone activity in response to proteotoxic stresses independent of heat stress could be a general regulation principle of sHsps.
|Structure viewer||Molecule: |
Downloads & links
A: Heat shock protein 26
B: Heat shock protein 26
I: Heat shock protein 26
J: Heat shock protein 26
X: Heat shock protein 26
Mass: 23910.586 Da / Num. of mol.: 5
Source method: isolated from a genetically manipulated source
Source: (gene. exp.) Saccharomyces cerevisiae (strain ATCC 204508 / S288c) (yeast)
Strain: ATCC 204508 / S288c / Gene: HSP26, YBR072W, YBR0714 / Plasmid: pQE60::HSP26 / Production host: Escherichia coli HB101 (bacteria) / References: UniProt: P15992
|Experiment||Method: ELECTRON MICROSCOPY|
|EM experiment||Aggregation state: PARTICLE / 3D reconstruction method: single particle reconstruction|
|Component||Name: Top two rings (16 subunits) of a 40mer complex of Hsp26 mutant S207E. (use 0.487 as threshold to visualise)|
Type: COMPLEX / Entity ID: #1 / Source: RECOMBINANT
|Molecular weight||Value: 0.382 MDa / Experimental value: NO|
|Source (natural)||Organism: Saccharomyces cerevisiae (baker's yeast)|
|Source (recombinant)||Organism: Escherichia coli (E. coli) / Strain: HB101 / Plasmid: pQE60::HSP26|
|Buffer solution||pH: 7.4|
|Specimen||Embedding applied: NO / Shadowing applied: NO / Staining applied: NO / Vitrification applied: YES|
|Vitrification||Instrument: FEI VITROBOT MARK IV / Cryogen name: ETHANE-PROPANE / Humidity: 100 % / Chamber temperature: 294 K|
-Electron microscopy imaging
Model: Titan Krios / Image courtesy: FEI Company
|Microscopy||Model: FEI TITAN KRIOS|
|Electron gun||Electron source: FIELD EMISSION GUN / Accelerating voltage: 300 kV / Illumination mode: FLOOD BEAM|
|Electron lens||Mode: BRIGHT FIELDBright-field microscopy / Nominal magnification: 105000 X / Nominal defocus max: 2800 nm / Nominal defocus min: 600 nm / Cs: 2.7 mm|
|Specimen holder||Cryogen: NITROGEN / Model: FEI TITAN KRIOS AUTOGRID HOLDER|
|Image recording||Average exposure time: 8 sec. / Electron dose: 45 e/Å2 / Detector mode: COUNTING / Film or detector model: GATAN K2 SUMMIT (4k x 4k) / Num. of real images: 5010|
|EM imaging optics||Energyfilter name: GIF Quantum LS / Energyfilter slit width: 20 eV|
|Image scans||Movie frames/image: 40|
|CTF correction||Type: PHASE FLIPPING AND AMPLITUDE CORRECTION|
|Particle selection||Num. of particles selected: 688419|
|Symmetry||Point symmetry: C4 (4 fold cyclic)|
|3D reconstruction||Resolution: 7.8 Å / Resolution method: FSC 0.143 CUT-OFF / Num. of particles: 375385 / Details: sharpened map / Symmetry type: POINT|
|Atomic model building||Protocol: FLEXIBLE FIT / Space: REAL / Target criteria: Correlation coefficient|
Details: Homology model generated with ITASSER with 1GME as template. Fitted with Chimera and flexibly fitted with NAMD. Residues 63 to 214 present in the model.
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