PDBsum entry: 2h50

Chaperone

PDB id: 2h50

Contents

Protein chains

(+ 18 more) 93 a.a. *

* Residue conservation analysis

PDB id:

2h50

Name:

Chaperone

Title:

Multiple distinct assemblies reveal conformational flexibili small heat shock protein hsp26

Structure:

Small heat shock protein hsp26. Chain: a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r v, w, x

Source:

Saccharomyces cerevisiae. Baker's yeast. Organism_taxid: 4932

Biol. unit:

Dimer (from PQS)

Authors:

H.E.White,E.V.Orlova,S.Chen,L.Wang,A.Ignatiou,B.Gowen,T.Stro T.M.Franzmann,M.Haslbeck,J.Buchner,H.R.Saibil

Key ref:

H.E.White et al. (2006). Multiple distinct assemblies reveal conformational flexibility in the small heat shock protein Hsp26. Structure, 14, 1197-1204. PubMed id: 16843901 DOI: 10.1016/j.str.2006.05.021

Date:

25-May-06 Release date: 01-Aug-06

Protein chains

Q41560  (HS16B_WHEAT) -  16.9 kDa class I heat shock protein 2

Seq: 151 a.a.

Struc: 93 a.a.

DOI no: 10.1016/j.str.2006.05.021

Structure 14:1197-1204 (2006)

PubMed id: 16843901

Multiple distinct assemblies reveal conformational flexibility in the small heat shock protein Hsp26.

H.E.White, E.V.Orlova, S.Chen, L.Wang, A.Ignatiou, B.Gowen, T.Stromer, T.M.Franzmann, M.Haslbeck, J.Buchner, H.R.Saibil.

ABSTRACT

Small heat shock proteins are a superfamily of molecular chaperones that suppress protein aggregation and provide protection from cell stress. A key issue for understanding their action is to define the interactions of subunit domains in these oligomeric assemblies. Cryo-electron microscopy of yeast Hsp26 reveals two distinct forms, each comprising 24 subunits arranged in a porous shell with tetrahedral symmetry. The subunits form elongated, asymmetric dimers that assemble via trimeric contacts. Modifications of both termini cause rearrangements that yield a further four assemblies. Each subunit contains an N-terminal region, a globular middle domain, the alpha-crystallin domain, and a C-terminal tail. Twelve of the C termini form 3-fold assembly contacts which are inserted into the interior of the shell, while the other 12 C termini form contacts on the surface. Hinge points between the domains allow a variety of assembly contacts, providing the flexibility required for formation of supercomplexes with non-native proteins.

Selected figure(s)

Figure 2.
Figure 2. Structure Determination
(A) Cryo-EM image of wt Hsp26 complexes. In the raw images, it is impossible to discern which particles belong to the compact and expanded classes. Protein density is displayed as white. Scale bar, 500 Å.
(B and C) Examples of averaged views of the compact and expanded assemblies, after alignment and classification. Views along the symmetry directions are indicated. Resolution curves and a larger set of class averages, along with the corresponding reprojections of the 3D structures, are provided as Supplemental Data (Figures S1 and S2).
(D and E) Surface rendered views of the compact (green) and expanded (blue) maps of wt Hsp26. One surface assembly unit is outlined on (E).
(F and G) Sliced open views of the compact and expanded maps, showing the inserted densities. One of the four densities is circled in (G), and examples of an open and a closed 3-fold position are shown by open and closed triangles. There is additional density at the surface of the closed 3-folds. The 3D maps were rendered in Iris Explorer (NAG).

Figure 6.
Figure 6. Location of the Domains in Hsp26
(A) Location of the N-terminal region (“N”), the middle globular domain (“M”), the α-crystallin domain (“α”), and the surface C-terminal tails (“C”).
(B) Location of the inserted C-terminal trimers. The map in (A) has been smoothed for clarity.

The above figures are reprinted by permission from Cell Press: Structure (2006, 14, 1197-1204) copyright 2006.

Figures were selected by an automated process.