PDBsum entry: 1gme

Chaperone

PDB id: 1gme

Contents

Protein chains

150 a.a. *

109 a.a. *

Waters ×33

* Residue conservation analysis

PDB id:

1gme

Name:

Chaperone

Title:

Crystal structure and assembly of an eukaryotic small heat shock protein

Structure:

Heat shock protein 16.9b. Chain: a, b, c, d. Engineered: yes

Source:

Triticum aestivum. Wheat. Organism_taxid: 4565. Expressed in: escherichia coli. Expression_system_taxid: 511693.

Biol. unit:

Dodecamer (from PDB file)

Resolution:

2.70Å R-factor: 0.231 R-free: 0.286

Authors:

R.L.M.Van Montfort,E.Basha,K.L.Friedrich,C.Slingsby, E.Vierling

Key ref:

R.L.van Montfort et al. (2001). Crystal structure and assembly of a eukaryotic small heat shock protein. Nat Struct Biol, 8, 1025-1030. PubMed id: 11702068 DOI: 10.1038/nsb722

Date:

13-Sep-01 Release date: 29-Nov-01

Protein chains

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

Seq: 151 a.a.

Struc: 150 a.a.*

Protein chains

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

Seq: 151 a.a.

Struc: 109 a.a.

* PDB and UniProt seqs differ at 1 residue position (black cross)

 Gene Ontology (GO) functional annotation 

• Cellular component: cytoplasm (1 term)
• Biological process: response to stress (2 terms)

DOI no: 10.1038/nsb722

Nat Struct Biol 8:1025-1030 (2001)

PubMed id: 11702068

Crystal structure and assembly of a eukaryotic small heat shock protein.

R.L.van Montfort, E.Basha, K.L.Friedrich, C.Slingsby, E.Vierling.

ABSTRACT

The 2.7 A structure of wheat HSP16.9, a member of the small heat shock proteins (sHSPs), indicates how its alpha-crystallin domain and flanking extensions assemble into a dodecameric double disk. The folding of the monomer and assembly of the oligomer are mutually interdependent, involving strand exchange, helix swapping, loose knots and hinged extensions. In support of the chaperone mechanism, the substrate-bound dimers, in temperature-dependent equilibrium with higher assembly forms, have unfolded N-terminal arms and exposed conserved hydrophobic binding sites on the alpha-crystallin domain. The structure also provides a model by which members of the sHSP protein family bind unfolded substrates, which are involved in a variety of neurodegenerative diseases and cataract formation.

Selected figure(s)

Figure 3.
Figure 3. Different chaperone assemblies but with the same fold. a, The quaternary structures of the wheat HSP16.9 dodecameric double disk, with 32 symmetry, on the left and the M. jannaschii HSP16.5 spherical 24-mer, with 432 symmetry, on the right. The C-terminal extensions make equivalent interface interactions around two-, three- (HSP16.9) and four-fold (HSP16.5) axes. b, Superposition of the monomeric human p23 cochaperone of HSP90, shown in green, on a dimer of HSP16.9 displayed using the same color scheme as in Fig. 2. The C-terminal residues of p23 coincide with the -strand exchange loop of the HSP16.9 dimer. c, Superposition of the monomers of M. jannaschii HSP16.5 (blue) and wheat HSP16.9 (red). N- and C-termini are labeled. Residues close to the N-terminus of HSP16.9 coincide with the 1 strand of HSP16.5 but run in the opposite direction. (b,c) were made with GRASP41.

Figure 4.
Figure 4. Patching the -crystallin domain and putative substrate binding sites. a, Outside view of one of the sides of the HSP16.9 dodecamer, showing how dimers from both top and bottom disks are related by a two-fold axis to form an eclipsed tetramer. In the top dimer, the monomer with the disordered N-terminal arm is shown as a pink ribbon, whereas the monomer with the ordered arm is shown as a solid molecular surface, with surface hydrophobic patches shown in blue. The corresponding monomers of the bottom dimer are shown as yellow and orange ribbons, respectively. Covering of a hydrophobic groove in the solid top monomer by Ile 147 and Ile 149 of the IXI/V motif in the C-terminal extension from the bottom monomer (yellow) illustrates how extensions can cover putative substrate binding sites. The picture was made using GRASP41. b, The top dimer from panel (a) is rotated by 180° about a vertical axis to view the dimer from the inside of the dodecamer. The molecular surface of the -crystallin domain of the ordered monomer is now shown as a semitransparent surface with hydrophobic patches mapped to the surface in blue, while revealing the monomer fold in ribbon with hydrophobic residues Trp 48 and Phe 110 in rod representation. These residues form a surface hydrophobic patch and putative substrate binding site that must become exposed upon the unraveling of the ordered N-terminal arm (green) during subunit exchange. In the assembly, the patch is covered by Phe 10 (green) in the N-terminal arm. The picture was made with DINO (http://www.dino3d.org). c, A close-up view of both the hydrophobic and polar intramolecular interactions between the N-terminal arm and surface hydrophobic patch on the -crystallin domain. Ser 7, Phe 10, Trp 48, Phe 110 and Arg 109 are the five residues of the three-dimensional fingerprint in the sHSP alignment (Fig. 1a). The color scheme is the same as in Fig. 2b, with carbon atoms on the -crystallin domain in pink and on the N-terminal arm in green. d, A zoomed-out view shows the N-terminal arm (green) from one -crystallin domain (red) forming an ordered helical domain with an N-terminal arm from another monomer (sage) and interacting with the equivalent surface hydrophobic patch from two -crystallin domains (red and yellow). The red, sage and yellow monomers are from different dimers. Phe 10 forms intramolecular hydrophobic interactions with Trp 48 and Phe 110. Val 4 makes intermolecular hydrophobic interactions with Trp 48 and Phe 110 of the yellow monomer. This interaction is further stabilized by two intermolecular hydrogen bonds between Val 4 N and Arg 109 O, and Val 4 O and Arg 111 N (not shown). e, Stereo view of the hydrophobic interface between the N-terminal arm and a conserved hydrophobic patch on the -crystallin domain. 2F[o] - F[c] electron density is shown in blue. The model is displayed in ball-and-stick representation, with carbon, oxygen and nitrogen atoms in yellow, red and blue, respectively.

The above figures are reprinted by permission from Macmillan Publishers Ltd: Nat Struct Biol (2001, 8, 1025-1030) copyright 2001.

Figures were selected by the author.