2KLR: Solid-state NMR structure of the alpha-crystallin domain in alphaB-crystallin oligomers

The small heat shock protein alphaB-crystallin (alphaB) contributes to cellular protection against stress. For decades, high-resolution structural studies on oligomeric alphaB have been confounded by its polydisperse nature. Here, we present a structural basis of oligomer assembly and activation of the chaperone using solid-state NMR and small-angle X-ray scattering (SAXS). The basic building block is a curved dimer, with an angle of approximately 121 degrees between the planes of the beta-sandwich formed by alpha-crystallin domains. The highly conserved IXI motif covers a substrate binding site at pH 7.5. We observe a pH-dependent modulation of the interaction of the IXI motif with beta4 and beta8, consistent with a pH-dependent regulation of the chaperone function. N-terminal region residues Ser59-Trp60-Phe61 are involved in intermolecular interaction with beta3. Intermolecular restraints from NMR and volumetric restraints from SAXS were combined to calculate a model of a 24-subunit alphaB oligomer with tetrahedral symmetry.
PDB ID: 2KLRDownload
MMDB ID: 83130
PDB Deposition Date: 2009/7/8
Updated in MMDB: 2011/10
Experimental Method:
solid-state nmr
Source Organism:
Similar Structures:
Biological Unit for 2KLR: dimeric; determined by author
Molecular Components in 2KLR
Label Count Molecule
Proteins (2 molecules)
Alpha-crystallin B Chain(Gene symbol: CRYAB)
Molecule annotation
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Citing MMDB