4jut

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Crystal structure of a mutant fragment of Human HSPB6Crystal structure of a mutant fragment of Human HSPB6

Structural highlights

4jut is a 8 chain structure with sequence from Homo sapiens. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:X-ray diffraction, Resolution 2.196Å
Ligands:
Resources:FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

HSPB6_HUMAN

Publication Abstract from PubMed

ATP-independent small heat-shock proteins (sHSPs) are an essential component of the cellular chaperoning machinery. Under both normal and stress conditions, sHSPs bind partially unfolded proteins and prevent their irreversible aggregation. Canonical vertebrate sHSPs, such as the alpha-crystallins, form large polydisperse oligomers from which smaller, functionally active subspecies dissociate. Here we focus on human HSPB6 which, despite having considerable homology to the alpha-crystallins in both the N-terminal region and the signature alpha-crystallin domain (ACD), only forms dimers in solution that represent the basic chaperoning subspecies. We addressed the three-dimensional structure and functional properties of HSPB6 in a hybrid study employing X-ray crystallography, solution small-angle X-ray scattering (SAXS), mutagenesis, size-exclusion chromatography and chaperoning assays. The crystal structure of a proteolytically stable fragment reveals typical ACD dimers which further form tetrameric assemblies as a result of extensive inter-dimer patching of the beta4/beta8 grooves. The patching is surprisingly mediated by tripeptide motifs, found in the N-terminal domain directly adjacent to the ACD, that are resembling but distinct from the canonical IxI sequence commonly binding this groove. By combining the crystal structure with SAXS data for the full-length protein, we derive a molecular model of the latter. In solution, HSPB6 shows a strong attractive self-interaction, a property that correlates with its chaperoning activity. Both properties are dictated by the unstructured yet compact N-terminal domain, specifically a region highly conserved across vertebrate sHSPs.

Molecular structure and dynamics of the dimeric human small heat shock protein HSPB6.,Weeks SD, Baranova EV, Heirbaut M, Beelen S, Shkumatov AV, Gusev NB, Strelkov SV J Struct Biol. 2013 Dec 29. pii: S1047-8477(13)00336-5. doi:, 10.1016/j.jsb.2013.12.009. PMID:24382496[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

See Also

References

  1. Weeks SD, Baranova EV, Heirbaut M, Beelen S, Shkumatov AV, Gusev NB, Strelkov SV. Molecular structure and dynamics of the dimeric human small heat shock protein HSPB6. J Struct Biol. 2013 Dec 29. pii: S1047-8477(13)00336-5. doi:, 10.1016/j.jsb.2013.12.009. PMID:24382496 doi:http://dx.doi.org/10.1016/j.jsb.2013.12.009

4jut, resolution 2.20Å

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OCA