3guf

Crystal Structure of the hspA from Xanthomonas axonopodis

spinqualitylabelsall models 3guf, resolution 2.28Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3guf is a 2 chain structure with sequence from Xanthomonas citri. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.28Å Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function Q8PNC2_XANAC Publication Abstract from PubMed Small heat shock proteins (sHsps) are ubiquitous low-molecular-weight chaperones that prevent protein aggregation under cellular stresses. sHsps contain a structurally conserved alpha-crystallin domain (ACD) of about 100 amino acid residues flanked by varied N- and C-terminal extensions and usually exist as oligomers. Oligomerization is important for the biological functions of most sHsps. However, the active oligomeric states of sHsps are not defined yet. We present here crystal structures (up to 1.65 A resolution) of the sHspA from the plant pathogen Xanthomonas (XaHspA). XaHspA forms closed or open trimers of dimers (hexamers) in crystals but exists predominantly as 36mers in solution as estimated by size-exclusion chromatography. The XaHspA monomer structures mainly consist of alpha-crystallin domain with disordered N- and C-terminal extensions, indicating that the extensions are flexible and not essential for the formation of dimers and 36mers. Under reducing conditions where alpha-lactalbumin (LA) unfolds and aggregates, XaHspA 36mers formed complexes with one LA per XaHspA dimer. Based on XaHspA dimer-dimer interactions observed in crystals, we propose that XaHspA 36mers have four possible conformations, but only XaHspA 36merB, which is formed by open hexamers in 12mer-6mer-6mer-12mer with protruding dimers accessible for substrate (unfolding protein) binding, can bind to 18 reduced LA molecules. Together, our results unravel the structural basis of an active sHsp oligomer. Crystal structures of Xanthomonas small heat shock protein provide a structural basis for an active molecular chaperone oligomer.,Hilario E, Martin FJ, Bertolini MC, Fan L J Mol Biol. 2011 Apr 22;408(1):74-86. Epub 2011 Feb 15. PMID:21315085 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Heat Shock Protein structures

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