ジャーナル: Structure / 年: 2006 タイトル: Multiple distinct assemblies reveal conformational flexibility in the small heat shock protein Hsp26. 著者: Helen E White / Elena V Orlova / Shaoxia Chen / Luchun Wang / Athanasios Ignatiou / Brent Gowen / Thusnelda Stromer / Titus M Franzmann / Martin Haslbeck / Johannes Buchner / Helen R Saibil / 要旨: 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 ...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.
Protocol: Rigid Body. The alpha crystallin domains were fitted manually into a the same region of density observed in the WT maps prior to refinement in URO