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Mouse Hsp25, a small heat shock protein. The role of its C-terminal extension in oligomerization and chaperone action

Item Type:Article
Title:Mouse Hsp25, a small heat shock protein. The role of its C-terminal extension in oligomerization and chaperone action
Creators Name:Lindner, R.A. and Carver, J.A. and Ehrnsperger, M. and Buchner, J. and Esposito, G. and Behlke, J. and Lutsch, G. and Kotlyarov, A. and Gaestel, M.
Abstract:Under conditions of cellular stress, small heat shock proteins (sHsps), e.g. Hsp25, stabilize unfolding proteins and prevent their precipitation from solution. 1H NMR spectroscopy has shown that mammalian sHsps possess short, polar anti highly flexible C-terminal extensions. A mutant of mouse Hsp25 without this extension has been constructed. CD spectroscopy reveals some differences in secondary and tertiary structure between this mutant and the wild-type protein but analytical ultracentrifugation and electron microscopy show that the proteins have very similar oligomeric masses and quaternary structures. The mutant shows chaperone ability comparable to that of wild- type Hsp25 in a thermal aggregation assay using citrate synthase, but does not stabilize α-lactalbumin against precipitation following reduction with dithiothreitol. The accessible hydrophobic surface of the mutant protein is less than that of the wild-type protein and the mutant is also less stable at elevated temperature. 1H NMR spectroscopy reveals that deletion of the C- terminal extension of Hsp25 leads to induction of extra C-terminal flexibility in the molecule. Monitoring complex formation between Hsp25 and dithiothreitol-reduced α-lactalbumin by 1H NMR spectroscopy indicates that the C-terminal extension of Hsp25 retains its flexibility during this interaction. Overall, these data suggest that a highly flexible C-terminal extension in mammalian sHsps is required for full chaperone activity.
Keywords:Flexibility, Hsp25, Molecular Chaperone, Small Heat Shock Protein, Spectroscopy, Animals
Source:European Journal of Biochemistry
Publisher:Blackwell Publishing
Page Range:1923-1932
Date:1 April 2000
Official Publication:https://doi.org/10.1046/j.1432-1327.2000.01188.x
PubMed:View item in PubMed

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