Structural aspects and chaperone activity of human HspB3: role of the “C-terminal extension”

Asthana, Abhishek ; Raman, Bakthisaran ; Ramakrishna, Tangirala ; Rao, Mohan Ch. (2012) Structural aspects and chaperone activity of human HspB3: role of the “C-terminal extension” Cell Biochemistry and Biophysics, 64 (1). pp. 61-72. ISSN 1085-9195

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Official URL: http://link.springer.com/article/10.1007%2Fs12013-...

Related URL: http://dx.doi.org/10.1007/s12013-012-9366-x

Abstract

HspB3, an as yet uncharacterized sHsp, is present in muscle, brain, heart, and in fetal tissues. A point mutation correlates with the development of axonal motor neuropathy. We purified recombinant human HspB3. Circular dichroism studies indicate that it exhibits β-sheet structure. Gel filtration and sedimentation velocity experiments show that HspB3 exhibits polydisperse populations with predominantly trimeric species. HspB3 exhibits molecular chaperone-like activity in preventing the heat-induced aggregation of alcohol dehydrogenase (ADH). It exhibits moderate chaperone-like activity towards heat-induced aggregation of citrate synthase. However, it does not prevent the DTT-induced aggregation of insulin, indicating that it exhibits target protein-dependent molecular chaperone-like activity. Unlike other sHsps, it has a very short C-terminal extension. Fusion of the C-terminal extension of αB-crystallin results in altered tertiary and quaternary structure, and increase in polydispersity of the chimeric protein, HspB3αB-CT. The chimeric protein shows comparable chaperone-like activity towards heat-induced aggregation of ADH and citrate synthase. However, it shows enhanced activity towards DTT-induced aggregation of insulin. Our study, for the first time, provides the structural and chaperone functional characterization of HspB3 and also sheds light on the role of the C-terminal extension of sHsps.

Item Type:Article
Source:Copyright of this article belongs to Springer-Verlag.
Keywords:Small Heat Shock Proteins; HspB3; Molecular Chaperone; αB-crystallin; C-terminal Extension; Chimeric Protein
ID Code:97910
Deposited On:03 Jan 2014 11:56
Last Modified:03 Jan 2014 11:56

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