Functional mode of NtHSP17.6, a cytosolic small heat-shock protein fromNicotiana tabacum

Small heat-shock proteins (sHsps) are ubiquitous stress proteins with molecular chaperone activity. They share characteristic homology with the α-crystallin protein of the mammalian eye lens as well as being ATP-independent in their chaperone activity. We isolated a clone for a cytosolic class I sHs...

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Bibliographic Details
Published in:Journal of plant biology = Singmul Hakhoe chi 2005-03, Vol.48 (1), p.120-127
Main Authors: Yoon, Hae-jeong, Kim, Keun Pill, Park, Soo Min, Hong, Choo Bong
Format: Article
Language:English
Subjects:
Crystallin
Eye lens
Heat shock
Heat shock proteins
Heat stress
Heat tolerance
Homology
Hydrophobicity
Overexpression
Proteins
Stress proteins
Substrates
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Summary:Small heat-shock proteins (sHsps) are ubiquitous stress proteins with molecular chaperone activity. They share characteristic homology with the α-crystallin protein of the mammalian eye lens as well as being ATP-independent in their chaperone activity. We isolated a clone for a cytosolic class I sHsp,NtHSP17.6, fromNicotiana tabacum, and analyzed its functional mode for such activity. Following its transformation intoEscherichia coli and its over-expression, NtHSPI 7.6 was purified and examinedin vitro. This purified NtHSPI 7.6 exhibited typical chaperone activity in a light-scattering test. It was enable to protect a model substrate, firefly luciferase, from heat-induced aggregation. Non-denaturing PAGE showed that NtHSP17.6 formed a dodecamer in its native conformation, and was bound to its substrate under heat stress. A labeling test with bis-ANS indicated that this binding might be linked to newly exposed hydrophobic sites of the NtHSPI 7.6 complexes during heat shock. Based on these data, we suggest that NtHSP17.6 is a molecular chaperone that functions as a dodecamer in a heat-induced manner.
ISSN:1226-9239
1867-0725
DOI:10.1007/BF03030571