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KMID : 0368420050480010120
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Journal of Plant Biology
2005 Volume.48 No. 1 p.120 ~ p.120
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Functional mode of NtHSP17.6, a cytosolic small heat-shock protein fromNicotiana tabacum
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Yoon Hae-Jeong
Kim Keun-Pill
Park Soo-Min
Hong Choo-Bong
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Abstract
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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.
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KEYWORD
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in vitro activity, luciferase (Luc), molecular chaperone, small heat-shock protein (sHsp)
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