In vitro evidence of Hsc70 functioning as a molecular chaperone during cold stress.

C Zhang, C L Guy

Plant Molecular and Cellular Biology Program, University of Florida, Gainesville, FL 32610, USA. chunz@ufl.edu

Plant physiology and biochemistry : PPB / Société française de physiologie végétale 2006 Nov-Dec

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Hsp70 molecular chaperones have been shown to play an important role in helping cells to cope with adverse environments, especially in response to high temperatures. The molecular chaperone function of Hsc70 at low temperature was investigated. A cold-inducible spinach cytosolic Hsc70 was subcloned into a protein expression vector and the recombinant protein was expressed in bacterial cells. Recombinant Hsc70 bound a permanently unfolded substrate: alpha-carboxymethylated lactalbumin (CMLA) in the presence of 3 mM ATP and MgCl(2) at low temperature (4 and -4 degrees C). Radiolabeling with (35)S-Met and (35)S-Cys and immunoprecipitation with cytosolic Hsc70 monoclonal antibodies showed that there were several proteins co-immunoprecipitated at low temperature (4 and -4 degrees C) but not at room temperature. Enhanced co-purification of sHsp17.7 with Hsc70 at low temperature was observed and suggests that co-chaperone interactions can contribute to molecular chaperone function during cold stress. These results suggest that the molecular chaperone Hsc70 may have a functional role in plants during low temperature stress.

Citation

C Zhang, C L Guy. In vitro evidence of Hsc70 functioning as a molecular chaperone during cold stress. Plant physiology and biochemistry : PPB / Société française de physiologie végétale. 2006 Nov-Dec;44(11-12):844-50