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

Area of Science:

• Plant molecular biology
• Biochemistry
• Stress physiology

Background:

• Heat shock proteins (HSPs) like Hsp70 are crucial for cellular stress response, primarily known for high-temperature adaptation.
• The role of Hsp70 in low-temperature stress tolerance in plants remains less understood.

Purpose of the Study:

• To investigate the molecular chaperone function of Hsc70 (a type of Hsp70) in plants under cold stress conditions.
• To explore the interaction of Hsc70 with other proteins at low temperatures.

Main Methods:

• Subcloning and bacterial expression of a cold-inducible spinach cytosolic Hsc70.
• In vitro binding assays using recombinant Hsc70 and an unfolded substrate (CMLA) at low temperatures (4°C and -4°C).
• Radiolabeling and immunoprecipitation techniques to identify co-purified proteins.

Main Results:

• Recombinant Hsc70 demonstrated binding to the unfolded substrate CMLA at low temperatures in the presence of ATP and MgCl(2).
• Several proteins were co-immunoprecipitated with Hsc70 at low temperatures but not at room temperature.
• Increased co-purification of sHsp17.7 with Hsc70 at low temperatures was observed, suggesting co-chaperone involvement.

Conclusions:

• The molecular chaperone Hsc70 exhibits functional activity at low temperatures in vitro.
• Co-chaperone interactions, such as with sHsp17.7, may contribute to Hsc70's role in cold stress response.
• Hsc70 likely plays a functional role in plant adaptation to low-temperature stress.