Mode of action of the COR15a gene on the freezing tolerance of Arabidopsis thaliana

• DOI: 10.1073/pnas.95.24.14570
• Publication Date: 2002-07-26T14:40:11Z
• Authors: Peter L. Steponkus; Matsuo Uemura; Raymond A. Joseph; Sarah J. Gilmour; Michael F. Thomashow
• Keywords: 0301 basic medicine; Magnetic Resonance Spectroscopy; Arabidopsis Proteins; Acclimatization; Phosphatidylethanolamines; Protoplasts; Arabidopsis; Plant Leaves; 03 medical and health sciences; Gene Expression Regulation, Plant; Freezing; Thermodynamics; Desiccation; Plant Proteins

Constitutive expression of the co ld- r egulated COR15a gene of Arabidopsis thaliana results in a significant increase in the survival of isolated protoplasts frozen over the range of −4.5 to −7°C. The increased freezing tolerance is the result of a decreased incidence of freeze-induced lamellar-to-hexagonal II phase transitions that occur in regions where the plasma membrane is brought into close apposition with the chloroplast envelope as a result of freeze-induced dehydration. Moreover, the mature polypeptide encoded by this gene, COR15am, increases the lamellar-to-hexagonal II phase transition temperature of dioleoylphosphatidylethanolamine and promotes formation of the lamellar phase in a lipid mixture composed of the major lipid species that comprise the chloroplast envelope. We propose that COR15am, which is located in the chloroplast stroma, defers freeze-induced formation of the hexagonal II phase to lower temperatures (lower hydrations) by altering the intrinsic curvature of the inner membrane of the chloroplast envelope.