Synergism between the chaperone-like activity of the stress regulated ASR1 protein and the osmolyte glycine-betaine.
Abiotic stress may result in protein denaturation. To confront protein inactivation, plants activate protective mechanisms that include chaperones and chaperone-like proteins, and low-molecular weight organic molecules, known as osmolytes or compatible solutes. If these protective processes fail, the irreversibly damaged proteins are targeted for degradation. Tomato ASR1 (SlASR1) is encoded by a plant-specific gene. Steady state levels of transcripts and protein are transiently induced by salt and water stress in an ABA-dependent manner. SlASR1 is localized in both the cytosol as unstructured monomers and in the nucleus as structured DNA-bound dimers. We show here that the unstructured form of SlASR1 has chaperone-like activity and can stabilize a number of proteins against denaturation caused by heat and freeze-thaw cycles. The protective activity of SlASR1 is synergistic with that of the osmolyte glycine-betaine, which accumulates under stress conditions. We suggest that the cytosolic pool of ASR1 protects proteins from denaturation.
Konrad
Zvia
Z
Department of Life Sciences, Ben-Gurion University of the Negev, 84105, Beer-Sheva, Israel.
Bar-Zvi
Dudy
D
D000040:Abscisic Acid / Q000494:pharmacology; D001622:Betaine / Q000494:pharmacology*; D004357:Drug Synergism; D006360:Heat-Shock Proteins / Q000502:physiology; D007700:Kinetics; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D018551:Solanum lycopersicum / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D018832:Molecular Chaperones / Q000502:physiology*; D010940:Plant Proteins / Q000235:genetics / Q000502:physiology*; D013053:Spectrophotometry
C091853:Asr1 protein, Lycopersicon esculentum; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; D010940:Plant Proteins; D001622:Betaine; D000040:Abscisic Acid; D007770:L-Lactate Dehydrogenase