Prevention of protein denaturation under heat stress by the chaperonin Hsp60.
The increased synthesis of heat shock proteins is a ubiquitous physiological response of cells to environmental stress. How these proteins function in protecting cellular structures is not yet understood. The mitochondrial heat shock protein 60 (Hsp60) has now been shown to form complexes with a variety of polypeptides in organelles exposed to heat stress. The Hsp60 was required to prevent the thermal inactivation in vivo of native dihydrofolate reductase (DHFR) imported into mitochondria. In vitro, Hsp60 bound to DHFR in the course of thermal denaturation, preventing its aggregation, and mediated its adenosine triphosphate-dependent refolding at increased temperatures. These results suggest a general mechanism by which heat shock proteins of the Hsp60 family stabilize preexisting proteins under stress conditions.
Martin
J
J
Program of Cellular Biochemistry and Biophysics, Rockefeller Research Laboratories, Sloan-Kettering Institute, New York, NY 10021.
Horwich
A L
AL
Hartl
F U
FU
D000255:Adenosine Triphosphate / Q000378:metabolism; D001426:Bacterial Proteins / Q000378:metabolism; D002364:Caseins / Q000378:metabolism; D018835:Chaperonin 10; D018834:Chaperonin 60; D004591:Electrophoresis, Polyacrylamide Gel; D006360:Heat-Shock Proteins / Q000378:metabolism / Q000502:physiology*; D006358:Hot Temperature; D008928:Mitochondria / Q000378:metabolism; D009492:Neurospora crassa / Q000648:ultrastructure; D011489:Protein Denaturation; D017510:Protein Folding; D012441:Saccharomyces cerevisiae / Q000648:ultrastructure; D013762:Tetrahydrofolate Dehydrogenase / Q000737:chemistry / Q000378:metabolism; D013816:Thermodynamics
D001426:Bacterial Proteins; D002364:Caseins; D018835:Chaperonin 10; D018834:Chaperonin 60; D006360:Heat-Shock Proteins; D000255:Adenosine Triphosphate; D013762:Tetrahydrofolate Dehydrogenase