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Free keywords:
Bacterial Proteins
Carrier Proteins/physiology
Fungal Proteins/genetics/*physiology
HSP40 Heat-Shock Proteins
HSP70 Heat-Shock Proteins/genetics/*physiology
Heat-Shock Proteins/genetics/*physiology
Heat-Shock Response/*physiology
Luciferases/metabolism
Membrane Proteins/genetics/*physiology
*Membrane Transport Proteins
Mitochondria/physiology
Mitochondrial Membrane Transport Proteins
Molecular Chaperones
Mutation
Saccharomyces cerevisiae/*physiology
*Saccharomyces cerevisiae Proteins
Abstract:
The role of the mitochondrial Hsp70 system in the prevention of heat-induced protein aggregation was studied in isolated mitochondria from Saccharomyces cerevisiae. Firefly luciferase was employed as a thermolabile tester protein. After shift to 40 degrees Celsius transient increase of mt-Hsp70/luciferase complex was observed, which required functional Mdj1p and Mge1p, the mitochondrial homologues of DnaJ and GrpE. The kinetics of luciferase aggregation, however, were not influenced by mutations in either mt-Hsp70 or Mge1p. Only the absence of Mdj1p led to enhanced protein aggregation. Thus, a central role in the transient protection against heat stress is attributed to this mitochondrial DnaJ homologue.
