Mitochondrial heat shock protein 70, a molecular chaperone for proteins encoded by mitochondrial DNA

J Cell Biol. 1994 Nov;127(4):893-902. doi: 10.1083/jcb.127.4.893.


Mitochondrial heat shock protein 70 (mt-Hsp70) has been shown to play an important role in facilitating import into, as well as folding and assembly of nuclear-encoded proteins in the mitochondrial matrix. Here, we describe a role for mt-Hsp70 in chaperoning proteins encoded by mitochondrial DNA and synthesized within mitochondria. The availability of mt-Hsp70 function influences the pattern of proteins synthesized in mitochondria of yeast both in vivo and in vitro. In particular, we show that mt-Hsp70 acts in maintaining the var1 protein, the only mitochondrially encoded subunit of mitochondrial ribosomes, in an assembly competent state, especially under heat stress conditions. Furthermore, mt-Hsp70 helps to facilitate assembly of mitochondrially encoded subunits of the ATP synthase complex. By interacting with the ATP-ase 9 oligomer, mt-Hsp70 promotes assembly of ATP-ase 6, and thereby protects the latter protein from proteolytic degradation. Thus mt-Hsp70 by acting as a chaperone for proteins encoded by the mitochondrial DNA, has a critical role in the assembly of supra-molecular complexes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • DNA, Mitochondrial / metabolism*
  • Fungal Proteins / biosynthesis*
  • Fungal Proteins / isolation & purification
  • HSP70 Heat-Shock Proteins / biosynthesis*
  • HSP70 Heat-Shock Proteins / isolation & purification
  • HSP70 Heat-Shock Proteins / metabolism
  • Macromolecular Substances
  • Mitochondria / metabolism*
  • Models, Biological
  • Protein Biosynthesis
  • Protein Processing, Post-Translational
  • Proton-Translocating ATPases / biosynthesis
  • Proton-Translocating ATPases / isolation & purification
  • Ribosomes / metabolism
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / metabolism*
  • Temperature


  • DNA, Mitochondrial
  • Fungal Proteins
  • HSP70 Heat-Shock Proteins
  • Macromolecular Substances
  • Proton-Translocating ATPases