Molecular chaperones cooperate with PIM1 protease in the degradation of misfolded proteins in mitochondria.
ATP dependent proteolytic degradation of misfolded proteins in the mitochondrial matrix is mediated by the PIM1 protease and depends on the molecular chaperone proteins mt-hsp70 and Mdj1p. Chaperone function is essential to maintain misfolded proteins in a soluble state, a prerequisite for their degradation by PIM1 protease. In the absence of functional mt-hsp70 or Mdj1p misfolded proteins either remain associated with mt-hsp70 or form aggregates and thereby are no longer substrates for PIM1 protease. Mdj1p is shown to regulate the ATP dependent association of an unfolded polypeptide chain with mt-hsp70 affecting binding to as well as release from mt-hsp70. These findings establish a central role of molecular chaperone proteins in the degradation of misfolded proteins by PIM1 protease and thereby demonstrate a functional interrelation between components of the folding machinery and the proteolytic system within mitochondria.
Institut für Physiologische Chemie, Universität München, Germany.
I
I
Wagner
H
H
Arlt
L
L
van Dyck
T
T
Langer
W
W
Neupert
D049069:ATP-Dependent Proteases; D000255:Adenosine Triphosphate / Q000378:metabolism; D050956:HSP40 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D007770:L-Lactate Dehydrogenase / Q000235:genetics / Q000378:metabolism; D042844:L-Lactate Dehydrogenase (Cytochrome); D007768:Lactalbumin / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism*; D024101:Mitochondrial Proteins; D018832:Molecular Chaperones / Q000378:metabolism*; D017510:Protein Folding; D021382:Protein Sorting Signals / Q000235:genetics / Q000378:metabolism; D006180:Proton-Translocating ATPases / Q000235:genetics / Q000378:metabolism; D015800:Protozoan Proteins; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid; D012697:Serine Endopeptidases / Q000235:genetics / Q000378:metabolism*; D013762:Tetrahydrofolate Dehydrogenase / Q000235:genetics / Q000378:metabolism
D050956:HSP40 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; C087041:MDJ1 protein, S cerevisiae; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D018832:Molecular Chaperones; D021382:Protein Sorting Signals; D015800:Protozoan Proteins; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; C061945:mtp70 protein, Trypanosoma cruzi; D000255:Adenosine Triphosphate; D007768:Lactalbumin; D007770:L-Lactate Dehydrogenase; D042844:L-Lactate Dehydrogenase (Cytochrome); D013762:Tetrahydrofolate Dehydrogenase; D049069:ATP-Dependent Proteases; C085155:PIM1 protein, S cerevisiae; D012697:Serine Endopeptidases; D006180:Proton-Translocating ATPases