The AAA-ATPase p97 is essential for outer mitochondrial membrane protein turnover.
Recent studies have revealed a role for the ubiquitin/proteasome system in the regulation and turnover of outer mitochondrial membrane (OMM)-associated proteins. Although several molecular components required for this process have been identified, the mechanism of proteasome-dependent degradation of OMM-associated proteins is currently unclear. We show that an AAA-ATPase, p97, is required for the proteasomal degradation of Mcl1 and Mfn1, two unrelated OMM proteins with short half-lives. A number of biochemical assays, as well as imaging of changes in localization of photoactivable GFP-fused Mcl1, revealed that p97 regulates the retrotranslocation of Mcl1 from mitochondria to the cytosol, prior to, or concurrent with, proteasomal degradation. Mcl1 retrotranslocation from the OMM depends on the activity of the ATPase domain of p97. Furthermore, p97-mediated retrotranslocation of Mcl1 can be recapitulated in vitro, confirming a direct mitochondrial role for p97. Our results establish p97 as a novel and essential component of the OMM-associated protein degradation pathway.
Center for Biomedical Engineering and Technology, University of Maryland, Baltimore, MD 21201, USA.
Shan
S
Xu
Guihong
G
Peng
Yang
Y
Wang
Shengyun
S
Fang
Mariusz
M
Karbowski
D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000502:physiology*; D003600:Cytosol / Q000378:metabolism; D020558:GTP Phosphohydrolases / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000032:analysis; D006367:HeLa Cells; D006801:Humans; D026901:Membrane Transport Proteins / Q000378:metabolism; D033681:Mitochondrial Membrane Transport Proteins; D051336:Mitochondrial Membranes / Q000378:metabolism*; D024101:Mitochondrial Proteins / Q000378:metabolism; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D009687:Nuclear Proteins / Q000737:chemistry / Q000502:physiology*; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism / Q000502:physiology; D055550:Protein Stability; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000032:analysis / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000032:analysis
D026901:Membrane Transport Proteins; D033681:Mitochondrial Membrane Transport Proteins; D024101:Mitochondrial Proteins; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D009687:Nuclear Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D046988:Proteasome Endopeptidase Complex; D000251:Adenosine Triphosphatases; D020558:GTP Phosphohydrolases; C404942:p97 ATPase; C470017:Mfn1 protein, human