Mitochondrial protein import: biochemical and genetic evidence for interaction of matrix hsp70 and the inner membrane protein MIM44
| Autor: | E A Craig, A C Maarse, Joachim Rassow, E Krainer, Hanne Müller, M Kübrich, Nikolaus Pfanner, M Meijer |
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| Přispěvatelé: | Molecular Biology and Microbial Food Safety (SILS, FNWI) |
| Rok vydání: | 1994 |
| Předmět: |
Vesicle-associated membrane protein 8
Saccharomyces cerevisiae Proteins Molecular Sequence Data Saccharomyces cerevisiae Plasma protein binding Mitochondrial Membrane Transport Proteins Fungal Proteins Mitochondrial membrane transport protein Adenosine Triphosphate Suppression Genetic Mitochondrial Precursor Protein Import Complex Proteins Inner membrane HSP70 Heat-Shock Proteins Amino Acid Sequence Protein Precursors Heat-Shock Proteins Fungal protein biology Membrane transport protein Membrane Proteins Membrane Transport Proteins Biological Transport Articles Cell Biology HSP40 Heat-Shock Proteins Precipitin Tests Cell Compartmentation Mitochondria Cell biology Cross-Linking Reagents Membrane protein Biochemistry Mutation Translocase of the inner membrane biology.protein Carrier Proteins Protein Binding |
| Zdroj: | The Journal of Cell Biology Journal of Cell Biology, 127, 1547-1556. Rockefeller University Press |
| ISSN: | 1540-8140 0021-9525 |
| DOI: | 10.1083/jcb.127.6.1547 |
| Popis: | The import of preproteins into mitochondria involves translocation of the polypeptide chains through putative channels in the outer and inner membranes. Preprotein-binding proteins are needed to drive the unidirectional translocation of the precursor polypeptides. Two of these preprotein-binding proteins are the peripheral inner membrane protein MIM44 and the matrix heat shock protein hsp70. We report here that MIM44 is mainly exposed on the matrix side, and a fraction of mt-hsp70 is reversibly bound to the inner membrane. Mt-hsp70 binds to MIM44 in a 1:1 ratio, suggesting that mt-hsp70 is localizing to the membrane via its interaction with MIM44. Formation of the complex requires a functional ATPase domain of mt-hsp70. Addition of Mg-ATP leads to dissociation of the complex. Overexpression of mt-hsp70 rescues the protein import defect of mutants in MIM44; conversely, overexpression of MIM44 rescues protein import defects of mt-hsp70 mutants. In addition, yeast strains with conditional mutations in both MIM44 and mt-hsp70 are barely viable, showing a synthetic growth defect compared to strains carrying single mutations. We propose that MIM44 and mt-hsp70 cooperate in translocation of preproteins. By binding to MIM44, mt-hsp70 is recruited at the protein import sites of the inner membrane, and preproteins arriving at MIM44 may be directly handed over to mt-hsp70. |
| Databáze: | OpenAIRE |
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