Dynamic interaction between Isp45 and mitochondrial hsp70 in the protein import system of the yeast mitochondrial inner membrane.
- 20 December 1994
- journal article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences
- Vol. 91 (26), 12818-12822
- https://doi.org/10.1073/pnas.91.26.12818
Abstract
The protein import system of the yeast mitochondrial inner membrane includes at least three membrane proteins that presumably form a transmembrane channel as well as several chaperone proteins that mediate the import and refolding of precursor proteins. We show that one of the membrane proteins, Isp45, spans the mitochondrial inner membrane yet is extracted from this membrane at high pH. Solubilization of mitochondria with a nonionic detergent releases Isp45 as a complex with the chaperones mitochondrial hsp70 (mhsp70) and GrpEp. Both chaperones reversibly dissociate from Isp45 upon addition of ATP or adenosine 5'-[gamma-thio]triphosphate, suggesting that dissociation requires the binding of ATP. Control experiments indicate that the interaction between mhsp70 and Isp45 occurs in the intact mitochondria. We propose that Isp45 lines the inside of a proteinaceous channel across the inner membrane and that it is the membrane anchor for an ATP-driven "import motor" composed of mhsp70 and GrpEp. This arrangement is reminiscent of the protein transport systems of the yeast endoplasmic reticulum and the bacterial plasma membrane.Keywords
This publication has 15 references indexed in Scilit:
- Mitochondrial Hsp70/MIM44 complex facilitates protein importNature, 1994
- Mdj1p, a novel chaperone of the DnaJ family, is involved in mitochondrial biogenesis and protein foldingCell, 1994
- The essential yeast protein MIM44 (encoded by MPI1) is involved in an early step of preprotein translocation across the mitochondrial inner membrane.Molecular and Cellular Biology, 1993
- Protein import into mitochondria: a paradigm for the translocation of polypeptides across membranesCurrent Opinion in Cell Biology, 1993
- Identification of a 45-kDa protein at the protein import site of the yeast mitochondrial inner membrane.Proceedings of the National Academy of Sciences, 1992
- Cytochromes c1 and b2 are sorted to the intermembrane space of yeast mitochondria by a stop-transfer mechanismCell, 1992
- Protein import into mitochondria: two systems acting in tandem?Trends in Cell Biology, 1991
- FK 506-binding protein proline rotamase is a target for the immunosuppressive agent FK 506 in Saccharomyces cerevisiae.Proceedings of the National Academy of Sciences, 1991
- Chapter 20 Protein Import into Isolated Yeast MitochondriaMethods in Cell Biology, 1991
- Requirement for hsp70 in the mitochondrial matrix for translocation and folding of precursor proteinsNature, 1990