The MOM (mitochondrial outer membrane) contains SA (signal-anchored) proteins that bear at their N-terminus a single hydrophobic segment that serves as both a mitochondrial targeting signal and an anchor at the membrane. These proteins, like the vast majority of mitochondrial proteins, are encoded in the nucleus and have to be imported into the organelle. Currently, the mechanisms by which they are targeted to and inserted into the OM (outer membrane) are unclear. To shed light on these issues, we employed a recombinant version of the SA protein OM45 and a synthetic peptide corresponding to its signal-anchor segment. Both forms are associated with isolated mitochondria independently of cytosolic factors. Interaction with mitochondria was diminished when a mutated form of the signal-anchor was employed. We demonstrate that the signal-anchor peptide acquires an α-helical structure in a lipid environment and adopted a TM (transmembrane) topology within artificial lipid bilayers. Moreover, the peptide's affinity to artificial membranes with OM-like lipid composition was much higher than that of membranes with ER (endoplasmic reticulum)-like lipid composition. Collectively, our results suggest that SA proteins are specifically inserted into the MOM by a process that is not dependent on additional proteins, but is rather facilitated by the distinct lipid composition of this membrane.
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Research Article|
February 13 2012
Membrane integration of a mitochondrial signal-anchored protein does not require additional proteinaceous factors
Elisa Merklinger;
Elisa Merklinger
*Interfaculty Institute of Biochemistry, Hoppe-Seyler-Strasse 4, University of Tübingen, 72076 Tübingen, Germany
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Yana Gofman;
Yana Gofman
†Helmholtz-Zentrum, Max-Planck-Strasse 1, 21502 Geesthacht, Germany
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Alexej Kedrov;
Alexej Kedrov
‡Department of Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute and the Zernike Institute for Advanced Materials, University of Groningen, 9747 AG Groningen, The Netherlands
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Arnold J. M. Driessen;
Arnold J. M. Driessen
‡Department of Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute and the Zernike Institute for Advanced Materials, University of Groningen, 9747 AG Groningen, The Netherlands
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Nir Ben-Tal;
Nir Ben-Tal
§Department of Biochemistry and Molecular Biology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
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Yechiel Shai;
Yechiel Shai
¶Department of Biological Chemistry, The Weizmann Institute of Science, Rehovot 76100, Israel
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Doron Rapaport
Doron Rapaport
1
*Interfaculty Institute of Biochemistry, Hoppe-Seyler-Strasse 4, University of Tübingen, 72076 Tübingen, Germany
1To whom correspondence should be addressed (email doron.rapaport@uni-tuebingen.de).
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Publisher: Portland Press Ltd
Received:
July 27 2011
Revision Received:
November 22 2011
Accepted:
December 05 2011
Accepted Manuscript online:
December 05 2011
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© The Authors Journal compilation © 2012 Biochemical Society
2012
Biochem J (2012) 442 (2): 381–389.
Article history
Received:
July 27 2011
Revision Received:
November 22 2011
Accepted:
December 05 2011
Accepted Manuscript online:
December 05 2011
Citation
Elisa Merklinger, Yana Gofman, Alexej Kedrov, Arnold J. M. Driessen, Nir Ben-Tal, Yechiel Shai, Doron Rapaport; Membrane integration of a mitochondrial signal-anchored protein does not require additional proteinaceous factors. Biochem J 1 March 2012; 442 (2): 381–389. doi: https://doi.org/10.1042/BJ20111363
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