title: Characterization of the targeting signal in mitochondrial β-barrel proteins.
abstract: Mitochondrial β-barrel proteins are synthesized on cytosolic ribosomes and must be specifically targeted to the organelle before their integration into the mitochondrial outer membrane. The signal that assures such precise targeting and its recognition by the organelle remained obscure. In the present study we show that a specialized β-hairpin motif is this long searched for signal. We demonstrate that a synthetic β-hairpin peptide competes with the import of mitochondrial β-barrel proteins and that proteins harbouring a β-hairpin peptide fused to passenger domains are targeted to mitochondria. Furthermore, a β-hairpin motif from mitochondrial proteins targets chloroplast β-barrel proteins to mitochondria. The mitochondrial targeting depends on the hydrophobicity of the β-hairpin motif. Finally, this motif interacts with the mitochondrial import receptor Tom20. Collectively, we reveal that β-barrel proteins are targeted to mitochondria by a dedicated β-hairpin element, and this motif is recognized at the organelle surface by the outer membrane translocase.
authors.affiliation: Interfaculty Institute of Biochemistry, University of Tuebingen, Hoppe-Seyler-Str. 4, 72076 Tuebingen, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Jores
authors.affiliation: Molecular Cell Biology of Plants, Goethe University, Max-von-Laue-Str. 9, 60438 Frankfurt, Germany.
authors.forename: Anna
authors.initials: A
authors.lastname: Klinger
authors.affiliation: Molecular Cell Biology of Plants, Goethe University, Max-von-Laue-Str. 9, 60438 Frankfurt, Germany.
authors.forename: Lucia E
authors.initials: LE
authors.lastname: Groß
authors.affiliation: Faculty of Life Sciences, Kyoto Sangyo University, Kyoto 603-8555, Japan.
authors.forename: Shin
authors.initials: S
authors.lastname: Kawano
authors.affiliation: Molecular Cell Biology of Plants, Goethe University, Max-von-Laue-Str. 9, 60438 Frankfurt, Germany.
authors.forename: Nadine
authors.initials: N
authors.lastname: Flinner
authors.affiliation: Institute for Molecular Biosciences, Center for Biomolecular Magnetic Resonance, Goethe University, Max-von-Laue Str. 9, 60438 Frankfurt, Germany.
authors.forename: Elke
authors.initials: E
authors.lastname: Duchardt-Ferner
authors.affiliation: Institute for Molecular Biosciences, Center for Biomolecular Magnetic Resonance, Goethe University, Max-von-Laue Str. 9, 60438 Frankfurt, Germany.
authors.forename: Jens
authors.initials: J
authors.lastname: Wöhnert
authors.affiliation: Interfaculty Institute of Biochemistry, University of Tuebingen, Hoppe-Seyler-Str. 4, 72076 Tuebingen, Germany.
authors.forename: Hubert
authors.initials: H
authors.lastname: Kalbacher
authors.affiliation: Faculty of Life Sciences, Kyoto Sangyo University, Kyoto 603-8555, Japan.
authors.forename: Toshiya
authors.initials: T
authors.lastname: Endo
authors.affiliation: Molecular Cell Biology of Plants, Goethe University, Max-von-Laue-Str. 9, 60438 Frankfurt, Germany.|Cluster of Excellence Frankfurt, Goethe University, Max-von-Laue Str. 9, 60438 Frankfurt, Germany.|Buchmann Institute for Molecular Life Sciences, Goethe University, Max-von-Laue Str. 9, 60438 Frankfurt, Germany.
authors.forename: Enrico
authors.initials: E
authors.lastname: Schleiff
authors.affiliation: Interfaculty Institute of Biochemistry, University of Tuebingen, Hoppe-Seyler-Str. 4, 72076 Tuebingen, Germany.
authors.forename: Doron
authors.initials: D
authors.lastname: Rapaport
mesh_terms: D020816:Amino Acid Motifs; D017360:Arabidopsis; D051336:Mitochondrial Membranes / Q000378:metabolism*; D024101:Mitochondrial Proteins / Q000737:chemistry* / Q000502:physiology; D008958:Models, Molecular; D011487:Protein Conformation; D021382:Protein Sorting Signals / Q000502:physiology*; D021381:Protein Transport / Q000502:physiology*; D011523:Protoplasts; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D024101:Mitochondrial Proteins; D021382:Protein Sorting Signals; D029701:Saccharomyces cerevisiae Proteins