Signal for targeting β-barrel proteins to mitochondria identified
June 2016. 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. A team of scientists from the Goethe University Frankfurt and Tuebingen University has solved the puzzle: a specialized β-hairpin motif is this long searched for signal. The team demonstrated 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. This motif also interacts with the mitochondrial import receptor Tom20. This new study, which was published on 27 June 2016 by the journal Nature Communications, reveals 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. Link to publication
Contact:
Enrico Schleiff
Buchmann Institute for Molecular Life Sciences
Institute of Molecular Biosciences
Goethe University Frankfurt, Germany
schleiff(at)bio.uni-frankfurt.de
Full reference:
Jores T, Klinger A, Grosz LE, Kawano S, Flinner N, Duchardt-Ferner E, Wöhnert J, Kalbacher H, Endo T, Schleiff E, Rapaport D (2016) Characterization of the targeting signal in mitochondrial β-barrel proteins. Nat Comm 7, published 27 June 2016, DOI 10.1038/ncomms12036. Link