NMR identification of the Tom20 binding segment in mitochondrial presequences.
Many mitochondrial proteins are synthesized in the cytosol as precursors with N-terminal presequences, and are imported into mitochondria with the aid of translocator protein complexes containing presequence-binding proteins. Tom20, a receptor protein which functions in an early step of the mitochondrial protein import, recognizes presequences with divergent amino acid sequences. Here, we report the identification of the segments involved in binding to Tom20 in mitochondrial presequences. We monitored the chemical shift perturbation of the NMR signals of five different 15N-labeled presequence peptides by the addition of the cytosolic receptor domain of rat or yeast Tom20. The perturbed segments occupy different positions, either near the N terminus or at the C terminus, in the presequences. Spin label experiments revealed that this is not due to different orientations of the presequence peptides bound to Tom20. The results presented here will offer a starting point to perform detailed analyses of Tom20-binding elements by systematic amino acid replacements.
Department of Structural Biology, Biomolecular Engineering Research Institute, Suita, 565-0874, Japan.
T
T
Muto
T
T
Obita
Y
Y
Abe
T
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Shodai
T
T
Endo
D
D
Kohda
D000595:Amino Acid Sequence; D000818:Animals; D009682:Magnetic Resonance Spectroscopy; D008565:Membrane Proteins / Q000378:metabolism*; D026901:Membrane Transport Proteins; D008928:Mitochondria / Q000378:metabolism*; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D021382:Protein Sorting Signals; D021381:Protein Transport; D051381:Rats; D011956:Receptors, Cell Surface; D013113:Spin Labels; D013379:Substrate Specificity; D015003:Yeasts
D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D010446:Peptide Fragments; D021382:Protein Sorting Signals; D011956:Receptors, Cell Surface; D013113:Spin Labels; C489998:Tomm20 protein, rat