Tom22 is a multifunctional organizer of the mitochondrial preprotein translocase

• Published in: Nature (London) Vol. 401; no. 6752; pp. 485 - 489
• Main Authors: Pfanner, Nikolaus, van Wilpe, Sandra, Ryan, Michael T, Hill, Kerstin, Maarse, Ammy C, Meisinger, Chris, Brix, Jan, Dekker, Peter J. T, Moczko, Martin, Wagner, Richard, Meijer, Michiel, Guiard, Bernard, Hönlinger, Angelika
• Format: Journal Article
• Language: English
• Published: London Nature Publishing 30-09-1999; Nature Publishing Group
• Subjects: Biological and medical sciences; Biological Transport; Carrier Proteins - genetics; Carrier Proteins - metabolism; Carrier Proteins - physiology; Cellular biology; Channels; Classical genetics, quantitative genetics, hybrids; Docking; Electrophysiology; Fundamental and applied biological sciences. Psychology; Fungal Proteins - genetics; Fungal Proteins - metabolism; Fungal Proteins - physiology; Gating and risering; Gene Deletion; Genetics of eukaryotes. Biological and molecular evolution; Imports; Intracellular Membranes - metabolism; Ion Channels - metabolism; Membrane Proteins - genetics; Membrane Proteins - metabolism; Membrane Proteins - physiology; Membrane Transport Proteins; Membranes; Mitochondria - metabolism; Mitochondrial ADP, ATP Translocases - genetics; Mitochondrial ADP, ATP Translocases - metabolism; Mitochondrial Membrane Transport Proteins; Polymerase Chain Reaction; Porosity; Protein Binding; Protein Precursors - metabolism; Proteins; Receptors; Receptors, Cell Surface; Receptors, Cytoplasmic and Nuclear - metabolism; Recombinant Fusion Proteins - genetics; Recombinant Fusion Proteins - metabolism; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - physiology; Saccharomyces cerevisiae Proteins; Spores, Fungal; Tetrahydrofolate Dehydrogenase - genetics; Tetrahydrofolate Dehydrogenase - metabolism; Thallophyta, bryophyta; Vegetals; Yeast; Yeasts; Translocation; Intracellular transport; Yeast; Electrophysiology; Molecular interaction; Protein; Fungi; Mitochondria; Gene; Ascomycetes; Mutation; Saccharomyces cerevisiae; Thallophyta; Biological receptor
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/46802

Mitochondrial preproteins are imported by a multisubunit translocase of the outer membrane (TOM), including receptor proteins and a general import pore. The central receptor Tom22 binds preproteins through both its cytosolic domain and its intermembrane space domain and is stably associated with the channel protein Tom40 (refs 11,12,13). Here we report the unexpected observation that a yeast strain can survive without Tom22, although it is strongly reduced in growth and the import of mitochondrial proteins. Tom22 is a multifunctional protein that is required for the higher-level organization of the TOM machinery. In the absence of Tom22, the translocase dissociates into core complexes, representing the basic import units, but lacks a tight control of channel gating. The single membrane anchor of Tom22 is required for a stable interaction between the core complexes, whereas its cytosolic domain serves as docking point for the peripheral receptors Tom20 and Tom70. Thus a preprotein translocase can combine receptor functions with distinct organizing roles in a multidomain protein.