title: Tom22 is a multifunctional organizer of the mitochondrial preprotein translocase.
abstract: 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 11-13). 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.
authors.affiliation: Institute for Molecular Cell Biology, BioCentrum Amsterdam, The Netherlands.
authors.forename: S
authors.initials: S
authors.lastname: van Wilpe
authors.forename: M T
authors.initials: MT
authors.lastname: Ryan
authors.forename: K
authors.initials: K
authors.lastname: Hill
authors.forename: A C
authors.initials: AC
authors.lastname: Maarse
authors.forename: C
authors.initials: C
authors.lastname: Meisinger
authors.forename: J
authors.initials: J
authors.lastname: Brix
authors.forename: P J
authors.initials: PJ
authors.lastname: Dekker
authors.forename: M
authors.initials: M
authors.lastname: Moczko
authors.forename: R
authors.initials: R
authors.lastname: Wagner
authors.forename: M
authors.initials: M
authors.lastname: Meijer
authors.forename: B
authors.initials: B
authors.lastname: Guiard
authors.forename: A
authors.initials: A
authors.lastname: Hönlinger
authors.forename: N
authors.initials: N
authors.lastname: Pfanner
mesh_terms: D001692:Biological Transport; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D004594:Electrophysiology; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D017353:Gene Deletion; D007425:Intracellular Membranes / Q000378:metabolism; D007473:Ion Channels / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D026901:Membrane Transport Proteins; D008928:Mitochondria / Q000378:metabolism*; D000226:Mitochondrial ADP, ATP Translocases / Q000235:genetics / Q000378:metabolism; D033681:Mitochondrial Membrane Transport Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D016133:Polymerase Chain Reaction; D011485:Protein Binding; D011498:Protein Precursors / Q000378:metabolism*; D011956:Receptors, Cell Surface; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins; D013172:Spores, Fungal; D013762:Tetrahydrofolate Dehydrogenase / Q000235:genetics / Q000378:metabolism
chemical_list: D002352:Carrier Proteins; D005656:Fungal Proteins; D007473:Ion Channels; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D033681:Mitochondrial Membrane Transport Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D011498:Protein Precursors; D011956:Receptors, Cell Surface; D018160:Receptors, Cytoplasmic and Nuclear; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; C489350:TOM20 protein, S cerevisiae; C090857:TOM22 protein, S cerevisiae; C489039:TOM70 protein, S cerevisiae; D000226:Mitochondrial ADP, ATP Translocases; D013762:Tetrahydrofolate Dehydrogenase