Tom22 is a multifunctional organizer of the mitochondrial preprotein translocase.
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.
van Wilpe
S
S
Institute for Molecular Cell Biology, BioCentrum Amsterdam, The Netherlands.
Ryan
M T
MT
Hill
K
K
Maarse
A C
AC
Meisinger
C
C
Brix
J
J
Dekker
P J
PJ
Moczko
M
M
Wagner
R
R
Meijer
M
M
Guiard
B
B
Hönlinger
A
A
Pfanner
N
N
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
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