Abstract
The translocase of the outer mitochondrial membrane (TOM complex) is the general entry site for newly synthesized proteins into mitochondria. This complex is essential for the formation and maintenance of mitochondria. Here, we report on the role of the integral outer membrane protein, Mim1 (mitochondrial import), in the biogenesis of mitochondria. Depletion of Mim1 abrogates assembly of the TOM complex and results in accumulation of Tom40, the principal constituent of the TOM complex, as a low-molecular-mass species. Like all mitochondrial beta-barrel proteins, the precursor of Tom40 is inserted into the outer membrane by the TOB complex. Mim1 is likely to be required for a step after this TOB-complex-mediated insertion. Mim1 is a constituent of neither the TOM complex nor the TOB complex; rather, it seems to be a subunit of another, as yet unidentified, complex. We conclude that Mim1 has a vital and specific function in the assembly of the TOM complex.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Intracellular Membranes / chemistry
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Intracellular Membranes / metabolism*
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Membrane Proteins / chemistry
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Membrane Proteins / genetics
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Membrane Proteins / metabolism*
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Membrane Transport Proteins / metabolism*
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Mitochondria / chemistry*
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Mitochondria / genetics
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Mitochondria / metabolism*
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Mitochondrial Membrane Transport Proteins
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Molecular Sequence Data
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Multiprotein Complexes / chemistry
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Multiprotein Complexes / metabolism
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Protein Binding
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Saccharomyces cerevisiae / cytology*
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Saccharomyces cerevisiae / genetics
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Saccharomyces cerevisiae / metabolism*
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Saccharomyces cerevisiae Proteins / chemistry
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Saccharomyces cerevisiae Proteins / genetics
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Saccharomyces cerevisiae Proteins / metabolism*
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Sequence Alignment
Substances
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MIM1 protein, S cerevisiae
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Membrane Proteins
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Membrane Transport Proteins
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Mitochondrial Membrane Transport Proteins
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Multiprotein Complexes
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Saccharomyces cerevisiae Proteins
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Tom40 protein, S cerevisiae