Abstract
β barrel outer membrane proteins (β-OMPs) play vital roles in mitochondria, chloroplasts, and Gram-negative bacteria. Evolutionarily conserved complexes such as the mitochondrial sorting and assembly machinery (SAM) mediate the assembly of β-OMPs. We investigated the SAM-mediated assembly of the translocase of the outer membrane (TOM) core complex. Cryo–electron microscopy structures of SAM–fully folded Tom40 and the SAM-Tom40/Tom5/Tom6 complexes at ~3-angstrom resolution reveal that Sam37 stabilizes the mature Tom40 mainly through electrostatic interactions, thus facilitating subsequent TOM assembly. These results support the β barrel switching model and provide structural insights into the assembly and release of β barrel complexes.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Carrier Proteins / chemistry*
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Carrier Proteins / metabolism*
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Cell Line
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Cryoelectron Microscopy
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Humans
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Membrane Proteins / chemistry
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Membrane Proteins / metabolism
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Mitochondrial Membrane Transport Proteins / chemistry*
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Mitochondrial Membrane Transport Proteins / metabolism*
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Mitochondrial Membranes / metabolism*
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Mitochondrial Precursor Protein Import Complex Proteins
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Models, Molecular
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Multiprotein Complexes / chemistry*
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Multiprotein Complexes / metabolism*
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Protein Conformation
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Protein Folding
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Protein Structure, Secondary
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Protein Subunits / chemistry
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Protein Subunits / metabolism
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Protein Transport
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Saccharomyces cerevisiae Proteins / chemistry
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Saccharomyces cerevisiae Proteins / metabolism
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Static Electricity
Substances
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Carrier Proteins
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Membrane Proteins
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Mitochondrial Membrane Transport Proteins
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Mitochondrial Precursor Protein Import Complex Proteins
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Multiprotein Complexes
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Protein Subunits
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SAM37 protein, S cerevisiae
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Saccharomyces cerevisiae Proteins
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Tom40 protein, S cerevisiae