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Characterization of the insertase for ?-barrel proteins of the outer mitochondrial membrane.

ABSTRACT: The TOB-SAM complex is an essential component of the mitochondrial outer membrane that mediates the insertion of ?-barrel precursor proteins into the membrane. We report here its isolation and determine its size, composition, and structural organization. The complex from Neurospora crassa was composed of Tob55-Sam50, Tob38-Sam35, and Tob37-Sam37 in a stoichiometry of 1:1:1 and had a molecular mass of 140 kD. A very minor fraction of the purified complex was associated with one Mdm10 protein. Using molecular homology modeling for Tob55 and cryoelectron microscopy reconstructions of the TOB complex, we present a model of the TOB-SAM complex that integrates biochemical and structural data. We discuss our results and the structural model in the context of a possible mechanism of the TOB insertase.

SUBMITTER: Klein A

PROVIDER: S-EPMC3494861 | biostudies-literature | 2012 Nov

REPOSITORIES: biostudies-literature

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Characterization of the insertase for β-barrel proteins of the outer mitochondrial membrane.

Klein Astrid A Israel Lars L Lackey Sebastian W K SW Nargang Frank E FE Imhof Axel A Baumeister Wolfgang W Neupert Walter W Thomas Dennis R DR

The Journal of cell biology 20121105 4

The TOB-SAM complex is an essential component of the mitochondrial outer membrane that mediates the insertion of β-barrel precursor proteins into the membrane. We report here its isolation and determine its size, composition, and structural organization. The complex from Neurospora crassa was composed of Tob55-Sam50, Tob38-Sam35, and Tob37-Sam37 in a stoichiometry of 1:1:1 and had a molecular mass of 140 kD. A very minor fraction of the purified complex was associated with one Mdm10 protein. Usi ...[more]

PMID: 23128244

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