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TOM core complex - Cryo-EM Structure of the TOM Core Complex from Neurospora crassa

ABSTRACT: The structure of the TOM-complex from Neurospora crassa was characterized using single particle electron microscopy. In order to unambigously identify and characterize the constituting subunits and exclude the presence of previously uncharacterized subunits, the samples were analyzed using proteolytic digests and LC-MS/MS prior to EM structure determination.

INSTRUMENT(S): LTQ Orbitrap Elite, Q Exactive

ORGANISM(S): Neurospora Crassa

SUBMITTER: Julian Langer

LAB HEAD: Julian Langer

PROVIDER: PXD006827 | Pride | 2017-08-16

REPOSITORIES: Pride

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			Action	DRS
	170403_1349_ThBausewein_120min_FASP.msf	Msf
	170403_1349_ThBausewein_120min_FASP.raw	Raw
	170403_1349_ThBausewein_120min_insolution.msf	Msf
	170403_1349_ThBausewein_120min_insolution.raw	Raw

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Publications

Cryo-EM Structure of the TOM Core Complex from Neurospora crassa.

Bausewein Thomas T Mills Deryck J DJ Langer Julian D JD Nitschke Beate B Nussberger Stephan S Kühlbrandt Werner W

Cell 20170801 4

The TOM complex is the main entry gate for protein precursors from the cytosol into mitochondria. We have determined the structure of the TOM core complex by cryoelectron microscopy (cryo-EM). The complex is a 148 kDa symmetrical dimer of ten membrane protein subunits that create a shallow funnel on the cytoplasmic membrane surface. In the core of the dimer, the β-barrels of the Tom40 pore form two identical preprotein conduits. Each Tom40 pore is surrounded by the transmembrane segments of the ...[more]

PMID: 28802041

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Atomic structure of human TOM core complex.

Project description:The translocase of the outer mitochondrial membrane (TOM) complex is the main entry gate for mitochondrial precursor proteins synthesized on cytosolic ribosomes. Here we report the single-particle cryo-electron microscopy (cryo-EM) structure of the dimeric human TOM core complex (TOM-CC). Two Tom40 β-barrel proteins, connected by two Tom22 receptor subunits and one phospholipid, form the protein-conducting channels. The small Tom proteins Tom5, Tom6, and Tom7 surround the channel and have notable configurations. The distinct electrostatic features of the complex, including the pronounced negative interior and the positive regions at the periphery and center of the dimer on the intermembrane space (IMS) side, provide insight into the preprotein translocation mechanism. Further, two dimeric TOM complexes may associate to form tetramer in the shape of a parallelogram, offering a potential explanation into the unusual structural features of Tom subunits and a new perspective of viewing the import of mitochondrial proteins.

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Spatiotemporal stop-and-go dynamics of the mitochondrial TOM core complex correlates with channel activity.

Project description:Single-molecule studies can reveal phenomena that remain hidden in ensemble measurements. Here we show the correlation between lateral protein diffusion and channel activity of the general protein import pore of mitochondria (TOM-CC) in membranes resting on ultrathin hydrogel films. Using electrode-free optical recordings of ion flux, we find that TOM-CC switches reversibly between three states of ion permeability associated with protein diffusion. While freely diffusing TOM-CC molecules are predominantly in a high permeability state, non-mobile molecules are mostly in an intermediate or low permeability state. We explain this behavior by the mechanical binding of the two protruding Tom22 subunits to the hydrogel and a concomitant combinatorial opening and closing of the two β-barrel pores of TOM-CC. TOM-CC could thus represent a β-barrel membrane protein complex to exhibit membrane state-dependent mechanosensitive properties, mediated by its two Tom22 subunits.

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Reconstituted TOM core complex and Tim9/Tim10 complex of mitochondria are sufficient for translocation of the ADP/ATP carrier across membranes.

Project description:Precursor proteins of the solute carrier family and of channel forming Tim components are imported into mitochondria in two main steps. First, they are translocated through the TOM complex in the outer membrane, a process assisted by the Tim9/Tim10 complex. They are passed on to the TIM22 complex, which facilitates their insertion into the inner membrane. In the present study, we have analyzed the function of the Tim9/Tim10 complex in the translocation of substrates across the outer membrane of mitochondria. The purified TOM core complex was reconstituted into lipid vesicles in which purified Tim9/Tim10 complex was entrapped. The precursor of the ADP/ATP carrier (AAC) was found to be translocated across the membrane of such lipid vesicles. Thus, these components are sufficient for translocation of AAC precursor across the outer membrane. Peptide libraries covering various substrate proteins were used to identify segments that are bound by Tim9/Tim10 complex upon translocation through the TOM complex. The patterns of binding sites on the substrate proteins suggest a mechanism by which portions of membrane-spanning segments together with flanking hydrophilic segments are recognized and bound by the Tim9/Tim10 complex as they emerge from the TOM complex into the intermembrane space.

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Non-core subunits of the PRC2 complex are collectively required for its target site specificity

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Structural insights into assembly of human mitochondrial translocase TOM complex.

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Structure of nucleosome-bound human PBAF complex

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