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1.
Cell ; 154(3): 596-608, 2013 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-23911324

RESUMO

The mitochondrial outer membrane harbors two protein translocases that are essential for cell viability: the translocase of the outer mitochondrial membrane (TOM) and the sorting and assembly machinery (SAM). The precursors of ß-barrel proteins use both translocases-TOM for import to the intermembrane space and SAM for export into the outer membrane. It is unknown if the translocases cooperate and where the ß-barrel of newly imported proteins is formed. We established a position-specific assay for monitoring ß-barrel formation in vivo and in organello and demonstrated that the ß-barrel was formed and membrane inserted while the precursor was bound to SAM. ß-barrel formation was inhibited by SAM mutants and, unexpectedly, by mutants of the central import receptor, Tom22. We show that the cytosolic domain of Tom22 links TOM and SAM into a supercomplex, facilitating precursor transfer on the intermembrane space side. Our study reveals receptor-mediated coupling of import and export translocases as a means of precursor channeling.


Assuntos
Mitocôndrias/metabolismo , Proteínas de Transporte da Membrana Mitocondrial/metabolismo , Proteínas Mitocondriais/metabolismo , Transporte Proteico , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/metabolismo , Proteínas de Transporte da Membrana Mitocondrial/genética , Proteínas Mitocondriais/química , Mutação , Porinas/química , Porinas/metabolismo , Dobramento de Proteína , Estrutura Secundária de Proteína , Proteínas de Saccharomyces cerevisiae/química , Proteínas de Saccharomyces cerevisiae/genética
2.
Proc Natl Acad Sci U S A ; 118(33)2021 08 17.
Artigo em Inglês | MEDLINE | ID: mdl-34385311

RESUMO

Death receptor-mediated apoptosis requires the mitochondrial apoptosis pathway in many mammalian cells. In response to death receptor signaling, the truncated BH3-only protein BID can activate the proapoptotic BCL-2 proteins BAX and BAK and trigger the permeabilization of the mitochondria. BAX and BAK are inhibited by prosurvival BCL-2 proteins through retrotranslocation from the mitochondria into the cytosol, but a specific resistance mechanism to truncated BID-dependent apoptosis is unknown. Here, we report that hexokinase 1 and hexokinase 2 inhibit the apoptosis activator truncated BID as well as the effectors BAX and BAK by retrotranslocation from the mitochondria into the cytosol. BCL-2 protein shuttling and protection from TRAIL- and FasL-induced cell death requires mitochondrial hexokinase localization and interactions with the BH3 motifs of BCL-2 proteins but not glucose phosphorylation. Together, our work establishes hexokinase-dependent retrotranslocation of truncated BID as a selective protective mechanism against death receptor-induced apoptosis on the mitochondria.


Assuntos
Apoptose/fisiologia , Hexoquinase/metabolismo , Mitocôndrias/metabolismo , Proteína Killer-Antagonista Homóloga a bcl-2/metabolismo , Proteína X Associada a bcl-2/metabolismo , Antibacterianos/farmacologia , Antibióticos Antineoplásicos/farmacologia , Linhagem Celular , Ciclosporina/farmacologia , Dactinomicina/farmacologia , Doxorrubicina/farmacologia , Inibidores Enzimáticos/farmacologia , Proteína Ligante Fas/farmacologia , Deleção de Genes , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Hexoquinase/genética , Humanos , Ligante Indutor de Apoptose Relacionado a TNF/farmacologia , Proteína Killer-Antagonista Homóloga a bcl-2/genética , Proteína X Associada a bcl-2/genética
3.
J Cell Sci ; 130(17): 2903-2913, 2017 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-28760928

RESUMO

The pro-apoptotic BCL-2 protein BAX commits human cells to apoptosis by permeabilizing the outer mitochondrial membrane. BAX activation has been suggested to require the separation of helix α5 from α6 - the 'latch' from the 'core' domain - among other conformational changes. Here, we show that conformational changes in this region impair BAX translocation to the mitochondria and retrotranslocation back into the cytosol, and therefore BAX inhibition, but not activation. Redirecting misregulated BAX to the mitochondria revealed an alternative mechanism of BAX inhibition. The E3 ligase parkin, which is known to trigger mitochondria-specific autophagy, ubiquitylates BAX K128 and targets the pro-apoptotic BCL-2 protein for proteasomal degradation. Retrotranslocation-deficient BAX is completely degraded in a parkin-dependent manner. Although only a minor pool of endogenous BAX escapes retrotranslocation into the cytosol, parkin-dependent targeting of misregulated BAX on the mitochondria provides substantial protection against BAX apoptotic activity.


Assuntos
Complexo de Endopeptidases do Proteassoma/metabolismo , Proteólise , Ubiquitina-Proteína Ligases/metabolismo , Proteína X Associada a bcl-2/metabolismo , Apoptose , Citoproteção , Células HCT116 , Humanos , Lisina/metabolismo , Mitocôndrias/metabolismo , Estrutura Secundária de Proteína , Transporte Proteico , Ubiquitinação , Proteína X Associada a bcl-2/química
4.
Biochim Biophys Acta Mol Cell Res ; 1864(4): 737-746, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-27614134

RESUMO

The elaborate membrane architecture of mitochondria is a prerequisite for efficient respiration and ATP generation. The cristae membranes, invaginations of the inner mitochondrial membrane, represent a specialized compartment that harbors the complexes of the respiratory chain and the F1Fo-ATP synthase. Crista junctions form narrow openings that connect the cristae membranes to the inner boundary membrane. The mitochondrial contact site and cristae organizing system (MICOS) is located at crista junctions where it stabilizes membrane curvature and forms contact sites between the mitochondrial inner and outer membranes. MICOS is a large machinery, consisting of two dynamic subcomplexes that are anchored in the inner membrane and expose domains to the intermembrane space. The functions of MICOS in mitochondrial membrane architecture and biogenesis are influenced by numerous interaction partners and the phospholipid environment.


Assuntos
DNA Mitocondrial/genética , Mitocôndrias/metabolismo , Proteínas de Transporte da Membrana Mitocondrial/genética , Membranas Mitocondriais/metabolismo , ATPases Translocadoras de Prótons/genética , Animais , DNA Mitocondrial/metabolismo , Regulação da Expressão Gênica , Humanos , Mitocôndrias/ultraestrutura , Proteínas de Transporte da Membrana Mitocondrial/metabolismo , Membranas Mitocondriais/ultraestrutura , Fosfolipídeos/metabolismo , Ligação Proteica , ATPases Translocadoras de Prótons/metabolismo , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Transdução de Sinais , Especificidade da Espécie
5.
Biol Chem ; 393(11): 1247-61, 2012 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-23109542

RESUMO

Mitofilin proteins are crucial organizers of mitochondrial architecture. They are located in the inner mitochondrial membrane and interact with several protein complexes of the outer membrane, thereby generating contact sites between the two membrane systems of mitochondria. Within the inner membrane, mitofilins are part of hetero-oligomeric protein complexes that have been termed the mitochondrial inner membrane organizing system (MINOS). MINOS integrity is required for the maintenance of the characteristic morphology of the inner mitochondrial membrane, with an inner boundary region closely apposed to the outer membrane and cristae membranes, which form large tubular invaginations that protrude into the mitochondrial matrix and harbor the enzyme complexes of the oxidative phosphorylation machinery. MINOS deficiency comes along with a loss of crista junction structures and the detachment of cristae from the inner boundary membrane. MINOS has been conserved in evolution from unicellular eukaryotes to humans, where alterations of MINOS subunits are associated with multiple pathological conditions.


Assuntos
Sequência Conservada , Membranas Mitocondriais/metabolismo , Proteínas Mitocondriais/química , Proteínas Mitocondriais/metabolismo , Animais , Humanos , Membranas Mitocondriais/química , Modelos Biológicos , Proteínas Musculares/química , Proteínas Musculares/metabolismo
6.
Cell Metab ; 33(12): 2464-2483.e18, 2021 12 07.
Artigo em Inglês | MEDLINE | ID: mdl-34800366

RESUMO

Mitochondria are key organelles for cellular energetics, metabolism, signaling, and quality control and have been linked to various diseases. Different views exist on the composition of the human mitochondrial proteome. We classified >8,000 proteins in mitochondrial preparations of human cells and defined a mitochondrial high-confidence proteome of >1,100 proteins (MitoCoP). We identified interactors of translocases, respiratory chain, and ATP synthase assembly factors. The abundance of MitoCoP proteins covers six orders of magnitude and amounts to 7% of the cellular proteome with the chaperones HSP60-HSP10 being the most abundant mitochondrial proteins. MitoCoP dynamics spans three orders of magnitudes, with half-lives from hours to months, and suggests a rapid regulation of biosynthesis and assembly processes. 460 MitoCoP genes are linked to human diseases with a strong prevalence for the central nervous system and metabolism. MitoCoP will provide a high-confidence resource for placing dynamics, functions, and dysfunctions of mitochondria into the cellular context.


Assuntos
Mitocôndrias , Proteoma , Humanos , Mitocôndrias/metabolismo , Membranas Mitocondriais/metabolismo , Proteínas Mitocondriais/metabolismo , Proteoma/metabolismo
7.
J Mol Biol ; 429(8): 1162-1170, 2017 04 21.
Artigo em Inglês | MEDLINE | ID: mdl-28315355

RESUMO

The mitochondrial contact site and cristae organizing system (MICOS) is crucial for maintaining the architecture of the mitochondrial inner membrane. MICOS is enriched at crista junctions that connect the two inner membrane domains: inner boundary membrane and cristae membrane. MICOS promotes the formation of crista junctions, whereas the oligomeric F1Fo-ATP synthase is crucial for shaping cristae rims, indicating antagonistic functions of these machineries in organizing inner membrane architecture. We report that the MICOS core subunit Mic10, but not Mic60, binds to the F1Fo-ATP synthase. Mic10 selectively associates with the dimeric form of the ATP synthase and supports the formation of ATP synthase oligomers. Our results suggest that Mic10 plays a dual role in mitochondrial inner membrane architecture. In addition to its central function in sculpting crista junctions, a fraction of Mic10 molecules interact with the cristae rim-forming F1Fo-ATP synthase.


Assuntos
Proteínas de Membrana/metabolismo , Proteínas Mitocondriais/metabolismo , ATPases Mitocondriais Próton-Translocadoras/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Proteínas de Membrana/genética , Mitocôndrias/metabolismo , Proteínas Mitocondriais/genética , ATPases Mitocondriais Próton-Translocadoras/genética , Multimerização Proteica , Transporte Proteico , Proteínas de Saccharomyces cerevisiae/genética
8.
Nat Commun ; 8: 15258, 2017 05 31.
Artigo em Inglês | MEDLINE | ID: mdl-28561061

RESUMO

The mitochondrial contact site and cristae organizing system (MICOS) is crucial for the formation of crista junctions and mitochondrial inner membrane architecture. MICOS contains two core components. Mic10 shows membrane-bending activity, whereas Mic60 (mitofilin) forms contact sites between inner and outer membranes. Here we report that Mic60 deforms liposomes into thin membrane tubules and thus displays membrane-shaping activity. We identify a membrane-binding site in the soluble intermembrane space-exposed part of Mic60. This membrane-binding site is formed by a predicted amphipathic helix between the conserved coiled-coil and mitofilin domains. The mitofilin domain negatively regulates the membrane-shaping activity of Mic60. Binding of Mic19 to the mitofilin domain modulates this activity. Membrane binding and shaping by the conserved Mic60-Mic19 complex is crucial for crista junction formation, mitochondrial membrane architecture and efficient respiratory activity. Mic60 thus plays a dual role by shaping inner membrane crista junctions and forming contact sites with the outer membrane.


Assuntos
Membranas Mitocondriais/metabolismo , Proteínas Mitocondriais/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Sequência de Aminoácidos , Membrana Celular/metabolismo , Lipossomos , Proteínas Mitocondriais/química , Ligação Proteica , Saccharomyces cerevisiae/metabolismo , Homologia de Sequência de Aminoácidos
9.
Oncotarget ; 8(23): 37478-37490, 2017 Jun 06.
Artigo em Inglês | MEDLINE | ID: mdl-28415582

RESUMO

The anthraquinone emodin has been shown to have antineoplastic properties and a wealth of unconnected effects have been linked to its use, most of which are likely secondary outcomes of the drug treatment. The primary activity of emodin on cells has remained unknown. In the present study we demonstrate dramatic and extensive effects of emodin on the redox state of cells and on mitochondrial homeostasis, irrespectively of the cell type and organism, ranging from the yeast Saccharomyces cerevisiae to human cell lines and primary cells. Emodin binds to redox-active enzymes and its effectiveness depends on the oxidative and respiratory status of cells. We show that cells with efficient respiratory metabolism are less susceptible to emodin, whereas cells under glycolytic metabolism are more vulnerable to the compound. Our findings indicate that emodin acts in a similar way as known uncouplers of the mitochondrial electron transport chain and causes oxidative stress that particularly disturbs cancer cells.


Assuntos
Proliferação de Células/efeitos dos fármacos , Emodina/farmacologia , Mitocôndrias/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Células A549 , Células CACO-2 , Sobrevivência Celular/efeitos dos fármacos , Células Cultivadas , Fibroblastos/citologia , Fibroblastos/efeitos dos fármacos , Fibroblastos/metabolismo , Células HeLa , Humanos , Células MCF-7 , Neoplasias/metabolismo , Neoplasias/patologia , Fosforilação/efeitos dos fármacos , Inibidores de Proteínas Quinases/farmacologia , Proteínas Quinases/metabolismo , Proteômica/métodos , Saccharomyces cerevisiae/efeitos dos fármacos , Saccharomyces cerevisiae/crescimento & desenvolvimento , Saccharomyces cerevisiae/metabolismo
10.
Microb Cell ; 3(11): 565-568, 2016 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-28357325

RESUMO

Altered mitochondrial activities play an important role in many different human disorders, including cancer and neurodegeneration. At the Freiburg Institute of Advanced Studies (FRIAS) Junior Researcher Conference "One Mitochondrion, Many Diseases - Biological and Molecular Perspectives" (University of Freiburg, Freiburg, Germany), junior and experienced researches discussed common and distinct mechanisms of mitochondrial contributions to various human disorders.

11.
J Mol Biol ; 428(8): 1485-92, 2016 Apr 24.
Artigo em Inglês | MEDLINE | ID: mdl-26968360

RESUMO

The mitochondrial inner membrane consists of two morphologically distinct domains, the inner boundary membrane and large invaginations termed cristae. Narrow membrane structures, the crista junctions, link these two domains. Maintenance of this elaborate architecture depends on the evolutionarily conserved mitochondrial contact site and cristae organizing system (MICOS), a multisubunit inner membrane protein complex. MICOS consists of two functional modules, a Mic60-Mic19 subcomplex that forms Mic60-mediated contact sites with the outer mitochondrial membrane and a Mic10-Mic12-Mic26-Mic27 membrane-sculpting subcomplex that contains large Mic10 oligomers. Deletion of MIC10 or MIC60 results in the loss of most crista junctions. Distinct views have been discussed about how the MICOS modules cooperate with each other. We searched for components required for the structural organization of MICOS and identified Mic12 and Mic27 as crucial factors with specific roles in MICOS complex formation. Mic27 promotes the stability of the Mic10 oligomers in the membrane-sculpting subcomplex, whereas Mic12 is required for the coupling of the two MICOS subcomplexes. We conclude that in addition to the MICOS core components Mic10 and Mic60, Mic12 and Mic27 play specific roles in the organization of the MICOS complex.


Assuntos
Proteínas de Membrana/fisiologia , Mitocôndrias/metabolismo , Membranas Mitocondriais/metabolismo , Proteínas de Saccharomyces cerevisiae/fisiologia , Saccharomyces cerevisiae/metabolismo , Deleção de Genes , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Proteínas Mitocondriais/metabolismo , Mutação , Ligação Proteica , Estrutura Terciária de Proteína , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/genética
12.
Sci Rep ; 6: 32994, 2016 09 13.
Artigo em Inglês | MEDLINE | ID: mdl-27620692

RESUMO

The pro-apoptotic Bcl-2 protein Bax can permeabilize the outer mitochondrial membrane and therefore commit human cells to apoptosis. Bax is regulated by constant translocation to the mitochondria and retrotranslocation back into the cytosol. Bax retrotranslocation depends on pro-survival Bcl-2 proteins and stabilizes inactive Bax. Here we show that Bax retrotranslocation shuttles membrane-associated and membrane-integral Bax from isolated mitochondria. We further discover the mitochondrial porin voltage-dependent anion channel 2 (VDAC2) as essential component and platform for Bax retrotranslocation. VDAC2 ensures mitochondria-specific membrane association of Bax and in the absence of VDAC2 Bax localizes towards other cell compartments. Bax retrotranslocation is also regulated by nucleotides and calcium ions, suggesting a potential role of the transport of these ions through VDAC2 in Bax retrotranslocation. Together, our results reveal the unanticipated bifunctional role of VDAC2 to target Bax specifically to the mitochondria and ensure Bax inhibition by retrotranslocation into the cytosol.


Assuntos
Mitocôndrias/metabolismo , Canal de Ânion 2 Dependente de Voltagem/metabolismo , Proteína X Associada a bcl-2/metabolismo , Apoptose , Cátions Bivalentes/metabolismo , Citosol/metabolismo , Técnicas de Inativação de Genes , Células HCT116 , Humanos , Membranas Mitocondriais/metabolismo , Modelos Biológicos , Nucleotídeos/metabolismo , Transporte Proteico , Proteína X Associada a bcl-2/antagonistas & inibidores , Proteína X Associada a bcl-2/genética
13.
Cell Metab ; 21(5): 747-55, 2015 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-25955210

RESUMO

The mitochondrial contact site and cristae organizing system (MICOS) is a conserved multi-subunit complex crucial for maintaining the characteristic architecture of mitochondria. Studies with deletion mutants identified Mic10 and Mic60 as core subunits of MICOS. Mic60 has been studied in detail; however, topogenesis and function of Mic10 are unknown. We report that targeting of Mic10 to the mitochondrial inner membrane requires a positively charged internal loop, but no cleavable presequence. Both transmembrane segments of Mic10 carry a characteristic four-glycine motif, which has been found in the ring-forming rotor subunit of F1Fo-ATP synthases. Overexpression of Mic10 profoundly alters the architecture of the inner membrane independently of other MICOS components. The four-glycine motifs are dispensable for interaction of Mic10 with other MICOS subunits but are crucial for the formation of large Mic10 oligomers. Our studies identify a unique role of Mic10 oligomers in promoting the formation of inner membrane crista junctions.


Assuntos
Proteínas de Membrana/metabolismo , Mitocôndrias/metabolismo , Mitocôndrias/ultraestrutura , Proteínas Mitocondriais/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/citologia , Saccharomyces cerevisiae/metabolismo , Sequência de Aminoácidos , Proteínas de Membrana/análise , Mitocôndrias/química , Membranas Mitocondriais/química , Membranas Mitocondriais/metabolismo , Membranas Mitocondriais/ultraestrutura , Proteínas Mitocondriais/análise , Dados de Sequência Molecular , Saccharomyces cerevisiae/química , Proteínas de Saccharomyces cerevisiae/análise
14.
Methods Mol Biol ; 1033: 325-44, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23996187

RESUMO

The isolation and functional reconstitution of large membrane protein complexes is an important step towards the biochemical characterization of such sophisticated molecular machines. Reconstitution is a multistep process that requires the mild solubilization of membrane protein complexes from native membrane preparations, the purification of the complexes from protein-detergent solutions, and their incorporation into artificial phospholipid vesicles through controlled detergent removal. The major challenge is to preserve the integrity and catalytic activity of the often fragile membrane protein assemblies during the entire procedure. Here we describe the protocols for a particularly intricate example, the functional reconstitution of the mitochondrial presequence translocase (TIM23 complex). This highly versatile and dynamic protein complex is the main protein translocation machinery of the inner mitochondrial membrane and mediates the import of precursor proteins with N-terminal presequences from the cytosol.


Assuntos
Mitocôndrias/metabolismo , Proteínas de Transporte da Membrana Mitocondrial/metabolismo , Proteolipídeos/metabolismo , Detergentes/química , Lipossomos/química , Proteínas de Membrana Transportadoras/química , Proteínas de Membrana Transportadoras/metabolismo , Proteínas de Transporte da Membrana Mitocondrial/química , Proteínas do Complexo de Importação de Proteína Precursora Mitocondrial , Complexos Multiproteicos/química , Complexos Multiproteicos/isolamento & purificação , Complexos Multiproteicos/metabolismo , Fosfolipídeos/isolamento & purificação , Proteolipídeos/química , Proteínas de Saccharomyces cerevisiae/química , Proteínas de Saccharomyces cerevisiae/metabolismo , Solubilidade
15.
J Mol Biol ; 422(2): 183-91, 2012 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-22575891

RESUMO

The mitochondrial inner membrane contains a large protein complex crucial for membrane architecture, the mitochondrial inner membrane organizing system (MINOS). MINOS is required for keeping cristae membranes attached to the inner boundary membrane via crista junctions and interacts with protein complexes of the mitochondrial outer membrane. To study if outer membrane interactions and maintenance of cristae morphology are directly coupled, we generated mutant forms of mitofilin/Fcj1 (formation of crista junction protein 1), a core component of MINOS. Mitofilin consists of a transmembrane anchor in the inner membrane and intermembrane space domains, including a coiled-coil domain and a conserved C-terminal domain. Deletion of the C-terminal domain disrupted the MINOS complex and led to release of cristae membranes from the inner boundary membrane, whereas the interaction of mitofilin with the translocase of the outer membrane (TOM) and the sorting and assembly machinery (SAM) were enhanced. Deletion of the coiled-coil domain also disturbed the MINOS complex and cristae morphology; however, the interactions of mitofilin with TOM and SAM were differentially affected. Finally, deletion of both intermembrane space domains disturbed MINOS integrity as well as interactions with TOM and SAM. Thus, the intermembrane space domains of mitofilin play distinct roles in interactions with outer membrane complexes and maintenance of MINOS and cristae morphology, demonstrating that MINOS contacts to TOM and SAM are not sufficient for the maintenance of inner membrane architecture.


Assuntos
Mitocôndrias/metabolismo , Proteínas de Transporte da Membrana Mitocondrial/genética , Membranas Mitocondriais/metabolismo , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Proteínas de Transporte da Membrana Mitocondrial/metabolismo , Proteínas Mitocondriais/genética , Proteínas Mitocondriais/metabolismo , Estrutura Terciária de Proteína , Transporte Proteico , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo
16.
Mol Biol Cell ; 23(20): 3948-56, 2012 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-22918945

RESUMO

Mitochondria contain two membranes, the outer membrane and the inner membrane with folded cristae. The mitochondrial inner membrane organizing system (MINOS) is a large protein complex required for maintaining inner membrane architecture. MINOS interacts with both preprotein transport machineries of the outer membrane, the translocase of the outer membrane (TOM) and the sorting and assembly machinery (SAM). It is unknown, however, whether MINOS plays a role in the biogenesis of outer membrane proteins. We have dissected the interaction of MINOS with TOM and SAM and report that MINOS binds to both translocases independently. MINOS binds to the SAM complex via the conserved polypeptide transport-associated domain of Sam50. Mitochondria lacking mitofilin, the large core subunit of MINOS, are impaired in the biogenesis of ß-barrel proteins of the outer membrane, whereas mutant mitochondria lacking any of the other five MINOS subunits import ß-barrel proteins in a manner similar to wild-type mitochondria. We show that mitofilin is required at an early stage of ß-barrel biogenesis that includes the initial translocation through the TOM complex. We conclude that MINOS interacts with TOM and SAM independently and that the core subunit mitofilin is involved in biogenesis of outer membrane ß-barrel proteins.


Assuntos
Mitocôndrias/metabolismo , Membranas Mitocondriais/metabolismo , Proteínas Mitocondriais/biossíntese , Biossíntese de Proteínas , Proteínas de Saccharomyces cerevisiae/biossíntese , Saccharomyces cerevisiae/metabolismo , Deleção de Genes , Proteínas Mitocondriais/química , Complexos Multiproteicos/isolamento & purificação , Complexos Multiproteicos/metabolismo , Peptídeos/metabolismo , Ligação Proteica , Estrutura Terciária de Proteína , Subunidades Proteicas/isolamento & purificação , Subunidades Proteicas/metabolismo , Transporte Proteico , Proteínas de Saccharomyces cerevisiae/química
17.
Dev Cell ; 21(4): 694-707, 2011 Oct 18.
Artigo em Inglês | MEDLINE | ID: mdl-21944719

RESUMO

The mitochondrial inner membrane consists of two domains, inner boundary membrane and cristae membrane that are connected by crista junctions. Mitofilin/Fcj1 was reported to be involved in formation of crista junctions, however, different views exist on its function and possible partner proteins. We report that mitofilin plays a dual role. Mitofilin is part of a large inner membrane complex, and we identify five partner proteins as constituents of the mitochondrial inner membrane organizing system (MINOS) that is required for keeping cristae membranes connected to the inner boundary membrane. Additionally, mitofilin is coupled to the outer membrane and promotes protein import via the mitochondrial intermembrane space assembly pathway. Our findings indicate that mitofilin is a central component of MINOS and functions as a multifunctional regulator of mitochondrial architecture and protein biogenesis.


Assuntos
Membranas Intracelulares/metabolismo , Mitocôndrias/metabolismo , Proteínas de Transporte da Membrana Mitocondrial/metabolismo , Membranas Mitocondriais/metabolismo , Proteínas Mitocondriais/metabolismo , Biossíntese de Proteínas , Proteínas de Saccharomyces cerevisiae/metabolismo , Cromatografia de Afinidade , Humanos , Ligação Proteica , Transporte Proteico , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/crescimento & desenvolvimento , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz , Transposases/metabolismo
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