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Antón Z, Mullally G, Ford HC, van der Kamp MW, Szczelkun MD, Lane JD. Mitochondrial import, health and mtDNA copy number variability seen when using type II and type V CRISPR effectors. J Cell Sci 2020; 133:jcs.248468. [PMID: 32843580 DOI: 10.1242/jcs.248468] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 08/10/2020] [Indexed: 12/18/2022] Open
Abstract
Current methodologies for targeting the mitochondrial genome for research and/or therapy development in mitochondrial diseases are restricted by practical limitations and technical inflexibility. A molecular toolbox for CRISPR-mediated mitochondrial genome editing is desirable, as this could enable targeting of mtDNA haplotypes using the precision and tuneability of CRISPR enzymes. Such 'MitoCRISPR' systems described to date lack reproducibility and independent corroboration. We have explored the requirements for MitoCRISPR in human cells by CRISPR nuclease engineering, including the use of alternative mitochondrial protein targeting sequences and smaller paralogues, and the application of guide (g)RNA modifications for mitochondrial import. We demonstrate varied mitochondrial targeting efficiencies and effects on mitochondrial dynamics/function of different CRISPR nucleases, with Lachnospiraceae bacterium ND2006 (Lb) Cas12a being better targeted and tolerated than Cas9 variants. We also provide evidence of Cas9 gRNA association with mitochondria in HeLa cells and isolated yeast mitochondria, even in the absence of a targeting RNA aptamer. Our data link mitochondrial-targeted LbCas12a/crRNA with increased mtDNA copy number dependent upon DNA binding and cleavage activity. We discuss reproducibility issues and the future steps necessary for MitoCRISPR.
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Affiliation(s)
- Zuriñe Antón
- Cell Biology Laboratories, School of Biochemistry, Faculty of Life Sciences, University of Bristol, Bristol BS8 1TD, UK
| | - Grace Mullally
- DNA-Protein Interactions Unit, School of Biochemistry, Faculty of Life Sciences, University of Bristol, Bristol BS8 1TD, UK
| | - Holly C Ford
- DNA-Protein Interactions Unit, School of Biochemistry, Faculty of Life Sciences, University of Bristol, Bristol BS8 1TD, UK
| | - Marc W van der Kamp
- School of Biochemistry, Faculty of Life Sciences, University of Bristol, Bristol BS8 1TD, UK.,Centre for Computational Chemistry, School of Chemistry, Faculty of Science, University of Bristol, Bristol BS8 1TD, UK.,BrisSynBio, Life Sciences Building, Tyndall Avenue, University of Bristol, Bristol BS8 1TQ, UK
| | - Mark D Szczelkun
- DNA-Protein Interactions Unit, School of Biochemistry, Faculty of Life Sciences, University of Bristol, Bristol BS8 1TD, UK .,BrisSynBio, Life Sciences Building, Tyndall Avenue, University of Bristol, Bristol BS8 1TQ, UK
| | - Jon D Lane
- Cell Biology Laboratories, School of Biochemistry, Faculty of Life Sciences, University of Bristol, Bristol BS8 1TD, UK .,BrisSynBio, Life Sciences Building, Tyndall Avenue, University of Bristol, Bristol BS8 1TQ, UK
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Horten P, Colina-Tenorio L, Rampelt H. Biogenesis of Mitochondrial Metabolite Carriers. Biomolecules 2020; 10:E1008. [PMID: 32645990 PMCID: PMC7408425 DOI: 10.3390/biom10071008] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 07/02/2020] [Accepted: 07/03/2020] [Indexed: 12/28/2022] Open
Abstract
: Metabolite carriers of the mitochondrial inner membrane are crucial for cellular physiology since mitochondria contribute essential metabolic reactions and synthesize the majority of the cellular ATP. Like almost all mitochondrial proteins, carriers have to be imported into mitochondria from the cytosol. Carrier precursors utilize a specialized translocation pathway dedicated to the biogenesis of carriers and related proteins, the carrier translocase of the inner membrane (TIM22) pathway. After recognition and import through the mitochondrial outer membrane via the translocase of the outer membrane (TOM) complex, carrier precursors are ushered through the intermembrane space by hexameric TIM chaperones and ultimately integrated into the inner membrane by the TIM22 carrier translocase. Recent advances have shed light on the mechanisms of TOM translocase and TIM chaperone function, uncovered an unexpected versatility of the machineries, and revealed novel components and functional crosstalk of the human TIM22 translocase.
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Affiliation(s)
- Patrick Horten
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany; (P.H.); (L.C.-T.)
- Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Lilia Colina-Tenorio
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany; (P.H.); (L.C.-T.)
- CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany
| | - Heike Rampelt
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany; (P.H.); (L.C.-T.)
- CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany
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Rampelt H, Sucec I, Bersch B, Horten P, Perschil I, Martinou JC, van der Laan M, Wiedemann N, Schanda P, Pfanner N. The mitochondrial carrier pathway transports non-canonical substrates with an odd number of transmembrane segments. BMC Biol 2020; 18:2. [PMID: 31907035 PMCID: PMC6945462 DOI: 10.1186/s12915-019-0733-6] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Accepted: 12/17/2019] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND The mitochondrial pyruvate carrier (MPC) plays a central role in energy metabolism by transporting pyruvate across the inner mitochondrial membrane. Its heterodimeric composition and homology to SWEET and semiSWEET transporters set the MPC apart from the canonical mitochondrial carrier family (named MCF or SLC25). The import of the canonical carriers is mediated by the carrier translocase of the inner membrane (TIM22) pathway and is dependent on their structure, which features an even number of transmembrane segments and both termini in the intermembrane space. The import pathway of MPC proteins has not been elucidated. The odd number of transmembrane segments and positioning of the N-terminus in the matrix argues against an import via the TIM22 carrier pathway but favors an import via the flexible presequence pathway. RESULTS Here, we systematically analyzed the import pathways of Mpc2 and Mpc3 and report that, contrary to an expected import via the flexible presequence pathway, yeast MPC proteins with an odd number of transmembrane segments and matrix-exposed N-terminus are imported by the carrier pathway, using the receptor Tom70, small TIM chaperones, and the TIM22 complex. The TIM9·10 complex chaperones MPC proteins through the mitochondrial intermembrane space using conserved hydrophobic motifs that are also required for the interaction with canonical carrier proteins. CONCLUSIONS The carrier pathway can import paired and non-paired transmembrane helices and translocate N-termini to either side of the mitochondrial inner membrane, revealing an unexpected versatility of the mitochondrial import pathway for non-cleavable inner membrane proteins.
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Affiliation(s)
- Heike Rampelt
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104, Freiburg, Germany.
- CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, 79104, Freiburg, Germany.
| | - Iva Sucec
- Institut de Biologie Structurale (IBS), Univ. Grenoble Alpes, CEA, CNRS, 38000, Grenoble, France
| | - Beate Bersch
- Institut de Biologie Structurale (IBS), Univ. Grenoble Alpes, CEA, CNRS, 38000, Grenoble, France
| | - Patrick Horten
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104, Freiburg, Germany
- CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, 79104, Freiburg, Germany
- Faculty of Biology, University of Freiburg, 79104, Freiburg, Germany
| | - Inge Perschil
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104, Freiburg, Germany
| | | | - Martin van der Laan
- Medical Biochemistry and Molecular Biology, Center for Molecular Signaling, PZMS, Saarland University, 66421 Homburg, Germany
| | - Nils Wiedemann
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104, Freiburg, Germany
- CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, 79104, Freiburg, Germany
- BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79104, Freiburg, Germany
| | - Paul Schanda
- Institut de Biologie Structurale (IBS), Univ. Grenoble Alpes, CEA, CNRS, 38000, Grenoble, France
| | - Nikolaus Pfanner
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104, Freiburg, Germany.
- CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, 79104, Freiburg, Germany.
- BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79104, Freiburg, Germany.
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Ceh-Pavia E, Spiller MP, Lu H. Folding and biogenesis of mitochondrial small Tim proteins. Int J Mol Sci 2013; 14:16685-705. [PMID: 23945562 PMCID: PMC3759932 DOI: 10.3390/ijms140816685] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Revised: 08/01/2013] [Accepted: 08/07/2013] [Indexed: 01/15/2023] Open
Abstract
Correct and timely folding is critical to the function of all proteins. The importance of this is illustrated in the biogenesis of the mitochondrial intermembrane space (IMS) “small Tim” proteins. Biogenesis of the small Tim proteins is regulated by dedicated systems or pathways, beginning with synthesis in the cytosol and ending with assembly of individually folded proteins into functional complexes in the mitochondrial IMS. The process is mostly centered on regulating the redox states of the conserved cysteine residues: oxidative folding is crucial for protein function in the IMS, but oxidized (disulfide bonded) proteins cannot be imported into mitochondria. How the redox-sensitive small Tim precursor proteins are maintained in a reduced, import-competent form in the cytosol is not well understood. Recent studies suggest that zinc and the cytosolic thioredoxin system play a role in the biogenesis of these proteins. In the IMS, the mitochondrial import and assembly (MIA) pathway catalyzes both import into the IMS and oxidative folding of the small Tim proteins. Finally, assembly of the small Tim complexes is a multistep process driven by electrostatic and hydrophobic interactions; however, the chaperone function of the complex might require destabilization of these interactions to accommodate the substrate. Here, we review how folding of the small Tim proteins is regulated during their biogenesis, from maintenance of the unfolded precursors in the cytosol, to their import, oxidative folding, complex assembly and function in the IMS.
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Affiliation(s)
- Efrain Ceh-Pavia
- Manchester Institute of Biotechnology, Faculty of Life Sciences, University of Manchester, Manchester, UK.
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Kulawiak B, Höpker J, Gebert M, Guiard B, Wiedemann N, Gebert N. The mitochondrial protein import machinery has multiple connections to the respiratory chain. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2012; 1827:612-26. [PMID: 23274250 DOI: 10.1016/j.bbabio.2012.12.004] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2012] [Revised: 12/12/2012] [Accepted: 12/17/2012] [Indexed: 01/09/2023]
Abstract
The mitochondrial inner membrane harbors the complexes of the respiratory chain and protein translocases required for the import of mitochondrial precursor proteins. These complexes are functionally interdependent, as the import of respiratory chain precursor proteins across and into the inner membrane requires the membrane potential. Vice versa the membrane potential is generated by the proton pumping complexes of the respiratory chain. Besides this basic codependency four different systems for protein import, processing and assembly show further connections to the respiratory chain. The mitochondrial intermembrane space import and assembly machinery oxidizes cysteine residues within the imported precursor proteins and is able to donate the liberated electrons to the respiratory chain. The presequence translocase of the inner membrane physically interacts with the respiratory chain. The mitochondrial processing peptidase is homologous to respiratory chain subunits and the carrier translocase of the inner membrane even shares a subunit with the respiratory chain. In this review we will summarize the import of mitochondrial precursor proteins and highlight these special links between the mitochondrial protein import machinery and the respiratory chain. This article is part of a Special Issue entitled: Respiratory complex II: Role in cellular physiology and disease.
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Affiliation(s)
- Bogusz Kulawiak
- Institut für Biochemie und Molekularbiologie, ZBMZ, Universität Freiburg, Freiburg, Germany
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Betin VMS, MacVicar TDB, Parsons SF, Anstee DJ, Lane JD. A cryptic mitochondrial targeting motif in Atg4D links caspase cleavage with mitochondrial import and oxidative stress. Autophagy 2012; 8:664-76. [PMID: 22441018 DOI: 10.4161/auto.19227] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The Atg4 cysteine proteases play crucial roles in the processing of Atg8 proteins during autophagy, but their regulation during cellular stress and differentiation remains poorly understood. We have found that two Atg4 family members--Atg4C and Atg4D--contain cryptic mitochondrial targeting sequences immediately downstream of their canonical (DEVD) caspase cleavage sites. Consequently, caspase-cleaved Atg4D (ΔN63 Atg4D) localizes to the mitochondrial matrix when expressed in mammalian cells, where it undergoes further processing to a ~42 kDa mitochondrial form. Interestingly, caspase cleavage is not needed for Atg4D mitochondrial import, because ~42 kDa mitochondrial Atg4D is observed in cells treated with caspase inhibitors and in cells expressing caspase-resistant Atg4D (DEVA(63)). Using HeLa cell lines stably expressing ΔN63 Atg4D, we showed that mitochondrial Atg4D sensitizes cells to cell death in the presence of the mitochondrial uncoupler, CCCP, and that mitochondrial cristae are less extensive in these cells. We further showed that the organization of mitochondrial cristae is altered during the mitochondrial clearance phase in differentiating primary human erythroblasts stably expressing ΔN63 Atg4D, and that these cells have elevated levels of mitochondrial reactive oxygen species (ROS) during late stages of erythropoiesis. Together these data suggest that the import of Atg4D during cellular stress and differentiation may play important roles in the regulation of mitochondrial physiology, ROS, mitophagy and cell viability.
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Affiliation(s)
- Virginie M S Betin
- Cell Biology Laboratories, Department of Biochemistry, School of Medical and Veterinary Sciences, University of Bristol, University Walk, Bristol UK
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Morita T, Ito E, Fukuoka T, Imura T, Kitamoto D. The role of PaAAC1 encoding a mitochondrial ADP/ATP carrier in the biosynthesis of extracellular glycolipids, mannosylerythritol lipids, in the basidiomycetous yeast Pseudozyma antarctica. Yeast 2010; 27:379-88. [DOI: 10.1002/yea.1761] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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de Marcos-Lousa C, Sideris DP, Tokatlidis K. Translocation of mitochondrial inner-membrane proteins: conformation matters. Trends Biochem Sci 2006; 31:259-67. [PMID: 16616497 DOI: 10.1016/j.tibs.2006.03.006] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2005] [Revised: 02/15/2006] [Accepted: 03/23/2006] [Indexed: 10/24/2022]
Abstract
Most of the mitochondrial inner-membrane proteins are generated without a presequence and their targeting depends on inadequately defined internal segments. Despite the numerous components of the import machinery identified by proteomics, the properties of hydrophobic import substrates remain poorly understood. Recent studies support several principles for these membrane proteins: first, they become organized into partially assembled forms within the translocon; second, they present noncontiguous targeting signals; and third, they induce conformational changes in translocase subunits, thereby mediating "assembly on demand" of the import machinery. It is possible that the energy needed for these proteins to pass across the outer membrane, to travel through the intermembrane space and to target the inner-membrane surface is provided by conformational changes involving import components that seem to have natively unfolded structures. Such structural malleability might render some of the translocase subunits more adept at driving the protein import process.
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Affiliation(s)
- Carine de Marcos-Lousa
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology (IMBB-FORTH), PO Box 1385, Heraklion 71110, Crete, Greece
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Allen S, Balabanidou V, Sideris DP, Lisowsky T, Tokatlidis K. Erv1 mediates the Mia40-dependent protein import pathway and provides a functional link to the respiratory chain by shuttling electrons to cytochrome c. J Mol Biol 2005; 353:937-44. [PMID: 16185707 DOI: 10.1016/j.jmb.2005.08.049] [Citation(s) in RCA: 190] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2005] [Revised: 07/29/2005] [Accepted: 08/23/2005] [Indexed: 11/20/2022]
Abstract
Unlike matrix-targeted or inner membrane proteins, those that are targeted to the mitochondrial intermembrane space (IMS) do not require ATP or the inner membrane electrochemical potential. Their import is mediated primarily by the essential IMS protein Mia40/Tim40. Here, we show that the mitochondrial flavin adenine dinucleotide (FAD)-linked sulfhydryl oxidase Erv1 (essential for respiration and vegetative growth 1) plays a central role in the biogenesis of small, cysteine proteins of the IMS that are import substrates for Mia40. In a temperature-sensitive strain of Erv1, steady-state levels of small translocases of the inner membrane (Tims) are specifically affected when cells are grown at the non-permissive temperature. Furthermore, mitochondria isolated from the erv1-ts show a specific import and assembly defect for the small Tims but not in any other protein import pathway. Erv1 does not directly oxidise the small Tims, as thiol trapping assays show that the small Tims can still be oxidised in erv1-ts cells grown at the non-permissive temperature and in isolated mitochondria from this strain. Moreover, addition of pure Erv1 into erv1-ts mitochondria lacking the endogenous protein restores import and assembly of the small Tims only to an extent, arguing for a cascade of interactions with Erv1 rather than for a direct interaction of Erv1 with the small Tims. Cytochrome c (cyt c) is the in vivo oxidase for Erv1, as yeast cells mutated in cyt c cannot grow under anaerobic conditions. Therefore, Erv1 functionally links the Mia40-dependent import pathway to the Mia40-independent cyt c import pathway transferring electrons from the incoming precursors to cyt c as an acceptor. In this context, the protein import process is linked to the respiratory chain via the communication of Erv1 with cyt c.
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Affiliation(s)
- Scott Allen
- Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, UK
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Current awareness on yeast. Yeast 2005; 22:745-52. [PMID: 16106592 DOI: 10.1002/yea.1165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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Brandner K, Rehling P, Truscott KN. The carboxyl-terminal third of the dicarboxylate carrier is crucial for productive association with the inner membrane twin-pore translocase. J Biol Chem 2004; 280:6215-21. [PMID: 15591051 DOI: 10.1074/jbc.m412269200] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The carrier proteins of the mitochondrial inner membrane consist of three structurally related tandem repeats (modules). Several different, and in some cases contradictory, views exist on the role individual modules play in carrier transport across the mitochondrial membranes and how they promote protein insertion into the inner membrane. Thus, by use of specific translocation intermediates, we performed a detailed analysis of carrier biogenesis and assessed the physical association of carrier modules with the inner membrane translocation machinery. Here we have reported that each module of the dicarboxylate carrier contains sufficient targeting information for its transport across the outer mitochondrial membrane. The carboxyl-terminal module possesses major targeting information to facilitate the direct binding of the carrier protein to the inner membrane twin-pore translocase and subsequent insertion into the inner membrane in a membrane potential-dependent manner. We concluded that, in this case, a single structural repeat can drive inner membrane insertion, whereas all three related units contribute targeting information for outer membrane translocation.
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Affiliation(s)
- Katrin Brandner
- Institut für Biochemie und Molekularbiologie, Universität Freiburg, D-79104 Freiburg, Germany
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