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Kizmaz B, Nutz A, Egeler A, Herrmann JM. Protein insertion into the inner membrane of mitochondria: routes and mechanisms. FEBS Open Bio 2024; 14:1627-1639. [PMID: 38664330 PMCID: PMC11452304 DOI: 10.1002/2211-5463.13806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2024] [Revised: 03/28/2024] [Accepted: 04/11/2024] [Indexed: 10/06/2024] Open
Abstract
The inner membrane of mitochondria contains hundreds of different integral membrane proteins. These proteins transport molecules into and out of the matrix, they carry out multifold catalytic reactions and they promote the biogenesis or degradation of mitochondrial constituents. Most inner membrane proteins are encoded by nuclear genes and synthesized in the cytosol from where they are imported into mitochondria by translocases in the outer and inner membrane. Three different import routes direct proteins into the inner membrane and allow them to acquire their appropriate membrane topology. First, mitochondrial import intermediates can be arrested at the level of the TIM23 inner membrane translocase by a stop-transfer sequence to reach the inner membrane by lateral insertion. Second, proteins can be fully translocated through the TIM23 complex into the matrix from where they insert into the inner membrane in an export-like reaction. Carriers and other polytopic membrane proteins embark on a third insertion pathway: these hydrophobic proteins employ the specialized TIM22 translocase to insert from the intermembrane space (IMS) into the inner membrane. This review article describes these three targeting routes and provides an overview of the machinery that promotes the topogenesis of mitochondrial inner membrane proteins.
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Affiliation(s)
- Büsra Kizmaz
- Cell BiologyUniversity of Kaiserslautern, RPTUGermany
| | - Annika Nutz
- Cell BiologyUniversity of Kaiserslautern, RPTUGermany
| | - Annika Egeler
- Cell BiologyUniversity of Kaiserslautern, RPTUGermany
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Knöringer K, Groh C, Krämer L, Stein KC, Hansen KG, Zimmermann J, Morgan B, Herrmann JM, Frydman J, Boos F. The unfolded protein response of the endoplasmic reticulum supports mitochondrial biogenesis by buffering nonimported proteins. Mol Biol Cell 2023; 34:ar95. [PMID: 37379206 PMCID: PMC10551703 DOI: 10.1091/mbc.e23-05-0205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Revised: 06/15/2023] [Accepted: 06/22/2023] [Indexed: 06/30/2023] Open
Abstract
Almost all mitochondrial proteins are synthesized in the cytosol and subsequently targeted to mitochondria. The accumulation of nonimported precursor proteins occurring upon mitochondrial dysfunction can challenge cellular protein homeostasis. Here we show that blocking protein translocation into mitochondria results in the accumulation of mitochondrial membrane proteins at the endoplasmic reticulum, thereby triggering the unfolded protein response (UPRER). Moreover, we find that mitochondrial membrane proteins are also routed to the ER under physiological conditions. The level of ER-resident mitochondrial precursors is enhanced by import defects as well as metabolic stimuli that increase the expression of mitochondrial proteins. Under such conditions, the UPRER is crucial to maintain protein homeostasis and cellular fitness. We propose the ER serves as a physiological buffer zone for those mitochondrial precursors that cannot be immediately imported into mitochondria while engaging the UPRER to adjust the ER proteostasis capacity to the extent of precursor accumulation.
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Affiliation(s)
| | - Carina Groh
- Cell Biology, University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Lena Krämer
- Cell Biology, University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Kevin C. Stein
- Department of Biology, Stanford University, Stanford, CA 94305
| | - Katja G. Hansen
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA 02115
| | - Jannik Zimmermann
- Institute of Biochemistry, Center for Human and Molecular Biology (ZHMB), Saarland University, 66123 Saarbrücken, Germany
| | - Bruce Morgan
- Institute of Biochemistry, Center for Human and Molecular Biology (ZHMB), Saarland University, 66123 Saarbrücken, Germany
| | | | - Judith Frydman
- Department of Biology, Stanford University, Stanford, CA 94305
- Department of Genetics, Stanford University, Stanford, CA 94305
| | - Felix Boos
- Cell Biology, University of Kaiserslautern, 67663 Kaiserslautern, Germany
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3
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Smutok O, Kavetskyy T, Gonchar M, Katz E. Microbial L‐ and D‐Lactate Selective Oxidoreductases as a Very Prospective but Still Uncommon Tool in Commercial Biosensors. ChemElectroChem 2021. [DOI: 10.1002/celc.202101149] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- Oleh Smutok
- Department of Chemistry and Biomolecular Science Clarkson University 8 Clarkson Avenue, Potsdam NY 13699 New York USA
| | - Taras Kavetskyy
- Drohobych Ivan Franko State Pedagogical University I. Franko Str. 24 82100 Drohobych Ukraine
- The John Paul II Catholic University of Lublin Al. Racławickie 14 20-950 Lublin Poland
| | - Mykhailo Gonchar
- Drohobych Ivan Franko State Pedagogical University I. Franko Str. 24 82100 Drohobych Ukraine
- Department of Analytical Biotechnology Institute of Cell Biology NAS of Ukraine Drahomanov Street 14/16 79005 Lviv Ukraine
| | - Evgeny Katz
- Department of Chemistry and Biomolecular Science Clarkson University 8 Clarkson Avenue, Potsdam NY 13699 New York USA
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Roosterman D, Cottrell GS. The two-cell model of glucose metabolism: a hypothesis of schizophrenia. Mol Psychiatry 2021; 26:1738-1747. [PMID: 33402704 PMCID: PMC8440173 DOI: 10.1038/s41380-020-00980-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2020] [Revised: 11/16/2020] [Accepted: 12/01/2020] [Indexed: 02/07/2023]
Abstract
Schizophrenia is a chronic and severe mental disorder that affects over 20 million people worldwide. Common symptoms include distortions in thinking, perception, emotions, language, and self awareness. Different hypotheses have been proposed to explain the development of schizophrenia, however, there are no unifying features between the proposed hypotheses. Schizophrenic patients have perturbed levels of glucose in their cerebrospinal fluid, indicating a disturbance in glucose metabolism. We have explored the possibility that disturbances in glucose metabolism can be a general mechanism for predisposition and manifestation of the disease. We discuss glucose metabolism as a network of signaling pathways. Glucose and glucose metabolites can have diverse actions as signaling molecules, such as regulation of transcription factors, hormone and cytokine secretion and activation of neuronal cells, such as microglia. The presented model challenges well-established concepts in enzyme kinetics and glucose metabolism. We have developed a 'two-cell' model of glucose metabolism, which can explain the effects of electroconvulsive therapy and the beneficial and side effects of olanzapine treatment. Arrangement of glycolytic enzymes into metabolic signaling complexes within the 'two hit' hypothesis, allows schizophrenia to be formulated in two steps. The 'first hit' is the dysregulation of the glucose signaling pathway. This dysregulation of glucose metabolism primes the central nervous system for a pathological response to a 'second hit' via the astrocytic glycogenolysis signaling pathway.
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Affiliation(s)
- Dirk Roosterman
- Ruhr Universität Bochum, LWL-Hospital of Psychiatry, Bochum, Germany.
| | - Graeme Stuart Cottrell
- grid.9435.b0000 0004 0457 9566School of Pharmacy, University of Reading, Reading, RG6 6AP UK
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5
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Sekine S. PINK1 import regulation at a crossroad of mitochondrial fate: the molecular mechanisms of PINK1 import. J Biochem 2020; 167:217-224. [PMID: 31504668 DOI: 10.1093/jb/mvz069] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Accepted: 08/17/2019] [Indexed: 12/17/2022] Open
Abstract
PTEN-induced kinase 1 (PINK1) is a mitochondrial kinase whose activity is tightly regulated by the mitochondrial health status. In response to mitochondrial damage, activated PINK1 can promote mitophagy, an autophagic elimination of damaged mitochondria, by cooperating with Parkin ubiquitin ligase. Loss-of-function of PINK1/Parkin-mediated mitophagy results in the accumulation of dysfunctional mitochondria, which could be one aetiology of Parkinson's disease (PD). Within step-by-step signalling cascades of PINK1/Parkin-mediated mitophagy, mitochondrial damage-dependent PINK1 kinase activation is a critical step to trigger the mitophagy signal. Recent investigation of this process reveals that this stress-dependent PINK1 kinase activation is achieved by its regulated import into different mitochondrial compartments. Thus, PINK1 import regulation stands at an important crossroad to determine the mitochondrial fate-'keep' or 'remove'? In this review, we will summarize how the PINK1 import is regulated in a mitochondrial health status-dependent manner and how this process could be pharmacologically modulated to activate the PINK1/Parkin pathway.
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Affiliation(s)
- Shiori Sekine
- Aging Institute, Division of Cardiology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15219, USA
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Abstract
Mitochondria are essential organelles of eukaryotic cells. They consist of hundreds of different proteins that exhibit crucial activities in respiration, catabolic metabolism and the synthesis of amino acids, lipids, heme and iron-sulfur clusters. With the exception of a handful of hydrophobic mitochondrially encoded membrane proteins, all these proteins are synthesized on cytosolic ribosomes, targeted to receptors on the mitochondrial surface, and transported across or inserted into the outer and inner mitochondrial membrane before they are folded and assembled into their final native structure. This review article provides a comprehensive overview of the mechanisms and components of the mitochondrial protein import systems with a particular focus on recent developments in the field.
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Affiliation(s)
- Katja G Hansen
- Cell Biology, University of Kaiserslautern, Erwin-Schrödinger-Strasse 13, 67663, Kaiserslautern, Germany
| | - Johannes M Herrmann
- Cell Biology, University of Kaiserslautern, Erwin-Schrödinger-Strasse 13, 67663, Kaiserslautern, Germany.
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7
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de Bari L, Atlante A, Armeni T, Kalapos MP. Synthesis and metabolism of methylglyoxal, S-D-lactoylglutathione and D-lactate in cancer and Alzheimer's disease. Exploring the crossroad of eternal youth and premature aging. Ageing Res Rev 2019; 53:100915. [PMID: 31173890 DOI: 10.1016/j.arr.2019.100915] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Revised: 02/27/2019] [Accepted: 05/31/2019] [Indexed: 12/15/2022]
Abstract
Both cancer and Alzheimer's disease (AD) are emerging as metabolic diseases in which aberrant/dysregulated glucose metabolism and bioenergetics occur, and play a key role in disease progression. Interestingly, an enhancement of glucose uptake, glycolysis and pentose phosphate pathway occurs in both cancer cells and amyloid-β-resistant neurons in the early phase of AD. However, this metabolic shift has its adverse effects. One of them is the increase in methylglyoxal production, a physiological cytotoxic by-product of glucose catabolism. Methylglyoxal is mainly detoxified via cytosolic glyoxalase route comprising glyoxalase 1 and glyoxalase 2 with the production of S-D-lactoylglutathione and D-lactate as intermediate and end-product, respectively. Due to the existence of mitochondrial carriers and intramitochondrial glyoxalase 2 and D-lactate dehydrogenase, the transport and metabolism of both S-D-lactoylglutathione and D-lactate in mitochondria can contribute to methylglyoxal elimination, cellular antioxidant power and energy production. In this review, it is supposed that the different ability of cancer cells and AD neurons to metabolize methylglyoxal, S-D-lactoylglutathione and D-lactate scores cell fate, therefore being at the very crossroad of the "eternal youth" of cancer and the "premature death" of AD neurons. Understanding of these processes would help to elaborate novel metabolism-based therapies for cancer and AD treatment.
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Sekine S, Wang C, Sideris DP, Bunker E, Zhang Z, Youle RJ. Reciprocal Roles of Tom7 and OMA1 during Mitochondrial Import and Activation of PINK1. Mol Cell 2019; 73:1028-1043.e5. [DOI: 10.1016/j.molcel.2019.01.002] [Citation(s) in RCA: 87] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Revised: 11/05/2018] [Accepted: 12/28/2018] [Indexed: 12/26/2022]
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Smutok O, Karkovska M, Prokopiv T, Kavetskyy T, Sibirnyj W, Gonchar M. D-lactate-selective amperometric biosensor based on the mitochondrial fraction of Ogataea polymorpha recombinant cells. Yeast 2018; 36:341-348. [PMID: 30523645 DOI: 10.1002/yea.3372] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 11/23/2018] [Accepted: 11/29/2018] [Indexed: 12/21/2022] Open
Abstract
During the recent decades, a lot of data about the significance of D-lactate determination in food technology and quality control have been accumulated. Nowadays, the development of new methods for the determination of D-lactate is very relevant, especially with regard to biosensors. To construct a D-lactate-selective biosensor, we suggest using the mitochondria of recombinant yeast cells of Ogataea (Hansenula) polymorpha "tr6" (gcr1 catX/Δcyb2, prAOX_DLDH) overproducing D-lactate: cytochrome c-oxidoreductase (DLDH, EC 1.1.2.4) and lacking an L-lactate-specific enzyme (flavocytochrome b2 , E.C. 1.1.2.3). The usage of the pure enzyme is problematic due to the complexity of its isolation and stabilization because of the intramembranous localization of DLDH. The enzyme catalyzes D-lactate oxidation to pyruvate coupled with ferricytochrome c reduction to ferrocytochrome c. The constructed biosensor is characterized by high sensitivity (18.5 А·М-1 ·m-2 ), a low detection limit (3 μM of D-lactate), wide linear ranges, good selectivity, and sufficient stability. The real samples' analysis of D-lactate in dairy products was performed, and high correlation of the obtained results with the reference approach (0.7 < r < 1) and literature data was demonstrated.
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Affiliation(s)
- Oleh Smutok
- Department of Analytical Biotechnology, Institute of Cell Biology, NAS of Ukraine, Lviv, Ukraine
| | - Maria Karkovska
- Department of Analytical Biotechnology, Institute of Cell Biology, NAS of Ukraine, Lviv, Ukraine
| | - Tetiana Prokopiv
- Department of Analytical Biotechnology, Institute of Cell Biology, NAS of Ukraine, Lviv, Ukraine
| | - Taras Kavetskyy
- Department of Biology and Chemistry, and Department of Physics of Drohobych Ivan Franko State Pedagogical University, Drohobych, Ukraine.,The John Paul II Catholic University of Lublin, Lublin, Poland
| | - Wladimir Sibirnyj
- Department of Bioenergy Technologies, Faculty of Biology and Agriculture, University of Rzeszow, Poland
| | - Mykhailo Gonchar
- Department of Analytical Biotechnology, Institute of Cell Biology, NAS of Ukraine, Lviv, Ukraine
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10
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Wang Y, Li G, Wan F, Dai B, Ye D. Prognostic value of D-lactate dehydrogenase in patients with clear cell renal cell carcinoma. Oncol Lett 2018; 16:866-874. [PMID: 29963157 PMCID: PMC6019897 DOI: 10.3892/ol.2018.8782] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Accepted: 09/28/2017] [Indexed: 12/31/2022] Open
Abstract
Lactate dehydrogenase (LDH) is an enzyme involved in anaerobic glycolysis and is associated with the prognosis of patients with renal cell carcinoma (RCC). The human genome has four LDH genes: LDHA, LDHB, LDHC and LDHD. In order to determine which of these four LDH genes may predict clear cell RCC (ccRCC), a total of 509 patients with ccRCC from The Cancer Genome Atlas (TCGA) cohort and 192 patients with ccRCC from the Fudan University Shanghai Cancer Centre (FUSCC) cohort were enrolled in the present study. The expression profiles of LDHD genes in the TCGA cohort were obtained from the TCGA RNAseq database. The Cox proportional hazards regression model and Kaplan-Meier curves were used to assess relative factors. The LDH family genes that were revealed to have an association with overall survival (OS) were further validated in the FUSCC cohort. In the TCGA cohort, following Cox proportional hazards analysis, LDHD expression (P=0.0400; hazard ratio, 0.872; 95% confidence interval, 0.764-0.994) was revealed to be predictive of the prognosis of patients with ccRCC. Further analysis revealed that low LDHD expression (P<0.0001) was significantly associated with a poor prognosis in terms of OS. Additionally, the expression of LDHD (P<0.0001) was significantly different in patients with ccRCC compared with paired controls. In the FUSCC cohort, low LDHD expression was also associated with a poor OS (P=0.0103), and the tumour pathological T stage was a factor that influenced the expression of LDHD (P=0.0120). Furthermore, the expression of LDHD influenced the serum LDH level (P=0.0126). The downregulation of LDHD expression may be a predictor of poor prognosis in patients with ccRCC.
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Affiliation(s)
- Yue Wang
- Department of Urology, Fudan University Shanghai Cancer Centre, Shanghai 200032, P.R. China
- Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, P.R. China
| | - Gaoxiang Li
- Department of Urology, Fudan University Shanghai Cancer Centre, Shanghai 200032, P.R. China
- Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, P.R. China
| | - Fangning Wan
- Department of Urology, Fudan University Shanghai Cancer Centre, Shanghai 200032, P.R. China
- Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, P.R. China
| | - Bo Dai
- Department of Urology, Fudan University Shanghai Cancer Centre, Shanghai 200032, P.R. China
- Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, P.R. China
| | - Dingwei Ye
- Department of Urology, Fudan University Shanghai Cancer Centre, Shanghai 200032, P.R. China
- Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, P.R. China
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11
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Zhou T, Qin L, Zhu X, Shen W, Zou J, Wang Z, Wei Y. The D-lactate dehydrogenase MoDLD1 is essential for growth and infection-related development in Magnaporthe oryzae. Environ Microbiol 2017; 19:3938-3958. [PMID: 28654182 DOI: 10.1111/1462-2920.13794] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Revised: 04/28/2017] [Accepted: 05/04/2017] [Indexed: 12/28/2022]
Abstract
Rice blast disease caused by Magnaporthe oryzae is initiated by the attachment of conidia to plant surfaces. Germ tubes emerging from conidia develop melanized appressoria to physically penetrate the host surface. Previous studies revealed that appressorium development requires the breakdown of storage lipids and glycogen that occur in peroxisomes and the cytosol respectively, culminating in production of pyruvate. However, the downstream product(s) entering the mitochondria for further oxidation is unclear. In this study, we aimed to investigate the molecular basis underlying the metabolic flux towards the mitochondria associated with the infectious-related development in M. oryzae. We showed that D-lactate is a key intermediate metabolite of the mobilization of lipids and glycogen, and its oxidative conversion to pyruvate is catalysed by a mitochondrial D-lactate dehydrogenase MoDLD1. Deletion of MoDLD1 caused defects in conidiogenesis and appressorium formation, and subsequently the loss of fungal pathogenicity. Further analyses demonstrated that MoDLD1 activity is involved in the maintenance of redox homeostasis during conidial germination. Thus, MoDLD1 is a critical modulator that channels metabolite flow to the mitochondrion coupling cellular redox state, and contributes to development and virulence of M. oryzae.
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Affiliation(s)
- Tengsheng Zhou
- Department of Biology, College of Arts and Science, University of Saskatchewan, Saskatoon, SK, S7N 5E2, Canada
| | - Li Qin
- Department of Biology, College of Arts and Science, University of Saskatchewan, Saskatoon, SK, S7N 5E2, Canada
| | - Xiaohan Zhu
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Wenyun Shen
- National Research Council of Canada, Plant Biotechnology Institute, Saskatoon SK, S7N 0W9, Canada
| | - Jitao Zou
- National Research Council of Canada, Plant Biotechnology Institute, Saskatoon SK, S7N 0W9, Canada
| | - Zonghua Wang
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Yangdou Wei
- Department of Biology, College of Arts and Science, University of Saskatchewan, Saskatoon, SK, S7N 5E2, Canada
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Peleh V, Cordat E, Herrmann JM. Mia40 is a trans-site receptor that drives protein import into the mitochondrial intermembrane space by hydrophobic substrate binding. eLife 2016; 5. [PMID: 27343349 PMCID: PMC4951193 DOI: 10.7554/elife.16177] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Accepted: 06/24/2016] [Indexed: 11/13/2022] Open
Abstract
Many proteins of the mitochondrial IMS contain conserved cysteines that are oxidized to disulfide bonds during their import. The conserved IMS protein Mia40 is essential for the oxidation and import of these proteins. Mia40 consists of two functional elements: an N-terminal cysteine-proline-cysteine motif conferring substrate oxidation, and a C-terminal hydrophobic pocket for substrate binding. In this study, we generated yeast mutants to dissect both Mia40 activities genetically and biochemically. Thereby we show that the substrate-binding domain of Mia40 is both necessary and sufficient to promote protein import, indicating that trapping by Mia40 drives protein translocation. An oxidase-deficient Mia40 mutant is inviable, but can be partially rescued by the addition of the chemical oxidant diamide. Our results indicate that Mia40 predominantly serves as a trans-site receptor of mitochondria that binds incoming proteins via hydrophobic interactions thereby mediating protein translocation across the outer membrane by a ‘holding trap’ rather than a ‘folding trap’ mechanism. DOI:http://dx.doi.org/10.7554/eLife.16177.001 Human, yeast and other eukaryotic cells contain compartments called mitochondria that perform several vital tasks, including supplying the cell with energy. Each mitochondrion is surrounded by an inner and an outer membrane, which are separated by an intermembrane space that contains a host of molecules, including proteins. Intermembrane space proteins are made in the cytosol before being transported into the intermembrane space through pores in the mitochondrion’s outer membrane. Many of these proteins have the ability to form disulfide bonds within their structures, which help the proteins to fold and assemble correctly, but they only acquire these bonds once they have entered the intermembrane space. An enzyme called Mia40 sits inside the intermembrane space and helps other proteins to fold correctly. This Mia40-induced folding had been suggested to help proteins to move into the intermembrane space. Mia40 contains two important regions: one region acts as an enzyme and adds disulfide bonds to other proteins, and the other region binds to the intermembrane space proteins. Peleh et al. have now generated versions of Mia40 that lack one or the other of these regions in yeast cells, and then tested to see if these mutants could drive proteins across the outer membrane of mitochondria. The results show that it is the ability of Mia40 to bind proteins – and not its enzyme activity – that is essential for importing proteins into the intermembrane space. As disulfide bond formation is not critical for importing proteins into the intermembrane space, future studies could test whether Mia40 also helps to transport proteins that cannot form disulfide bonds. Presumably, Mia40 has a much broader relevance for importing mitochondrial proteins than was previously thought. DOI:http://dx.doi.org/10.7554/eLife.16177.002
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Affiliation(s)
- Valentina Peleh
- Cell Biology, University of Kaiserslautern, Kaiserslautern, Germany
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13
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Storey KB. Comparative enzymology-new insights from studies of an "old" enzyme, lactate dehydrogenase. Comp Biochem Physiol B Biochem Mol Biol 2015; 199:13-20. [PMID: 26688543 DOI: 10.1016/j.cbpb.2015.12.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2015] [Revised: 12/07/2015] [Accepted: 12/08/2015] [Indexed: 12/12/2022]
Abstract
Comparative enzymology explores the molecular mechanisms that alter the properties of enzymes to best fit and adapt them to the biotic demands and abiotic stresses that affect the cellular environment in which these protein catalysts function. For many years, comparative enzymology was primarily concerned with analyzing enzyme functional properties (e.g. substrate affinities, allosteric effectors, responses to temperature or pH, stabilizers, denaturants, etc.) in order to determine how enzyme properties were optimized to function under changing conditions. More recently it became apparent that posttranslational modifications of enzymes play a huge role in metabolic regulation. At first, such modifications appeared to target just crucial regulatory enzymes but recent work is showing that many dehydrogenases are also targets of posttranslational modification leading to substantial changes in enzyme properties. The present article focuses in particular on lactate dehydrogenase (LDH) showing that stress-induced changes in enzyme properties can be linked with reversible posttranslational modifications; e.g. changes in the phosphorylation state of LDH occur in response to dehydration stress in frogs and anoxia exposure of turtles and snails. Furthermore, these studies show that LDH is also a target of other posttranslational modifications including acetylation, methylation and ubiquitination that change in response to anoxia or dehydration stress. Selected new methods for exploring posttranslational modifications of dehydrogenases are discussed and new challenges for the future of comparative enzymology are presented that will help to achieve a deeper understanding of biochemical adaptation through enzyme regulation.
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Affiliation(s)
- Kenneth B Storey
- Institute of Biochemistry, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada.
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14
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Schulz C, Schendzielorz A, Rehling P. Unlocking the presequence import pathway. Trends Cell Biol 2015; 25:265-75. [DOI: 10.1016/j.tcb.2014.12.001] [Citation(s) in RCA: 103] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Revised: 11/26/2014] [Accepted: 12/01/2014] [Indexed: 10/24/2022]
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15
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Støving Dam C, Alejo Perez Henarejos S, Tsolakou T, Alexander Segato C, Gammelgaard B, Yellol GS, Ruiz J, Lambert IH, Stürup S. In vitro characterization of a novel C,N-cyclometalated benzimidazole Ru(II) arene complex: stability, intracellular distribution and binding, effects on organic osmolyte homeostasis and induction of apoptosis. Metallomics 2015; 7:885-95. [PMID: 25805368 DOI: 10.1039/c5mt00056d] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In the present work a novel C,N-cyclometalated benzimidazole Ru(ii) arene complex (GY34) was characterized by applying an alternative, diverse approach considering both chemical and biological aspects. RP-HPLC-ICP-MS and RP-HPLC-ESI-MS analysis proved that GY34 in both RPMI-1640 cell medium and ammonium acetate buffer was transformed into several subspecies and the importance of evaluating and controlling analyte stability throughout experiments was demonstrated. Applying a novel cell fractionation protocol GY34 was found to target cell nuclei and mitochondria in Ehrlich Lettré Ascites (ELA) cells, with the intracellular distribution depending on GY34 concentration in the cell medium during incubation. In ELA cells 96 ± 0.2% of cytosolic GY34 was bound to high-molecular species. Furthermore, using the tracer technique GY34 was found to reduce uptake and increase release of the organic osmolyte taurine in ELA cells, with innate resistance to Cisplatin and in A2780 human ovarian cancer cells, with acquired resistance to Cisplatin. Importantly, FACS analysis revealed that GY34 induced apoptosis in ELA cells. The present data suggest the potential of GY34 in overcoming Cisplatin resistance. The methodology applied can be used as a general protocol and an additional tool in the initial evaluation of novel metal-based drugs.
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Affiliation(s)
- Celina Støving Dam
- University of Copenhagen, Department of Pharmacy, Universitetsparken 2, 2100 Copenhagen Ø, Denmark.
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Gudipati V, Koch K, Lienhart WD, Macheroux P. The flavoproteome of the yeast Saccharomyces cerevisiae. BIOCHIMICA ET BIOPHYSICA ACTA 2014; 1844:535-44. [PMID: 24373875 PMCID: PMC3991850 DOI: 10.1016/j.bbapap.2013.12.015] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Revised: 12/18/2013] [Accepted: 12/21/2013] [Indexed: 01/29/2023]
Abstract
Genome analysis of the yeast Saccharomyces cerevisiae identified 68 genes encoding flavin-dependent proteins (1.1% of protein encoding genes) to which 47 distinct biochemical functions were assigned. The majority of flavoproteins operate in mitochondria where they participate in redox processes revolving around the transfer of electrons to the electron transport chain. In addition, we found that flavoenzymes play a central role in various aspects of iron metabolism, such as iron uptake, the biogenesis of iron-sulfur clusters and insertion of the heme cofactor into apocytochromes. Another important group of flavoenzymes is directly (Dus1-4p and Mto1p) or indirectly (Tyw1p) involved in reactions leading to tRNA-modifications. Despite the wealth of genetic information available for S. cerevisiae, we were surprised that many flavoproteins are poorly characterized biochemically. For example, the role of the yeast flavodoxins Pst2p, Rfs1p and Ycp4p with regard to their electron donor and acceptor is presently unknown. Similarly, the function of the heterodimeric Aim45p/Cir1p, which is homologous to the electron-transferring flavoproteins of higher eukaryotes, in electron transfer processes occurring in the mitochondrial matrix remains to be elucidated. This lack of information extends to the five membrane proteins involved in riboflavin or FAD transport as well as FMN and FAD homeostasis within the yeast cell. Nevertheless, several yeast flavoproteins, were identified as convenient model systems both in terms of their mechanism of action as well as structurally to improve our understanding of diseases caused by dysfunctional human flavoprotein orthologs.
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Affiliation(s)
- Venugopal Gudipati
- Graz University of Technology, Institute of Biochemistry, Petersgasse 12, A-8010 Graz, Austria
| | - Karin Koch
- Graz University of Technology, Institute of Biochemistry, Petersgasse 12, A-8010 Graz, Austria
| | - Wolf-Dieter Lienhart
- Graz University of Technology, Institute of Biochemistry, Petersgasse 12, A-8010 Graz, Austria
| | - Peter Macheroux
- Graz University of Technology, Institute of Biochemistry, Petersgasse 12, A-8010 Graz, Austria.
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Potent l-lactic acid assimilation of the fermentative and heterothallic haploid yeast Saccharomyces cerevisiae NAM34-4C. J Biosci Bioeng 2014; 117:65-70. [DOI: 10.1016/j.jbiosc.2013.06.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Revised: 05/10/2013] [Accepted: 06/03/2013] [Indexed: 11/22/2022]
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Hewitt VL, Gabriel K, Traven A. The ins and outs of the intermembrane space: diverse mechanisms and evolutionary rewiring of mitochondrial protein import routes. Biochim Biophys Acta Gen Subj 2013; 1840:1246-53. [PMID: 23994494 DOI: 10.1016/j.bbagen.2013.08.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2013] [Revised: 08/09/2013] [Accepted: 08/20/2013] [Indexed: 11/24/2022]
Abstract
BACKGROUND Mitochondrial biogenesis is an essential process in all eukaryotes. Import of proteins from the cytosol into mitochondria is a key step in organelle biogenesis. Recent evidence suggests that a given mitochondrial protein does not take the same import route in all organisms, suggesting that pathways of mitochondrial protein import can be rewired through evolution. Examples of this process so far involve proteins destined to the mitochondrial intermembrane space (IMS). SCOPE OF REVIEW Here we review the components, substrates and energy sources of the known mechanisms of protein import into the IMS. We discuss evolutionary rewiring of the IMS import routes, focusing on the example of the lactate utilisation enzyme cytochrome b2 (Cyb2) in the model yeast Saccharomyces cerevisiae and the human fungal pathogen Candida albicans. MAJOR CONCLUSIONS There are multiple import pathways used for protein entry into the IMS and they form a network capable of importing a diverse range of substrates. These pathways have been rewired, possibly in response to environmental pressures, such as those found in the niches in the human body inhabited by C. albicans. GENERAL SIGNIFICANCE We propose that evolutionary rewiring of mitochondrial import pathways can adjust the metabolic fitness of a given species to their environmental niche. This article is part of a Special Issue entitled Frontiers of Mitochondrial.
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Affiliation(s)
- Victoria L Hewitt
- Department of Biochemistry and Molecular Biology, Building 77, Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne 3800, Australia.
| | - Kipros Gabriel
- Department of Biochemistry and Molecular Biology, Building 77, Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne 3800, Australia.
| | - Ana Traven
- Department of Biochemistry and Molecular Biology, Building 77, Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne 3800, Australia.
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Park K, Botelho SC, Hong J, Österberg M, Kim H. Dissecting stop transfer versus conservative sorting pathways for mitochondrial inner membrane proteins in vivo. J Biol Chem 2012. [PMID: 23184936 DOI: 10.1074/jbc.m112.409748] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mitochondrial inner membrane proteins that carry an N-terminal presequence are sorted by one of two pathways: stop transfer or conservative sorting. However, the sorting pathway is known for only a small number of proteins, in part due to the lack of robust experimental tools with which to study. Here we present an approach that facilitates determination of inner membrane protein sorting pathways in vivo by fusing a mitochondrial inner membrane protein to the C-terminal part of Mgm1p containing the rhomboid cleavage region. We validated the Mgm1 fusion approach using a set of proteins for which the sorting pathway is known, and determined sorting pathways of inner membrane proteins for which the sorting mode was previously uncharacterized. For Sdh4p, a multispanning membrane protein, our results suggest that both conservative sorting and stop transfer mechanisms are required for insertion. Furthermore, the sorting process of Mgm1 fusion proteins was analyzed under different growth conditions and yeast mutant strains that were defective in the import motor or the m-AAA protease function. Our results show that the sorting of mitochondrial proteins carrying moderately hydrophobic transmembrane segments is sensitive to cellular conditions, implying that mitochondrial import and membrane sorting in the physiological environment may be dynamically tuned.
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Affiliation(s)
- Kwangjin Park
- School of Biological Sciences, Seoul National University, Building 504-421, Seoul 151-747, South Korea
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20
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Mitochondrial involvement to methylglyoxal detoxification: D-Lactate/Malate antiporter in Saccharomyces cerevisiae. Antonie van Leeuwenhoek 2012; 102:163-75. [PMID: 22460278 DOI: 10.1007/s10482-012-9724-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2011] [Accepted: 03/14/2012] [Indexed: 12/11/2022]
Abstract
Research during the last years has accumulated a large body of data that suggest that a permanent high flux through the glycolytic pathway may be a source of intracellular toxicity via continuous generation of endogenous reactive dicarbonyl compound methylglyoxal (MG). MG detoxification by the action of the glyoxalase system produces D-lactate. Thus, this article extends our previous work and presents new insights concerning D-lactate fate in aerobically grown yeast cells. Biochemical studies using intact functional mitochondrial preparations derived from Saccharomyces cerevisiae show that D-lactate produced in the extramitochondrial phase can be taken up by mitochondria, metabolised inside the organelles with efflux of newly synthesized malate. Experiments were carried out photometrically and the rate of malate efflux was measured by use of NADP(+) and malic enzyme and it depended on the rate of transport across the mitochondrial membrane. It showed saturation characteristics (K(m) = 20 μM; V(max) = 6 nmol min(-1) mg(-1) of mitochondrial protein) and was inhibited by α-cyanocinnamate, a non-penetrant compound. Our data reveal that reducing equivalents export from mitochondria is due to the occurrence of a putative D-lactate/malate antiporter which differs from both D-lactate/pyruvate antiporter and D-lactate/H(+) symporter as shown by the different V(max) values, pH profile and inhibitor sensitivity. Based on these results we propose that D-lactate translocators and D-lactate dehydrogenases work together for decreasing the production of MG from the cytosol, thus mitochondria could play a pro-survival role in the metabolic stress response as well as for D-lactate-dependent gluconeogenesis.
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Abstract
Depending on the organism, mitochondria consist approximately of 500-1,400 different proteins. By far most of these proteins are encoded by nuclear genes and synthesized on cytosolic ribosomes. Targeting signals direct these proteins into mitochondria and there to their respective subcompartment: the outer membrane, the intermembrane space (IMS), the inner membrane, and the matrix. Membrane-embedded translocation complexes allow the translocation of proteins across and, in the case of membrane proteins, the insertion into mitochondrial membranes. A small number of proteins are encoded by the mitochondrial genome: Most mitochondrial translation products represent hydrophobic proteins of the inner membrane which-together with many nuclear-encoded proteins-form the respiratory chain complexes. This chapter gives an overview on the mitochondrial protein translocases and the mechanisms by which they drive the transport and assembly of mitochondrial proteins.
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Froehlich JE, Keegstra K. The role of the transmembrane domain in determining the targeting of membrane proteins to either the inner envelope or thylakoid membrane. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2011; 68:844-56. [PMID: 21838779 DOI: 10.1111/j.1365-313x.2011.04735.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Chloroplastic membrane proteins can be targeted to any of three distinct membrane systems, i.e., the outer envelope membrane (OEM), inner envelope membrane (IEM), and thylakoid membrane. This complex structure of chloroplasts adds significantly to the challenge of studying protein targeting to various membrane sub-compartments within a chloroplast. In this investigation, we examined the role played by the transmembrane domain (TMD) in directing membrane proteins to either the IEM or thylakoid membrane. Using the IEM protein, Arc6 (Accumulation and Replication of Chloroplasts 6), we exchanged the stop-transfer TMD of Arc6 with various TMDs derived from different IEM and thylakoid membrane proteins and monitored the subcellular localization of these Arc6-hybrid proteins. We showed that when the Arc6 TMD was replaced with a TMD derived from various thylakoid membrane proteins, these Arc6(thylTMD) hybrid proteins could be directed to the thylakoid membrane rather than to the IEM. Conversely, when the TMD of the thylakoid membrane proteins, STN8 (State Transition protein kinase 8) or Plsp1 (Plastidic type I signal peptidase 1), was replaced with the stop-transfer TMD of Arc6, STN8 and Plsp1 were halted at the IEM. From our investigation, we conclude that the TMD plays a critical role in targeting integral membrane proteins to either the IEM or thylakoid membrane.
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Affiliation(s)
- John E Froehlich
- Michigan State University-Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI 48824, USA.
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23
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Role of the import motor in insertion of transmembrane segments by the mitochondrial TIM23 complex. EMBO Rep 2011; 12:542-8. [PMID: 21546912 DOI: 10.1038/embor.2011.72] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2010] [Revised: 03/16/2011] [Accepted: 03/18/2011] [Indexed: 11/08/2022] Open
Abstract
The TIM23 complex mediates translocation of proteins across, and their lateral insertion into, the mitochondrial inner membrane. Translocation of proteins requires both the membrane-embedded core of the complex and its ATP-dependent import motor. Insertion of some proteins, however, occurs in the absence of ATP, questioning the need for the import motor during lateral insertion. We show here that the import motor associates with laterally inserted proteins even when its ATPase activity is not required. Furthermore, our results suggest a role for the import motor in lateral insertion. Thus, the import motor is involved in ATP-dependent translocation and ATP-independent lateral insertion.
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24
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Charged flanking residues control the efficiency of membrane insertion of the first transmembrane segment in yeast mitochondrial Mgm1p. FEBS Lett 2011; 585:1238-42. [PMID: 21457713 DOI: 10.1016/j.febslet.2011.03.056] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2011] [Revised: 03/24/2011] [Accepted: 03/24/2011] [Indexed: 11/20/2022]
Abstract
Mgm1p is a nuclearly encoded GTPase important for mitochondrial fusion. Long and short isoforms of the protein are generated in a unique "alternative topogenesis" process in which the most N-terminal of two hydrophobic segments in the protein is inserted into the inner mitochondrial membrane in about half of the molecules and translocated across the inner membrane in the other half. In the latter population, the second hydrophobic segment is cleaved by the inner membrane protease Pcp1p, generating the short isoform. Here, we show that charged residues in the regions flanking the first segment critically affect the ratio between the two isoforms, providing new insight into the importance of charged residues in the insertion of proteins into the mitochondrial inner membrane.
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25
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Sakai H, Nagahama K, Taguchi H, Akamatsu T, Morimura S, Kida K, Matsuoka M. Functional replacement of yeast flavocytochrome b2 with bacterial l-lactate dehydrogenase. J Biosci Bioeng 2010; 110:269-72. [DOI: 10.1016/j.jbiosc.2010.03.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2010] [Revised: 03/16/2010] [Accepted: 03/23/2010] [Indexed: 11/30/2022]
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26
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Schäfer A, Zick M, Kief J, Steger M, Heide H, Duvezin-Caubet S, Neupert W, Reichert AS. Intramembrane proteolysis of Mgm1 by the mitochondrial rhomboid protease is highly promiscuous regarding the sequence of the cleaved hydrophobic segment. J Mol Biol 2010; 401:182-93. [PMID: 20558178 DOI: 10.1016/j.jmb.2010.06.014] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2010] [Revised: 05/28/2010] [Accepted: 06/08/2010] [Indexed: 11/19/2022]
Abstract
Rhomboids are a family of intramembrane serine proteases that are conserved in bacteria, archaea, and eukaryotes. They are required for numerous fundamental cellular functions such as quorum sensing, cell signaling, and mitochondrial dynamics. Mitochondrial rhomboids form an evolutionarily distinct class of rhomboids. It is largely unclear how their activity is controlled and which substrate determinants are responsible for recognition and cleavage. We investigated these requirements for the mitochondrial rhomboid protease Pcp1 and its substrate Mgm1. In contrast to several other rhomboid proteases, Pcp1 does not require helix-breaking amino acids in the cleaved hydrophobic region of Mgm1, termed 'rhomboid cleavage region' (RCR). Even transmembrane segments of inner membrane proteins that are normally not processed by Pcp1 become cleavable when put in place of the authentic RCR of Mgm1. We further show that mutational alterations of a highly negatively charged region located C-terminally to the RCR led to a strong processing defect. Moreover, we show that the determinants required for Mgm1 processing by mitochondrial rhomboid protease are conserved during evolution, as PARL (the human ortholog of Pcp1) showed similar substrate requirements. These results suggest a surprising promiscuity of the mitochondrial rhomboid protease regarding the sequence requirements of the cleaved hydrophobic segment. We propose a working hypothesis on how the mitochondrial rhomboid protease can, despite this promiscuity, achieve a high specificity in recognizing Mgm1. This hypothesis relates to the exceptional biogenesis pathway of Mgm1.
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Affiliation(s)
- Anja Schäfer
- CEF Makromolekulare Komplexe, Mitochondriale Biologie, Fachbereich Medizin, Goethe-Universität Frankfurt am Main, Theodor-Stern-Kai 7, 60590 Frankfurt am Main, Germany
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27
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Mokranjac D, Neupert W. The many faces of the mitochondrial TIM23 complex. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2010; 1797:1045-54. [PMID: 20116361 DOI: 10.1016/j.bbabio.2010.01.026] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2009] [Revised: 01/18/2010] [Accepted: 01/21/2010] [Indexed: 01/24/2023]
Abstract
The TIM23 complex in the inner membrane of mitochondria mediates import of essentially all matrix proteins and a large number of inner membrane proteins. Here we present an overview on the latest insights into the structure and function of this remarkable molecular machine.
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Affiliation(s)
- Dejana Mokranjac
- Institute for Physiological Chemistry and Munich Center for Integrated Protein Science CIPSM, Ludwig-Maximilians University, Butenandtstr. 5, 81377 Munich, Germany.
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28
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Novikova LA, Faletrov YV, Kovaleva IE, Mauersberger S, Luzikov VN, Shkumatov VM. From structure and functions of steroidogenic enzymes to new technologies of gene engineering. BIOCHEMISTRY (MOSCOW) 2010; 74:1482-504. [DOI: 10.1134/s0006297909130057] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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29
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An unusual ERAD-like complex is targeted to the apicoplast of Plasmodium falciparum. EUKARYOTIC CELL 2009; 8:1134-45. [PMID: 19502583 DOI: 10.1128/ec.00083-09] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Many apicomplexan parasites, including Plasmodium falciparum, harbor a so-called apicoplast, a complex plastid of red algal origin which was gained by a secondary endosymbiotic event. The exact molecular mechanisms directing the transport of nuclear-encoded proteins to the apicoplast of P. falciparum are not well understood. Recently, in silico analyses revealed a second copy of proteins homologous to components of the endoplasmic reticulum (ER)-associated protein degradation (ERAD) system in organisms with secondary plastids, including the malaria parasite P. falciparum. These proteins are predicted to be endowed with an apicoplast targeting signal and are suggested to play a role in the transport of nuclear-encoded proteins to the apicoplast. Here, we have studied components of this ERAD-derived putative preprotein translocon complex in malaria parasites. Using transfection technology coupled with fluorescence imaging techniques we can demonstrate that the N terminus of several ERAD-derived components targets green fluorescent protein to the apicoplast. Furthermore, we confirm that full-length PfsDer1-1 and PfsUba1 (homologues of yeast ERAD components) localize to the apicoplast, where PfsDer1-1 tightly associates with membranes. Conversely, PfhDer1-1 (a host-specific copy of the Der1-1 protein) localizes to the ER. Our data suggest that ERAD components have been "rewired" to provide a conduit for protein transport to the apicoplast. Our results are discussed in relation to the nature of the apicoplast protein transport machinery.
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30
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Import of hybrid forms of CYP11A1 into yeast mitochondria. Biochim Biophys Acta Gen Subj 2008; 1780:1121-30. [DOI: 10.1016/j.bbagen.2008.06.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2008] [Revised: 06/05/2008] [Accepted: 06/16/2008] [Indexed: 11/21/2022]
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31
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Yamada Y, Harashima H. Mitochondrial drug delivery systems for macromolecule and their therapeutic application to mitochondrial diseases. Adv Drug Deliv Rev 2008; 60:1439-62. [PMID: 18655816 DOI: 10.1016/j.addr.2008.04.016] [Citation(s) in RCA: 185] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2008] [Accepted: 04/21/2008] [Indexed: 11/30/2022]
Abstract
Mitochondrial dysfunction has been implicated in a variety of human disorders--the so-called mitochondrial diseases. Therefore, the organelle is a promising therapeutic drug target. In this review, we describe the key role of mitochondria in living cells, a number of mitochondrial drug delivery systems and mitochondria-targeted therapeutic strategies. In particular, we discuss mitochondrial delivery of macromolecules, such as proteins and nucleic acids. The discussion of protein delivery is limited primarily to the mitochondrial import machinery. In the section on mitochondrial gene delivery and therapy, we discuss mitochondrial diseases caused by mutations in mitochondrial DNA, several gene delivery strategies and approaches to mitochondrial gene therapy. This review also summarizes our current efforts regarding liposome-based delivery system including use of a multifunctional envelope-type nano-device (MEND) and mitochondrial liposome-based delivery as anti-cancer therapies. Furthermore, we introduce the novel MITO-Porter--a liposome-based mitochondrial delivery system that functions using a membrane-fusion mechanism.
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Affiliation(s)
- Yuma Yamada
- Laboratory for Molecular Design of Pharmaceutics, Faculty of Pharmaceutical Sciences, Hokkaido University, Kita-12, Nishi-6, Kita-ku, Sapporo 060-0812, Japan
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32
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Protein complexes in bacterial and yeast mitochondrial membranes differ in their sensitivity towards dissociation by SDS. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2008; 1784:2012-8. [PMID: 18817900 DOI: 10.1016/j.bbapap.2008.08.020] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2008] [Revised: 08/20/2008] [Accepted: 08/22/2008] [Indexed: 11/22/2022]
Abstract
Previously, a 2D gel electrophoresis approach was developed for the Escherichia coli inner membrane, which detects membrane protein complexes that are stable in sodium dodecyl sulfate (SDS) at room temperature, and dissociate under the influence of trifluoroethanol [R. E. Spelbrink et al., J. Biol. Chem. 280 (2005), 28742-8]. Here, the method was applied to the evolutionarily related mitochondrial inner membrane that was isolated from the yeast Saccharomyces cerevisiae. Surprisingly, only very few proteins were found to be dissociated by trifluoroethanol of which Lpd1p, a component of multiple protein complexes localized in the mitochondrial matrix, is the most prominent. Usage of either milder or more stringent conditions did not yield any additional proteins that were released by fluorinated alcohols. This strongly suggests that membrane protein complexes in yeast are less stable in SDS solution than their E. coli counterparts, which might be due to the overall reduced hydrophobicity of mitochondrial transmembrane proteins.
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Chapter 5 New Insights into the Mechanism of Precursor Protein Insertion into the Mitochondrial Membranes. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2008; 268:147-90. [DOI: 10.1016/s1937-6448(08)00805-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/10/2023]
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34
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Tripp J, Inoue K, Keegstra K, Froehlich JE. A novel serine/proline-rich domain in combination with a transmembrane domain is required for the insertion of AtTic40 into the inner envelope membrane of chloroplasts. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2007; 52:824-38. [PMID: 17883373 DOI: 10.1111/j.1365-313x.2007.03279.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
AtTic40 is part of the chloroplastic protein import apparatus that is anchored in the inner envelope membrane by a single N-terminal transmembrane domain, and has a topology in which the bulk of the C-terminal domain is oriented toward the stroma. The targeting of AtTic40 to the inner envelope membrane involves two steps. Using an in vitro import assay, we showed that the sorting of AtTic40 requires a bipartite transit peptide, which was first cleaved by the stromal processing peptidase (SPP), thus generating a soluble AtTic40 stromal intermediate (iAtTic40). iAtTic40 was further processed by a second unknown peptidase, which generates its mature form (mAtTic40). Using deletion mutants, we identified a sequence motif N-terminal of the transmembrane domain that was essential for reinsertion of iAtTic40 into the inner envelope membrane. We have designated this region a serine/proline-rich (S/P-rich) domain and present a model describing its role in the targeting of AtTic40 to the inner envelope membrane.
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Affiliation(s)
- Joanna Tripp
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI 48823, USA
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35
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Abstract
About 10% to 15% of the nuclear genes of eukaryotic organisms encode mitochondrial proteins. These proteins are synthesized in the cytosol and recognized by receptors on the surface of mitochondria. Translocases in the outer and inner membrane of mitochondria mediate the import and intramitochondrial sorting of these proteins; ATP and the membrane potential are used as energy sources. Chaperones and auxiliary factors assist in the folding and assembly of mitochondrial proteins into their native, three-dimensional structures. This review summarizes the present knowledge on the import and sorting of mitochondrial precursor proteins, with a special emphasis on unresolved questions and topics of current research.
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Affiliation(s)
- Walter Neupert
- Institut für Physiologische Chemie, Universität München, 81377 München, Germany.
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36
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MacKenzie JA, Payne RM. Mitochondrial protein import and human health and disease. Biochim Biophys Acta Mol Basis Dis 2006; 1772:509-23. [PMID: 17300922 PMCID: PMC2702852 DOI: 10.1016/j.bbadis.2006.12.002] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2006] [Revised: 12/06/2006] [Accepted: 12/07/2006] [Indexed: 12/31/2022]
Abstract
The targeting and assembly of nuclear-encoded mitochondrial proteins are essential processes because the energy supply of humans is dependent upon the proper functioning of mitochondria. Defective import of mitochondrial proteins can arise from mutations in the targeting signals within precursor proteins, from mutations that disrupt the proper functioning of the import machinery, or from deficiencies in the chaperones involved in the proper folding and assembly of proteins once they are imported. Defects in these steps of import have been shown to lead to oxidative stress, neurodegenerative diseases, and metabolic disorders. In addition, protein import into mitochondria has been found to be a dynamically regulated process that varies in response to conditions such as oxidative stress, aging, drug treatment, and exercise. This review focuses on how mitochondrial protein import affects human health and disease.
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Affiliation(s)
- James A MacKenzie
- Department of Biological Sciences, 133 Piez Hall, State University of New York at Oswego, Oswego, NY 13126, USA.
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37
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Kleijn RJ, Geertman JMA, Nfor BK, Ras C, Schipper D, Pronk JT, Heijnen JJ, van Maris AJA, van Winden WA. Metabolic flux analysis of a glycerol-overproducing Saccharomyces cerevisiae strain based on GC-MS, LC-MS and NMR-derived C-labelling data. FEMS Yeast Res 2006; 7:216-31. [PMID: 17132142 DOI: 10.1111/j.1567-1364.2006.00180.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
This study focuses on unravelling the carbon and redox metabolism of a previously developed glycerol-overproducing Saccharomyces cerevisiae strain with deletions in the structural genes encoding triosephosphate isomerase (TPI1), the external mitochondrial NADH dehydrogenases (NDE1 and NDE2) and the respiratory chain-linked glycerol-3-phosphate dehydrogenase (GUT2). Two methods were used for analysis of metabolic fluxes: metabolite balancing and (13)C-labelling-based metabolic flux analysis. The isotopic enrichment of intracellular primary metabolites was measured both directly (liquid chromatography-MS) and indirectly through proteinogenic amino acids (nuclear magnetic resonance and gas chromatography-MS). Because flux sensitivity around several important metabolic nodes proved to be dependent on the applied technique, the combination of the three (13)C quantification techniques generated the most accurate overall flux pattern. When combined, the measured conversion rates and (13)C-labelling data provided evidence that a combination of assimilatory metabolism and pentose phosphate pathway activity diverted some of the carbon away from glycerol formation. Metabolite balancing indicated that this results in excess cytosolic NADH, suggesting the presence of a cytosolic NADH sink in addition to those that were deleted. The exchange flux of four-carbon dicarboxylic acids across the mitochondrial membrane, as measured by the (13)C-labelling data, supports a possible role of a malate/aspartate or malate/oxaloacetate redox shuttle in the transfer of these redox equivalents from the cytosol to the mitochondrial matrix.
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Affiliation(s)
- Roelco J Kleijn
- Department of Biotechnology, Delft University of Technology, Delft, the Netherlands
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38
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Cheung ECC, Joza N, Steenaart NAE, McClellan KA, Neuspiel M, McNamara S, MacLaurin JG, Rippstein P, Park DS, Shore GC, McBride HM, Penninger JM, Slack RS. Dissociating the dual roles of apoptosis-inducing factor in maintaining mitochondrial structure and apoptosis. EMBO J 2006; 25:4061-73. [PMID: 16917506 PMCID: PMC1560366 DOI: 10.1038/sj.emboj.7601276] [Citation(s) in RCA: 153] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2006] [Accepted: 07/19/2006] [Indexed: 11/09/2022] Open
Abstract
The mitochondrial protein apoptosis-inducing factor (AIF) translocates to the nucleus and induces apoptosis. Recent studies, however, have indicated the importance of AIF for survival in mitochondria. In the absence of a means to dissociate these two functions, the precise roles of AIF remain unclear. Here, we dissociate these dual roles using mitochondrially anchored AIF that cannot be released during apoptosis. Forebrain-specific AIF null (tel. AifDelta) mice have defective cortical development and reduced neuronal survival due to defects in mitochondrial respiration. Mitochondria in AIF deficient neurons are fragmented with aberrant cristae, indicating a novel role of AIF in controlling mitochondrial structure. While tel. AifDelta Apaf1(-/-) neurons remain sensitive to DNA damage, mitochondrially anchored AIF expression in these cells significantly enhanced survival. AIF mutants that cannot translocate into nucleus failed to induce cell death. These results indicate that the proapoptotic role of AIF can be uncoupled from its physiological function. Cell death induced by AIF is through its proapoptotic activity once it is translocated to the nucleus, not due to the loss of AIF from the mitochondria.
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Affiliation(s)
- Eric C C Cheung
- Ottawa Health Research Institute, Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Nicholas Joza
- IMBA, Institute of Molecular Biotechnology of the Austria Academy of Sciences, Vienna, Austria
| | | | - Kelly A McClellan
- Ottawa Health Research Institute, Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Margaret Neuspiel
- Ottawa Heart Institute, University of Ottawa, Ottawa, Ontario, Canada
| | - Stephen McNamara
- Ottawa Health Research Institute, Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Jason G MacLaurin
- Ottawa Health Research Institute, Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Peter Rippstein
- Ottawa Heart Institute, University of Ottawa, Ottawa, Ontario, Canada
| | - David S Park
- Ottawa Health Research Institute, Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Gordon C Shore
- Department of Biochemistry, McGill University, Montreal, Quebec, Canada
| | - Heidi M McBride
- Ottawa Heart Institute, University of Ottawa, Ottawa, Ontario, Canada
| | - Josef M Penninger
- IMBA, Institute of Molecular Biotechnology of the Austria Academy of Sciences, Vienna, Austria
| | - Ruth S Slack
- Ottawa Health Research Institute, Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
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39
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Major T, von Janowsky B, Ruppert T, Mogk A, Voos W. Proteomic analysis of mitochondrial protein turnover: identification of novel substrate proteins of the matrix protease pim1. Mol Cell Biol 2006; 26:762-76. [PMID: 16428434 PMCID: PMC1347025 DOI: 10.1128/mcb.26.3.762-776.2006] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
ATP-dependent oligomeric proteases are major components of cellular protein quality control systems. To investigate the role of proteolytic processes in the maintenance of mitochondrial functions, we analyzed the dynamic behavior of the mitochondrial proteome of Saccharomyces cerevisiae by two-dimensional (2D) polyacrylamide gel electrophoresis. By a characterization of the influence of temperature on protein turnover in isolated mitochondria, we were able to define four groups of proteins showing a differential susceptibility to proteolysis. The protein Pim1/LON has been shown to be the main protease in the mitochondrial matrix responsible for the removal of damaged or nonnative proteins. To assess the substrate range of Pim1 under in vivo conditions, we performed a quantitative comparison of the 2D protein spot patterns between wild-type and pim1Delta mitochondria. We were able to identify a novel subset of mitochondrial proteins that are putative endogenous substrates of Pim1. Using an in organello degradation assay, we confirmed the Pim1-specific, ATP-dependent proteolysis of the newly identified substrate proteins. We could demonstrate that the functional integrity of the Pim1 substrate proteins, in particular, the presence of intact prosthetic groups, had a major influence on the susceptibility to proteolysis.
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Affiliation(s)
- Tamara Major
- Institut für Biochemie und Molekularbiologie, Universität Freiburg, Hermann Herder Str. 7, 79104 Freiburg, Germany.
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40
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Minenko AN, Luzikov VN, Kovaleva IE. Use of the Addressing Sequence of Yeast D-Lactate Dehydrogenase for Insertion of CYP11A1p into the Inner Membrane of Yeast Mitochondria. BIOCHEMISTRY (MOSCOW) 2006; 71:32-8. [PMID: 16457615 DOI: 10.1134/s0006297906010044] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Mammalian cytochrome P450scc (CYP11A1p) is a pseudointegral protein of the inner membrane of mitochondria with the active center exposed in the matrix. Upon import of the CYP11A1p precursor into yeast mitochondria, only a minor part was incorporated into the inner mitochondrial membrane and acquired catalytic activity (Kovaleva, I. E., Novikova, L. A., Nazarov, P. A., Grivennikov, S. I., and Luzikov, V. N. (2003) Eur. J. Biochem., 270, 222-229). The present work is an attempt to increase the efficiency of this process by substitution of the inherent N-terminal presequence of CYP11A1p by the addressing signal of D-lactate dehydrogenase (D-LD) of the yeast Saccharomyces cerevisiae. D-LD is known to be inserted into the inner membrane of mitochondria through its transmembrane domain located close to the N-terminus of the polypeptide chain in such a way that the protein globule is exposed in the intermembrane space. The hybrid protein D-LD(1-72)-mCYP11A1p synthesized in yeast cells was imported into yeast mitochondria, underwent processing, and was inserted into the inner membrane on the side of the intermembrane space. In the presence of adrenodoxin and adrenodoxin reductase, the hybrid protein exhibited cholesterol side-chain cleavage activity. Thus, CYP11A1p insertion into the inner membrane of mitochondria mediated by the D-LD topogenic signal resulted in the catalytically active mCYP11A1p domain in the hybrid protein.
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Affiliation(s)
- A N Minenko
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
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41
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Meier S, Neupert W, Herrmann JM. Proline residues of transmembrane domains determine the sorting of inner membrane proteins in mitochondria. ACTA ACUST UNITED AC 2005; 170:881-8. [PMID: 16157698 PMCID: PMC2171449 DOI: 10.1083/jcb.200505126] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Most inner membrane proteins of mitochondria are synthesized in the cytosol and reach the inner membrane using one of two alternative sorting pathways. On the stop transfer route, proteins are arrested during import at the level of the inner membrane. The conservative sorting pathway involves translocation through the inner membrane and insertion from the matrix. It is unclear how the translocase of the inner membrane 23 protein translocation machinery differentiates between the two classes of proteins. Here we show that proline residues in hydrophobic stretches strongly disfavor the translocation arrest of transmembrane domains (TMDs) and favor the transfer of preproteins to the matrix. We propose that proline residues, together with the hydrophobicity of the TMD and the presence of charged residues COOH-terminally flanking the TMD, are determinants of the intramitochondrial sorting of inner membrane proteins.
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Affiliation(s)
- Stephan Meier
- Institut für Physiologische Chemie, Universität München, 81377 Munich, Germany
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42
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Pallotta ML, Valenti D, Iacovino M, Passarella S. Two separate pathways for d-lactate oxidation by Saccharomyces cerevisiae mitochondria which differ in energy production and carrier involvement. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2004; 1608:104-13. [PMID: 14871487 DOI: 10.1016/j.bbabio.2003.10.008] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2003] [Revised: 10/17/2003] [Accepted: 10/31/2003] [Indexed: 10/26/2022]
Abstract
In this work we looked at whether and how mitochondria isolated from Saccharomyces cerevisiae (SCM) oxidize d-lactate. We found that: (1). externally added d-lactate causes oxygen uptake by SCM with P/O ratio equal to 1.5; in the presence of antimycin A (AA), P/O ratio was 1.8, differently in the presence of the non-penetrant alpha-cyanocinnamate (alpha-CCN-) no P/O ratio could be measured. Consistently, mitochondrial electrical membrane potential (deltapsi) generation was found, due to externally added d-lactate in the presence of antimycin A, but not of alpha-CCN-. (2). SCM oxidize d-lactate in two different manners: (i). via inner membrane d-lactate dehydrogenase which leads to d-lactate oxidation without driving deltapsi generation and ATP synthesis and (ii). via the matrix d-lactate dehydrogenase, which drives deltapsi generation and ATP synthesis by using taken up d-lactate. (3). Pyruvate newly synthesised in the mitochondrial matrix is exported via the novel d-lactate/pyruvate antiporter. d-Lactate/pyruvate antiport proved to regulate the rate of pyruvate efflux in vitro. (4). The existence of the d-lactate/H+ symporter is also proposed as shown by mitochondrial swelling. The d-lactate carriers and d-lactate dehydrogenases could account for the removal of the toxic methylglyoxal from cytosol, as well as for the d-lactate-dependent gluconeogenesis.
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Affiliation(s)
- Maria Luigia Pallotta
- Dipartimento di Scienze Animali, Vegetali e dell'Ambiente, Università del Molise, Via De Sanctis, -86100 Campobasso, Italy
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43
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Endo T, Yamamoto H, Esaki M. Functional cooperation and separation of translocators in protein import into mitochondria, the double-membrane bounded organelles. J Cell Sci 2003; 116:3259-67. [PMID: 12857785 DOI: 10.1242/jcs.00667] [Citation(s) in RCA: 143] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Nearly all mitochondrial proteins are synthesized in the cytosol and subsequently imported into mitochondria with the aid of translocators: the TOM complex in the outer membrane, and the TIM23 and TIM22 complexes in the inner membrane. The TOM complex and the TIM complexes cooperate to achieve efficient transport of proteins to the matrix or into the inner membrane and several components, including Tom22, Tim23, Tim50 and small Tim proteins, mediate functional coupling of the two translocator systems. The TOM complex can be disconnected from the TIM systems and their energy sources (ATP and DeltaPsi), however, using alternative mechanisms to achieve vectorial protein translocation across the outer membrane
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Affiliation(s)
- Toshiya Endo
- Department of Chemistry, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan.
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44
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Herlan M, Vogel F, Bornhovd C, Neupert W, Reichert AS. Processing of Mgm1 by the rhomboid-type protease Pcp1 is required for maintenance of mitochondrial morphology and of mitochondrial DNA. J Biol Chem 2003; 278:27781-8. [PMID: 12707284 DOI: 10.1074/jbc.m211311200] [Citation(s) in RCA: 281] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The structure of mitochondria is highly dynamic and depends on the balance of fusion and fission processes. Deletion of the mitochondrial dynamin-like protein Mgm1 in yeast leads to extensive fragmentation of mitochondria and loss of mitochondrial DNA. Mgm1 and its human ortholog OPA1, associated with optic atrophy type I in humans, were proposed to be involved in fission or fusion of mitochondria or, alternatively, in remodeling of the mitochondrial inner membrane and cristae formation (Wong, E. D., Wagner, J. A., Gorsich, S. W., McCaffery, J. M., Shaw, J. M., and Nunnari, J. (2000) J. Cell Biol. 151, 341-352; Wong, E. D., Wagner, J. A., Scott, S. V., Okreglak, V., Holewinske, T. J., Cassidy-Stone, A., and Nunnari, J. (2003) J. Cell Biol. 160, 303-311; Sesaki, H., Southard, S. M., Yaffe, M. P., and Jensen, R. E. (2003) Mol. Biol. Cell, in press). Mgm1 and its orthologs exist in two forms of different lengths. To obtain new insights into their biogenesis and function, we have characterized these isoforms. The large isoform (l-Mgm1) contains an N-terminal putative transmembrane segment that is absent in the short isoform (s-Mgm1). The large isoform is an integral inner membrane protein facing the intermembrane space. Furthermore, the conversion of l-Mgm1 into s-Mgm1 was found to be dependent on Pcp1 (Mdm37/YGR101w) a recently identified component essential for wild type mitochondrial morphology. Pcp1 is a homolog of Rhomboid, a serine protease known to be involved in intercellular signaling in Drosophila melanogaster, suggesting a function of Pcp1 in the proteolytic maturation process of Mgm1. Expression of s-Mgm1 can partially complement the Deltapcp1 phenotype. Expression of both isoforms but not of either isoform alone was able to partially complement the Deltamgm1 phenotype. Therefore, processing of l-Mgm1 by Pcp1 and the presence of both isoforms of Mgm1 appear crucial for wild type mitochondrial morphology and maintenance of mitochondrial DNA.
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Affiliation(s)
- Mark Herlan
- Adolf-Butenandt-Institut für Physiologische Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 5, 81377 München, Germany
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45
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Abstract
During the evolution of mitochondria from free-living alpha-proteobacteria, many bacterial genes were transferred into the nuclear genome of eukaryotic cells. This required the development of both targeting signals on the respective polypeptides and protein translocation machineries (translocases) in the mitochondrial membranes. Most components of these translocases have no obvious homologies to bacterial proteins or proteins found in other organelles. Membrane integration of many inner membrane proteins, however, apparently occurs via a conserved sorting pathway whose components and characteristics resemble protein translocation in bacteria. Consistent with this, the topogenic signals of these mitochondrial inner membrane proteins mimic those of bacterial proteins. The requirement for post-translational transport to their final destination has placed considerable constraints on the evolution of mitochondrial protein sequences.
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Affiliation(s)
- Johannes M Herrmann
- Institut für Physiologische Chemie, Universität München, Butenandtstrasse 5, 81377 Münich, Germany.
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46
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Jensen RE, Dunn CD. Protein import into and across the mitochondrial inner membrane: role of the TIM23 and TIM22 translocons. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1592:25-34. [PMID: 12191765 DOI: 10.1016/s0167-4889(02)00261-6] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Import of nuclear-encoded mitochondrial proteins requires the action of at least two different import machines, called translocons, in the mitochondrial inner membrane (IM). The TIM23 complex mediates the translocation of proteins into the mitochondria matrix, whereas the TIM22 complex is required for the insertion of polytopic proteins into the IM. While the two translocons are distinct and composed of separate subunits, the essential reactions in each complex are carried out by homologous proteins. In addition, the core components of both the TIM23 and TIM22 translocons have been shown to form aqueous pores in the mitochondrial IM. In this review, we summarize what is known about import of proteins across the mitochondrial IM.
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Affiliation(s)
- Robert E Jensen
- Department of Cell Biology, The Johns Hopkins University School of Medicine, 725 N. Wolfe Street, Baltimore, MD 21205, USA.
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47
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Stuart R. Insertion of proteins into the inner membrane of mitochondria: the role of the Oxa1 complex. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1592:79-87. [PMID: 12191770 DOI: 10.1016/s0167-4889(02)00266-5] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The inner mitochondrial membrane harbors a large number of proteins that display a wide range of topological arrangements. The majority of these proteins are encoded in the cell's nucleus, but a few polytopic proteins, all subunits of respiratory chain complexes are encoded by the mitochondrial genome. A number of distinct sorting mechanisms exist to direct these proteins into the mitochondrial inner membrane. One of these pathways involves the export of proteins from the matrix into the inner membrane and is used by both proteins synthesized within the mitochondria, as well as by a subset of nuclear encoded proteins. Prior to embarking on the export pathway, nuclear encoded proteins using this sorting route are initially imported into the mitochondrial matrix from the cytosol, their site of synthesis. Protein export from the matrix into the inner membrane bears similarities to Sec-independent protein export in bacteria and requires the function of the Oxa1 protein. Oxa1 is a component of a general protein insertion site in yeast mitochondrial inner membrane used by both nuclear and mitochondrial DNA encoded proteins. Oxa1 is a member of the conserved Oxa1/YidC/Alb3 protein family found throughout prokaryotes throughout eukaryotes (where it is found in mitochondria and chloroplasts). The evidence to demonstrate that the Oxa1/YidC/Alb3 protein family represents a novel evolutionarily conserved membrane insertion machinery is reviewed here.
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Affiliation(s)
- Rosemary Stuart
- Department of Biology, Marquette University, 530 N. 15th Street, Milwaukee, WI 53233, USA.
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48
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Lode A, Paret C, Rödel G. Molecular characterization of Saccharomyces cerevisiae Sco2p reveals a high degree of redundancy with Sco1p. Yeast 2002; 19:909-22. [PMID: 12125048 DOI: 10.1002/yea.883] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
The Saccharomyces cerevisiae gene SCO1 has been shown to play an essential role in the transfer of copper to the Cu(A)-centre of the mitochondrial cytochrome c oxidase subunit Cox2p. By contrast, the function of Sco2p, the gene product of the highly homologous SCO2 gene, remains to be elucidated. Deletion of the SCO2 gene does not affect growth on a variety of carbon sources, including glycerol, lactate and ethanol. We report here, that Sco2p is anchored in the mitochondrial membrane by a single transmembrane segment and displays a similar tripartite structure as Sco1p. Most parts of Sco1p can be replaced by the homologous parts of Sco2p without loss of function. A short stretch of 13 amino acids, immediately adjacent to the transmembrane region, is crucial for Sco1p function and cannot be replaced by its Sco2p counterpart. We propose that this region is relevant for the correct spatial orientation of the C-terminal part of the protein. Immunoprecipitation and in vitro binding assays show that Sco2p interacts with the C-terminal portion of Cox2p. This interaction is neither dependent on bound copper ions nor on the presence of Sco1p. Furthermore we report on in vitro binding assays which show that Sco2p can form homomeric complexes, but also heteromeric complexes with Sco1p. Our data suggest that Sco2p is involved in the transfer of copper to Cox2p, but that this activity is insufficient for oxidative growth and not able to substitute for Sco1p activity.
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Affiliation(s)
- Anja Lode
- Institut für Genetik, Technische Universität Dresden, Mommsenstrasse 13, 01062 Dresden, Germany
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49
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Abstract
Proteins that are destined for the matrix of mitochondria are transported into this organelle by two translocases: the TOM complex, which transports proteins across the outer mitochondrial membrane; and the TIM23 complex, which gets them through the inner mitochondrial membrane. Two models have been proposed to explain how this protein-import machinery works -- a targeted Brownian ratchet, in which random motion is translated into vectorial motion, or a 'power stroke', which is exerted by a component of the import machinery. Here, we review the data for and against each model.
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Affiliation(s)
- Walter Neupert
- Institut für Physiologische Chemie, Universität München, Butenandtstrabetae 5, Gebäude B, D-81377 Munich, Germany.
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50
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Flick MJ, Konieczny SF. Identification of putative mammalian D-lactate dehydrogenase enzymes. Biochem Biophys Res Commun 2002; 295:910-6. [PMID: 12127981 DOI: 10.1016/s0006-291x(02)00768-4] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Mammalian L-isomer dehydrogenases represent an expansive and well characterized class of metabolic enzymes. Surprisingly, little is known regarding their evolutionarily distinct counterparts, D-isomer dehydrogenases, since few mammalian D-isomer 2-hydroxy acid enzymes have been isolated. Here we present the identification and initial characterization of putative human and murine D-lactate dehydrogenases (DLD) that can interact with the muscle-specific cysteine-rich protein CRP3/MLP. Sequence analysis reveals that the human and mouse transcripts encode novel proteins that display strong similarities to the yeast D-lactate dehydrogenase proteins DLD1, AIP2, and YEL071W. Expression analysis of the mammalian proteins indicates widespread distribution with transcripts present in striated muscle tissues and a variety of other tissue types. Immunofluorescence subcellular localization of the mouse DLD protein indicates that it resides within mitochondria, a feature shared by many dehydrogenases. The identification of the human and mouse DLD clones provides new insight regarding the activity of D-isomer-specific enzymes in mammalian cells.
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Affiliation(s)
- Matthew J Flick
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907-1392, USA
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