1
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Haynes V, Giulivi C. Calcium-Dependent Interaction of Nitric Oxide Synthase with Cytochrome c Oxidase: Implications for Brain Bioenergetics. Brain Sci 2023; 13:1534. [PMID: 38002494 PMCID: PMC10669843 DOI: 10.3390/brainsci13111534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Revised: 10/24/2023] [Accepted: 10/27/2023] [Indexed: 11/26/2023] Open
Abstract
Targeted nitric oxide production is relevant for maintaining cellular energy production, protecting against oxidative stress, regulating cell death, and promoting neuroprotection. This study aimed to characterize the putative interaction of nitric-oxide synthase with mitochondrial proteins. The primary finding of this study is that cytochrome c oxidase (CCO) subunit IV (CCOIV) is associated directly with NOS in brain mitochondria when calcium ions are present. The matrix side of CCOIV binds to the N-terminus of NOS, supported by the abrogation of the binding by antibodies towards the N-terminus of NOS. Evidence supporting the interaction between CCOIV and NOS was provided by the coimmunoprecipitation of NOS from detergent-solubilized whole rat brain mitochondria with antibodies to CCOIV and the coimmunoprecipitation of CCOIV from crude brain NOS preparations using antibodies to NOS. The CCOIV domain that interacts with NOS was identified using a series of overlapping peptides derived from the primary sequence of CCOIV. As calcium ions not only activate NOS, but also facilitate the docking of NOS to CCOIV, this study points to a dynamic mechanism of controlling the bioenergetics by calcium changes, thereby adapting bioenergetics to cellular demands.
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Affiliation(s)
- Virginia Haynes
- School of Veterinary Medicine, Department Molecular Biosciences, University of California Davis, Davis, CA 95616, USA
| | - Cecilia Giulivi
- School of Veterinary Medicine, Department Molecular Biosciences, University of California Davis, Davis, CA 95616, USA
- Medical Investigation of Neurodevelopmental Disorders (MIND) Institute UCDH, University of California Davis, Sacramento, CA 95817, USA
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2
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Ebanks B, Katyal G, Lucassen M, Papetti C, Chakrabarti L. Proteomic analysis of the ATP synthase interactome in notothenioids highlights a pathway that inhibits ceruloplasmin production. Am J Physiol Regul Integr Comp Physiol 2022; 323:R181-R192. [PMID: 35639858 PMCID: PMC9291420 DOI: 10.1152/ajpregu.00069.2022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Antarctic notothenioids have unique adaptations that allow them to thrive in sub-zero Antarctic waters. Within the suborder Notothenioidei, species of the family Channichthyidae (icefish) lack haemoglobin and in some instances myoglobin too. In studies of mitochondrial function of notothenioids, few have focussed specifically on ATP synthase. In this study, we find that the icefish Champsocephalus gunnari has a significantly higher level of ATP synthase subunit α expression than in red-blooded Notothenia rossii, but a much smaller interactome than the other species. We characterise the interactome of ATP synthase subunit a in two red-blooded species Trematomus bernacchii, N. rossii, and in the icefish Chionodraco rastrospinosus, and C. gunnari and find that in comparison with the other species, reactome enrichment for C. gunnari lacks chaperonin-mediated protein folding, and fewer oxidative-stress-associated proteins are present in the identified interactome of C. gunnari. Reactome enrichment analysis also identifies a transcript-specific translational silencing pathway for the iron oxidase protein ceruloplasmin, which has previously been reported in studies of icefish as distinct from other red-blooded fish and vertebrates in its activity and RNA transcript expression. Ceruloplasmin protein expression is detected by Western blot in the liver of T. bernacchii, but not in N. rossii, C. rastrospinosus, and C. gunnari. We suggest that the translation of ceruloplasmin transcripts is silenced by the identified pathway in icefish notothenioids, which is indicative of altered iron metabolism and Fe(II) detoxification.
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Affiliation(s)
- Brad Ebanks
- School of Veterinary Medicine and Science, University of Nottingham, Nottingham, United Kingdom
| | - Gunjan Katyal
- School of Veterinary Medicine and Science, University of Nottingham, Nottingham, United Kingdom
| | | | | | - Lisa Chakrabarti
- School of Veterinary Medicine and Science, University of Nottingham, Nottingham, United Kingdom.,MRC Versus Arthritis Centre for Musculoskeletal Ageing Research, United Kingdom
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3
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Gui YM, Wang RJ, Wang X, Wei YY. Using Deep Neural Networks to Improve the Performance of Protein–Protein Interactions Prediction. INT J PATTERN RECOGN 2020. [DOI: 10.1142/s0218001420520126] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Protein–protein interactions (PPIs) help to elucidate the molecular mechanisms of life activities and have a certain role in promoting disease treatment and new drug development. With the advent of the proteomics era, some PPIs prediction methods have emerged. However, the performances of these PPIs prediction methods still need to be optimized and improved. In order to optimize the performance of the PPIs prediction methods, we used the dropout method to reduce over-fitting by deep neural networks (DNNs), and combined with three types of feature extraction methods, conjoint triad (CT), auto covariance (AC) and local descriptor (LD), to build DNN models based on amino acid sequences. The results showed that the accuracy of the CT, AC and LD increased from 97.11% to 98.12%, 96.84% to 98.17%, and 95.30% to 95.60%, respectively. The loss values of the CT, AC and LD decreased from 27.47% to 14.96%, 65.91% to 17.82% and 36.23% to 15.34%, respectively. Experimental results show that dropout can optimize the performances of the DNN models. The results can provide a resource for scholars in future studies involving the prediction of PPIs. The experimental code is available at https://github.com/smalltalkman/hppi-tensorflow .
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Affiliation(s)
- Yuan-Miao Gui
- Institute of Intelligent Machines, Hefei Institute of Physics, Chinese Academy of Sciences, Hefei City, Anhui Province, P. R. China
- University of Science and Technology of China, Hefei City, Anhui Province, P. R. China
| | - Ru-Jing Wang
- Institute of Intelligent Machines, Hefei Institute of Physics, Chinese Academy of Sciences, Hefei City, Anhui Province, P. R. China
| | - Xue Wang
- Institute of Intelligent Machines, Hefei Institute of Physics, Chinese Academy of Sciences, Hefei City, Anhui Province, P. R. China
| | - Yuan-Yuan Wei
- Institute of Intelligent Machines, Hefei Institute of Physics, Chinese Academy of Sciences, Hefei City, Anhui Province, P. R. China
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4
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Motor recruitment to the TIM23 channel's lateral gate restricts polypeptide release into the inner membrane. Nat Commun 2018; 9:4028. [PMID: 30279421 PMCID: PMC6168564 DOI: 10.1038/s41467-018-06492-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 09/07/2018] [Indexed: 01/05/2023] Open
Abstract
The presequence translocase of the mitochondrial inner membrane (TIM23 complex) facilitates anterograde precursor transport into the matrix and lateral release of precursors with stop-transfer signal into the membrane (sorting). Sorting requires precursor exit from the translocation channel into the lipid phase through the lateral gate of the TIM23 complex. How the two transport modes are regulated and balanced against each other is unknown. Here we show that the import motor J-protein Pam18, which is essential for matrix import, controls lateral protein release into the lipid bilayer. Constitutively translocase-associated Pam18 obstructs lateral precursor transport. Concomitantly, Mgr2, implicated in precursor quality control, is displaced from the translocase. We conclude that during motor-dependent matrix protein transport, the transmembrane segment of Pam18 closes the lateral gate to promote anterograde polypeptide movement. This finding explains why a motor-free form of the translocase facilitates the lateral movement of precursors with a stop-transfer signal. The mitochondrial TIM23-complex facilitates anterograde precursor transport across the inner membrane into the matrix and lateral release of precursors into the membrane. Here authors show that the import motor J-protein Pam18 controls lateral protein release into the lipid bilayer.
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5
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Ke X, Xia XY, Zheng RC, Zheng YG. Identification of a consensus motif in Erg28p required for C-4 demethylation in yeast ergosterol biosynthesis based on mutation analysis. FEMS Microbiol Lett 2018; 365:4793250. [PMID: 29319811 DOI: 10.1093/femsle/fny002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Accepted: 01/02/2018] [Indexed: 01/15/2023] Open
Abstract
The Erg28p protein is localized to the endoplasmic reticulum, where it acts as a scaffold to tether the C-4 demethylase complex involved in the sterol biosynthesis pathway of Saccharomyces cerevisiae. However, due to the challenges involved in characterizing the interactions of membrane proteins, the precise region of Erg28p that is responsible for the assembly of this enzyme complex remains unknown. To address this question, mutants with serial truncations in the C-terminus of Erg28p were constructed based on a topology prediction of its transmembrane domain. Sterol profiles demonstrated that intermediates involved in the stepwise removal of the two C-4 methyl groups from the tetracyclic sterol ring were accumulated in the ERG28Δ135-447 strain. Homologous alignment of Erg28p further identified a highly conserved 10-amino acid sequence (63LS/QARTFGT/LWT72) within the truncated region of ERG28Δ136-273. Complementation of the BY4741/erg28 strain with the ScERG28Δ175-204 plasmid resulted both in a significant growth inhibition and a reduction of ergosterol biosynthesis compared with the plasmid without the Δ175-204 truncation. Furthermore, homology modeling of the Erg28p mutant indicated that the deletion of residues 63-72 significantly disrupted the 3D structure of the four parallel helices in Erg28p. Taken together, the data indicate that the region spanning amino acids 63-72 constitutes a key consensus motif within Erg28p that is required for sterol C-4 demethylation during ergosterol biosynthesis in S. cerevisiae.
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Affiliation(s)
- Xia Ke
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310014, P. R. China.,Engineering Research Center of Bioconversion and Biopurification of the Ministry of Education, Zhejiang University of Technology, Hangzhou 310014, P. R. China
| | - Xiao-Yuan Xia
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310014, P. R. China.,Engineering Research Center of Bioconversion and Biopurification of the Ministry of Education, Zhejiang University of Technology, Hangzhou 310014, P. R. China
| | - Ren-Chao Zheng
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310014, P. R. China.,Engineering Research Center of Bioconversion and Biopurification of the Ministry of Education, Zhejiang University of Technology, Hangzhou 310014, P. R. China
| | - Yu-Guo Zheng
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310014, P. R. China.,Engineering Research Center of Bioconversion and Biopurification of the Ministry of Education, Zhejiang University of Technology, Hangzhou 310014, P. R. China
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6
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Denkert N, Schendzielorz AB, Barbot M, Versemann L, Richter F, Rehling P, Meinecke M. Cation selectivity of the presequence translocase channel Tim23 is crucial for efficient protein import. eLife 2017; 6. [PMID: 28857742 PMCID: PMC5578737 DOI: 10.7554/elife.28324] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Accepted: 07/31/2017] [Indexed: 01/09/2023] Open
Abstract
Virtually all mitochondrial matrix proteins and a considerable number of inner membrane proteins carry a positively charged, N-terminal presequence and are imported by the TIM23 complex (presequence translocase) located in the inner mitochondrial membrane. The voltage-regulated Tim23 channel constitutes the actual protein-import pore wide enough to allow the passage of polypeptides with a secondary structure. In this study, we identify amino acids important for the cation selectivity of Tim23. Structure based mutants show that selectivity is provided by highly conserved, pore-lining amino acids. Mutations of these amino acid residues lead to reduced selectivity properties, reduced protein import capacity and they render the Tim23 channel insensitive to substrates. We thus show that the cation selectivity of the Tim23 channel is a key feature for substrate recognition and efficient protein import. The cells of animals, plants and other eukaryotic organisms contain compartments known as organelles that play many different roles. For example, compartments called mitochondria are responsible for supplying the chemical energy cells need to survive and grow. Two membranes surround each mitochondrion and energy is converted on the surface of the inner one. Mitochondria contain over 1,000 different proteins, most of which are produced in the main part of the cell and have to be transported into the mitochondria. A transport protein called Tim23 is part of a larger group or ‘complex’ of proteins that helps to import many other proteins into the mitochondria. This complex sits in the inner membrane, with the Tim23 protein forming a large, water-filled pore through its core that provides a route for proteins to pass through the membrane. Proteins are made of building blocks called amino acids. The proteins transported by the complex containing Tim23 all have a short chain of amino acids at one end known as an N-terminal presequence. However, it is not clear how the inside of the Tim23 channel identifies and transports this presequence to allow the right proteins to pass through the inner membrane. Denkert, Schendzielorz et al. studied the normal and mutant versions of a Tim23 channel from yeast to find out which parts of the protein are involved in detecting the N-terminal presequence after it enters the pore. The experiments show that there are several amino acids in Tim23 that play important roles in this process. Furthermore, mitochondria containing mutant Tim23 channels, that are less able to identify the N-terminal presequence, are impaired in their ability to import proteins. Tim23 proteins in humans and other organisms also contain most or all of the specific amino acids identified in this study, suggesting that the findings of Denkert, Schendzielorz et al. will also apply to other species. Furthermore, the experimental strategy used in this study could be adapted to investigate transport proteins in other cell compartments.
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Affiliation(s)
- Niels Denkert
- Department of Cellular Biochemistry, University Medical Center Göttingen, Göttingen, Germany
| | | | - Mariam Barbot
- Department of Cellular Biochemistry, University Medical Center Göttingen, Göttingen, Germany
| | - Lennart Versemann
- Department of Cellular Biochemistry, University Medical Center Göttingen, Göttingen, Germany
| | - Frank Richter
- Department of Cellular Biochemistry, University Medical Center Göttingen, Göttingen, Germany
| | - Peter Rehling
- Department of Cellular Biochemistry, University Medical Center Göttingen, Göttingen, Germany.,Max Planck Institute for Biophysical Chemistry, Göttingen, Germany.,Göttinger Zentrum für Molekulare Biowissenschaften, Göttingen, Germany
| | - Michael Meinecke
- Department of Cellular Biochemistry, University Medical Center Göttingen, Göttingen, Germany.,Göttinger Zentrum für Molekulare Biowissenschaften, Göttingen, Germany.,European Neuroscience Institute Göttingen, Göttingen, Germany
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7
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Schendzielorz AB, Schulz C, Lytovchenko O, Clancy A, Guiard B, Ieva R, van der Laan M, Rehling P. Two distinct membrane potential-dependent steps drive mitochondrial matrix protein translocation. J Cell Biol 2016; 216:83-92. [PMID: 28011846 PMCID: PMC5223606 DOI: 10.1083/jcb.201607066] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Revised: 09/30/2016] [Accepted: 11/28/2016] [Indexed: 12/03/2022] Open
Abstract
Schendzielorz et al. report that mitochondrial precursors display different dependencies on the membrane potential (Δψ) for translocation. Two distinct Δψ-dependent steps promote precursor translocation, the first driving presequence translocation and the second acting on the mature portion of the polypeptide chain. Two driving forces energize precursor translocation across the inner mitochondrial membrane. Although the membrane potential (Δψ) is considered to drive translocation of positively charged presequences through the TIM23 complex (presequence translocase), the activity of the Hsp70-powered import motor is crucial for the translocation of the mature protein portion into the matrix. In this study, we show that mitochondrial matrix proteins display surprisingly different dependencies on the Δψ. However, a precursor’s hypersensitivity to a reduction of the Δψ is not linked to the respective presequence, but rather to the mature portion of the polypeptide chain. The presequence translocase constituent Pam17 is specifically recruited by the receptor Tim50 to promote the transport of hypersensitive precursors into the matrix. Our analyses show that two distinct Δψ-driven translocation steps energize precursor passage across the inner mitochondrial membrane. The Δψ- and Pam17-dependent import step identified in this study is positioned between the two known energy-dependent steps: Δψ-driven presequence translocation and adenosine triphosphate–driven import motor activity.
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Affiliation(s)
- Alexander Benjamin Schendzielorz
- Department of Cellular Biochemistry, University Medical Center Göttingen, Georg-August-Universität Göttingen, 37073 Göttingen, Germany
| | - Christian Schulz
- Department of Cellular Biochemistry, University Medical Center Göttingen, Georg-August-Universität Göttingen, 37073 Göttingen, Germany
| | - Oleksandr Lytovchenko
- Department of Cellular Biochemistry, University Medical Center Göttingen, Georg-August-Universität Göttingen, 37073 Göttingen, Germany
| | - Anne Clancy
- Department of Molecular Biology, University Medical Center Göttingen, Georg-August-Universität Göttingen, 37073 Göttingen, Germany
| | - Bernard Guiard
- Centre de Génétique Moléculaire, Centre National de la Recherche Scientifique, 91190 Gif-sur-Yvette, France
| | - Raffaele Ieva
- Laboratoire de Microbiologie et Génétique Moléculaire, Centre de Biologie Intégrative, Université de Toulouse, Centre National de la Recherche Scientifique, Unité Propre de Service, 31062 Toulouse, France.,Institute of Biochemistry and Molecular Biology, Center for Biochemistry and Molecular Cell Research, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
| | - Martin van der Laan
- Institute of Biochemistry and Molecular Biology, Center for Biochemistry and Molecular Cell Research, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany.,Medical Biochemistry and Molecular Biology, Saarland University, 66421 Homburg, Germany
| | - Peter Rehling
- Department of Cellular Biochemistry, University Medical Center Göttingen, Georg-August-Universität Göttingen, 37073 Göttingen, Germany .,Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
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8
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de Oliveira PSL, Ferraz FAN, Pena DA, Pramio DT, Morais FA, Schechtman D. Revisiting protein kinase-substrate interactions: Toward therapeutic development. Sci Signal 2016; 9:re3. [PMID: 27016527 DOI: 10.1126/scisignal.aad4016] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Despite the efforts of pharmaceutical companies to develop specific kinase modulators, few drugs targeting kinases have been completely successful in the clinic. This is primarily due to the conserved nature of kinases, especially in the catalytic domains. Consequently, many currently available inhibitors lack sufficient selectivity for effective clinical application. Kinases phosphorylate their substrates to modulate their activity. One of the important steps in the catalytic reaction of protein phosphorylation is the correct positioning of the target residue within the catalytic site. This positioning is mediated by several regions in the substrate binding site, which is typically a shallow crevice that has critical subpockets that anchor and orient the substrate. The structural characterization of this protein-protein interaction can aid in the elucidation of the roles of distinct kinases in different cellular processes, the identification of substrates, and the development of specific inhibitors. Because the region of the substrate that is recognized by the kinase can be part of a linear consensus motif or a nonlinear motif, advances in technology beyond simple linear sequence scanning for consensus motifs were needed. Cost-effective bioinformatics tools are already frequently used to predict kinase-substrate interactions for linear consensus motifs, and new tools based on the structural data of these interactions improve the accuracy of these predictions and enable the identification of phosphorylation sites within nonlinear motifs. In this Review, we revisit kinase-substrate interactions and discuss the various approaches that can be used to identify them and analyze their binding structures for targeted drug development.
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Affiliation(s)
- Paulo Sérgio L de Oliveira
- Laboratório Nacional de Biociências, Centro Nacional de Pesquisa em Energia e Materiais, Campinas 13083-970, Brazil
| | - Felipe Augusto N Ferraz
- Laboratório Nacional de Biociências, Centro Nacional de Pesquisa em Energia e Materiais, Campinas 13083-970, Brazil
| | - Darlene A Pena
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo 05508000, Brazil
| | - Dimitrius T Pramio
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo 05508000, Brazil
| | - Felipe A Morais
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo 05508000, Brazil
| | - Deborah Schechtman
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo 05508000, Brazil.
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9
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Lytovchenko O, Melin J, Schulz C, Kilisch M, Hutu DP, Rehling P. Signal recognition initiates reorganization of the presequence translocase during protein import. EMBO J 2013; 32:886-98. [PMID: 23403928 DOI: 10.1038/emboj.2013.23] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Accepted: 01/17/2013] [Indexed: 11/09/2022] Open
Abstract
The mitochondrial presequence translocase interacts with presequence-containing precursors at the intermembrane space (IMS) side of the inner membrane to mediate their translocation into the matrix. Little is known as too how these matrix-targeting signals activate the translocase in order to initiate precursor transport. Therefore, we analysed how signal recognition by the presequence translocase initiates reorganization among Tim-proteins during import. Our analyses revealed that the presequence receptor Tim50 interacts with Tim21 in a signal-sensitive manner in a process that involves the IMS-domain of the Tim23 channel. The signal-driven release of Tim21 from Tim50 promotes recruitment of Pam17 and thus triggers formation of the motor-associated form of the TIM23 complex required for matrix transport.
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10
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Pinzón A, Barreto E, Bernal A, Achenie L, González Barrios AF, Isea R, Restrepo S. Computational models in plant-pathogen interactions: the case of Phytophthora infestans. Theor Biol Med Model 2009; 6:24. [PMID: 19909526 PMCID: PMC2787490 DOI: 10.1186/1742-4682-6-24] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2009] [Accepted: 11/12/2009] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Phytophthora infestans is a devastating oomycete pathogen of potato production worldwide. This review explores the use of computational models for studying the molecular interactions between P. infestans and one of its hosts, Solanum tuberosum. MODELING AND CONCLUSION Deterministic logistics models have been widely used to study pathogenicity mechanisms since the early 1950s, and have focused on processes at higher biological resolution levels. In recent years, owing to the availability of high throughput biological data and computational resources, interest in stochastic modeling of plant-pathogen interactions has grown. Stochastic models better reflect the behavior of biological systems. Most modern approaches to plant pathology modeling require molecular kinetics information. Unfortunately, this information is not available for many plant pathogens, including P. infestans. Boolean formalism has compensated for the lack of kinetics; this is especially the case where comparative genomics, protein-protein interactions and differential gene expression are the most common data resources.
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Affiliation(s)
- Andrés Pinzón
- Mycology and Phytopathology Laboratory, Department of Biological Sciences, Universidad de los Andes, Bogotá, Colombia
- Bioinformatics center, Colombian EMBnet node, Biotechnology Institute, National University of Colombia, Bogotá, Colombia
| | - Emiliano Barreto
- Bioinformatics center, Colombian EMBnet node, Biotechnology Institute, National University of Colombia, Bogotá, Colombia
| | - Adriana Bernal
- Mycology and Phytopathology Laboratory, Department of Biological Sciences, Universidad de los Andes, Bogotá, Colombia
| | - Luke Achenie
- Department of Chemical Engineering, Virginia Polytechnic Institute and State University, Blacksburg Virginia, USA
| | - Andres F González Barrios
- Grupo de Diseño de Productos y Procesos, Department of Chemical Engineering, Los Andes University, Bogotá, Colombia
| | - Raúl Isea
- Fundación IDEA, Centro de Biociencias, Hoyo de la puerta, Baruta 1080, Venezuela
| | - Silvia Restrepo
- Mycology and Phytopathology Laboratory, Department of Biological Sciences, Universidad de los Andes, Bogotá, Colombia
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11
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Perez-Martinez X, Butler CA, Shingu-Vazquez M, Fox TD. Dual functions of Mss51 couple synthesis of Cox1 to assembly of cytochrome c oxidase in Saccharomyces cerevisiae mitochondria. Mol Biol Cell 2009; 20:4371-80. [PMID: 19710419 DOI: 10.1091/mbc.e09-06-0522] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Functional interactions of the translational activator Mss51 with both the mitochondrially encoded COX1 mRNA 5'-untranslated region and with newly synthesized unassembled Cox1 protein suggest that it has a key role in coupling Cox1 synthesis with assembly of cytochrome c oxidase. Mss51 is present at levels that are near rate limiting for expression of a reporter gene inserted at COX1 in mitochondrial DNA, and a substantial fraction of Mss51 is associated with Cox1 protein in assembly intermediates. Thus, sequestration of Mss51 in assembly intermediates could limit Cox1 synthesis in wild type, and account for the reduced Cox1 synthesis caused by most yeast mutations that block assembly. Mss51 does not stably interact with newly synthesized Cox1 in a mutant lacking Cox14, suggesting that the failure of nuclear cox14 mutants to decrease Cox1 synthesis, despite their inability to assemble cytochrome c oxidase, is due to a failure to sequester Mss51. The physical interaction between Mss51 and Cox14 is dependent upon Cox1 synthesis, indicating dynamic assembly of early cytochrome c oxidase intermediates nucleated by Cox1. Regulation of COX1 mRNA translation by Mss51 seems to be an example of a homeostatic mechanism in which a positive effector of gene expression interacts with the product it regulates in a posttranslational assembly process.
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Affiliation(s)
- Xochitl Perez-Martinez
- Departamento de Bioquímica, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México D.F. 04510, México
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12
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Dagley MJ, Dolezal P, Likic VA, Smid O, Purcell AW, Buchanan SK, Tachezy J, Lithgow T. The protein import channel in the outer mitosomal membrane of Giardia intestinalis. Mol Biol Evol 2009; 26:1941-7. [PMID: 19531743 DOI: 10.1093/molbev/msp117] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The identification of mitosomes in Giardia generated significant debate on the evolutionary origin of these organelles, whether they were highly reduced mitochondria or the product of a unique endosymbiotic event in an amitochondrial organism. As the protein import pathway is a defining characteristic of mitochondria, we sought to discover a TOM (translocase in the outer mitochondrial membrane) complex in Giardia. A Hidden Markov model search of the Giardia genome identified a Tom40 homologous sequence (GiTom40), where Tom40 is the protein translocation channel of the TOM complex. The GiTom40 protein is located in the membrane of mitosomes in a approximately 200-kDa TOM complex. As Tom40 was derived in the development of mitochondria to serve as the protein import channel in the outer membrane, its presence in Giardia evidences the mitochondrial ancestry of mitosomes.
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Affiliation(s)
- Michael J Dagley
- Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Australia
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13
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Li J, Ge J, Yin Y, Zhong W. Multiplexed affinity-based protein complex purification. Anal Chem 2008; 80:7068-74. [PMID: 18715017 DOI: 10.1021/ac801251y] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Here we proved the principle of a multiplexed affinity-based protein complex purification (MAPcP) technique that targets simultaneous extraction of multiple protein complexes with superior purity. Microspheres of various sizes and coupled with different affinity probes extract several protein complexes concurrently and specifically. After the coextraction, flow-field flow fractionation (Fl-FFF) rapidly washes the microspheres as well as separates them based on their sizes to recover the clean individual complex for downstream analysis. Demonstration of the parallel extraction of two immuno-complexes from the yeast whole cell lysate showed that MAPcP can enhance the sample purity significantly compared to the traditional centrifugation and magnetic pull-down methods used for small scale protein purification. Simultaneous isolation of multiple protein complexes can facilitate the elucidation of the functional relationship among protein complexes and improve our understanding of the biological network.
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Affiliation(s)
- Jishan Li
- Department of Chemistry, University of California, Riverside, California 92521, USA
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14
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Markham K, Bai Y, Schmitt-Ulms G. Co-immunoprecipitations revisited: an update on experimental concepts and their implementation for sensitive interactome investigations of endogenous proteins. Anal Bioanal Chem 2007; 389:461-73. [PMID: 17583802 DOI: 10.1007/s00216-007-1385-x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2007] [Revised: 05/14/2007] [Accepted: 05/22/2007] [Indexed: 10/23/2022]
Abstract
The study of protein-protein interactions involving endogenous proteins frequently relies on the immunoaffinity capture of a protein of interest followed by mass spectrometry-based identification of co-purifying interactors. A notorious problem with this approach is the difficulty of distinguishing physiological interactors from unspecific binders. Additional challenges pose the need to employ a strategy that is compatible with downstream mass spectrometry and minimizes sample losses during handling steps. Finally, the complexity of data sets demands solutions for data filtering. Here we present an update on co-immunoprecipitation procedures for sensitive interactome mapping applications. We define the relevant terminology, review methodological advances that reduce sample losses, and discuss experimental strategies that facilitate recognition of candidate interactors through a combination of informative controls and data filtering. Finally, we provide starting points for initial validation experiments and propose conventions for manuscripts which report on co-immunoprecipitation work.
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Affiliation(s)
- Kelly Markham
- Centre for Research in Neurodegenerative Diseases, University of Toronto, Tanz Neuroscience Building, 6 Queen's Park Crescent West, Toronto, ON M5S 3H2, Canada
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15
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19 Analysis of Gene Function of Mitochondria. J Microbiol Methods 2007. [DOI: 10.1016/s0580-9517(06)36019-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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16
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Brandina I, Graham J, Lemaitre-Guillier C, Entelis N, Krasheninnikov I, Sweetlove L, Tarassov I, Martin RP. Enolase takes part in a macromolecular complex associated to mitochondria in yeast. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2006; 1757:1217-28. [PMID: 16962558 DOI: 10.1016/j.bbabio.2006.07.001] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2006] [Revised: 06/16/2006] [Accepted: 07/06/2006] [Indexed: 10/24/2022]
Abstract
In eucaryotes, glycolytic enzymes are classically regarded as being localised in the cytosol. Recently, we have shown that part of the cellular pool of the glycolytic enzyme, enolase, is tightly associated with the mitochondrial surface in the yeast Saccharomyces cerevisiae (N. Entelis, I. Brandina, P. Kamenski, I.A. Krasheninnikov, R.P. Martin and I. Tarassov, A glycolytic enzyme, enolase, is recruited as a cofactor of tRNA targeting toward mitochondria in Saccharomyces cerevisiae, Genes Dev. 20 (2006) 1609-1620). Here, using enzymatic assays, we show that all glycolytic enzymes are associated with mitochondria in yeast, to extents similar to those previously reported for Arabidopsis cells. Using separation of mitochondrial complexes by blue-native/SDS-PAGE and coimmunoprecipitation of mitochondrial proteins with anti-enolase antibodies, we found that enolase takes part in a large macromolecular complex associated to mitochondria. The identified components included additional glycolytic enzymes, mitochondrial membrane carriers, and enzymes of the TCA cycle. We suggest a possible role of the enolase complex in the channeling of pyruvate, the terminal product of glycolysis, towards the TCA cycle within mitochondria. Moreover, we show that the mitochondrial enolase-containing complex also contains the cytosolic tRNA(CUU)Lys, which is mitochondrially-imported, and its presumed import carrier, the precursor of the mitochondrial lysyl-tRNA synthetase. This suggests an unsuspected novel function for this complex in tRNA mitochondrial import.
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Affiliation(s)
- Irina Brandina
- UMR 7156 Génétique Moléculaire, Génomique et Microbiologie CNRS, Université Louis Pasteur Strasbourg I; Institut de Physiologie et Chimie Biologique, 21 rue René Descartes, 67084 Strasbourg, France
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17
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Eubel H, Braun HP, Millar AH. Blue-native PAGE in plants: a tool in analysis of protein-protein interactions. PLANT METHODS 2005; 1:11. [PMID: 16287510 PMCID: PMC1308860 DOI: 10.1186/1746-4811-1-11] [Citation(s) in RCA: 108] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/05/2005] [Accepted: 11/16/2005] [Indexed: 05/05/2023]
Abstract
Intact protein complexes can be separated by apparent molecular mass using a standard polyacrylamide gel electrophoresis system combining mild detergents and the dye Coomassie Blue. Referring to the blue coloured gel and the gentle method of solubilization yielding native and enzymatically active protein complexes, this technique has been named Blue-Native Polyacrylamide Gel-Electrophoresis (BN-PAGE). BN-PAGE has become the method of choice for the investigation of the respiratory protein complexes of the electron transfer chains of a range of organisms, including bacteria, yeasts, animals and plants. It allows the separation in two dimensions of extremely hydrophobic protein sets for analysis and also provides information on their native interactions. In this review we discuss the capabilities of BN-PAGE in proteomics and the wider investigation of protein:protein interactions with a focus on its use and potential in plant science.
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Affiliation(s)
- Holger Eubel
- ARC Centre of Excellence in Plant Energy Biology, University of Western Australia, 35 Stirling Hwy, Crawley 6009, Perth, Australia
| | - Hans-Peter Braun
- Abteilung Angewandte Genetik, Universität Hannover, Herrenhäuser Str. 2, 30419 Hannover, Germany
| | - A Harvey Millar
- ARC Centre of Excellence in Plant Energy Biology, University of Western Australia, 35 Stirling Hwy, Crawley 6009, Perth, Australia
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18
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Mesecke N, Terziyska N, Kozany C, Baumann F, Neupert W, Hell K, Herrmann JM. A disulfide relay system in the intermembrane space of mitochondria that mediates protein import. Cell 2005; 121:1059-69. [PMID: 15989955 DOI: 10.1016/j.cell.2005.04.011] [Citation(s) in RCA: 433] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2005] [Revised: 03/11/2005] [Accepted: 04/11/2005] [Indexed: 11/25/2022]
Abstract
We describe here a pathway for the import of proteins into the intermembrane space (IMS) of mitochondria. Substrates of this pathway are proteins with conserved cysteine motifs, which are critical for import. After passage through the TOM channel, these proteins are covalently trapped by Mia40 via disulfide bridges. Mia40 contains cysteine residues, which are oxidized by the sulfhydryl oxidase Erv1. Depletion of Erv1 or conditions reducing Mia40 prevent protein import. We propose that Erv1 and Mia40 function as a disulfide relay system that catalyzes the import of proteins into the IMS by an oxidative folding mechanism. The existence of a disulfide exchange system in the IMS is unexpected in view of the free exchange of metabolites between IMS and cytosol via porin channels. We suggest that this process reflects the evolutionary origin of the IMS from the periplasmic space of the prokaryotic ancestors of mitochondria.
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Affiliation(s)
- Nikola Mesecke
- Institute für Physiologische Chemie, Universität München, Germany
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19
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Meier S, Neupert W, Herrmann JM. Conserved N-terminal Negative Charges in the Tim17 Subunit of the TIM23 Translocase Play a Critical Role in the Import of Preproteins into Mitochondria. J Biol Chem 2005; 280:7777-85. [PMID: 15618217 DOI: 10.1074/jbc.m412158200] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The TIM23 complex of the mitochondrial inner membrane mediates the import of preproteins that contain positively charged targeting signals. This translocase consists of the two phylogenetically related membrane-embedded subunits Tim17 and Tim23 to which four largely hydrophilic subunits, Tim50, Tim44, Tim16, and Tim14, are attached. Whereas in vitro reconstitution experiments have suggested a pore-forming capacity of recombinant Tim23, virtually nothing is known about the properties and function of Tim17. We employed a combined genetic and biochemical approach to address the function of Tim17 in preprotein translocation. Tim17 exposes an N-terminal hydrophilic stretch into the intermembrane space. Truncation of the first 11 amino acid residues of this stretch did not affect the stability or integrity of TIM23 subunits but strongly impaired the import of preproteins. Moreover, expression of the truncated Tim17 variant led to a dominant negative effect on the mitochondrial membrane potential. By an alanine-scanning approach we identified two conserved negative charges in the N terminus of Tim17 as critical for Tim17 function. The replacement of these positions by positively charged residues results in a strong growth defect, which can be cured by reverting two conserved positive charges into aspartate residues between transmembrane domains two and three of Tim17. On the basis of these observations we propose that charged residues in Tim17 are critical for the preprotein-induced gating of the TIM23 translocase.
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Affiliation(s)
- Stephan Meier
- Institut für Physiologische Chemie, Universität München, Butenandtstrasse 5, 81377 München, Germany
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20
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Preuss M, Ott M, Funes S, Luirink J, Herrmann JM. Evolution of mitochondrial oxa proteins from bacterial YidC. Inherited and acquired functions of a conserved protein insertion machinery. J Biol Chem 2005; 280:13004-11. [PMID: 15654078 DOI: 10.1074/jbc.m414093200] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Members of the Oxa1/YidC family are involved in the biogenesis of membrane proteins. In bacteria, YidC catalyzes the insertion and assembly of proteins of the inner membrane. Mitochondria of animals, fungi, and plants harbor two distant homologues of YidC, Oxa1 and Cox18/Oxa2. Oxa1 plays a pivotal role in the integration of mitochondrial translation products into the inner membrane of mitochondria. It contains a C-terminal ribosome-binding domain that physically interacts with mitochondrial ribosomes to facilitate the co-translational insertion of nascent membrane proteins. The molecular function of Cox18/Oxa2 is not well understood. Employing a functional complementation approach with mitochondria-targeted versions of YidC we show that YidC is able to functionally replace both Oxa1 and Cox18/Oxa2. However, to integrate mitochondrial translation products into the inner membrane of mitochondria, the ribosome-binding domain of Oxa1 has to be appended onto YidC. On the contrary, the fusion of the ribosome-binding domain onto YidC prevents its ability to complement COX18 mutants suggesting an indispensable post-translational activity of Cox18/Oxa2. Our observations suggest that during evolution of mitochondria from their bacterial ancestors the two descendents of YidC functionally segregated to perform two distinct activities, one co-translational and one post-translational.
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Affiliation(s)
- Marc Preuss
- Institut für Physiologische Chemie, Universität München, Butenandtstrasse 5, 81377 München, Germany
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21
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Phadnis N, Ayres Sia E. Role of the Putative Structural Protein Sed1p in Mitochondrial Genome Maintenance. J Mol Biol 2004; 342:1115-29. [PMID: 15351639 DOI: 10.1016/j.jmb.2004.07.096] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2004] [Revised: 07/08/2004] [Accepted: 07/22/2004] [Indexed: 11/17/2022]
Abstract
The nuclear gene MIP1 encodes the mitochondrial DNA polymerase responsible for replicating the mitochondrial genome in Saccharomyces cerevisiae. A number of other factors involved in replicating and segregating the mitochondrial genome are yet to be identified. Here, we report that a bacterial two-hybrid screen using the mitochondrial polymerase, Mip1p, as bait identified the yeast protein Sed1p. Sed1p is a cell surface protein highly expressed in the stationary phase. We find that several modified forms of Sed1p are expressed and the largest of these forms interacts with the mitochondrial polymerase in vitro. Deletion of SED1 causes a 3.5-fold increase in the rate of mitochondrial DNA point mutations as well as a 4.3-fold increase in the rate of loss of respiration. In contrast, we see no change in the rate of nuclear point mutations indicating the specific role of Sed1p function in mitochondrial genome stability. Indirect immunofluorescence analysis of Sed1p localization shows that Sed1p is targeted to the mitochondria. Moreover, Sed1p is detected in purified mitochondrial fractions and the localization to the mitochondria of the largest modified form is insensitive to the action of proteinase K. Deletion of the sed1 gene results in a reduction in the quantity of Mip1p and also affects the levels of a mitochondrially-expressed protein, Cox3p. Our results point towards a role for Sed1p in mitochondrial genome maintenance.
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Affiliation(s)
- Naina Phadnis
- Department of Biology, University of Rochester, Rochester, NY 14627-0211, USA
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22
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Tzagoloff A, Barrientos A, Neupert W, Herrmann JM. Atp10p assists assembly of Atp6p into the F0 unit of the yeast mitochondrial ATPase. J Biol Chem 2004; 279:19775-80. [PMID: 14998992 DOI: 10.1074/jbc.m401506200] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The F(0)F(1)-ATPase complex of yeast mitochondria contains three mitochondrial and at least 17 nuclear gene products. The coordinate assembly of mitochondrial and cytosolic translation products relies on chaperones and specific factors that stabilize the pools of some unassembled subunits. Atp10p was identified as a mitochondrial inner membrane component necessary for the biogenesis of the hydrophobic F(0) sector of the ATPase. Here we show that, following its synthesis on mitochondrial ribosomes, subunit 6 of the ATPase (Atp6p) can be cross-linked to Atp10p. This interaction is required for the integration of Atp6p into a partially assembled subcomplex of the ATPase. Pulse labeling and chase of mitochondrial translation products in vivo indicate that Atp6p is less stable and more rapidly degraded in an atp10 null mutant than in wild type. Based on these observations, we propose Atp10p to be an Atp6p-specific chaperone that facilitates the incorporation of Atp6p into an intermediate subcomplex of ATPase subunits.
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Affiliation(s)
- Alexander Tzagoloff
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
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23
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Funes S, Nargang FE, Neupert W, Herrmann JM. The Oxa2 protein of Neurospora crassa plays a critical role in the biogenesis of cytochrome oxidase and defines a ubiquitous subbranch of the Oxa1/YidC/Alb3 protein family. Mol Biol Cell 2004; 15:1853-61. [PMID: 14767059 PMCID: PMC379281 DOI: 10.1091/mbc.e03-11-0789] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Proteins of the Oxa1/YidC/Alb3 family mediate the insertion of proteins into membranes of mitochondria, bacteria, and chloroplasts. Here we report the identification of a second gene of the Oxa1/YidC/Alb3 family in the genome of Neurospora crassa, which we have named oxa2. Its gene product, Oxa2, is located in the inner membrane of mitochondria. Deletion of the oxa2 gene caused a specific defect in the biogenesis of cytochrome oxidase and resulted in induction of the alternative oxidase (AOD), which bypasses the need for complex IV of the respiratory chain. The Oxa2 protein of N. crassa complements Cox18-deficient yeast mutants suggesting a common function for both proteins. The oxa2 sequence allowed the identification of a new subfamily of Oxa1/YidC/Alb3 proteins whose members appear to be ubiquitously present in mitochondria of fungi, plants, and animals including humans.
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Affiliation(s)
- Soledad Funes
- Institut für Physiologische Chemie, Universität München, 81377 München, Germany
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24
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Abstract
The biogenesis of mitochondria requires the insertion of both nuclear and mitochondrially encoded proteins into the inner membrane. The inner membrane protein Oxa1 plays an important role in this process. Translocation of the terminal intermembrane space domains of subunit 2 of the cytochrome oxidase complex, Cox2, strictly depends on Oxa1. In contrast, other Oxa1 substrates can be inserted independently of Oxa1 function, although at reduced efficiency. A Saccharomyces cerevisiae mutant containing a large deletion in its mitochondrial genome allowed us to analyze the insertion process of a fusion protein of cytochrome b and Cox2. In this mutant, the N-terminal domain of Cox2 is synthesized as a hairpin loop that is flanked by hydrophobic transmembrane segments on both sides. Both genetic and biochemical evidences indicate that translocation of this region across the inner membrane still requires Oxa1 function. Thus, the position of intermembrane space domains within protein sequences does not appear to determine their dependence on the Oxa1 translocase. Our observations rather suggest that the dependence on Oxa1 correlates with the net charge of the domain that has to be translocated across the lipid bilayer.
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Affiliation(s)
- Johannes M Herrmann
- Institut für Physiologische Chemie, Universität München, Butenandtstrasse 5, München 81377, Germany.
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25
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Perez-Martinez X, Broadley SA, Fox TD. Mss51p promotes mitochondrial Cox1p synthesis and interacts with newly synthesized Cox1p. EMBO J 2003; 22:5951-61. [PMID: 14592991 PMCID: PMC275423 DOI: 10.1093/emboj/cdg566] [Citation(s) in RCA: 153] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The post-transcriptional role of Mss51p in mitochondrial gene expression is of great interest since MSS51 mutations suppress the respiratory defect caused by shy1 mutations. SHY1 is a Saccharomyces cerevisiae homolog of human SURF1, which when mutated causes a cytochrome oxidase assembly defect. We found that MSS51 is required for expression of the mitochondrial reporter gene ARG8(m) when it is inserted at the COX1 locus, but not when it is at COX2 or COX3. Unlike the COX1 mRNA-specific translational activator PET309, MSS51 has at least two targets in COX1 mRNA. MSS51 acts in the untranslated regions of the COX1 mRNA, since it was required to synthesize Arg8p when ARG8(m) completely replaced the COX1 codons. MSS51 also acts on a target specified by the COX1 coding region, since it was required to translate either COX1 or COX1:: ARG8(m) coding sequences from an ectopic COX2 locus. Mss51p was found to interact physically with newly synthesized Cox1p, suggesting that it could coordinate Cox1p synthesis with insertion into the inner membrane or cytochrome oxidase assembly.
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Affiliation(s)
- Xochitl Perez-Martinez
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853-2703, USA
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26
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Messerschmitt M, Jakobs S, Vogel F, Fritz S, Dimmer KS, Neupert W, Westermann B. The inner membrane protein Mdm33 controls mitochondrial morphology in yeast. J Cell Biol 2003; 160:553-64. [PMID: 12591915 PMCID: PMC2173741 DOI: 10.1083/jcb.200211113] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Mitochondrial distribution and morphology depend on MDM33, a Saccharomyces cerevisiae gene encoding a novel protein of the mitochondrial inner membrane. Cells lacking Mdm33 contain ring-shaped, mostly interconnected mitochondria, which are able to form large hollow spheres. On the ultrastructural level, these aberrant organelles display extremely elongated stretches of outer and inner membranes enclosing a very narrow matrix space. Dilated parts of Delta mdm33 mitochondria contain well-developed cristae. Overexpression of Mdm33 leads to growth arrest, aggregation of mitochondria, and generation of aberrant inner membrane structures, including septa, inner membrane fragments, and loss of inner membrane cristae. The MDM33 gene is required for the formation of net-like mitochondria in mutants lacking components of the outer membrane fission machinery, and mitochondrial fusion is required for the formation of extended ring-like mitochondria in cells lacking the MDM33 gene. The Mdm33 protein assembles into an oligomeric complex in the inner membrane where it performs homotypic protein-protein interactions. Our results indicate that Mdm33 plays a distinct role in the mitochondrial inner membrane to control mitochondrial morphology. We propose that Mdm33 is involved in fission of the mitochondrial inner membrane.
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27
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Saracco SA, Fox TD. Cox18p is required for export of the mitochondrially encoded Saccharomyces cerevisiae Cox2p C-tail and interacts with Pnt1p and Mss2p in the inner membrane. Mol Biol Cell 2002; 13:1122-31. [PMID: 11950926 PMCID: PMC102256 DOI: 10.1091/mbc.01-12-0580] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2001] [Revised: 12/03/2001] [Accepted: 12/24/2001] [Indexed: 11/11/2022] Open
Abstract
The amino- and carboxy-terminal domains of mitochondrially encoded cytochrome c oxidase subunit II (Cox2p) are translocated out of the matrix to the intermembrane space. We have carried out a genetic screen to identify components required to export the biosynthetic enzyme Arg8p, tethered to the Cox2p C terminus by a translational gene fusion inserted into mtDNA. We obtained multiple alleles of COX18, PNT1, and MSS2, as well as mutations in CBP1 and PET309. Focusing on Cox18p, we found that its activity is required to export the C-tail of Cox2p bearing a short C-terminal epitope tag. This is not a consequence of reduced membrane potential due to loss of cytochrome oxidase activity because Cox2p C-tail export was not blocked in mitochondria lacking Cox4p. Cox18p is not required to export the Cox2p N-tail, indicating that these two domains of Cox2p are translocated by genetically distinct mechanisms. Cox18p is a mitochondrial integral inner membrane protein. The inner membrane proteins Mss2p and Pnt1p both coimmunoprecipitate with Cox18p, suggesting that they work together in translocation of Cox2p domains, an inference supported by functional interactions among the three genes.
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Affiliation(s)
- Scott A Saracco
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853-2703, USA
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