1
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Polanco CM, Cavieres VA, Galarza AJ, Jara C, Torres AK, Cancino J, Varas-Godoy M, Burgos PV, Tapia-Rojas C, Mardones GA. GOLPH3 Participates in Mitochondrial Fission and Is Necessary to Sustain Bioenergetic Function in MDA-MB-231 Breast Cancer Cells. Cells 2024; 13:316. [PMID: 38391929 PMCID: PMC10887169 DOI: 10.3390/cells13040316] [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: 12/17/2023] [Revised: 02/03/2024] [Accepted: 02/05/2024] [Indexed: 02/24/2024] Open
Abstract
In this study, we investigated the inter-organelle communication between the Golgi apparatus (GA) and mitochondria. Previous observations suggest that GA-derived vesicles containing phosphatidylinositol 4-phosphate (PI(4)P) play a role in mitochondrial fission, colocalizing with DRP1, a key protein in this process. However, the functions of these vesicles and potentially associated proteins remain unknown. GOLPH3, a PI(4)P-interacting GA protein, is elevated in various types of solid tumors, including breast cancer, yet its precise role is unclear. Interestingly, GOLPH3 levels influence mitochondrial mass by affecting cardiolipin synthesis, an exclusive mitochondrial lipid. However, the mechanism by which GOLPH3 influences mitochondria is not fully understood. Our live-cell imaging analysis showed GFP-GOLPH3 associating with PI(4)P vesicles colocalizing with YFP-DRP1 at mitochondrial fission sites. We tested the functional significance of these observations with GOLPH3 knockout in MDA-MB-231 cells of breast cancer, resulting in a fragmented mitochondrial network and reduced bioenergetic function, including decreased mitochondrial ATP production, mitochondrial membrane potential, and oxygen consumption. Our findings suggest a potential negative regulatory role for GOLPH3 in mitochondrial fission, impacting mitochondrial function and providing insights into GA-mitochondria communication.
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Affiliation(s)
- Catalina M. Polanco
- Centro de Biología Celular y Biomedicina (CEBICEM), Facultad de Medicina y Ciencia, Universidad San Sebastián, Providencia, Santiago 7510156, Chile; (C.M.P.); (V.A.C.); (C.J.); (A.K.T.); (J.C.); (M.V.-G.); (P.V.B.)
| | - Viviana A. Cavieres
- Centro de Biología Celular y Biomedicina (CEBICEM), Facultad de Medicina y Ciencia, Universidad San Sebastián, Providencia, Santiago 7510156, Chile; (C.M.P.); (V.A.C.); (C.J.); (A.K.T.); (J.C.); (M.V.-G.); (P.V.B.)
- Departamento de Ciencias Biológicas y Químicas, Facultad de Medicina y Ciencia, Universidad San Sebastián, Campus Los Leones, Providencia, Santiago 7510156, Chile
| | - Abigail J. Galarza
- Escuela de Medicina, Facultad de Medicina y Ciencia, Universidad San Sebastián, Valdivia 5110693, Chile;
| | - Claudia Jara
- Centro de Biología Celular y Biomedicina (CEBICEM), Facultad de Medicina y Ciencia, Universidad San Sebastián, Providencia, Santiago 7510156, Chile; (C.M.P.); (V.A.C.); (C.J.); (A.K.T.); (J.C.); (M.V.-G.); (P.V.B.)
- Centro Científico y Tecnológico de Excelencia Ciencia & Vida, Fundación Ciencia & Vida, Huechuraba, Santiago 8580702, Chile
| | - Angie K. Torres
- Centro de Biología Celular y Biomedicina (CEBICEM), Facultad de Medicina y Ciencia, Universidad San Sebastián, Providencia, Santiago 7510156, Chile; (C.M.P.); (V.A.C.); (C.J.); (A.K.T.); (J.C.); (M.V.-G.); (P.V.B.)
- Centro de Excelencia en Biomedicina de Magallanes (CEBIMA), Universidad de Magallanes, Punta Arenas 6210427, Chile
| | - Jorge Cancino
- Centro de Biología Celular y Biomedicina (CEBICEM), Facultad de Medicina y Ciencia, Universidad San Sebastián, Providencia, Santiago 7510156, Chile; (C.M.P.); (V.A.C.); (C.J.); (A.K.T.); (J.C.); (M.V.-G.); (P.V.B.)
- Escuela de Medicina, Facultad de Medicina y Ciencia, Universidad San Sebastián, Valdivia 5110693, Chile;
| | - Manuel Varas-Godoy
- Centro de Biología Celular y Biomedicina (CEBICEM), Facultad de Medicina y Ciencia, Universidad San Sebastián, Providencia, Santiago 7510156, Chile; (C.M.P.); (V.A.C.); (C.J.); (A.K.T.); (J.C.); (M.V.-G.); (P.V.B.)
- Escuela de Medicina, Facultad de Medicina y Ciencia, Universidad San Sebastián, Valdivia 5110693, Chile;
- Centro Científico y Tecnológico de Excelencia Ciencia & Vida, Fundación Ciencia & Vida, Huechuraba, Santiago 8580702, Chile
| | - Patricia V. Burgos
- Centro de Biología Celular y Biomedicina (CEBICEM), Facultad de Medicina y Ciencia, Universidad San Sebastián, Providencia, Santiago 7510156, Chile; (C.M.P.); (V.A.C.); (C.J.); (A.K.T.); (J.C.); (M.V.-G.); (P.V.B.)
- Escuela de Medicina, Facultad de Medicina y Ciencia, Universidad San Sebastián, Valdivia 5110693, Chile;
- Centro Científico y Tecnológico de Excelencia Ciencia & Vida, Fundación Ciencia & Vida, Huechuraba, Santiago 8580702, Chile
| | - Cheril Tapia-Rojas
- Centro de Biología Celular y Biomedicina (CEBICEM), Facultad de Medicina y Ciencia, Universidad San Sebastián, Providencia, Santiago 7510156, Chile; (C.M.P.); (V.A.C.); (C.J.); (A.K.T.); (J.C.); (M.V.-G.); (P.V.B.)
- Centro Científico y Tecnológico de Excelencia Ciencia & Vida, Fundación Ciencia & Vida, Huechuraba, Santiago 8580702, Chile
| | - Gonzalo A. Mardones
- Escuela de Medicina, Facultad de Medicina y Ciencia, Universidad San Sebastián, Valdivia 5110693, Chile;
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2
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Zhang Y, Hu Y, Wang Z, Lin X, Li Z, Ren Y, Zhao J. The translocase of the inner mitochondrial membrane 22-2 is required for mitochondrial membrane function during Arabidopsis seed development. JOURNAL OF EXPERIMENTAL BOTANY 2023; 74:4427-4448. [PMID: 37105529 DOI: 10.1093/jxb/erad141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Accepted: 04/27/2023] [Indexed: 06/19/2023]
Abstract
The carrier translocase (also known as translocase of the inner membrane 22; TIM22 complex) is an important component of the mitochondrial protein import apparatus. However, the biological functions of AtTIM22-2 in Arabidopsis remain poorly defined. Here, we report studies on two tim22-2 mutants that exhibit defects in embryo and endosperm development, leading to seed abortion. AtTIM22-2, which was localized in mitochondria, was widely expressed in embryos and in various seedling organs. Loss of AtTIM22-2 function resulted in irregular mitochondrial cristae, decreased respiratory activity, and a lower membrane potential, together with changes in gene expression and enzyme activity related to reactive oxygen species (ROS) metabolism, leading to increased accumulation of ROS in the embryo. The levels of transcripts encoding mitochondrial protein import components were also altered in the tim22-2 mutants. Furthermore, mass spectrometry, bimolecular fluorescence complementation and co-immunoprecipitation assays revealed that AtTIM22-2 interacted with AtTIM23-2, AtB14.7 (a member of Arabidopsis OEP16 family encoded by At2G42210), and AT5G27395 (mitochondrial inner membrane translocase complex, subunit TIM44-related protein). Taken together, these results demonstrate that AtTIM22-2 is essential for maintaining mitochondrial membrane functions during seed development. These findings lay the foundations for a new model of the composition and functions of the TIM22 complex in higher plants.
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Affiliation(s)
- Yuqin Zhang
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Yuanyuan Hu
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Zhiqin Wang
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Xiaodi Lin
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Zihui Li
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Yafang Ren
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Jie Zhao
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China
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3
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You W, Zhou T, Knoops K, Berendschot TTJM, van Zandvoort MAMJ, Germeraad WTV, Benedikter B, Webers CAB, Reutelingsperger CPM, Gorgels TGMF. Stressed neuronal cells can recover from profound membrane blebbing, nuclear condensation and mitochondrial fragmentation, but not from cytochrome c release. Sci Rep 2023; 13:11045. [PMID: 37422517 PMCID: PMC10329692 DOI: 10.1038/s41598-023-38210-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2023] [Accepted: 07/05/2023] [Indexed: 07/10/2023] Open
Abstract
Loss of neurons in chronic neurodegenerative diseases may occur over a period of many years. Once initiated, neuronal cell death is accompanied by distinct phenotypic changes including cell shrinkage, neurite retraction, mitochondrial fragmentation, nuclear condensation, membrane blebbing and phosphatidylserine (PS) exposure at the plasma membrane. It is still poorly understood which events mark the point of no return for dying neurons. Here we analyzed the neuronal cell line SH-SY5Y expressing cytochrome C (Cyto.C)-GFP. Cells were exposed temporarily to ethanol (EtOH) and tracked longitudinally in time by light and fluorescent microscopy. Exposure to EtOH induced elevation of intracellular Ca2+ and reactive oxygen species, cell shrinkage, neurite retraction, mitochondrial fragmentation, nuclear condensation, membrane blebbing, PS exposure and Cyto.C release into the cytosol. Removing EtOH at predetermined time points revealed that all phenomena except Cyto.C release occurred in a phase of neuronal cell death in which full recovery to a neurite-bearing cell was still possible. Our findings underscore a strategy of treating chronic neurodegenerative diseases by removing stressors from neurons and harnessing intracellular targets that delay or prevent trespassing the point of no return.
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Affiliation(s)
- Wenting You
- University Eye Clinic Maastricht UMC+, Maastricht University Medical Center+, 6229 HX, Maastricht, The Netherlands
- Department of Biochemistry, CARIM School for Cardiovascular Disease, Maastricht University, 6229 ER, Maastricht, The Netherlands
- Department of Mental Health and Neuroscience, Maastricht University, 6229 ER, Maastricht, The Netherlands
| | - Tao Zhou
- University Eye Clinic Maastricht UMC+, Maastricht University Medical Center+, 6229 HX, Maastricht, The Netherlands
| | - Kèvin Knoops
- The Maastricht Multimodal Molecular Imaging Institute, Maastricht University, 6229 ER, Maastricht, The Netherlands
| | - Tos T J M Berendschot
- University Eye Clinic Maastricht UMC+, Maastricht University Medical Center+, 6229 HX, Maastricht, The Netherlands
| | - Marc A M J van Zandvoort
- Department of Molecular Cell Biology, CARIM School for Cardiovascular Disease, Maastricht University, 6229 ER, Maastricht, The Netherlands
- Institute of Molecular Cardiovascular Research, Universitätsklinikum Aachen, 52074, Aachen, Germany
| | - Wilfred T V Germeraad
- Division of Hematology, Department of Internal Medicine, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Birke Benedikter
- University Eye Clinic Maastricht UMC+, Maastricht University Medical Center+, 6229 HX, Maastricht, The Netherlands
| | - Carroll A B Webers
- University Eye Clinic Maastricht UMC+, Maastricht University Medical Center+, 6229 HX, Maastricht, The Netherlands
| | - Chris P M Reutelingsperger
- Department of Biochemistry, CARIM School for Cardiovascular Disease, Maastricht University, 6229 ER, Maastricht, The Netherlands.
| | - Theo G M F Gorgels
- University Eye Clinic Maastricht UMC+, Maastricht University Medical Center+, 6229 HX, Maastricht, The Netherlands.
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4
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Zhan M, Ding Y, Huang S, Liu Y, Xiao J, Yu H, Lu L, Wang X. Lysyl oxidase-like 3 restrains mitochondrial ferroptosis to promote liver cancer chemoresistance by stabilizing dihydroorotate dehydrogenase. Nat Commun 2023; 14:3123. [PMID: 37253718 DOI: 10.1038/s41467-023-38753-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Accepted: 05/11/2023] [Indexed: 06/01/2023] Open
Abstract
To overcome chemotherapy resistance, novel strategies sensitizing cancer cells to chemotherapy are required. Here, we screen the lysyl-oxidase (LOX) family to clarify its contribution to chemotherapy resistance in liver cancer. LOXL3 depletion significantly sensitizes liver cancer cells to Oxaliplatin by inducing ferroptosis. Chemotherapy-activated EGFR signaling drives LOXL3 to interact with TOM20, causing it to be hijacked into mitochondria, where LOXL3 lysyl-oxidase activity is reinforced by phosphorylation at S704. Metabolic adenylate kinase 2 (AK2) directly phosphorylates LOXL3-S704. Phosphorylated LOXL3-S704 targets dihydroorotate dehydrogenase (DHODH) and stabilizes it by preventing its ubiquitin-mediated proteasomal degradation. K344-deubiquitinated DHODH accumulates in mitochondria, in turn inhibiting chemotherapy-induced mitochondrial ferroptosis. CRISPR-Cas9-mediated site-mutation of mouse LOXL3-S704 to D704 causes a reduction in lipid peroxidation. Using an advanced liver cancer mouse model, we further reveal that low-dose Oxaliplatin in combination with the DHODH-inhibitor Leflunomide effectively inhibit liver cancer progression by inducing ferroptosis, with increased chemotherapy sensitivity and decreased chemotherapy toxicity.
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Affiliation(s)
- Meixiao Zhan
- Zhuhai Interventional Medical Center, Guangdong Provincial Key Laboratory of Tumour Interventional Diagnosis and Treatment, Zhuhai People's Hospital, Zhuhai Hospital affiliated with Jinan University, Zhuhai, 519000, Guangdong, China
| | - Yufeng Ding
- Precise Genome Engineering Center, School of Life Sciences, Guangzhou University, 510006, Guangzhou, China.
| | - Shanzhou Huang
- Department of General Surgery, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, 510080, Guangzhou, China
| | - Yuhang Liu
- Precise Genome Engineering Center, School of Life Sciences, Guangzhou University, 510006, Guangzhou, China
| | - Jing Xiao
- Zhuhai Interventional Medical Center, Guangdong Provincial Key Laboratory of Tumour Interventional Diagnosis and Treatment, Zhuhai People's Hospital, Zhuhai Hospital affiliated with Jinan University, Zhuhai, 519000, Guangdong, China
| | - Hua Yu
- Precise Genome Engineering Center, School of Life Sciences, Guangzhou University, 510006, Guangzhou, China.
| | - Ligong Lu
- Zhuhai Interventional Medical Center, Guangdong Provincial Key Laboratory of Tumour Interventional Diagnosis and Treatment, Zhuhai People's Hospital, Zhuhai Hospital affiliated with Jinan University, Zhuhai, 519000, Guangdong, China.
| | - Xiongjun Wang
- Precise Genome Engineering Center, School of Life Sciences, Guangzhou University, 510006, Guangzhou, China.
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5
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Mogensen DJ, Etzerodt M, Ogilby PR. Photoinduced Bleaching in an Efficient Singlet Oxygen Photosensitizing Protein: Identifying a Culprit in the Flavin-Binding LOV-Based Protein SOPP3. J Photochem Photobiol A Chem 2022. [DOI: 10.1016/j.jphotochem.2022.113894] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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6
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Gowda P, Reddy PH, Kumar S. Deregulated mitochondrial microRNAs in Alzheimer's disease: Focus on synapse and mitochondria. Ageing Res Rev 2022; 73:101529. [PMID: 34813976 PMCID: PMC8692431 DOI: 10.1016/j.arr.2021.101529] [Citation(s) in RCA: 54] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2021] [Revised: 10/17/2021] [Accepted: 11/16/2021] [Indexed: 01/03/2023]
Abstract
Alzheimer's disease (AD) is the most common cause of dementia and is currently one of the biggest public health concerns in the world. Mitochondrial dysfunction in neurons is one of the major hallmarks of AD. Emerging evidence suggests that mitochondrial miRNAs potentially play important roles in the mitochondrial dysfunctions, focusing on synapse in AD progression. In this meta-analysis paper, a comprehensive literature review was conducted to identify and discuss the (1) role of mitochondrial miRNAs that regulate mitochondrial and synaptic functions; (2) the role of various factors such as mitochondrial dynamics, biogenesis, calcium signaling, biological sex, and aging on synapse and mitochondrial function; (3) how synapse damage and mitochondrial dysfunctions contribute to AD; (4) the structure and function of synapse and mitochondria in the disease process; (5) latest research developments in synapse and mitochondria in healthy and disease states; and (6) therapeutic strategies that improve synaptic and mitochondrial functions in AD. Specifically, we discussed how differences in the expression of mitochondrial miRNAs affect ATP production, oxidative stress, mitophagy, bioenergetics, mitochondrial dynamics, synaptic activity, synaptic plasticity, neurotransmission, and synaptotoxicity in neurons observed during AD. However, more research is needed to confirm the locations and roles of individual mitochondrial miRNAs in the development of AD.
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Affiliation(s)
- Prashanth Gowda
- Department of Internal Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - P. Hemachandra Reddy
- Department of Internal Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA.,Neuroscience & Pharmacology, Texas Tech University Health Sciences Center, Lubbock, TX, USA.,Neurology, Departments of School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA.,Public Health Department of Graduate School of Biomedical Sciences, Texas Tech University Health Sciences Center, Lubbock, TX, USA.,Department of Speech, Language and Hearing Sciences, School Health Professions, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Subodh Kumar
- Department of Internal Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
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7
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Peggion C, Massimino ML, Bonadio RS, Lia F, Lopreiato R, Cagnin S, Calì T, Bertoli A. Regulation of Endoplasmic Reticulum-Mitochondria Tethering and Ca 2+ Fluxes by TDP-43 via GSK3β. Int J Mol Sci 2021; 22:11853. [PMID: 34769284 PMCID: PMC8584823 DOI: 10.3390/ijms222111853] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 10/27/2021] [Accepted: 10/29/2021] [Indexed: 12/13/2022] Open
Abstract
Mitochondria-ER contacts (MERCs), tightly regulated by numerous tethering proteins that act as molecular and functional connections between the two organelles, are essential to maintain a variety of cellular functions. Such contacts are often compromised in the early stages of many neurodegenerative disorders, including amyotrophic lateral sclerosis (ALS). TDP-43, a nuclear protein mainly involved in RNA metabolism, has been repeatedly associated with ALS pathogenesis and other neurodegenerative diseases. Although TDP-43 neuropathological mechanisms are still unclear, the accumulation of the protein in cytoplasmic inclusions may underlie a protein loss-of-function effect. Accordingly, we investigated the impact of siRNA-mediated TDP-43 silencing on MERCs and the related cellular parameters in HeLa cells using GFP-based probes for MERCs quantification and aequorin-based probes for local Ca2+ measurements, combined with targeted protein and mRNA profiling. Our results demonstrated that TDP-43 down-regulation decreases MERCs density, thereby remarkably reducing mitochondria Ca2+ uptake after ER Ca2+ release. Thorough mRNA and protein analyses did not highlight altered expression of proteins involved in MERCs assembly or Ca2+-mediated ER-mitochondria cross-talk, nor alterations of mitochondrial density and morphology were observed by confocal microscopy. Further mechanistic inspections, however, suggested that the observed cellular alterations are correlated to increased expression/activity of GSK3β, previously associated with MERCs disruption.
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Affiliation(s)
- Caterina Peggion
- Department of Biomedical Sciences, University of Padova, 35131 Padova, Italy; (F.L.); (R.L.); (T.C.)
| | | | - Raphael Severino Bonadio
- Department of Biology, CRIBI Biotechnology Center, University of Padova, 35131 Padova, Italy; (R.S.B.); (S.C.)
| | - Federica Lia
- Department of Biomedical Sciences, University of Padova, 35131 Padova, Italy; (F.L.); (R.L.); (T.C.)
| | - Raffaele Lopreiato
- Department of Biomedical Sciences, University of Padova, 35131 Padova, Italy; (F.L.); (R.L.); (T.C.)
| | - Stefano Cagnin
- Department of Biology, CRIBI Biotechnology Center, University of Padova, 35131 Padova, Italy; (R.S.B.); (S.C.)
- CIR-Myo Myology Center, University of Padova, 35131 Padova, Italy
| | - Tito Calì
- Department of Biomedical Sciences, University of Padova, 35131 Padova, Italy; (F.L.); (R.L.); (T.C.)
- Padova Neuroscience Center, University of Padova, 35131 Padova, Italy
| | - Alessandro Bertoli
- Department of Biomedical Sciences, University of Padova, 35131 Padova, Italy; (F.L.); (R.L.); (T.C.)
- CNR—Neuroscience Institute, 35131 Padova, Italy;
- Padova Neuroscience Center, University of Padova, 35131 Padova, Italy
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8
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Potent antitumor activity of a glutamyltransferase-derived peptide via an activation of oncosis pathway. Sci Rep 2021; 11:16507. [PMID: 34389740 PMCID: PMC8363616 DOI: 10.1038/s41598-021-93055-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 03/08/2021] [Indexed: 12/09/2022] Open
Abstract
Hepatocellular carcinoma (HCC) still presents poor prognosis with high mortality rate, despite of the improvement in the management. The challenge for precision treatment was due to the fact that little targeted therapeutics are available for HCC. Recent studies show that metabolic and circulating peptides serve as endogenous switches for correcting aberrant cellular plasticity. Here we explored the antitumor activity of low molecular components in human umbilical serum and identified a high abundance peptide VI-13 by peptidome analysis, which was recognized as the part of glutamyltransferase signal peptide. We modified VI-13 by inserting four arginines and obtained an analog peptide VI-17 to improve its solubility. Our analyses showed that the peptide VI-17 induced rapid context-dependent cell death, and exhibited a higher sensitivity on hepatoma cells, which is attenuated by polyethylene glycol but not necrotic inhibitors such as z-VAD-fmk or necrostatin-1. Morphologically, VI-17 induced cell swelling, blebbing and membrane rupture with release of cellular ATP and LDH into extracellular media, which is hallmark of oncotic process. Mechanistically, VI-17 induced cell membrane pore formation, degradation of α-tubulin via influx of calcium ion. These results indicated that the novel peptide VI-17 induced oncosis in HCC cells, which could serve as a promising lead for development of therapeutic intervention of HCC.
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9
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Bausewein T, Naveed H, Liang J, Nussberger S. The structure of the TOM core complex in the mitochondrial outer membrane. Biol Chem 2021; 401:687-697. [PMID: 32142473 DOI: 10.1515/hsz-2020-0104] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2020] [Accepted: 03/03/2020] [Indexed: 02/05/2023]
Abstract
In the past three decades, significant advances have been made in providing the biochemical background of TOM (translocase of the outer mitochondrial membrane)-mediated protein translocation into mitochondria. In the light of recent cryoelectron microscopy-derived structures of TOM isolated from Neurospora crassa and Saccharomyces cerevisiae, the interpretation of biochemical and biophysical studies of TOM-mediated protein transport into mitochondria now rests on a solid basis. In this review, we compare the subnanometer structure of N. crassa TOM core complex with that of yeast. Both structures reveal remarkably well-conserved symmetrical dimers of 10 membrane protein subunits. The structural data also validate predictions of weakly stable regions in the transmembrane β-barrel domains of the protein-conducting subunit Tom40, which signal the existence of β-strands located in interfaces of protein-protein interactions.
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Affiliation(s)
- Thomas Bausewein
- Max-Planck-Institute of Biophysics, Department of Structural Biology, Max-von-Laue-Str. 3, D-60438Frankfurt am Main, Germany
| | - Hammad Naveed
- National University of Computer and Emerging Sciences, Department of Computer Science, A. K. Brohi Road H-11/4, Islamabad 44000, Pakistan
| | - Jie Liang
- Richard and Loan Hill Department of Bioengineering, MC-063, University of Illinois, Chicago, IL 60607-7052, USA
| | - Stephan Nussberger
- University of Stuttgart, Institute of Biomaterials and Biomolecular Systems, Department of Biophysics, Pfaffenwaldring 57, D-70569Stuttgart, Germany
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10
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Rout S, Oeljeklaus S, Makki A, Tachezy J, Warscheid B, Schneider A. Determinism and contingencies shaped the evolution of mitochondrial protein import. Proc Natl Acad Sci U S A 2021; 118:e2017774118. [PMID: 33526678 PMCID: PMC8017667 DOI: 10.1073/pnas.2017774118] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Mitochondrial protein import requires outer membrane receptors that evolved independently in different lineages. Here we used quantitative proteomics and in vitro binding assays to investigate the substrate preferences of ATOM46 and ATOM69, the two mitochondrial import receptors of Trypanosoma brucei The results show that ATOM46 prefers presequence-containing, hydrophilic proteins that lack transmembrane domains (TMDs), whereas ATOM69 prefers presequence-lacking, hydrophobic substrates that have TMDs. Thus, the ATOM46/yeast Tom20 and the ATOM69/yeast Tom70 pairs have similar substrate preferences. However, ATOM46 mainly uses electrostatic, and Tom20 hydrophobic, interactions for substrate binding. In vivo replacement of T. brucei ATOM46 by yeast Tom20 did not restore import. However, replacement of ATOM69 by the recently discovered Tom36 receptor of Trichomonas hydrogenosomes, while not allowing for growth, restored import of a large subset of trypanosomal proteins that lack TMDs. Thus, even though ATOM69 and Tom36 share the same domain structure and topology, they have different substrate preferences. The study establishes complementation experiments, combined with quantitative proteomics, as a highly versatile and sensitive method to compare in vivo preferences of protein import receptors. Moreover, it illustrates the role determinism and contingencies played in the evolution of mitochondrial protein import receptors.
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Affiliation(s)
- Samuel Rout
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, CH-3012 Bern, Switzerland
| | - Silke Oeljeklaus
- Biochemistry and Functional Proteomics, Institute of Biology II, Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
- Signalling Research Centres BIOSS and CIBSS, University of Freiburg, 79104 Freiburg, Germany
| | - Abhijith Makki
- Department of Parasitology, Faculty of Science, Charles University, BIOCEV, 12843 Prague, Czech Republic
| | - Jan Tachezy
- Department of Parasitology, Faculty of Science, Charles University, BIOCEV, 12843 Prague, Czech Republic
| | - Bettina Warscheid
- Biochemistry and Functional Proteomics, Institute of Biology II, Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany;
| | - André Schneider
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, CH-3012 Bern, Switzerland;
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11
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Schneider A. Evolution of mitochondrial protein import – lessons from trypanosomes. Biol Chem 2020; 401:663-676. [DOI: 10.1515/hsz-2019-0444] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 03/02/2020] [Indexed: 01/02/2023]
Abstract
AbstractThe evolution of mitochondrial protein import and the systems that mediate it marks the boundary between the endosymbiotic ancestor of mitochondria and a true organelle that is under the control of the nucleus. Protein import has been studied in great detail inSaccharomyces cerevisiae. More recently, it has also been extensively investigated in the parasitic protozoanTrypanosoma brucei, making it arguably the second best studied system. A comparative analysis of the protein import complexes of yeast and trypanosomes is provided. Together with data from other systems, this allows to reconstruct the ancestral features of import complexes that were present in the last eukaryotic common ancestor (LECA) and to identify which subunits were added later in evolution. How these data can be translated into plausible scenarios is discussed, providing insights into the evolution of (i) outer membrane protein import receptors, (ii) proteins involved in biogenesis of α-helically anchored outer membrane proteins, and (iii) of the intermembrane space import and assembly system. Finally, it is shown that the unusual presequence-associated import motor of trypanosomes suggests a scenario of how the two ancestral inner membrane protein translocases present in LECA evolved into the single bifunctional one found in extant trypanosomes.
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Affiliation(s)
- André Schneider
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
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12
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Chaudhuri A, Das S, Das B. Localization elements and zip codes in the intracellular transport and localization of messenger RNAs in Saccharomyces cerevisiae. WILEY INTERDISCIPLINARY REVIEWS-RNA 2020; 11:e1591. [PMID: 32101377 DOI: 10.1002/wrna.1591] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 02/05/2020] [Accepted: 02/07/2020] [Indexed: 12/13/2022]
Abstract
Intracellular trafficking and localization of mRNAs provide a mechanism of regulation of expression of genes with excellent spatial control. mRNA localization followed by localized translation appears to be a mechanism of targeted protein sorting to a specific cell-compartment, which is linked to the establishment of cell polarity, cell asymmetry, embryonic axis determination, and neuronal plasticity in metazoans. However, the complexity of the mechanism and the components of mRNA localization in higher organisms prompted the use of the unicellular organism Saccharomyces cerevisiae as a simplified model organism to study this vital process. Current knowledge indicates that a variety of mRNAs are asymmetrically and selectively localized to the tip of the bud of the daughter cells, to the vicinity of endoplasmic reticulum, mitochondria, and nucleus in this organism, which are connected to diverse cellular processes. Interestingly, specific cis-acting RNA localization elements (LEs) or RNA zip codes play a crucial role in the localization and trafficking of these localized mRNAs by providing critical binding sites for the specific RNA-binding proteins (RBPs). In this review, we present a comprehensive account of mRNA localization in S. cerevisiae, various types of localization elements influencing the mRNA localization, and the RBPs, which bind to these LEs to implement a number of vital physiological processes. Finally, we emphasize the significance of this process by highlighting their connection to several neuropathological disorders and cancers. This article is categorized under: RNA Export and Localization > RNA Localization.
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Affiliation(s)
- Anusha Chaudhuri
- Department of Life Science and Biotechnology, Jadavpur University, Kolkata, India
| | - Subhadeep Das
- Department of Life Science and Biotechnology, Jadavpur University, Kolkata, India
| | - Biswadip Das
- Department of Life Science and Biotechnology, Jadavpur University, Kolkata, India
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Hu Y, Zou W, Wang Z, Zhang Y, Hu Y, Qian J, Wu X, Ren Y, Zhao J. Translocase of the Outer Mitochondrial Membrane 40 Is Required for Mitochondrial Biogenesis and Embryo Development in Arabidopsis. FRONTIERS IN PLANT SCIENCE 2019; 10:389. [PMID: 31001303 PMCID: PMC6455079 DOI: 10.3389/fpls.2019.00389] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Accepted: 03/13/2019] [Indexed: 05/08/2023]
Abstract
In eukaryotes, mitochondrion is an essential organelle which is surrounded by a double membrane system, including the outer membrane, intermembrane space and the inner membrane. The translocase of the outer mitochondrial membrane (TOM) complex has attracted enormous interest for its role in importing the preprotein from the cytoplasm into the mitochondrion. However, little is understood about the potential biological function of the TOM complex in Arabidopsis. The aim of the present study was to investigate how AtTOM40, a gene encoding the core subunit of the TOM complex, works in Arabidopsis. As a result, we found that lack of AtTOM40 disturbed embryo development and its pattern formation after the globular embryo stage, and finally caused albino ovules and seed abortion at the ratio of a quarter in the homozygous tom40 plants. Further investigation demonstrated that AtTOM40 is wildly expressed in different tissues, especially in cotyledons primordium during Arabidopsis embryogenesis. Moreover, we confirmed that the encoded protein AtTOM40 is localized in mitochondrion, and the observation of the ultrastructure revealed that mitochondrion biogenesis was impaired in tom40-1 embryo cells. Quantitative real-time PCR was utilized to determine the expression of genes encoding outer mitochondrial membrane proteins in the homozygous tom40-1 mutant embryos, including the genes known to be involved in import, assembly and transport of mitochondrial proteins, and the results demonstrated that most of the gene expressions were abnormal. Similarly, the expression of genes relevant to embryo development and pattern formation, such as SAM (shoot apical meristem), cotyledon, vascular primordium and hypophysis, was also affected in homozygous tom40-1 mutant embryos. Taken together, we draw the conclusion that the AtTOM40 gene is essential for the normal structure of the mitochondrion, and participates in early embryo development and pattern formation through maintaining the biogenesis of mitochondria. The findings of this study may provide new insight into the biological function of the TOM40 subunit in higher plants.
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"Multiple partial recognitions in dynamic equilibrium" in the binding sites of proteins form the molecular basis of promiscuous recognition of structurally diverse ligands. Biophys Rev 2017; 10:421-433. [PMID: 29243092 DOI: 10.1007/s12551-017-0365-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2017] [Accepted: 11/19/2017] [Indexed: 12/12/2022] Open
Abstract
Promiscuous recognition of ligands by proteins is as important as strict recognition in numerous biological processes. In living cells, many short, linear amino acid motifs function as targeting signals in proteins to specify the final destination of the protein transport. In general, the target signal is defined by a consensus sequence containing wild-characters, and hence represented by diverse amino acid sequences. The classical lock-and-key or induced-fit/conformational selection mechanism may not cover all aspects of the promiscuous recognition. On the basis of our crystallographic and NMR studies on the mitochondrial Tom20 protein-presequence interaction, we proposed a new hypothetical mechanism based on "a rapid equilibrium of multiple states with partial recognitions". This dynamic, multiple recognition mode enables the Tom20 receptor to recognize diverse mitochondrial presequences with nearly equal affinities. The plant Tom20 is evolutionally unrelated to the animal Tom20 in our study, but is a functional homolog of the animal/fungal Tom20. NMR studies by another research group revealed that the presequence binding by the plant Tom20 was not fully explained by simple interaction modes, suggesting the presence of a similar dynamic, multiple recognition mode. Circumstantial evidence also suggested that similar dynamic mechanisms may be applicable to other promiscuous recognitions of signal peptides by the SRP54/Ffh and SecA proteins.
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Burggren AC, Mahmood Z, Harrison TM, Siddarth P, Miller KJ, Small GW, Merrill DA, Bookheimer SY. Hippocampal thinning linked to longer TOMM40 poly-T variant lengths in the absence of the APOE ε4 variant. Alzheimers Dement 2017; 13:739-748. [PMID: 28183529 DOI: 10.1016/j.jalz.2016.12.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Revised: 12/06/2016] [Accepted: 12/11/2016] [Indexed: 01/30/2023]
Abstract
INTRODUCTION The translocase of outer mitochondrial membrane 40 (TOMM40), which lies in linkage disequilibrium with apolipoprotein E (APOE), has received attention more recently as a promising gene in Alzheimer's disease (AD) risk. TOMM40 influences AD pathology through mitochondrial neurotoxicity, and the medial temporal lobe (MTL) is the most likely brain region for identifying early manifestations of AD-related morphology changes. METHODS In this study, we examined the effects of TOMM40 using high-resolution magnetic resonance imaging in 65 healthy, older subjects with and without the APOE ε4 AD-risk variant. RESULTS Examining individual subregions within the MTL, we found a significant relationship between increasing poly-T lengths of the TOMM40 variant and thickness of the entorhinal cortex only in subjects who did not carry the APOE ε4 allele. DISCUSSION Our data provide support for TOMM40 variant repeat length as an important contributor to AD-like MTL pathology in the absence of APOE ε4.
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Affiliation(s)
- Alison C Burggren
- Center for Cognitive Neurosciences, University of California, Los Angeles, CA, USA; Department of Psychiatry and Biobehavioral Sciences, University of California, Los Angeles, CA, USA; Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine, University of California, Los Angeles, CA, USA.
| | - Zanjbeel Mahmood
- Department of Psychiatry and Biobehavioral Sciences, University of California, Los Angeles, CA, USA
| | - Theresa M Harrison
- Center for Cognitive Neurosciences, University of California, Los Angeles, CA, USA; Department of Psychiatry and Biobehavioral Sciences, University of California, Los Angeles, CA, USA; Interdepartmental Graduate Program in Neuroscience, University of California, Los Angeles, CA, USA
| | - Prabha Siddarth
- Department of Psychiatry and Biobehavioral Sciences, University of California, Los Angeles, CA, USA; Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine, University of California, Los Angeles, CA, USA; Division of Geriatric Psychiatry, Longevity Center, University of California, Los Angeles, CA, USA
| | - Karen J Miller
- Department of Psychiatry and Biobehavioral Sciences, University of California, Los Angeles, CA, USA; Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine, University of California, Los Angeles, CA, USA; Division of Geriatric Psychiatry, Longevity Center, University of California, Los Angeles, CA, USA
| | - Gary W Small
- Department of Psychiatry and Biobehavioral Sciences, University of California, Los Angeles, CA, USA; Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine, University of California, Los Angeles, CA, USA; Division of Geriatric Psychiatry, Longevity Center, University of California, Los Angeles, CA, USA
| | - David A Merrill
- Department of Psychiatry and Biobehavioral Sciences, University of California, Los Angeles, CA, USA; Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine, University of California, Los Angeles, CA, USA; Division of Geriatric Psychiatry, Longevity Center, University of California, Los Angeles, CA, USA
| | - Susan Y Bookheimer
- Center for Cognitive Neurosciences, University of California, Los Angeles, CA, USA; Department of Psychiatry and Biobehavioral Sciences, University of California, Los Angeles, CA, USA; Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine, University of California, Los Angeles, CA, USA; Department of Psychology, University of California, Los Angeles, CA, USA
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Harsman A, Schneider A. Mitochondrial protein import in trypanosomes: Expect the unexpected. Traffic 2017; 18:96-109. [PMID: 27976830 DOI: 10.1111/tra.12463] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Revised: 12/01/2016] [Accepted: 12/06/2016] [Indexed: 12/11/2022]
Abstract
Mitochondria have many different functions, the most important one of which is oxidative phosphorylation. They originated from an endosymbiotic event between a bacterium and an archaeal host cell. It was the evolution of a protein import system that marked the boundary between the endosymbiotic ancestor of the mitochondrion and a true organelle that is under the control of the nucleus. In present day mitochondria more than 95% of all proteins are imported from the cytosol in a proces mediated by hetero-oligomeric protein complexes in the outer and inner mitochondrial membranes. In this review we compare mitochondrial protein import in the best studied model system yeast and the parasitic protozoan Trypanosoma brucei. The 2 organisms are phylogenetically only remotely related. Despite the fact that mitochondrial protein import has the same function in both species, only very few subunits of their import machineries are conserved. Moreover, while yeast has 2 inner membrane protein translocases, one specialized for presequence-containing and one for mitochondrial carrier proteins, T. brucei has a single inner membrane translocase only, that mediates import of both types of substrates. The evolutionary implications of these findings are discussed.
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Affiliation(s)
- Anke Harsman
- Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland
| | - André Schneider
- Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland
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Desy S, Mani J, Harsman A, Käser S, Schneider A. TbLOK1/ATOM19 is a novel subunit of the noncanonical mitochondrial outer membrane protein translocase of Trypanosoma brucei. Mol Microbiol 2016; 102:520-529. [PMID: 27501349 DOI: 10.1111/mmi.13476] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/31/2016] [Indexed: 11/28/2022]
Abstract
TbLOK1 has previously been characterized as a trypanosomatid-specific mitochondrial outer membrane protein whose ablation caused a collapse of the mitochondrial network, disruption of the membrane potential and loss of mitochondrial DNA. Here we show that ablation of TbLOK1 primarily abolishes mitochondrial protein import, both in vivo and in vitro. Co-immunprecipitations together with blue native gel analysis demonstrate that TbLOK1 is a stable and stoichiometric component of the archaic protein translocase of the outer membrane (ATOM), the highly diverged functional analogue of the TOM complex in other organisms. Furthermore, we show that TbLOK1 together with the other ATOM subunits forms a complex functional network where ablation of individual subunits either causes degradation of a specific set of other subunits or their exclusion from the ATOM complex. In summary these results establish that TbLOK1 is an essential novel subunit of the ATOM complex and thus that its primary molecular function is linked to mitochondrial protein import across the outer membrane. The previously described phenotypes can all be explained as consequences of the lack of mitochondrial protein import. We therefore suggest that in line with the nomenclature of the ATOM complex subunits, TbLOK1 should be renamed to ATOM19.
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Affiliation(s)
- Silvia Desy
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, Bern, CH-3012, Switzerland
| | - Jan Mani
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, Bern, CH-3012, Switzerland
| | - Anke Harsman
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, Bern, CH-3012, Switzerland
| | - Sandro Käser
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, Bern, CH-3012, Switzerland
| | - André Schneider
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, Bern, CH-3012, Switzerland.
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18
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Mechanisms of Superoxide Generation and Signaling in Cytochrome bc Complexes. ADVANCES IN PHOTOSYNTHESIS AND RESPIRATION 2016. [DOI: 10.1007/978-94-017-7481-9_20] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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19
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Fast-twitch skeletal muscle fiber adaptation to SERCA1 deficiency in a Dutch Improved Red and White calf pseudomyotonia case. Neuromuscul Disord 2015; 25:888-97. [DOI: 10.1016/j.nmd.2015.08.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Revised: 08/19/2015] [Accepted: 08/29/2015] [Indexed: 11/21/2022]
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Mani J, Meisinger C, Schneider A. Peeping at TOMs-Diverse Entry Gates to Mitochondria Provide Insights into the Evolution of Eukaryotes. Mol Biol Evol 2015; 33:337-51. [PMID: 26474847 DOI: 10.1093/molbev/msv219] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Mitochondria are essential for eukaryotic life and more than 95% of their proteins are imported as precursors from the cytosol. The targeting signals for this posttranslational import are conserved in all eukaryotes. However, this conservation does not hold true for the protein translocase of the mitochondrial outer membrane that serves as entry gate for essentially all precursor proteins. Only two of its subunits, Tom40 and Tom22, are conserved and thus likely were present in the last eukaryotic common ancestor. Tom7 is found in representatives of all supergroups except the Excavates. This suggests that it was added to the core of the translocase after the Excavates segregated from all other eukaryotes. A comparative analysis of the biochemically and functionally characterized outer membrane translocases of yeast, plants, and trypanosomes, which represent three eukaryotic supergroups, shows that the receptors that recognize the conserved import signals differ strongly between the different systems. They present a remarkable example of convergent evolution at the molecular level. The structural diversity of the functionally conserved import receptors therefore provides insight into the early evolutionary history of mitochondria.
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Affiliation(s)
- Jan Mani
- Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland
| | - Chris Meisinger
- Institut für Biochemie und Molekularbiologie, ZBMZ and BIOSS Centre for Biological Signalling Studies, Universität Freiburg, Freiburg, Germany
| | - André Schneider
- Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland
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Malhotra A, Dey A, Prasad N, Kenney AM. Sonic Hedgehog Signaling Drives Mitochondrial Fragmentation by Suppressing Mitofusins in Cerebellar Granule Neuron Precursors and Medulloblastoma. Mol Cancer Res 2015; 14:114-24. [PMID: 26446920 DOI: 10.1158/1541-7786.mcr-15-0278] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Accepted: 09/28/2015] [Indexed: 12/22/2022]
Abstract
UNLABELLED Sonic hedgehog (Shh) signaling is closely coupled with bioenergetics of medulloblastoma, the most common malignant pediatric brain tumor. Shh-associated medulloblastoma arises from cerebellar granule neuron precursors (CGNP), a neural progenitor whose developmental expansion requires signaling by Shh, a ligand secreted by the neighboring Purkinje neurons. Previous observations show that Shh signaling inhibits fatty acid oxidation although driving increased fatty acid synthesis. Proliferating CGNPs and mouse Shh medulloblastomas feature high levels of glycolytic enzymes in vivo and in vitro. Because both of these metabolic processes are closely linked to mitochondrial bioenergetics, the role of Shh signaling in mitochondrial biogenesis was investigated. This report uncovers a surprising decrease in mitochondrial membrane potential (MMP) and overall ATP production in CGNPs exposed to Shh, consistent with increased glycolysis resulting in high intracellular acidity, leading to mitochondrial fragmentation. Ultrastructural examination of mitochondria revealed a spherical shape in Shh-treated cells, in contrast to the elongated appearance in vehicle-treated postmitotic cells. Expression of mitofusin 1 and 2 was reduced in these cells, although their ectopic expression restored the MMP to the nonproliferating state and the morphology to a fused, interconnected state. Mouse Shh medulloblastoma cells featured drastically impaired mitochondrial morphology, restoration of which by ectopic mitofusin expression was also associated with a decrease in the expression of Cyclin D2 protein, a marker for proliferation. IMPLICATIONS This report exposes a novel role for Shh in regulating mitochondrial dynamics and rescue of the metabolic profile of tumor cells to that of nontransformed, nonproliferating cells and represents a potential avenue for development of medulloblastoma therapeutics.
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Affiliation(s)
- Anshu Malhotra
- Department of Pediatric Oncology, Emory University, Atlanta, Georgia
| | - Abhinav Dey
- Department of Pediatric Oncology, Emory University, Atlanta, Georgia
| | - Niyathi Prasad
- Department of Pediatric Oncology, Emory University, Atlanta, Georgia
| | - Anna Marie Kenney
- Department of Pediatric Oncology, Emory University, Atlanta, Georgia. Winship Cancer Institute, Atlanta, Georgia.
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22
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Kuszak AJ, Jacobs D, Gurnev PA, Shiota T, Louis JM, Lithgow T, Bezrukov SM, Rostovtseva TK, Buchanan SK. Evidence of Distinct Channel Conformations and Substrate Binding Affinities for the Mitochondrial Outer Membrane Protein Translocase Pore Tom40. J Biol Chem 2015; 290:26204-17. [PMID: 26336107 DOI: 10.1074/jbc.m115.642173] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Indexed: 12/14/2022] Open
Abstract
Nearly all mitochondrial proteins are coded by the nuclear genome and must be transported into mitochondria by the translocase of the outer membrane complex. Tom40 is the central subunit of the translocase complex and forms a pore in the mitochondrial outer membrane. To date, the mechanism it utilizes for protein transport remains unclear. Tom40 is predicted to comprise a membrane-spanning β-barrel domain with conserved α-helical domains at both the N and C termini. To investigate Tom40 function, including the role of the N- and C-terminal domains, recombinant forms of the Tom40 protein from the yeast Candida glabrata, and truncated constructs lacking the N- and/or C-terminal domains, were functionally characterized in planar lipid membranes. Our results demonstrate that each of these Tom40 constructs exhibits at least four distinct conductive levels and that full-length and truncated Tom40 constructs specifically interact with a presequence peptide in a concentration- and voltage-dependent manner. Therefore, neither the first 51 amino acids of the N terminus nor the last 13 amino acids of the C terminus are required for Tom40 channel formation or for the interaction with a presequence peptide. Unexpectedly, substrate binding affinity was dependent upon the Tom40 state corresponding to a particular conductive level. A model where two Tom40 pores act in concert as a dimeric protein complex best accounts for the observed biochemical and electrophysiological data. These results provide the first evidence for structurally distinct Tom40 conformations playing a role in substrate recognition and therefore in transport function.
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Affiliation(s)
| | - Daniel Jacobs
- From the Laboratories of Molecular Biology and Program in Physical Biology, NICHD, National Institutes of Health, Bethesda, Maryland 20892
| | - Philip A Gurnev
- Program in Physical Biology, NICHD, National Institutes of Health, Bethesda, Maryland 20892, the Physics Department, University of Massachusetts, Amherst, Massachusetts 01003, and
| | - Takuya Shiota
- the Department of Microbiology, Monash University, Melbourne 3800, Victoria, Australia
| | | | - Trevor Lithgow
- the Department of Microbiology, Monash University, Melbourne 3800, Victoria, Australia
| | - Sergey M Bezrukov
- Program in Physical Biology, NICHD, National Institutes of Health, Bethesda, Maryland 20892
| | - Tatiana K Rostovtseva
- Program in Physical Biology, NICHD, National Institutes of Health, Bethesda, Maryland 20892,
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Wojtkowska M, Buczek D, Stobienia O, Karachitos A, Antoniewicz M, Slocinska M, Makałowski W, Kmita H. The TOM Complex of Amoebozoans: the Cases of the Amoeba Acanthamoeba castellanii and the Slime Mold Dictyostelium discoideum. Protist 2015; 166:349-62. [PMID: 26074248 DOI: 10.1016/j.protis.2015.05.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Revised: 05/10/2015] [Accepted: 05/14/2015] [Indexed: 11/29/2022]
Abstract
Protein import into mitochondria requires a wide variety of proteins, forming complexes in both mitochondrial membranes. The TOM complex (translocase of the outer membrane) is responsible for decoding of targeting signals, translocation of imported proteins across or into the outer membrane, and their subsequent sorting. Thus the TOM complex is regarded as the main gate into mitochondria for imported proteins. Available data indicate that mitochondria of representative organisms from across the major phylogenetic lineages of eukaryotes differ in subunit organization of the TOM complex. The subunit organization of the TOM complex in the Amoebozoa is still elusive, so we decided to investigate its organization in the soil amoeba Acanthamoeba castellanii and the slime mold Dictyostelium discoideum. They represent two major subclades of the Amoebozoa: the Lobosa and Conosa, respectively. Our results confirm the presence of Tom70, Tom40 and Tom7 in the A. castellanii and D. discoideum TOM complex, while the presence of Tom22 and Tom20 is less supported. Interestingly, the Tom proteins display the highest similarity to Opisthokonta cognate proteins, with the exception of Tom40. Thus representatives of two major subclades of the Amoebozoa appear to be similar in organization of the TOM complex, despite differences in their lifestyle.
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Affiliation(s)
- Małgorzata Wojtkowska
- Adam Mickiewicz University, Faculty of Biology, Institute of Molecular Biology and Biotechnology, Department of Bioenergetics, Poznań, Poland.
| | - Dorota Buczek
- Adam Mickiewicz University, Faculty of Biology, Institute of Molecular Biology and Biotechnology, Department of Bioenergetics, Poznań, Poland; University of Muenster, Faculty of Medicine Institute of Bioinformatics, Muenster, Germany
| | - Olgierd Stobienia
- Adam Mickiewicz University, Faculty of Biology, Institute of Molecular Biology and Biotechnology, Department of Bioenergetics, Poznań, Poland
| | - Andonis Karachitos
- Adam Mickiewicz University, Faculty of Biology, Institute of Molecular Biology and Biotechnology, Department of Bioenergetics, Poznań, Poland
| | - Monika Antoniewicz
- Adam Mickiewicz University, Faculty of Biology, Institute of Molecular Biology and Biotechnology, Department of Bioenergetics, Poznań, Poland
| | - Małgorzata Slocinska
- Adam Mickiewicz University, Faculty of Biology, Institute of Experimental Biology, Department of Animal Physiology and Development, Poznań, Poland
| | - Wojciech Makałowski
- University of Muenster, Faculty of Medicine Institute of Bioinformatics, Muenster, Germany
| | - Hanna Kmita
- Adam Mickiewicz University, Faculty of Biology, Institute of Molecular Biology and Biotechnology, Department of Bioenergetics, Poznań, Poland
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Yao X, Dürr UHN, Gattin Z, Laukat Y, Narayanan RL, Brückner AK, Meisinger C, Lange A, Becker S, Zweckstetter M. NMR-based detection of hydrogen/deuterium exchange in liposome-embedded membrane proteins. PLoS One 2014; 9:e112374. [PMID: 25375235 PMCID: PMC4223039 DOI: 10.1371/journal.pone.0112374] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Accepted: 10/05/2014] [Indexed: 11/17/2022] Open
Abstract
Membrane proteins play key roles in biology. Determination of their structure in a membrane environment, however, is highly challenging. To address this challenge, we developed an approach that couples hydrogen/deuterium exchange of membrane proteins to rapid unfolding and detection by solution-state NMR spectroscopy. We show that the method allows analysis of the solvent protection of single residues in liposome-embedded proteins such as the 349-residue Tom40, the major protein translocation pore in the outer mitochondrial membrane, which has resisted structural analysis for many years.
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Affiliation(s)
- Xuejun Yao
- Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Ulrich H N Dürr
- Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Zrinka Gattin
- Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Yvonne Laukat
- Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | | | | | - Chris Meisinger
- Institut für Biochemie und Molekularbiologie, ZBMZ and BIOSS Centre for Biological Signalling Studies, Universität Freiburg, Freiburg, Germany
| | - Adam Lange
- Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Stefan Becker
- Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Markus Zweckstetter
- Max Planck Institute for Biophysical Chemistry, Göttingen, Germany; German Center for Neurodegenerative Diseases (DZNE), Goöttingen, Germany; Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), University Medical Center, Göttingen, Germany
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Wang L, Liu Z, Dong Z, Pan J, Ma X. Azurocidin-induced inhibition of oxygen metabolism in mitochondria is antagonized by heparin. Exp Ther Med 2014; 8:1473-1478. [PMID: 25289044 PMCID: PMC4186485 DOI: 10.3892/etm.2014.1939] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Accepted: 08/11/2014] [Indexed: 01/05/2023] Open
Abstract
Heparin is a potent blood anticoagulant that has been demonstrated to attenuate inflammatory responses in sepsis. Sepsis is considered to be a microcirculation-mitochondrial distress syndrome. Azurocidin (AZU), a protein with strong heparin-binding potential that induces inflammatory responses and apoptosis, has been shown to increase the permeability of endothelial cells and induce the prognosis of sepsis. However, the function of AZU in mitochondrial oxygen metabolism has yet to be reported. The aim of the present study was to investigate whether heparin exhibits an antagonistic effect on AZU-induced mitochondrial dysfunction in human umbilical vein endothelial cells (HUVECs) and to further investigate the possible underlying mechanisms. HUVECs were randomly assigned into blank control, AZU, heparin plus AZU and heparin groups. The blank control group were incubated with phosphate-buffered saline for 12 h, while the AZU group were incubated with 1 μg/ml AZU for 12 h. The heparin plus AZU group were incubated with 100 μg/ml heparin for 2 h, followed by the addition of 1 μg/ml AZU and incubation for 12 h. The heparin group were incubated with 100 μg/ml heparin for 12 h. Flow cytometry was used to determine the mitochondrial membrane potential, while electron microscopy was used to determine the mitochondrial morphology. Western blotting and quantitative polymerase chain reaction were used to determine the protein and mRNA expression levels of Cox II in the mitochondria, respectively. Western blotting was also used to evaluate the concentration of AZU in cytoplasm, along with immunofluorescence analysis. AZU was revealed to decrease the mitochondrial membrane potential, reduce cytochrome c oxidase subunit II expression and destroy the morphology of the mitochondria. Heparin exhibited an antagonistic function on these processes and inhibited the endocytosis of AZU by HUVECs. In conclusion, the results indicated that AZU inhibited the oxygen metabolic function in mitochondria, and this function was effectively antagonized by heparin via the inhibition of AZU endocytosis by HUVECs. Therefore, heparin may be a potential therapeutic agent for treating mitochondrial dysfunction in the future.
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Affiliation(s)
- Liang Wang
- Department of Intensive Care Medicine, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Zhiyong Liu
- Department of Intensive Care Medicine, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Zhe Dong
- Department of Intensive Care Medicine, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Jieyi Pan
- Department of Intensive Care Medicine, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Xiaochun Ma
- Department of Intensive Care Medicine, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China
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Lackey SWK, Taylor RD, Go NE, Wong A, Sherman EL, Nargang FE. Evidence supporting the 19 β-strand model for Tom40 from cysteine scanning and protease site accessibility studies. J Biol Chem 2014; 289:21640-50. [PMID: 24947507 DOI: 10.1074/jbc.m114.578765] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Most proteins found in mitochondria are translated in the cytosol and enter the organelle via the TOM complex (translocase of the outer mitochondrial membrane). Tom40 is the pore forming component of the complex. Although the three-dimensional structure of Tom40 has not been determined, the structure of porin, a related protein, has been shown to be a β-barrel containing 19 membrane spanning β-strands and an N-terminal α-helical region. The evolutionary relationship between the two proteins has allowed modeling of Tom40 into a similar structure by several laboratories. However, it has been suggested that the 19-strand porin structure does not represent the native form of the protein. If true, modeling of Tom40 based on the porin structure would also be invalid. We have used substituted cysteine accessibility mapping to identify several potential β-strands in the Tom40 protein in isolated mitochondria. These data, together with protease accessibility studies, support the 19 β-strand model for Tom40 with the C-terminal end of the protein localized to the intermembrane space.
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Affiliation(s)
- Sebastian W K Lackey
- From the Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
| | - Rebecca D Taylor
- From the Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
| | - Nancy E Go
- From the Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
| | - Annie Wong
- From the Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
| | - E Laura Sherman
- From the Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
| | - Frank E Nargang
- From the Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
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Murcha MW, Kubiszewski-Jakubiak S, Wang Y, Whelan J. Evidence for interactions between the mitochondrial import apparatus and respiratory chain complexes via Tim21-like proteins in Arabidopsis. FRONTIERS IN PLANT SCIENCE 2014; 5:82. [PMID: 24653731 PMCID: PMC3949100 DOI: 10.3389/fpls.2014.00082] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2014] [Accepted: 02/21/2014] [Indexed: 05/06/2023]
Abstract
The mitochondrial import machinery and the respiratory chain complexes of the inner membrane are highly interdependent for the efficient import and assembly of nuclear encoded respiratory chain components and for the generation of a proton motive force essential for protein translocation into or across the inner membrane. In plant and non-plant systems functional, physical, and evolutionary associations have been observed between proteins of the respiratory chain and protein import apparatus. Here we identify two novel Tim21-like proteins encoded by At2g40800 and At3g56430 that are imported into the mitochondrial inner membrane. We propose that Tim21-like proteins may associate with respiratory chain Complex I, III, in addition to the TIM17:23 translocase of the inner membrane. These results are discussed further with regards to the regulation of mitochondrial activity and biogenesis.
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Affiliation(s)
- Monika W. Murcha
- ARC Centre of Excellence in Plant Energy Biology, The University of Western AustraliaPerth, WA, Australia
- *Correspondence: Monika W. Murcha, ARC Centre of Excellence in Plant Energy Biology, University of Western Australia, MCS Building M316, 35 Stirling Highway, Crawley, Perth, WA 6009, Australia e-mail:
| | | | - Yan Wang
- ARC Centre of Excellence in Plant Energy Biology, The University of Western AustraliaPerth, WA, Australia
| | - James Whelan
- Department of Botany, ARC Centre of Excellence in Plant Energy Biology, School of Life Sciences, La Trobe UniversityBundoora, VIC, Australia
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28
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Morgan RML, Hernández-Ramírez LC, Trivellin G, Zhou L, Roe SM, Korbonits M, Prodromou C. Structure of the TPR domain of AIP: lack of client protein interaction with the C-terminal α-7 helix of the TPR domain of AIP is sufficient for pituitary adenoma predisposition. PLoS One 2012; 7:e53339. [PMID: 23300914 PMCID: PMC3534021 DOI: 10.1371/journal.pone.0053339] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Accepted: 11/27/2012] [Indexed: 12/22/2022] Open
Abstract
Mutations of the aryl hydrocarbon receptor interacting protein (AIP) have been associated with familial isolated pituitary adenomas predisposing to young-onset acromegaly and gigantism. The precise tumorigenic mechanism is not well understood as AIP interacts with a large number of independent proteins as well as three chaperone systems, HSP90, HSP70 and TOMM20. We have determined the structure of the TPR domain of AIP at high resolution, which has allowed a detailed analysis of how disease-associated mutations impact on the structural integrity of the TPR domain. A subset of C-terminal α-7 helix (Cα-7h) mutations, R304* (nonsense mutation), R304Q, Q307* and R325Q, a known site for AhR and PDE4A5 client-protein interaction, occur beyond those that interact with the conserved MEEVD and EDDVE sequences of HSP90 and TOMM20. These C-terminal AIP mutations appear to only disrupt client-protein binding to the Cα-7h, while chaperone binding remains unaffected, suggesting that failure of client-protein interaction with the Cα-7h is sufficient to predispose to pituitary adenoma. We have also identified a molecular switch in the AIP TPR-domain that allows recognition of both the conserved HSP90 motif, MEEVD, and the equivalent sequence (EDDVE) of TOMM20.
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Affiliation(s)
- Rhodri M. L. Morgan
- Genome Damage and Stability Centre, University of Sussex, Brighton, United Kingdom
| | - Laura C. Hernández-Ramírez
- Department of Endocrinology, Barts and the London School of Medicine, Queen Mary University of London, London, United Kingdom
| | - Giampaolo Trivellin
- Department of Endocrinology, Barts and the London School of Medicine, Queen Mary University of London, London, United Kingdom
| | - Lihong Zhou
- Genome Damage and Stability Centre, University of Sussex, Brighton, United Kingdom
| | - S. Mark Roe
- Biochemistry and Molecular Biology, Chichester 2, University of Sussex, Brighton, United Kingdom
| | - Márta Korbonits
- Department of Endocrinology, Barts and the London School of Medicine, Queen Mary University of London, London, United Kingdom
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Balaker AE, Ishiyama P, Lopez IA, Ishiyama G, Ishiyama A. Immunocytochemical Localization of the Translocase of the Outer Mitochondrial Membrane (Tom20) in the Human Cochlea. Anat Rec (Hoboken) 2012; 296:326-32. [DOI: 10.1002/ar.22622] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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Duncan O, Murcha MW, Whelan J. Unique components of the plant mitochondrial protein import apparatus. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1833:304-13. [PMID: 22406071 DOI: 10.1016/j.bbamcr.2012.02.015] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2012] [Revised: 02/21/2012] [Accepted: 02/23/2012] [Indexed: 10/28/2022]
Abstract
The basic mitochondrial protein import apparatus was established in the earliest eukaryotes. Over the subsequent course of evolution and the divergence of the plant, animal and fungal lineages, this basic import apparatus has been modified and expanded in order to meet the specific needs of protein import in each kingdom. In the plant kingdom, the arrival of the plastid complicated the process of protein trafficking and is thought to have given rise to the evolution of a number of unique components that allow specific and efficient targeting of mitochondrial proteins from their site of synthesis in the cytosol, to their final location in the organelle. This includes the evolution of two unique outer membrane import receptors, plant Translocase of outer membrane 20 kDa subunit (TOM20) and Outer membrane protein of 64 kDa (OM64), the loss of a receptor domain from an ancestral import component, Translocase of outer membrane 22 kDa subunit (TOM22), evolution of unique features in the disulfide relay system of the inter membrane space, and the addition of an extra membrane spanning domain to another ancestral component of the inner membrane, Translocase of inner membrane 17 kDa subunit (TIM17). Notably, many of these components are encoded by multi-gene families and exhibit differential sub-cellular localisation and functional specialisation. This article is part of a Special Issue entitled: Protein Import and Quality Control in Mitochondria and Plastids.
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Affiliation(s)
- Owen Duncan
- ARC Centre of Excellence in Plant Energy Biology, Bayliss Building M316, The University of Western Australia, 35 Stirling Hwy, Crawley, WA 6009, Australia
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31
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Wojtkowska M, Jąkalski M, Pieńkowska JR, Stobienia O, Karachitos A, Przytycka TM, Weiner J, Kmita H, Makałowski W. Phylogenetic analysis of mitochondrial outer membrane β-barrel channels. Genome Biol Evol 2011; 4:110-25. [PMID: 22155732 PMCID: PMC3273162 DOI: 10.1093/gbe/evr130] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Transport of molecules across mitochondrial outer membrane is pivotal for a proper function of mitochondria. The transport pathways across the membrane are formed by ion channels that participate in metabolite exchange between mitochondria and cytoplasm (voltage-dependent anion-selective channel, VDAC) as well as in import of proteins encoded by nuclear genes (Tom40 and Sam50/Tob55). VDAC, Tom40, and Sam50/Tob55 are present in all eukaryotic organisms, encoded in the nuclear genome, and have β-barrel topology. We have compiled data sets of these protein sequences and studied their phylogenetic relationships with a special focus on the position of Amoebozoa. Additionally, we identified these protein-coding genes in Acanthamoeba castellanii and Dictyostelium discoideum to complement our data set and verify the phylogenetic position of these model organisms. Our analysis show that mitochondrial β-barrel channels from Archaeplastida (plants) and Opisthokonta (animals and fungi) experienced many duplication events that resulted in multiple paralogous isoforms and form well-defined monophyletic clades that match the current model of eukaryotic evolution. However, in representatives of Amoebozoa, Chromalveolata, and Excavata (former Protista), they do not form clearly distinguishable clades, although they locate basally to the plant and algae branches. In most cases, they do not posses paralogs and their sequences appear to have evolved quickly or degenerated. Consequently, the obtained phylogenies of mitochondrial outer membrane β-channels do not entirely reflect the recent eukaryotic classification system involving the six supergroups: Chromalveolata, Excavata, Archaeplastida, Rhizaria, Amoebozoa, and Opisthokonta.
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Affiliation(s)
- Małgorzata Wojtkowska
- Laboratory of Bioenergetics, Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University, Poznań, Poland
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32
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Jaedicke K, Rösler J, Gans T, Hughes J. Bellis perennis: a useful tool for protein localization studies. PLANTA 2011; 234:759-68. [PMID: 21626148 DOI: 10.1007/s00425-011-1443-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2011] [Accepted: 05/16/2011] [Indexed: 05/08/2023]
Abstract
Fluorescent fusion proteins together with transient transformation techniques are commonly used to investigate intracellular protein localisation in vivo. Biolistic transfection is reliable, efficient and avoids experimental problems associated with producing and handling fragile protoplasts. Onion epidermis pavement cells are frequently used with this technique, their excellent properties for microscopy resulting from their easy removal from the underlying tissues and large size. They also have advantages over mesophyll cells for fluorescence microscopy, as they are devoid of chloroplasts whose autofluorescence can pose problems. The arrested plastid development is peculiar to epidermal cells, however, and stands in the way of studies on protein targeting to plastids. We have developed a system enabling studies of in vivo protein targeting to organelles including chloroplasts within a photosynthetically active plant cell with excellent optical properties using a transient transformation procedure. We established biolistic transfection in epidermal pavement cells of the lawn daisy (Bellis perennis L., cultivar "Galaxy red") which unusually contain a moderate number of functional chloroplasts. These cells are excellent objects for fluorescence microscopy using current reporters, combining the advantages of the ease of biolistic transfection, the excellent optical properties of a single cell layer and access to chloroplast protein targeting. We demonstrate chloroplast targeting of plastid-localised heme oxygenase, and two further proteins whose localisation was equivocal. We also demonstrate unambiguous targeting to mitochondria, peroxisomes and nuclei. We thus propose that the Bellis system represents a valuable tool for protein localisation studies in living plant cells.
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Affiliation(s)
- Katharina Jaedicke
- Plant Physiology, Justus Liebig University Giessen, Senckenbergstr. 3, 35390 Giessen, Germany.
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33
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Pierron D, Wildman DE, Hüttemann M, Markondapatnaikuni GC, Aras S, Grossman LI. Cytochrome c oxidase: evolution of control via nuclear subunit addition. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2011; 1817:590-7. [PMID: 21802404 DOI: 10.1016/j.bbabio.2011.07.007] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2011] [Revised: 07/12/2011] [Accepted: 07/13/2011] [Indexed: 02/01/2023]
Abstract
According to theory, present eukaryotic cells originated from a beneficial association between two free-living cells. Due to this endosymbiotic event the pre-eukaryotic cell gained access to oxidative phosphorylation (OXPHOS), which produces more than 15 times as much ATP as glycolysis. Because cellular ATP needs fluctuate and OXPHOS both requires and produces entities that can be toxic for eukaryotic cells such as ROS or NADH, we propose that the success of endosymbiosis has largely depended on the regulation of endosymbiont OXPHOS. Several studies have presented cytochrome c oxidase as a key regulator of OXPHOS; for example, COX is the only complex of mammalian OXPHOS with known tissue-specific isoforms of nuclear encoded subunits. We here discuss current knowledge about the origin of nuclear encoded subunits and the appearance of different isozymes promoted by tissue and cellular environments such as hypoxia. We also review evidence for recent selective pressure acting on COX among vertebrates, particularly in primate lineages, and discuss the unique pattern of co-evolution between the nuclear and mitochondrial genomes. Finally, even though the addition of nuclear encoded subunits was a major event in eukaryotic COX evolution, this does not lead to emergence of a more efficient COX, as might be expected from an anthropocentric point of view, for the "higher" organism possessing large brains and muscles. The main function of these subunits appears to be "only" to control the activity of the mitochondrial subunits. We propose that this control function is an as yet under appreciated key point of evolution. Moreover, the importance of regulating energy supply may have caused the addition of subunits encoded by the nucleus in a process comparable to a "domestication scenario" such that the host tends to control more and more tightly the ancestral activity of COX performed by the mtDNA encoded subunits.
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Affiliation(s)
- Denis Pierron
- Wayne State University School of Medicine, Detroit, MI, USA
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34
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Saitoh T, Igura M, Miyazaki Y, Ose T, Maita N, Kohda D. Crystallographic Snapshots of Tom20–Mitochondrial Presequence Interactions with Disulfide-Stabilized Peptides. Biochemistry 2011; 50:5487-96. [DOI: 10.1021/bi200470x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Takashi Saitoh
- Division of Structural Biology, Medical Institute of Bioregulation, Kyushu University, Maidashi 3-1-1, Higashi-ku, Fukuoka 812-8582, Japan
| | - Mayumi Igura
- Division of Structural Biology, Medical Institute of Bioregulation, Kyushu University, Maidashi 3-1-1, Higashi-ku, Fukuoka 812-8582, Japan
| | - Yusuke Miyazaki
- Division of Structural Biology, Medical Institute of Bioregulation, Kyushu University, Maidashi 3-1-1, Higashi-ku, Fukuoka 812-8582, Japan
| | - Toyoyuki Ose
- Division of Structural Biology, Medical Institute of Bioregulation, Kyushu University, Maidashi 3-1-1, Higashi-ku, Fukuoka 812-8582, Japan
| | - Nobuo Maita
- Institute for Enzyme Research, Tokushima University, 2-24, Shinkura-cho, Tokushima 770-8501, Japan
| | - Daisuke Kohda
- Division of Structural Biology, Medical Institute of Bioregulation, Kyushu University, Maidashi 3-1-1, Higashi-ku, Fukuoka 812-8582, Japan
- Research Center for Advanced Immunology, Kyushu University, Maidashi 3-1-1, Higashi-ku, Fukuoka 812-8582, Japan
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35
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Danne JC, Waller RF. Analysis of dinoflagellate mitochondrial protein sorting signals indicates a highly stable protein targeting system across eukaryotic diversity. J Mol Biol 2011; 408:643-53. [PMID: 21376056 DOI: 10.1016/j.jmb.2011.02.057] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2010] [Revised: 02/21/2011] [Accepted: 02/24/2011] [Indexed: 11/17/2022]
Abstract
Protein targeting into mitochondria from the cytoplasm is fundamental to the cell biology of all eukaryotes. Our understanding of this process is heavily biased towards "model" organisms, such as animals and fungi, and it is less clear how conserved this process is throughout diverse eukaryotes. In this study, we have surveyed mitochondrial protein sorting signals from a representative of the dinoflagellate algae. Dinoflagellates are a phylum belonging to the group Alveolata, which also includes apicomplexan parasites and ciliates. We generated 46 mitochondrial gene sequences from the dinoflagellate Karlodinium micrum and analysed these for mitochondrial sorting signals. Most of the sequences contain predicted N-terminal peptide extensions that conform to mitochondrial targeting peptides from animals and fungi in terms of length, amino acid composition, and propensity to form amphipathic α-helices. The remainder lack predicted mitochondrial targeting peptides and represent carrier proteins of the inner mitochondrial membrane that have internal targeting signals in model eukaryotes. We tested for functional conservation of the dinoflagellate mitochondrial sorting signals by expressing K. micrum mitochondrial proteins in the fungus Saccharomyces cerevisiae. Both the N-terminal and internal targeting signals were sufficiently conserved to operate in this distantly related system. This study indicates that the character of mitochondrial sorting signals was well established prior to the radiation of major eukaryotic lineages and has shown remarkable conservation during long periods of evolution.
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Affiliation(s)
- Jillian C Danne
- School of Botany, University of Melbourne, Victoria 3010, Australia
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36
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Aulik NA, Hellenbrand KM, Kisiela D, Czuprynski CJ. Mannheimia haemolytica leukotoxin binds cyclophilin D on bovine neutrophil mitochondria. Microb Pathog 2011; 50:168-78. [PMID: 21220005 DOI: 10.1016/j.micpath.2011.01.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2010] [Revised: 12/28/2010] [Accepted: 01/03/2011] [Indexed: 01/03/2023]
Abstract
Mannheimia haemolytica is an important member of the bovine respiratory disease (BRD) complex that causes fibrinous and necrotizing pleuropneumonia in cattle. BRD is characterized by abundant neutrophil infiltration into the alveoli and fibrin deposition. The most important virulence factor of M. haemolytica is its leukotoxin. Previous research in our laboratory has shown that the leukotoxin is able to enter into and traffic to the mitochondria of a bovine lymphoblastoid cell line (BL-3). In this study, we evaluated the ability of LKT to be internalized and travel to mitochondria in bovine neutrophils. We demonstrate that LKT binds bovine neutrophil mitochondria and co-immunoprecipitates with TOM22 and TOM40, which are members of the translocase of the outer mitochondrial (TOM) membrane family. Upon entry into mitochondria, LKT co-immunoprecipitates with cyclophilin D, a member of the mitochondria permeability transition pore. Unlike BL-3 cells, bovine neutrophil mitochondria are not protected against LKT by the membrane-stabilizing agent cyclosporin A, nor were bovine neutrophil mitochondria protected by the permeability transition pore antagonist bongkrekic acid. In addition, we found that bovine neutrophil cyclophilin D is significantly smaller than that found in BL-3 cells. Bovine neutrophils were protected against LKT by protein transfection of an anti-cyclophilin D antibody directed at the C-terminal amino acids, but not an antibody against the first 50 N-terminal amino acids. In contrast, BL-3 cells were protected by antibodies against either the C-terminus or N-terminus of cyclophilin. These data confirm that LKT binds to bovine neutrophil mitochondria, but indicate there are distinctions between neutrophil and BL-3 mitochondria that might reflect differences in cyclophilin D.
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Affiliation(s)
- Nicole A Aulik
- Microbiology Doctoral Training Program, University of Wisconsin-Madison, Madison, WI 53706, USA
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37
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Schleiff E, Becker T. Common ground for protein translocation: access control for mitochondria and chloroplasts. Nat Rev Mol Cell Biol 2010; 12:48-59. [DOI: 10.1038/nrm3027] [Citation(s) in RCA: 200] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Harsman A, Krüger V, Bartsch P, Honigmann A, Schmidt O, Rao S, Meisinger C, Wagner R. Protein conducting nanopores. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:454102. [PMID: 21339590 DOI: 10.1088/0953-8984/22/45/454102] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
About 50% of the cellular proteins have to be transported into or across cellular membranes. This transport is an essential step in the protein biosynthesis. In eukaryotic cells secretory proteins are transported into the endoplasmic reticulum before they are transported in vesicles to the plasma membrane. Almost all proteins of the endosymbiotic organelles chloroplasts and mitochondria are synthesized on cytosolic ribosomes and posttranslationally imported. Genetic, biochemical and biophysical approaches led to rather detailed knowledge on the composition of the translocon-complexes which catalyze the membrane transport of the preproteins. Comprehensive concepts on the targeting and membrane transport of polypeptides emerged, however little detail on the molecular nature and mechanisms of the protein translocation channels comprising nanopores has been achieved. In this paper we will highlight recent developments of the diverse protein translocation systems and focus particularly on the common biophysical properties and functions of the protein conducting nanopores. We also provide a first analysis of the interaction between the genuine protein conducting nanopore Tom40(SC) as well as a mutant Tom40(SC) (S(54 --> E) containing an additional negative charge at the channel vestibule and one of its native substrates, CoxIV, a mitochondrial targeting peptide. The polypeptide induced a voltage-dependent increase in the frequency of channel closure of Tom40(SC) corresponding to a voltage-dependent association rate, which was even more pronounced for the Tom40(SC) S54E mutant. The corresponding dwelltime reflecting association/transport of the peptide could be determined with t(off) approximately = 1.1 ms for the wildtype, whereas the mutant Tom40(SC) S54E displayed a biphasic dwelltime distribution (t(off)(-1) approximately = 0.4 ms; t(off)(-2) approximately = 4.6 ms).
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Affiliation(s)
- Anke Harsman
- Biophysics, Department of Biology/Chemistry, University of Osnabrueck, Germany
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39
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Rimmer KA, Foo JH, Ng A, Petrie EJ, Shilling PJ, Perry AJ, Mertens HDT, Lithgow T, Mulhern TD, Gooley PR. Recognition of mitochondrial targeting sequences by the import receptors Tom20 and Tom22. J Mol Biol 2010; 405:804-18. [PMID: 21087612 DOI: 10.1016/j.jmb.2010.11.017] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2010] [Revised: 11/04/2010] [Accepted: 11/09/2010] [Indexed: 01/16/2023]
Abstract
The Tom20 and Tom22 receptor subunits of the TOM (translocase of the outer mitochondrial membrane) complex recognize N-terminal presequences of proteins that are to be imported into the mitochondrion. In plants, Tom20 is C-terminally anchored in the mitochondrial membrane, whereas Tom20 is N-terminally anchored in animals and fungi. Furthermore, the cytosolic domain of Tom22 in plants is smaller than its animal/fungal counterpart and contains fewer acidic residues. Here, NMR spectroscopy was used to explore presequence interactions with the cytosolic regions of receptors from the plant Arabidopsis thaliana and the fungus Saccharomyces cerevisiae (i.e., AtTom20, AtTom22, and ScTom22). It was found that AtTom20 possesses a discontinuous bidentate hydrophobic binding site for presequences. The presequences on plant mitochondrial proteins comprise two or more hydrophobic binding regions to match this bidentate site. NMR data suggested that while these presequences bind to ScTom22, they do not bind to AtTom22. AtTom22, however, binds to AtTom20 at the same binding site as presequences, suggesting that this domain competes with the presequences of imported proteins, thereby enabling their progression along the import pathway.
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Affiliation(s)
- Kieran A Rimmer
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria, Australia
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Zhang Y, Baaden M, Yan J, Shao J, Qiu S, Wu Y, Ding Y. The Molecular Recognition Mechanism for Superoxide Dismutase Presequence Binding to the Mitochondrial Protein Import Receptor Tom20 from Oryza sativa Involves an LRTLA Motif. J Phys Chem B 2010; 114:13839-46. [DOI: 10.1021/jp103547s] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Yubo Zhang
- Key Laboratory of Ministry of Education for Plant Developmental Biology, College of Life Sciences, Wuhan University, Wuhan 430072, P. R. China, Institut de Biologie Physico-Chimique, Laboratoire de Biochimie Théorique, CNRS UPR 9080, 13, rue Pierre et Marie Curie, F-75005 Paris, France, and State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, P. R. China
| | - Marc Baaden
- Key Laboratory of Ministry of Education for Plant Developmental Biology, College of Life Sciences, Wuhan University, Wuhan 430072, P. R. China, Institut de Biologie Physico-Chimique, Laboratoire de Biochimie Théorique, CNRS UPR 9080, 13, rue Pierre et Marie Curie, F-75005 Paris, France, and State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, P. R. China
| | - Junjie Yan
- Key Laboratory of Ministry of Education for Plant Developmental Biology, College of Life Sciences, Wuhan University, Wuhan 430072, P. R. China, Institut de Biologie Physico-Chimique, Laboratoire de Biochimie Théorique, CNRS UPR 9080, 13, rue Pierre et Marie Curie, F-75005 Paris, France, and State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, P. R. China
| | - Jinzhen Shao
- Key Laboratory of Ministry of Education for Plant Developmental Biology, College of Life Sciences, Wuhan University, Wuhan 430072, P. R. China, Institut de Biologie Physico-Chimique, Laboratoire de Biochimie Théorique, CNRS UPR 9080, 13, rue Pierre et Marie Curie, F-75005 Paris, France, and State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, P. R. China
| | - Su Qiu
- Key Laboratory of Ministry of Education for Plant Developmental Biology, College of Life Sciences, Wuhan University, Wuhan 430072, P. R. China, Institut de Biologie Physico-Chimique, Laboratoire de Biochimie Théorique, CNRS UPR 9080, 13, rue Pierre et Marie Curie, F-75005 Paris, France, and State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, P. R. China
| | - Yingliang Wu
- Key Laboratory of Ministry of Education for Plant Developmental Biology, College of Life Sciences, Wuhan University, Wuhan 430072, P. R. China, Institut de Biologie Physico-Chimique, Laboratoire de Biochimie Théorique, CNRS UPR 9080, 13, rue Pierre et Marie Curie, F-75005 Paris, France, and State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, P. R. China
| | - Yi Ding
- Key Laboratory of Ministry of Education for Plant Developmental Biology, College of Life Sciences, Wuhan University, Wuhan 430072, P. R. China, Institut de Biologie Physico-Chimique, Laboratoire de Biochimie Théorique, CNRS UPR 9080, 13, rue Pierre et Marie Curie, F-75005 Paris, France, and State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, P. R. China
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Carrie C, Giraud E, Duncan O, Xu L, Wang Y, Huang S, Clifton R, Murcha M, Filipovska A, Rackham O, Vrielink A, Whelan J. Conserved and novel functions for Arabidopsis thaliana MIA40 in assembly of proteins in mitochondria and peroxisomes. J Biol Chem 2010; 285:36138-48. [PMID: 20829360 DOI: 10.1074/jbc.m110.121202] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The disulfide relay system of the mitochondrial intermembrane space has been extensively characterized in Saccharomyces cerevisiae. It contains two essential components, Mia40 and Erv1. The genome of Arabidopsis thaliana contains a single gene for each of these components. Although insertional inactivation of Erv1 leads to a lethal phenotype, inactivation of Mia40 results in no detectable deleterious phenotype. A. thaliana Mia40 is targeted to and accumulates in mitochondria and peroxisomes. Inactivation of Mia40 results in an alteration of several proteins in mitochondria, an absence of copper/zinc superoxide dismutase (CSD1), the chaperone for superoxide dismutase (Ccs1) that inserts copper into CSD1, and a decrease in capacity and amount of complex I. In peroxisomes the absence of Mia40 leads to an absence of CSD3 and a decrease in abnormal inflorescence meristem 1 (Aim1), a β-oxidation pathway enzyme. Inactivation of Mia40 leads to an alteration of the transcriptome of A. thaliana, with genes encoding peroxisomal proteins, redox functions, and biotic stress significantly changing in abundance. Thus, the mechanistic operation of the mitochondrial disulfide relay system is different in A. thaliana compared with other systems, and Mia40 has taken on new roles in peroxisomes and mitochondria.
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Affiliation(s)
- Chris Carrie
- Australian Research Council Centre of Excellence in Plant Energy Biology, University of Western Australia, Crawley, Western Australia 6009, Australia
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Structure and evolution of mitochondrial outer membrane proteins of beta-barrel topology. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2010; 1797:1292-9. [PMID: 20450883 DOI: 10.1016/j.bbabio.2010.04.019] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2009] [Revised: 04/25/2010] [Accepted: 04/27/2010] [Indexed: 11/22/2022]
Abstract
Gram-negative bacteria are the ancestors of mitochondrial organelles. Consequently, both entities contain two surrounding lipid bilayers known as the inner and outer membranes. While protein synthesis in bacteria is accomplished in the cytoplasm, mitochondria import 90-99% of their protein ensemble from the cytosol in the opposite direction. Three protein families including Sam50, VDAC and Tom40 together with Mdm10 compose the set of integral beta-barrel proteins embedded in the mitochondrial outer membrane in S. cerevisiae (MOM). The 16-stranded Sam50 protein forms part of the sorting and assembly machinery (SAM) and shows a clear evolutionary relationship to members of the bacterial Omp85 family. By contrast, the evolution of VDAC and Tom40, both adopting the same fold cannot be traced to any bacterial precursor. This finding is in agreement with the specific function of Tom40 in the TOM complex not existent in the enslaved bacterial precursor cell. Models of Tom40 and Sam50 have been developed using X-ray structures of related proteins. These models are analyzed with respect to properties such as conservation and charge distribution yielding features related to their individual functions.
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Tom20 mediates localization of mRNAs to mitochondria in a translation-dependent manner. Mol Cell Biol 2010; 30:284-94. [PMID: 19858288 DOI: 10.1128/mcb.00651-09] [Citation(s) in RCA: 130] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
mRNAs encoding mitochondrial proteins are enriched in the vicinity of mitochondria, presumably to facilitate protein transport. A possible mechanism for enrichment may involve interaction of the translocase of the mitochondrial outer membrane (TOM) complex with the precursor protein while it is translated, thereby leading to association of polysomal mRNAs with mitochondria. To test this hypothesis, we isolated mitochondrial fractions from yeast cells lacking the major import receptor, Tom20, and compared their mRNA repertoire to that of wild-type cells by DNA microarrays. Most mRNAs encoding mitochondrial proteins were less associated with mitochondria, yet the extent of decrease varied among genes. Analysis of several mRNAs revealed that optimal association of Tom20 target mRNAs requires both translating ribosomes and features within the encoded mitochondrial targeting signal. Recently, Puf3p was implicated in the association of mRNAs with mitochondria through interaction with untranslated regions. We therefore constructed a tom20 Delta puf3 Delta double-knockout strain, which demonstrated growth defects under conditions where fully functional mitochondria are required. Mislocalization effects for few tested mRNAs appeared stronger in the double knockout than in the tom20 Delta strain. Taken together, our data reveal a large-scale mRNA association mode that involves interaction of Tom20p with the translated mitochondrial targeting sequence and may be assisted by Puf3p.
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Abstract
Abstract
The key enzymes that catalyze the insertion of proteins into membranes are the Sec translocase and the YidC membrane insertase. Recent insights into the structure and functional intermediates of these enzymes have provided a first molecular glimpse of how they help the newly synthesized proteins to enter the membrane bilayer. In this process, the new proteins undergo a number of specific interactions in the cytoplasm and at the membrane surface before they insert into the bilayer and translocate their external domains across the membrane. The components involved in this pathway recognize each other at the molecular level, forming a route the membrane protein can move along.
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Abu-Abied M, Avisar D, Belausov E, Holdengreber V, Kam Z, Sadot E. Identification of an Arabidopsis unknown small membrane protein targeted to mitochondria, chloroplasts, and peroxisomes. PROTOPLASMA 2009; 236:3-12. [PMID: 19283443 DOI: 10.1007/s00709-009-0038-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2009] [Accepted: 02/23/2009] [Indexed: 05/09/2023]
Abstract
In a functional genomic screen performed by combining an Arabidopsis-yellow fluorescent protein (YFP)-fused complementary DNA (cDNA) library, rat fibroblasts as host and automatic microscopy, we found a short protein with a predictable trans-membrane domain encoded on chromosome 2. In rat fibroblasts, its pattern of distribution was to various organelle-like structures. From the databases, we learned that it has another family member in Arabidopsis and homologs in several other plants, Chlamydomonas and fungi, with a highly conserved N-terminal region. We named this protein from Arabidopsis short membrane protein (SMP) 2. No SMP homologs were found in mammalian sequence databases. When the full-length cDNAs of SMP2 was fused to YFP under the 35S promoter, comparable distribution was observed in Nicotiana benthamiana leaves, suggesting an unknown, evolutionarily conserved localization signal. Similar localization was observed when SMP2 was expressed in N. benthamiana leaves under the control of its own 5' regulatory sequences. Colocalization studies with green fluorescent protein and red fluorescent protein chimeras revealed its colocalization with chloroplasts, peroxisomes, and mitochondria. No localization of SMP2 was observed in the Golgi. Immunostaining with specific antibodies corroborated the SMP2 localization to the three organelles.
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Affiliation(s)
- Mohamad Abu-Abied
- The Department of Ornamental Horticulture, The Institute of Plant Sciences, The Volcani Center, P.O. Box 6, Bet-Dagan, 50250, Israel
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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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Mills RD, Trewhella J, Qiu TW, Welte T, Ryan TM, Hanley T, Knott RB, Lithgow T, Mulhern TD. Domain Organization of the Monomeric Form of the Tom70 Mitochondrial Import Receptor. J Mol Biol 2009; 388:1043-58. [DOI: 10.1016/j.jmb.2009.03.070] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2009] [Revised: 03/24/2009] [Accepted: 03/30/2009] [Indexed: 11/28/2022]
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Kuhn S, Bussemer J, Chigri F, Vothknecht UC. Calcium depletion and calmodulin inhibition affect the import of nuclear-encoded proteins into plant mitochondria. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2009; 58:694-705. [PMID: 19175770 DOI: 10.1111/j.1365-313x.2009.03810.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Many metabolic processes essential for plant viability take place in mitochondria. Therefore, mitochondrial function has to be carefully balanced in accordance with the developmental stage and metabolic requirements of the cell. One way to adapt organellar function is the alteration of protein composition. Since most mitochondrial proteins are nuclear encoded, fine-tuning of mitochondrial protein content could be achieved by the regulation of protein translocation. Here we present evidence that the import of nuclear-encoded mitochondrial proteins into plant mitochondria is influenced by calcium and calmodulin. In pea mitochondria, the calmodulin inhibitor ophiobolin A as well as the calcium ionophores A23187 and ionomycin inhibit translocation of nuclear-encoded proteins in a concentration-dependent manner, an effect that can be countered by the addition of external calmodulin or calcium, respectively. Inhibition was observed exclusively for proteins translocating into or across the inner membrane but not for proteins residing in the outer membrane or the intermembrane space. Ophiobolin A and the calcium ionophores further inhibit translocation into mitochondria with disrupted outer membranes, but their effect is not mediated via a change in the membrane potential across the inner mitochondrial membrane. Together, our results suggest that calcium/calmodulin influences the import of a subset of mitochondrial proteins at the inner membrane. Interestingly, we could not observe any influence of ophiobolin A or the calcium ionophores on protein translocation into mitochondria of yeast, indicating that the effect of calcium/calmodulin on mitochondrial protein import might be a plant-specific trait.
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TOM-independent complex formation of Bax and Bak in mammalian mitochondria during TNFα-induced apoptosis. Cell Death Differ 2009; 16:697-707. [DOI: 10.1038/cdd.2008.194] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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