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Gore E, Duparc T, Genoux A, Perret B, Najib S, Martinez LO. The Multifaceted ATPase Inhibitory Factor 1 (IF1) in Energy Metabolism Reprogramming and Mitochondrial Dysfunction: A New Player in Age-Associated Disorders? Antioxid Redox Signal 2022; 37:370-393. [PMID: 34605675 PMCID: PMC9398489 DOI: 10.1089/ars.2021.0137] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Significance: The mitochondrial oxidative phosphorylation (OXPHOS) system, comprising the electron transport chain and ATP synthase, generates membrane potential, drives ATP synthesis, governs energy metabolism, and maintains redox balance. OXPHOS dysfunction is associated with a plethora of diseases ranging from rare inherited disorders to common conditions, including diabetes, cancer, neurodegenerative diseases, as well as aging. There has been great interest in studying regulators of OXPHOS. Among these, ATPase inhibitory factor 1 (IF1) is an endogenous inhibitor of ATP synthase that has long been thought to avoid the consumption of cellular ATP when ATP synthase acts as an ATP hydrolysis enzyme. Recent Advances: Recent data indicate that IF1 inhibits ATP synthesis and is involved in a multitude of mitochondrial-related functions, such as mitochondrial quality control, energy metabolism, redox balance, and cell fate. IF1 also inhibits the ATPase activity of cell-surface ATP synthase, and it is used as a cardiovascular disease biomarker. Critical Issues: Although recent data have led to a paradigm shift regarding IF1 functions, these have been poorly studied in entire organisms and in different organs. The understanding of the cellular biology of IF1 is, therefore, still limited. The aim of this review was to provide an overview of the current understanding of the role of IF1 in mitochondrial functions, health, and diseases. Future Directions: Further investigations of IF1 functions at the cell, organ, and whole-organism levels and in different pathophysiological conditions will help decipher the controversies surrounding its involvement in mitochondrial function and could unveil therapeutic strategies in human pathology. Antioxid. Redox Signal. 37, 370-393.
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Affiliation(s)
- Emilia Gore
- I2MC, University of Toulouse, INSERM, UPS, Toulouse, France
| | - Thibaut Duparc
- I2MC, University of Toulouse, INSERM, UPS, Toulouse, France
| | - Annelise Genoux
- I2MC, University of Toulouse, INSERM, UPS, Toulouse, France.,Service de Biochimie, Pôle de biologie, Hôpital de Purpan, CHU de Toulouse, Toulouse, France
| | - Bertrand Perret
- I2MC, University of Toulouse, INSERM, UPS, Toulouse, France.,Service de Biochimie, Pôle de biologie, Hôpital de Purpan, CHU de Toulouse, Toulouse, France
| | - Souad Najib
- I2MC, University of Toulouse, INSERM, UPS, Toulouse, France
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Juhaszova M, Kobrinsky E, Zorov DB, Nuss HB, Yaniv Y, Fishbein KW, de Cabo R, Montoliu L, Gabelli SB, Aon MA, Cortassa S, Sollott SJ. ATP Synthase K +- and H +-fluxes Drive ATP Synthesis and Enable Mitochondrial K +-"Uniporter" Function: II. Ion and ATP Synthase Flux Regulation. FUNCTION (OXFORD, ENGLAND) 2022; 3:zqac001. [PMID: 35187492 PMCID: PMC8850977 DOI: 10.1093/function/zqac001] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Revised: 01/12/2022] [Accepted: 01/18/2022] [Indexed: 01/07/2023]
Abstract
We demonstrated that ATP synthase serves the functions of a primary mitochondrial K+ "uniporter," i.e., the primary way for K+ to enter mitochondria. This K+ entry is proportional to ATP synthesis, regulating matrix volume and energy supply-vs-demand matching. We show that ATP synthase can be upregulated by endogenous survival-related proteins via IF1. We identified a conserved BH3-like domain of IF1 which overlaps its "minimal inhibitory domain" that binds to the β-subunit of F1. Bcl-xL and Mcl-1 possess a BH3-binding-groove that can engage IF1 and exert effects, requiring this interaction, comparable to diazoxide to augment ATP synthase's H+ and K+ flux and ATP synthesis. Bcl-xL and Mcl-1, but not Bcl-2, serve as endogenous regulatory ligands of ATP synthase via interaction with IF1 at this BH3-like domain, to increase its chemo-mechanical efficiency, enabling its function as the recruitable mitochondrial KATP-channel that can limit ischemia-reperfusion injury. Using Bayesian phylogenetic analysis to examine potential bacterial IF1-progenitors, we found that IF1 is likely an ancient (∼2 Gya) Bcl-family member that evolved from primordial bacteria resident in eukaryotes, corresponding to their putative emergence as symbiotic mitochondria, and functioning to prevent their parasitic ATP consumption inside the host cell.
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Affiliation(s)
| | | | | | | | | | - Kenneth W Fishbein
- Laboratory of Clinical Investigation, National Institute on Aging, NIH, Baltimore, MD 21224, USA
| | - Rafael de Cabo
- Translational Gerontology Branch, National Institute on Aging, NIH, Baltimore, MD 21224, USA
| | - Lluis Montoliu
- National Centre for Biotechnology (CNB-CSIC), Biomedical Research Networking Center on Rare Diseases (CIBERER-ISCIII), 28049 Madrid, Spain
| | - Sandra B Gabelli
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Miguel A Aon
- Laboratory of Cardiovascular Science, National Institute on Aging, NIH, Baltimore, MD 21224, USA
| | - Sonia Cortassa
- Laboratory of Cardiovascular Science, National Institute on Aging, NIH, Baltimore, MD 21224, USA
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3
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Niedzwiecka K, Tisi R, Penna S, Lichocka M, Plochocka D, Kucharczyk R. Two mutations in mitochondrial ATP6 gene of ATP synthase, related to human cancer, affect ROS, calcium homeostasis and mitochondrial permeability transition in yeast. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2017; 1865:117-131. [PMID: 28986220 DOI: 10.1016/j.bbamcr.2017.10.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 09/15/2017] [Accepted: 10/02/2017] [Indexed: 02/06/2023]
Abstract
The relevance of mitochondrial DNA (mtDNA) mutations in cancer process is still unknown. Since the mutagenesis of mitochondrial genome in mammals is not possible yet, we have exploited budding yeast S. cerevisiae as a model to study the effects of tumor-associated mutations in the mitochondrial MTATP6 gene, encoding subunit 6 of ATP synthase, on the energy metabolism. We previously reported that four mutations in this gene have a limited impact on the production of cellular energy. Here we show that two mutations, Atp6-P163S and Atp6-K90E (human MTATP6-P136S and MTATP6-K64E, found in prostate and thyroid cancer samples, respectively), increase sensitivity of yeast cells both to compounds inducing oxidative stress and to high concentrations of calcium ions in the medium, when Om45p, the component of porin complex in outer mitochondrial membrane (OM), was fused to GFP. In OM45-GFP background, these mutations affect the activation of yeast permeability transition pore (yPTP, also called YMUC, yeast mitochondrial unspecific channel) upon calcium induction. Moreover, we show that calcium addition to isolated mitochondria heavily induced the formation of ATP synthase dimers and oligomers, recently proposed to form the core of PTP, which was slower in the mutants. We show the genetic evidence for involvement of mitochondrial ATP synthase in calcium homeostasis and permeability transition in yeast. This paper is a first to show, although in yeast model organism, that mitochondrial ATP synthase mutations, which accumulate during carcinogenesis process, may be significant for cancer cell escape from apoptosis.
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Affiliation(s)
- Katarzyna Niedzwiecka
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | - Renata Tisi
- Dept. Biotechnology and Biosciences, University of Milano-Bicocca, Milan, Italy; Milan Center for Neuroscience, Milan, Italy
| | - Sara Penna
- Dept. Biotechnology and Biosciences, University of Milano-Bicocca, Milan, Italy
| | - Malgorzata Lichocka
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | - Danuta Plochocka
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | - Roza Kucharczyk
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland.
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García-Bermúdez J, Cuezva JM. The ATPase Inhibitory Factor 1 (IF1): A master regulator of energy metabolism and of cell survival. BIOCHIMICA ET BIOPHYSICA ACTA 2016; 1857:1167-1182. [PMID: 26876430 DOI: 10.1016/j.bbabio.2016.02.004] [Citation(s) in RCA: 99] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Revised: 01/28/2016] [Accepted: 02/07/2016] [Indexed: 12/19/2022]
Abstract
In this contribution we summarize most of the findings reported for the molecular and cellular biology of the physiological inhibitor of the mitochondrial H(+)-ATP synthase, the engine of oxidative phosphorylation (OXPHOS) and gate of cell death. We first describe the structure and major mechanisms and molecules that regulate the activity of the ATP synthase placing the ATPase Inhibitory Factor 1 (IF1) as a major determinant in the regulation of the activity of the ATP synthase and hence of OXPHOS. Next, we summarize the post-transcriptional mechanisms that regulate the expression of IF1 and emphasize, in addition to the regulation afforded by the protonation state of histidine residues, that the activity of IF1 as an inhibitor of the ATP synthase is also regulated by phosphorylation of a serine residue. Phosphorylation of S39 in IF1 by the action of a mitochondrial cAMP-dependent protein kinase A hampers its interaction with the ATP synthase, i.e., only dephosphorylated IF1 interacts with the enzyme. Upon IF1 interaction with the ATP synthase both the synthetic and hydrolytic activities of the engine of OXPHOS are inhibited. These findings are further placed into the physiological context to stress the emerging roles played by IF1 in metabolic reprogramming in cancer, in hypoxia and in cellular differentiation. We review also the implication of IF1 in other cellular situations that involve the malfunctioning of mitochondria. Special emphasis is given to the role of IF1 as driver of the generation of a reactive oxygen species signal that, emanating from mitochondria, is able to reprogram the nucleus of the cell to confer by various signaling pathways a cell-death resistant phenotype against oxidative stress. Overall, our intention is to highlight the urgent need of further investigations in the molecular and cellular biology of IF1 and of its target, the ATP synthase, to unveil new therapeutic strategies in human pathology. This article is part of a Special Issue entitled 'EBEC 2016: 19th European Bioenergetics Conference, Riva del Garda, Italy, July 2-6, 2016', edited by Prof. Paolo Bernardi.
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Affiliation(s)
- Javier García-Bermúdez
- Departamento de Biología Molecular, Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid (CSIC-UAM), Centro de Investigación Biomédica en Red de Enfermedades Raras CIBERER-ISCIII, Instituto de Investigación Hospital 12 de Octubre, Universidad Autónoma de Madrid, 28049, Madrid, Spain
| | - José M Cuezva
- Departamento de Biología Molecular, Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid (CSIC-UAM), Centro de Investigación Biomédica en Red de Enfermedades Raras CIBERER-ISCIII, Instituto de Investigación Hospital 12 de Octubre, Universidad Autónoma de Madrid, 28049, Madrid, Spain.
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5
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Bason JV, Montgomery MG, Leslie AGW, Walker JE. Pathway of binding of the intrinsically disordered mitochondrial inhibitor protein to F1-ATPase. Proc Natl Acad Sci U S A 2014; 111:11305-10. [PMID: 25049402 PMCID: PMC4128166 DOI: 10.1073/pnas.1411560111] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The hydrolysis of ATP by the ATP synthase in mitochondria is inhibited by a protein called IF1. Bovine IF1 has 84 amino acids, and its N-terminal inhibitory region is intrinsically disordered. In a known structure of bovine F1-ATPase inhibited with residues 1-60 of IF1, the inhibitory region from residues 1-50 is mainly α-helical and buried deeply at the α(DP)β(DP)-catalytic interface, where it forms extensive interactions with five of the nine subunits of F1-ATPase but mainly with the β(DP)-subunit. As described here, on the basis of two structures of inhibited complexes formed in the presence of large molar excesses of residues 1-60 of IF1 and of a version of IF1 with the mutation K39A, it appears that the intrinsically disordered inhibitory region interacts first with the αEβE-catalytic interface, the most open of the three catalytic interfaces, where the available interactions with the enzyme allow it to form an α-helix from residues 31-49. Then, in response to the hydrolysis of an ATP molecule and the associated partial closure of the interface to the αTPβTP state, the extent of the folded α-helical region of IF1 increases to residues 23-50 as more interactions with the enzyme become possible. Finally, in response to the hydrolysis of a second ATP molecule and a concomitant 120° rotation of the γ-subunit, the interface closes further to the α(DP)β(DP)-state, allowing more interactions to form between the enzyme and IF1. The structure of IF1 now extends to its maximally folded state found in the previously observed inhibited complex.
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Affiliation(s)
- John V Bason
- The Medical Research Council Mitochondrial Biology Unit, Cambridge Biomedical Campus, Cambridge CB2 0XY, United Kingdom; and
| | - Martin G Montgomery
- The Medical Research Council Mitochondrial Biology Unit, Cambridge Biomedical Campus, Cambridge CB2 0XY, United Kingdom; and
| | - Andrew G W Leslie
- The Medical Research Council Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge CB2 0QH, United Kingdom
| | - John E Walker
- The Medical Research Council Mitochondrial Biology Unit, Cambridge Biomedical Campus, Cambridge CB2 0XY, United Kingdom; and
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Dell'Aglio E, Giustini C, Salvi D, Brugière S, Delpierre F, Moyet L, Baudet M, Seigneurin-Berny D, Matringe M, Ferro M, Rolland N, Curien G. Complementary biochemical approaches applied to the identification of plastidial calmodulin-binding proteins. MOLECULAR BIOSYSTEMS 2013; 9:1234-48. [PMID: 23549413 DOI: 10.1039/c3mb00004d] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Ca(2+)/Calmodulin (CaM)-dependent signaling pathways play a major role in the modulation of cell responses in eukaryotes. In the chloroplast, few proteins such as the NAD(+) kinase 2 have been previously shown to interact with CaM, but a general picture of the role of Ca(2+)/CaM signaling in this organelle is still lacking. Using CaM-affinity chromatography and mass spectrometry, we identified 210 candidate CaM-binding proteins from different Arabidopsis and spinach chloroplast sub-fractions. A subset of these proteins was validated by an optimized in vitro CaM-binding assay. In addition, we designed two fluorescence anisotropy assays to quantitatively characterize the binding parameters and applied those assays to NAD(+) kinase 2 and selected candidate proteins. On the basis of our results, there might be many more plastidial CaM-binding proteins than previously estimated. In addition, we showed that an array of complementary biochemical techniques is necessary in order to characterize the mode of interaction of candidate proteins with CaM.
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Pagnozzi D, Birolo L, Leo G, Contessi S, Lippe G, Pucci P, Mavelli I. Stoichiometry and topology of the complex of the endogenous ATP synthase inhibitor protein IF(1) with calmodulin. Biochemistry 2010; 49:7542-52. [PMID: 20669893 DOI: 10.1021/bi100447t] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
IF(1), the natural inhibitor protein of F(O)F(1)ATP synthase able to regulate the ATP hydrolytic activity of both mitochondrial and cell surface enzyme, exists in two oligomeric states depending on pH: an inactive, highly helical, tetrameric form above pH 6.7 and an active, inhibitory, dimeric form below pH 6.7 [ Cabezon , E. , Butler , P. J. , Runswick , M. J. , and Walker , J. E. ( 2000 ) J. Biol. Chem. 275 , 25460 -25464 ]. IF(1) is known to interact in vitro with the archetypal EF-hand calcium sensor calmodulin (CaM), as well to colocalize with CaM on the plasma membrane of cultured cells. Low resolution structural data were herein obtained in order to get insights into the molecular interaction between IF(1) and CaM. A combined structural proteomic strategy was used which integrates limited proteolysis and chemical cross-linking with mass spectrometric analysis. Specifically, chemical cross-linking data clearly indicate that the C-terminal lobe of CaM molecule contacts IF(1) within the inhibitory, flexible N-terminal region that is not involved in the dimeric interface in IF(1). Nevertheless, native mass spectrometry analysis demonstrated that in the micromolar range the stoichiometry of the IF(1)-CaM complex is 1:1, thereby indicating that binding to CaM promotes IF(1) dimer dissociation without directly interfering with the intersubunit contacts of the IF(1) dimer. The relevance of the finding that only the C-terminal lobe of CaM is involved in the interaction is two fold: (i) the IF(1)-CaM complex can be included in the category of noncanonical structures of CaM complexes; (ii) it can be inferred that the N-terminal region of CaM might have the opportunity to bind to a second target.
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Affiliation(s)
- Daniela Pagnozzi
- Department of Organic Chemistry and Biochemistry, University of Napoli Federico II, viaCynthia 6, 80126 Napoli, Italy
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Giorgio V, Bisetto E, Franca R, Harris DA, Passamonti S, Lippe G. The ectopic F(O)F(1) ATP synthase of rat liver is modulated in acute cholestasis by the inhibitor protein IF1. J Bioenerg Biomembr 2010; 42:117-23. [PMID: 20180002 DOI: 10.1007/s10863-010-9270-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2009] [Accepted: 01/12/2010] [Indexed: 02/07/2023]
Abstract
Rat liver plasma membranes contain F(O)F(1) complexes (ecto-F(O)F(1)) displaying a similar molecular weight to the mitochondrial F(O)F(1) ATP synthase, as evidenced by Blue Native PAGE. Their ATPase activity was stably reduced in short-term extra-hepatic cholestasis. Immunoblotting and immunoprecipitation analyses demonstrated that the reduction in activity was not due to a decreased expression of ecto-F(O)F(1) complexes, but to an increased level of an inhibitory protein, ecto-IF(1), bound to ecto-F(O)F(1). Since cholestasis down regulates the hepatic uptake of HDL-cholesterol, and ecto-F(O)F(1) has been shown to mediate SR-BI-independent hepatic uptake of HDL-cholesterol, these findings provide support to the hypothesis that ecto-F(O)F(1) contributes to the fine control of reverse cholesterol transport, in parallel with SR-BI. No activity change of the mitochondrial F(O)F(1) ATP synthase (m-F(O)F(1)), or any variation of its association with m-IF(1) was observed in cholestasis, indicating that ecto-IF(1) expression level is modulated independently from that of ecto-F(O)F(1), m-IF(1) and m-F(O)F(1).
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Affiliation(s)
- Valentina Giorgio
- Department of Biomedical Sciences and Technologies, University of Udine, p.le Kolbe 4, I-33100, Udine, Italy
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Campanella M, Parker N, Tan CH, Hall AM, Duchen MR. IF(1): setting the pace of the F(1)F(o)-ATP synthase. Trends Biochem Sci 2009; 34:343-50. [PMID: 19559621 DOI: 10.1016/j.tibs.2009.03.006] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2009] [Revised: 03/26/2009] [Accepted: 03/26/2009] [Indexed: 12/15/2022]
Abstract
When mitochondrial function is compromised and the mitochondrial membrane potential (Deltapsi(m)) falls below a threshold, the F(1)F(o)-ATP synthase can reverse, hydrolysing ATP to pump protons out of the mitochondrial matrix. Although this activity can deplete ATP and precipitate cell death, it is limited by the mitochondrial protein IF(1), an endogenous F(1)F(o)-ATPase inhibitor. IF(1), therefore, preserves ATP at the expense of Deltapsi(m). Despite a wealth of detailed knowledge on the biochemistry of the interaction of IF(1) and the F(1)F(o)-ATPase, little is known about its physiological activity. Emerging research suggests that IF(1) has a wider ranging impact on mitochondrial structure and function than previously thought.
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Lippe G, Bisetto E, Comelli M, Contessi S, Di Pancrazio F, Mavelli I. Mitochondrial and cell-surface F0F1ATPsynthase in innate and acquired cardioprotection. J Bioenerg Biomembr 2009; 41:151-7. [PMID: 19387805 DOI: 10.1007/s10863-009-9208-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Mitochondria are central to heart function and dysfunction, and the pathways activated by different cardioprotective interventions mostly converge on mitochondria. In a context of perspectives in innate and acquired cardioprotection, we review some recent advances in F(0)F(1)ATPsynthase structure/function and regulation in cardiac cells. We focus on three topics regarding the mitochondrial F(0)F(1)ATPsynthase and the plasma membrane enzyme, i.e.: i) the crucial role of cardiac mitochondrial F(0)F(1)ATPsynthase regulation by the inhibitory protein IF(1) in heart preconditioning strategies; ii) the structure and function of mitochondrial F(0)F(1)ATPsynthase oligomers in mammalian myocardium as possible endogenous factors of mitochondria resistance to ischemic insult; iii) the external location and characterization of plasma membrane F(0)F(1) ATP synthase in search for possible actors of its regulation, such as IF(1) and calmodulin, at cell surface.
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Affiliation(s)
- Giovanna Lippe
- Department of Biomedical Sciences and Technologies and M.A.T.I. Centre of Excellence, University of Udine, P.le Kolbe 4, 33100, Udine, Italy
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Zoratti M, De Marchi U, Gulbins E, Szabò I. Novel channels of the inner mitochondrial membrane. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2008; 1787:351-63. [PMID: 19111672 DOI: 10.1016/j.bbabio.2008.11.015] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2008] [Revised: 11/24/2008] [Accepted: 11/26/2008] [Indexed: 12/15/2022]
Abstract
Along with a large number of carriers, exchangers and "pumps", the inner mitochondrial membrane contains ion-conducting channels which endow it with controlled permeability to small ions. Some have been shown to be the mitochondrial counterpart of channels present also in other cellular membranes. The manuscript summarizes the current state of knowledge on the major inner mitochondrial membrane channels, properties, identity and proposed functions. Considerable attention is currently being devoted to two K(+)-selective channels, mtK(ATP) and mtBK(Ca). Their activation in "preconditioning" is considered by many to underlie the protection of myocytes and other cells against subsequent ischemic damage. We have recently shown that in apoptotic lymphocytes inner membrane mtK(V)1.3 interacts with the pro-apoptotic protein Bax after the latter has inserted into the outer mitochondrial membrane. Whether the just-discovered mtIK(Ca) has similar cellular role(s) remains to be seen. The Ca(2+) "uniporter" has been characterized electrophysiologically, but still awaits a molecular identity. Chloride-selective channels are represented by the 107 pS channel, the first mitochondrial channel to be observed by patch-clamp, and by a approximately 400 pS pore we have recently been able to fully characterize in the inner membrane of mitochondria isolated from a colon tumour cell line. This we propose to represent a component of the Permeability Transition Pore. The available data exclude the previous tentative identification with porin, and indicate that it coincides instead with the still molecularly unidentified "maxi" chloride channel.
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Hou WR, Du YJ, Chen Y, Wu X, Peng ZS, Yang J, Zhou CQ. Nucleotide Sequence of cDNA Encoding the Mitochondrial Precursor Protein of the ATPase Inhibitor from the Giant Panda (Ailuropoda melanoleuca). DNA Cell Biol 2007; 26:799-802. [PMID: 17822358 DOI: 10.1089/dna.2007.0626] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Mitochondrial ATP synthase (F1Fo-ATPase) is regulated by an intrinsic ATPase inhibitor protein. In the present study, using RT-PCR combined with in silico cloning, we isolated and sequenced the cDNA encoding the inhibitor protein of the giant panda (Ailuropoda melanoleuca). The deduced protein sequence showed that the protein is composed of 106 amino acids and the estimated molecular weight of the ATPIF(1) protein is 12.32 kDa with an isoelectric point (pI) of 10.17. Alignment analysis revealed that the deduced protein sequence shares 66%, 78.3%, 66%, 72.6%, 77.4%, and 78.3% homology with that of Mus musculus, Pan troglodytes, Rattus norvegicus, Bos taurus, Macaca mulatta, and Homo sapiens, respectively. Topology prediction showed that there are three protein kinase C phosphorylation sites, one amidation site, three N-myristoylation sites, one casein kinase II phosphorylation site, and one tyrosine kinase phosphorylation site in the ATPase inhibitor. In particular, amino acids in the region between 39 and 72, which is the minimum sequence showing ATPase inhibitory activity, were highly conserved in the protein.
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Affiliation(s)
- Wan-ru Hou
- College of Life Science, China West Normal University, Nanchong, Sichuan, China.
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Contessi S, Comelli M, Cmet S, Lippe G, Mavelli I. IF(1) distribution in HepG2 cells in relation to ecto-F(0)F (1)ATPsynthase and calmodulin. J Bioenerg Biomembr 2007; 39:291-300. [PMID: 17851741 DOI: 10.1007/s10863-007-9091-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2007] [Accepted: 05/09/2007] [Indexed: 12/01/2022]
Abstract
F(0)F(1)ATPsynthase is now known to be expressed as a plasma membrane receptor for several extracellular ligands. On hepatocytes, ecto-F(0)F(1)ATPsynthase binds apoA-I and triggers HDL endocytosis concomitant with ATP hydrolysis. Considering that inhibitor protein IF(1) was shown to regulate the hydrolytic activity of ecto-F(0)F(1)ATPsynthase and to interact with calmodulin (CaM) in vitro, we investigated the subcellular distributions of IF(1), calmodulin (CaM), OSCP and beta subunits of F(0)F(1)ATPsynthase in HepG2 cells. Using immunofluorescence and Western blotting, we found that around 50% of total cellular IF(1) is localized outside mitochondria, a relevant amount of which is associated to the plasma membrane where we also found Ca(2+)-CaM, OSCP and beta. Confocal microscopy showed that IF(1) colocalized with Ca(2+)-CaM on plasma membrane but not in mitochondria, suggesting that Ca(2+)-CaM may modulate the cell surface availability of IF(1) and thus its ability to inhibit ATP hydrolysis by ecto-F(0)F(1)ATPsynthase. These observations support a hypothesis that the IF(1)-Ca(2+)-CaM complex, forming on plasma membrane, functions in the cellular regulation of HDL endocytosis by hepatocytes.
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Affiliation(s)
- Stefania Contessi
- Department of Biomedical Sciences and Technologies, MATI Centre of Excellence, University of Udine, Piazzale Kolbe 4, 33100 Udine, Italy
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Ichikawa N, Ando C, Fumino M. Caenorhabditis elegans MAI-1 protein, which is similar to mitochondrial ATPase inhibitor (IF1), can inhibit yeast F0F1-ATPase but cannot be transported to yeast mitochondria. J Bioenerg Biomembr 2006; 38:93-9. [PMID: 16897438 DOI: 10.1007/s10863-006-9009-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2006] [Accepted: 04/18/2006] [Indexed: 11/29/2022]
Abstract
In Caenorhabditis elegans, two proteins that are similar to mitochondrial ATPase inhibitor protein (IF(1)) have been found and named MAI-1 and MAI-2. In this study, we overexpressed and purified both the proteins and examined their properties. Circular dichroism spectra indicated that both the MAI-1 and MAI-2 predominantly consisted of beta- and random structure, and in contrast to mammalian IF(1), alpha-helixes were barely detected. Both MAI-1 and MAI-2 could inhibit yeast F(0)F(1)-ATPase, but the inhibition by MAI-1 was pH-independent. MAI-2-GFP fusion protein was transported to yeast mitochondria, but MAI-1-GFP was not. These results indicate that the MAI-2 is (C. elegans) IF(1). MAI-1 seems to be a cytosolic protein and may regulate cytosolic ATPase(s).
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Affiliation(s)
- Naoki Ichikawa
- Department of Food and Nutrition, Faculty of Human Life Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi, Osaka, 558-8585, Japan.
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