1
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Tai J, Guerra RM, Rogers SW, Fang Z, Muehlbauer LK, Shishkova E, Overmyer KA, Coon JJ, Pagliarini DJ. Hem25p is required for mitochondrial IPP transport in fungi. Nat Cell Biol 2023; 25:1616-1624. [PMID: 37813972 PMCID: PMC10759932 DOI: 10.1038/s41556-023-01250-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Accepted: 09/05/2023] [Indexed: 10/11/2023]
Abstract
Coenzyme Q (CoQ, ubiquinone) is an essential cellular cofactor composed of a redox-active quinone head group and a long hydrophobic polyisoprene tail. How mitochondria access cytosolic isoprenoids for CoQ biosynthesis is a longstanding mystery. Here, via a combination of genetic screening, metabolic tracing and targeted uptake assays, we reveal that Hem25p-a mitochondrial glycine transporter required for haem biosynthesis-doubles as an isopentenyl pyrophosphate (IPP) transporter in Saccharomyces cerevisiae. Mitochondria lacking Hem25p failed to efficiently incorporate IPP into early CoQ precursors, leading to loss of CoQ and turnover of CoQ biosynthetic proteins. Expression of Hem25p in Escherichia coli enabled robust IPP uptake and incorporation into the CoQ biosynthetic pathway. HEM25 orthologues from diverse fungi, but not from metazoans, were able to rescue hem25∆ CoQ deficiency. Collectively, our work reveals that Hem25p drives the bulk of mitochondrial isoprenoid transport for CoQ biosynthesis in fungi.
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Affiliation(s)
- Jonathan Tai
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA
- Morgridge Institute for Research, Madison, WI, USA
- Department of Cell Biology and Physiology, Washington University School of Medicine, St Louis, MO, USA
| | - Rachel M Guerra
- Department of Cell Biology and Physiology, Washington University School of Medicine, St Louis, MO, USA
| | - Sean W Rogers
- Department of Cell Biology and Physiology, Washington University School of Medicine, St Louis, MO, USA
| | - Zixiang Fang
- Department of Cell Biology and Physiology, Washington University School of Medicine, St Louis, MO, USA
| | - Laura K Muehlbauer
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, USA
| | - Evgenia Shishkova
- National Center for Quantitative Biology of Complex Systems, Madison, WI, USA
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, WI, USA
| | - Katherine A Overmyer
- Morgridge Institute for Research, Madison, WI, USA
- National Center for Quantitative Biology of Complex Systems, Madison, WI, USA
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, WI, USA
| | - Joshua J Coon
- Morgridge Institute for Research, Madison, WI, USA
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, USA
- National Center for Quantitative Biology of Complex Systems, Madison, WI, USA
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, WI, USA
| | - David J Pagliarini
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA.
- Morgridge Institute for Research, Madison, WI, USA.
- Department of Cell Biology and Physiology, Washington University School of Medicine, St Louis, MO, USA.
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St Louis, MO, USA.
- Department of Genetics, Washington University School of Medicine, St Louis, MO, USA.
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2
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Goyal S, Paspureddi A, Lu M, Chan H, Lyons SN, Wilson CN, Niere M, Ziegler M, Cambronne XA. Dynamics of SLC25A51 reveal preference for oxidized NAD + and substrate led transport. EMBO Rep 2023; 24:e56596. [PMID: 37575034 PMCID: PMC10561365 DOI: 10.15252/embr.202256596] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 07/23/2023] [Accepted: 07/27/2023] [Indexed: 08/15/2023] Open
Abstract
SLC25A51 is a member of the mitochondrial carrier family (MCF) but lacks key residues that contribute to the mechanism of other nucleotide MCF transporters. Thus, how SLC25A51 transports NAD+ across the inner mitochondrial membrane remains unclear. To elucidate its mechanism, we use Molecular Dynamics simulations to reconstitute SLC25A51 homology models into lipid bilayers and to generate hypotheses to test. We observe spontaneous binding of cardiolipin phospholipids to three distinct sites on the exterior of SLC25A51's central pore and find that mutation of these sites impairs cardiolipin binding and transporter activity. We also observe that stable formation of the required matrix gate is controlled by a single salt bridge. We identify binding sites in SLC25A51 for NAD+ and show that its selectivity for NAD+ is guided by an electrostatic interaction between the charged nicotinamide ring in the ligand and a negatively charged patch in the pore. In turn, interaction of NAD+ with interior residue E132 guides the ligand to dynamically engage and weaken the salt bridge gate, representing a ligand-induced initiation of transport.
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Affiliation(s)
- Shivansh Goyal
- Department of Molecular BiosciencesUniversity of Texas at AustinAustinTXUSA
| | | | - Mu‐Jie Lu
- Department of Molecular BiosciencesUniversity of Texas at AustinAustinTXUSA
| | - Hsin‐Ru Chan
- Department of Molecular BiosciencesUniversity of Texas at AustinAustinTXUSA
| | - Scott N Lyons
- Department of Molecular BiosciencesUniversity of Texas at AustinAustinTXUSA
| | - Crystal N Wilson
- Department of Molecular BiosciencesUniversity of Texas at AustinAustinTXUSA
| | - Marc Niere
- Department of BiomedicineUniversity of BergenBergenNorway
| | | | - Xiaolu A Cambronne
- Department of Molecular BiosciencesUniversity of Texas at AustinAustinTXUSA
- Livestrong Cancer InstituteUniversity of Texas at AustinAustinTXUSA
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3
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Tai J, Guerra RM, Rogers SW, Fang Z, Muehlbauer LK, Shishkova E, Overmyer KA, Coon JJ, Pagliarini DJ. Hem25p is a mitochondrial IPP transporter. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.14.532620. [PMID: 36993473 PMCID: PMC10055127 DOI: 10.1101/2023.03.14.532620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Coenzyme Q (CoQ, ubiquinone) is an essential cellular cofactor comprised of a redox-active quinone head group and a long hydrophobic polyisoprene tail. How mitochondria access cytosolic isoprenoids for CoQ biosynthesis is a longstanding mystery. Here, via a combination of genetic screening, metabolic tracing, and targeted uptake assays, we reveal that Hem25p-a mitochondrial glycine transporter required for heme biosynthesis-doubles as an isopentenyl pyrophosphate (IPP) transporter in Saccharomyces cerevisiae. Mitochondria lacking Hem25p fail to efficiently incorporate IPP into early CoQ precursors, leading to loss of CoQ and turnover of CoQ biosynthetic proteins. Expression of Hem25p in Escherichia coli enables robust IPP uptake demonstrating that Hem25p is sufficient for IPP transport. Collectively, our work reveals that Hem25p drives the bulk of mitochondrial isoprenoid transport for CoQ biosynthesis in yeast.
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Affiliation(s)
- Jonathan Tai
- Department of Biochemistry, University of Wisconsin–Madison, Madison, WI 53706, USA
- Morgridge Institute for Research, Madison, WI 53715, USA
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Rachel M. Guerra
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Sean W. Rogers
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Zixiang Fang
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Laura K. Muehlbauer
- Department of Chemistry, University of Wisconsin–Madison, Madison, WI 53706, USA
| | - Evgenia Shishkova
- National Center for Quantitative Biology of Complex Systems, Madison, WI 53706, USA
- Department of Biomolecular Chemistry, University of Wisconsin–Madison, Madison, WI 53706, USA
| | - Katherine A. Overmyer
- Morgridge Institute for Research, Madison, WI 53715, USA
- National Center for Quantitative Biology of Complex Systems, Madison, WI 53706, USA
- Department of Biomolecular Chemistry, University of Wisconsin–Madison, Madison, WI 53706, USA
| | - Joshua J. Coon
- Morgridge Institute for Research, Madison, WI 53715, USA
- Department of Chemistry, University of Wisconsin–Madison, Madison, WI 53706, USA
- National Center for Quantitative Biology of Complex Systems, Madison, WI 53706, USA
- Department of Biomolecular Chemistry, University of Wisconsin–Madison, Madison, WI 53706, USA
| | - David J. Pagliarini
- Department of Biochemistry, University of Wisconsin–Madison, Madison, WI 53706, USA
- Morgridge Institute for Research, Madison, WI 53715, USA
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110, USA
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA
- Department of Genetics, Washington University School of Medicine, St. Louis, MO 63110, USA
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4
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Mechanistic Insights into Multiple-step Transport of Mitochondrial ADP/ATP Carrier. Comput Struct Biotechnol J 2022; 20:1829-1840. [PMID: 35521544 PMCID: PMC9046947 DOI: 10.1016/j.csbj.2022.03.032] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Revised: 03/28/2022] [Accepted: 03/28/2022] [Indexed: 01/02/2023] Open
Abstract
The ADP/ATP carrier (AAC) is crucial for mitochondrial functions by importing ADP and exporting ATP across the inner mitochondrial membrane. However, the mechanism of highly specific ADP recognition and transport by AAC remains largely elusive. In this work, spontaneous ADP binding process to the ground c-state AAC was investigated through rigorous molecular dynamics simulations of over 31 microseconds in total. With improved simulation strategy, we have successfully identified a highly specific ADP binding site in the upper region of the cavity, and this site exhibits selectivity for ADP over ATP based on free-energy calculations. Sequence analyses on adenine nucleotide transporters also suggest that this subgroup uses the upper region of the cavity, rather than the previously proposed central binding site located at the bottom of the cavity to discriminate their substrates. Identification of the new site unveils the unusually high substrate specificity of AAC and explains the dependence of transport on the flexibility between anti and syn glycosidic conformers of ADP. Moreover, this new site together with the central site supports early biochemical findings. In light of these early findings, our simulations described a multi-step model in which the carrier uses different sites for substrate attraction, recognition and conformational transition. These results provide new insights into the transport mechanism of AAC and other adenine nucleotide transporters.
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5
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Chipot C, Dehez F, Schnell JR, Zitzmann N, Pebay-Peyroula E, Catoire LJ, Miroux B, Kunji ERS, Veglia G, Cross TA, Schanda P. Perturbations of Native Membrane Protein Structure in Alkyl Phosphocholine Detergents: A Critical Assessment of NMR and Biophysical Studies. Chem Rev 2018; 118:3559-3607. [PMID: 29488756 PMCID: PMC5896743 DOI: 10.1021/acs.chemrev.7b00570] [Citation(s) in RCA: 117] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Indexed: 12/25/2022]
Abstract
Membrane proteins perform a host of vital cellular functions. Deciphering the molecular mechanisms whereby they fulfill these functions requires detailed biophysical and structural investigations. Detergents have proven pivotal to extract the protein from its native surroundings. Yet, they provide a milieu that departs significantly from that of the biological membrane, to the extent that the structure, the dynamics, and the interactions of membrane proteins in detergents may considerably vary, as compared to the native environment. Understanding the impact of detergents on membrane proteins is, therefore, crucial to assess the biological relevance of results obtained in detergents. Here, we review the strengths and weaknesses of alkyl phosphocholines (or foscholines), the most widely used detergent in solution-NMR studies of membrane proteins. While this class of detergents is often successful for membrane protein solubilization, a growing list of examples points to destabilizing and denaturing properties, in particular for α-helical membrane proteins. Our comprehensive analysis stresses the importance of stringent controls when working with this class of detergents and when analyzing the structure and dynamics of membrane proteins in alkyl phosphocholine detergents.
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Affiliation(s)
- Christophe Chipot
- SRSMC, UMR 7019 Université de Lorraine CNRS, Vandoeuvre-les-Nancy F-54500, France
- Laboratoire
International Associé CNRS and University of Illinois at Urbana−Champaign, Vandoeuvre-les-Nancy F-54506, France
- Department
of Physics, University of Illinois at Urbana−Champaign, 1110 West Green Street, Urbana, Illinois 61801, United States
| | - François Dehez
- SRSMC, UMR 7019 Université de Lorraine CNRS, Vandoeuvre-les-Nancy F-54500, France
- Laboratoire
International Associé CNRS and University of Illinois at Urbana−Champaign, Vandoeuvre-les-Nancy F-54506, France
| | - Jason R. Schnell
- Department
of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, United Kingdom
| | - Nicole Zitzmann
- Department
of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, United Kingdom
| | | | - Laurent J. Catoire
- Laboratory
of Biology and Physico-Chemistry of Membrane Proteins, Institut de Biologie Physico-Chimique (IBPC), UMR
7099 CNRS, Paris 75005, France
- University
Paris Diderot, Paris 75005, France
- PSL
Research University, Paris 75005, France
| | - Bruno Miroux
- Laboratory
of Biology and Physico-Chemistry of Membrane Proteins, Institut de Biologie Physico-Chimique (IBPC), UMR
7099 CNRS, Paris 75005, France
- University
Paris Diderot, Paris 75005, France
- PSL
Research University, Paris 75005, France
| | - Edmund R. S. Kunji
- Medical
Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge CB2 0XY, United Kingdom
| | - Gianluigi Veglia
- Department
of Biochemistry, Molecular Biology, and Biophysics, and Department
of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Timothy A. Cross
- National
High Magnetic Field Laboratory, Florida
State University, Tallahassee, Florida 32310, United States
| | - Paul Schanda
- Université
Grenoble Alpes, CEA, CNRS, IBS, Grenoble F-38000, France
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6
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Woznicka-Misaila A, Juillan-Binard C, Baud D, Pebay-Peyroula E, Ravaud S. Cell-free production, purification and characterization of human mitochondrial ADP/ATP carriers. Protein Expr Purif 2017; 144:46-54. [PMID: 29217202 DOI: 10.1016/j.pep.2017.11.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 11/17/2017] [Accepted: 11/29/2017] [Indexed: 11/17/2022]
Abstract
Mitochondrial Carriers (MCs) are responsible for fluent traffic of a variety of compounds that need to be shuttled via mitochondrial inner membranes to maintain cell metabolism. The ADP/ATP Carriers (AACs) are responsible for the import of ADP inside the mitochondria and the export of newly synthesized ATP. In human, four different AACs isoforms are described which are expressed in tissue-specific manner. They are involved in different genetic diseases and play a role in cancerogenesis. Up to now only the structures of the bovine (isoform 1) and yeast (isoforms 2 and 3) AAC have been determined in one particular conformation, obtained in complex with the CATR inhibitor. Herein, we report that full-length human ADP/ATP Carriers isoform 1 and 3 were successfully expressed in cell-free system and purified in milligram amounts in detergent-solubilized state. The proteins exhibited the expected secondary structure content. Thermostability profiles showing stabilization by the CATR inhibitor suggest that the carriers are well folded.
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Affiliation(s)
| | - Céline Juillan-Binard
- Univ. Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale (IBS), 38000 Grenoble, France
| | - Delphine Baud
- Univ. Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale (IBS), 38000 Grenoble, France
| | - Eva Pebay-Peyroula
- Univ. Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale (IBS), 38000 Grenoble, France
| | - Stéphanie Ravaud
- Univ. Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale (IBS), 38000 Grenoble, France.
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7
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Quantification of Detergents Complexed with Membrane Proteins. Sci Rep 2017; 7:41751. [PMID: 28176812 PMCID: PMC5297245 DOI: 10.1038/srep41751] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Accepted: 12/23/2016] [Indexed: 01/20/2023] Open
Abstract
Most membrane proteins studies require the use of detergents, but because of the lack of a general, accurate and rapid method to quantify them, many uncertainties remain that hamper proper functional and structural data analyses. To solve this problem, we propose a method based on matrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOF MS) that allows quantification of pure or mixed detergents in complex with membrane proteins. We validated the method with a wide variety of detergents and membrane proteins. We automated the process, thereby allowing routine quantification for a broad spectrum of usage. As a first illustration, we show how to obtain information of the amount of detergent in complex with a membrane protein, essential for liposome or nanodiscs reconstitutions. Thanks to the method, we also show how to reliably and easily estimate the detergent corona diameter and select the smallest size, critical for favoring protein-protein contacts and triggering/promoting membrane protein crystallization, and to visualize the detergent belt for Cryo-EM studies.
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8
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Liu Y, Wang X, Chen XJ. Misfolding of mutant adenine nucleotide translocase in yeast supports a novel mechanism of Ant1-induced muscle diseases. Mol Biol Cell 2015; 26:1985-94. [PMID: 25833713 PMCID: PMC4472010 DOI: 10.1091/mbc.e15-01-0030] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 03/26/2015] [Indexed: 12/17/2022] Open
Abstract
Missense mutations in membrane proteins cause dominant diseases by unknown mechanisms. Pathogenic mutations in adenine nucleotide translocase 1 affect protein folding and the assembly of multiple protein complexes. The misfolding of one single protein is therefore sufficient to induce proteostatic stress on the membrane. Approximately one-third of proteins in the cell reside in the membrane. Mutations in membrane proteins can induce conformational changes and expose nonnative polar domains/residues to the lipid environment. The molecular effect of the resulting membrane stress is poorly defined. Adenine nucleotide translocase 1 (Ant1) is a mitochondrial inner membrane protein involved in ATP/ADP exchange. Missense mutations in the Ant1 isoform cause autosomal dominant progressive external ophthalmoplegia (adPEO), cardiomyopathy, and myopathy. The mechanism of the Ant1-induced pathologies is highly debated. Here we show that equivalent mutations in the yeast Aac2 protein cause protein misfolding. Misfolded Aac2 drastically affects the assembly and stability of multiple protein complexes in the membrane, which ultimately inhibits cell growth. Despite causing similar proteostatic damages, the adPEO- but not the cardiomyopathy/myopathy-type Aac2 proteins form large aggregates. The data suggest that the Ant1-induced diseases belong to protein misfolding disorders. Protein homeostasis is subtly maintained on the mitochondrial inner membrane and can be derailed by the misfolding of one single protein with or without aggregate formation. This finding could have broad implications for understanding other dominant diseases (e.g., retinitis pigmentosa) caused by missense mutations in membrane proteins.
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Affiliation(s)
- Yaxin Liu
- Department of Biochemistry and Molecular Biology, State University of New York Upstate Medical University, Syracuse, NY 13210
| | - Xiaowen Wang
- Department of Biochemistry and Molecular Biology, State University of New York Upstate Medical University, Syracuse, NY 13210
| | - Xin Jie Chen
- Department of Biochemistry and Molecular Biology, State University of New York Upstate Medical University, Syracuse, NY 13210
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9
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Mielke C, Lefort N, McLean C, Cordova JM, Langlais PR, Bordner AJ, Te JA, Ozkan SB, Willis WT, Mandarino LJ. Adenine nucleotide translocase is acetylated in vivo in human muscle: Modeling predicts a decreased ADP affinity and altered control of oxidative phosphorylation. Biochemistry 2014; 53:3817-29. [PMID: 24884163 PMCID: PMC4067143 DOI: 10.1021/bi401651e] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Proteomics techniques have revealed that lysine acetylation is abundant in mitochondrial proteins. This study was undertaken (1) to determine the relationship between mitochondrial protein acetylation and insulin sensitivity in human skeletal muscle, identifying key acetylated proteins, and (2) to use molecular modeling techniques to understand the functional consequences of acetylation of adenine nucleotide translocase 1 (ANT1), which we found to be abundantly acetylated. Eight lean and eight obese nondiabetic subjects had euglycemic clamps and muscle biopsies for isolation of mitochondrial proteins and proteomics analysis. A number of acetylated mitochondrial proteins were identified in muscle biopsies. Overall, acetylation of mitochondrial proteins was correlated with insulin action (r = 0.60; P < 0.05). Of the acetylated proteins, ANT1, which catalyzes ADP-ATP exchange across the inner mitochondrial membrane, was acetylated at lysines 10, 23, and 92. The extent of acetylation of lysine 23 decreased following exercise, depending on insulin sensitivity. Molecular dynamics modeling and ensemble docking simulations predicted the ADP binding site of ANT1 to be a pocket of positively charged residues, including lysine 23. Calculated ADP-ANT1 binding affinities were physiologically relevant and predicted substantial reductions in affinity upon acetylation of lysine 23. Insertion of these derived binding affinities as parameters into a complete mathematical description of ANT1 kinetics predicted marked reductions in adenine nucleotide flux resulting from acetylation of lysine 23. Therefore, acetylation of ANT1 could have dramatic physiological effects on ADP-ATP exchange. Dysregulation of acetylation of mitochondrial proteins such as ANT1 therefore could be related to changes in mitochondrial function that are associated with insulin resistance.
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Affiliation(s)
- Clinton Mielke
- Center for Metabolic and Vascular
Biology, Arizona State University, Tempe, Arizona 85004, United States
| | - Natalie Lefort
- Center for Metabolic and Vascular
Biology, Arizona State University, Tempe, Arizona 85004, United States
| | - Carrie
G. McLean
- Center for Metabolic and Vascular
Biology, Arizona State University, Tempe, Arizona 85004, United States
| | - Jeanine M. Cordova
- Center for Metabolic and Vascular
Biology, Arizona State University, Tempe, Arizona 85004, United States
| | - Paul R. Langlais
- Division of Endocrinology, Mayo Clinic
in Arizona, Scottsdale, Arizona 85259, United
States
| | - Andrew J. Bordner
- Division of Endocrinology, Mayo Clinic
in Arizona, Scottsdale, Arizona 85259, United
States
| | - Jerez A. Te
- Division of Endocrinology, Mayo Clinic
in Arizona, Scottsdale, Arizona 85259, United
States
| | - S. Banu Ozkan
- Center for Metabolic and Vascular
Biology, Arizona State University, Tempe, Arizona 85004, United States
| | - Wayne T. Willis
- Center for Metabolic and Vascular
Biology, Arizona State University, Tempe, Arizona 85004, United States
| | - Lawrence J. Mandarino
- Center for Metabolic and Vascular
Biology, Arizona State University, Tempe, Arizona 85004, United States
- Division of Endocrinology, Mayo Clinic
in Arizona, Scottsdale, Arizona 85259, United
States
- Department of Medicine, Mayo
Clinic in Arizona, Scottsdale, Arizona 85259, United States
- Mayo Clinic in Arizona, 13400 E.
Shea Blvd., Scottsdale, AZ 85259. E-mail: . Phone: (480) 965-8365. Fax: (480) 965-6899
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10
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Mifsud J, Ravaud S, Krammer EM, Chipot C, Kunji ERS, Pebay-Peyroula E, Dehez F. The substrate specificity of the human ADP/ATP carrier AAC1. Mol Membr Biol 2013; 30:160-8. [PMID: 23173940 DOI: 10.3109/09687688.2012.745175] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The mitochondrial ADP/ATP carrier imports ADP from the cytosol into the mitochondrial matrix for its conversion to ATP by ATP synthase and exports ATP out of the mitochondrion to replenish the eukaryotic cell with chemical energy. Here the substrate specificity of the human mitochondrial ADP/ATP carrier AAC1 was determined by two different approaches. In the first the protein was functionally expressed in Escherichia coli membranes as a fusion protein with maltose binding protein and the effect of excess of unlabeled compounds on the uptake of [(32)P]-ATP was measured. In the second approach the protein was expressed in the cytoplasmic membrane of Lactococcus lactis. The uptake of [(14)C]-ADP in whole cells was measured in the presence of excess of unlabeled compounds and in fused membrane vesicles loaded with unlabeled compounds to demonstrate their transport. A large number of nucleotides were tested, but only ADP and ATP are suitable substrates for human AAC1, demonstrating a very narrow specificity. Next we tried to understand the molecular basis of this specificity by carrying out molecular-dynamics simulations with selected nucleotides, which were placed at the entrance of the central cavity. The binding of the phosphate groups of guanine and adenine nucleotides is similar, yet there is a low probability for the base moiety to be bound, likely to be rooted in the greater polarity of guanine compared to adenine. AMP is unlikely to engage fully with all contact points of the substrate binding site, suggesting that it cannot trigger translocation.
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Affiliation(s)
- John Mifsud
- The Medical Research Council, Mitochondrial Biology Unit, Cambridge, UK
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