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Tang J, Li X, Li W, Cao C. The Protective Effect of Octanoic Acid on Sepsis: A Review. Nutr Rev 2024:nuae106. [PMID: 39101596 DOI: 10.1093/nutrit/nuae106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/06/2024] Open
Abstract
Sepsis, a systemic inflammation that occurs in response to a bacterial infection, is a significant medical challenge. Research conducted over the past decade has indicated strong associations among a patient's nutritional status, the composition of their gut microbiome, and the risk, severity, and prognosis of sepsis. Octanoic acid (OA) plays a vital role in combating sepsis and has a protective effect on both animal models and human patients. In this discussion, the potential protective mechanisms of OA in sepsis, focusing on its regulation of the inflammatory response, immune system, oxidative stress, gastrointestinal microbiome and barrier function, metabolic disorders and malnutrition, as well as organ dysfunction are explored. A comprehensive understanding of the mechanisms by which OA act may pave the way for new preventive and therapeutic approaches to sepsis.
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Affiliation(s)
- Jiabao Tang
- Department of General Surgery, Second Affiliated Hospital of Soochow University, Suzhou 215004, China
| | - Xiaohua Li
- Department of General Surgery, Second Affiliated Hospital of Soochow University, Suzhou 215004, China
- Department of Thyroid and Breast Surgery, Suzhou Wuzhong People's Hospital, Suzhou 215004, China
| | - Wei Li
- Department of General Surgery, Second Affiliated Hospital of Soochow University, Suzhou 215004, China
| | - Chun Cao
- Department of General Surgery, Second Affiliated Hospital of Soochow University, Suzhou 215004, China
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2
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Autio KJ, Koivisto H, Schmitz W, Puronurmi A, Tanila H, Kastaniotis AJ. Exploration of dietary interventions to treat mitochondrial fatty acid disorders in a mouse model. J Nutr Biochem 2024; 131:109692. [PMID: 38879137 DOI: 10.1016/j.jnutbio.2024.109692] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 06/07/2024] [Accepted: 06/11/2024] [Indexed: 07/12/2024]
Abstract
Mitochondrial fatty acids synthesis (mtFAS) is a conserved metabolic pathway essential for mitochondrial respiration. The best characterized mtFAS product is the medium-chain fatty acid octanoate (C8) used as a substrate in the synthesis of lipoic acid (LA), a cofactor required by several mitochondrial enzyme complexes. In humans, mutations in the mtFAS component enoyl reductase MECR cause childhood-onset neurodegenerative disorder MEPAN. A complete deletion of Mecr in mice is embryonically lethal, while selective deletion of Mecr in cerebellar Purkinje cells causes neurodegeneration in these cells. A fundamental question in the research of mtFAS deficiency is if the defect is amenable to treatment by supplementation with known mtFAS products. Here we used the Purkinje-cell specific mtFAS deficiency neurodegeneration model mice to study if feeding the mice with a medium-chain triacylglycerol-rich formula supplemented with LA could slow down or prevent the neurodegeneration in Purkinje cell-specific Mecr KO mice. Feeding started at the age of 4 weeks and continued until the age of 9 months. The neurological status on the mice was assessed at the age of 3, 6, and 9 months with behavioral tests and the state of the Purkinje cell deterioration in the cerebellum was studied histologically. We showed that feeding the mice with medium chain triacylglycerols and LA affected fatty acid profiles in the cerebellum and plasma but did not prevent the development of neurodegeneration in these mice. Our results indicate that dietary supplementation with medium chain fatty acids and LA alone is not an efficient way to treat mtFAS disorders.
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Affiliation(s)
- Kaija J Autio
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
| | | | - Werner Schmitz
- Faculty of Biochemistry and Molecular Biology, University of Würzburg, Würzburg, Germany
| | - Anna Puronurmi
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
| | - Heikki Tanila
- A.I. Virtanen Institute, University of Eastern Finland, Kuopio, Finland
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3
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De Blasi G, Lunetti P, Zara V, Ferramosca A. Mitochondrial citrate transporters Ctp1-Yhm2 and respiratory chain: A coordinated functional connection in Saccharomyces cerevisiae metabolism. Int J Biol Macromol 2024; 270:132364. [PMID: 38750837 DOI: 10.1016/j.ijbiomac.2024.132364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2024] [Revised: 05/10/2024] [Accepted: 05/12/2024] [Indexed: 05/18/2024]
Abstract
The mitochondrial inner membrane contains some hydrophobic proteins that mediate the exchange of metabolites between the mitochondrial matrix and the cytosol. Ctp1 and Yhm2 are two carrier proteins in the yeast Saccharomyces cerevisiae responsible for the transport of citrate, a tricarboxylate involved in several metabolic pathways. Since these proteins also contribute to respiratory metabolism, in this study we investigated for the first time whether changes in citrate transport can affect the structural organization and functional properties of respiratory complexes. Through experiments in yeast mutant cells in which the gene encoding Ctp1 or Yhm2 was deleted, we found that in the absence of either mitochondrial citrate transporter, mitochondrial respiration was impaired. Structural analysis of the respiratory complexes III and IV revealed different expression levels of the catalytic and supernumerary subunits in the Δctp1 and Δyhm2 strains. In addition, Δyhm2 mitochondria appeared to be more sensitive than Δctp1 to the oxidative damage. Our results provide the first evidence for a coordinated modulation of mitochondrial citrate transport and respiratory chain activity in S. cerevisiae metabolism.
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Affiliation(s)
- Gabriella De Blasi
- Department of Biological and Environmental Sciences and Technologies, University of Salento, I-73100 Lecce, Italy
| | - Paola Lunetti
- Department of Biological and Environmental Sciences and Technologies, University of Salento, I-73100 Lecce, Italy; Department of Experimental Medicine, University of Salento, I-73100 Lecce, Italy
| | - Vincenzo Zara
- Department of Biological and Environmental Sciences and Technologies, University of Salento, I-73100 Lecce, Italy; Department of Experimental Medicine, University of Salento, I-73100 Lecce, Italy
| | - Alessandra Ferramosca
- Department of Biological and Environmental Sciences and Technologies, University of Salento, I-73100 Lecce, Italy; Department of Experimental Medicine, University of Salento, I-73100 Lecce, Italy.
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4
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Xue J, Ye C. The role of lipoylation in mitochondrial adaptation to methionine restriction. Bioessays 2024; 46:e2300218. [PMID: 38616332 DOI: 10.1002/bies.202300218] [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: 11/11/2023] [Revised: 03/12/2024] [Accepted: 04/02/2024] [Indexed: 04/16/2024]
Abstract
Dietary methionine restriction (MR) is associated with a spectrum of health-promoting benefits. Being conducive to prevention of chronic diseases and extension of life span, MR can activate integrated responses at metabolic, transcriptional, and physiological levels. However, how the mitochondria of MR influence metabolic phenotypes remains elusive. Here, we provide a summary of cellular functions of methionine metabolism and an overview of the current understanding of effector mechanisms of MR, with a focus on the aspect of mitochondria-mediated responses. We propose that mitochondria can sense and respond to MR through a modulatory role of lipoylation, a mitochondrial protein modification sensitized by MR.
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Affiliation(s)
- Jingyuan Xue
- Zhejiang Provincial Key Laboratory for Cancer Molecular Cell Biology, Life Sciences Institute, Zhejiang University, Hangzhou, China
| | - Cunqi Ye
- Zhejiang Provincial Key Laboratory for Cancer Molecular Cell Biology, Life Sciences Institute, Zhejiang University, Hangzhou, China
- Hainan Institute, Zhejiang University, Sanya, China
- National R&D Center for Freshwater Fish Processing, Jiangxi Normal University, Nanchang, China
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5
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Dieckmann CL. A hub for regulation of mitochondrial metabolism: Fatty acid and lipoic acid biosynthesis. IUBMB Life 2024; 76:332-344. [PMID: 38088214 DOI: 10.1002/iub.2802] [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: 08/18/2023] [Accepted: 11/21/2023] [Indexed: 05/28/2024]
Abstract
Having evolved from a prokaryotic origin, mitochondria retain pathways required for the catabolism of energy-rich molecules and for the biosynthesis of molecules that aid catabolism and/or participate in other cellular processes essential for life of the cell. Reviewed here are details of the mitochondrial fatty acid biosynthetic pathway (FAS II) and its role in building both the octanoic acid precursor for lipoic acid biosynthesis (LAS) and longer-chain fatty acids functioning in chaperoning the assembly of mitochondrial multisubunit complexes. Also covered are the details of mitochondrial lipoic acid biosynthesis, which is distinct from that of prokaryotes, and the attachment of lipoic acid to subunits of pyruvate dehydrogenase, α-ketoglutarate dehydrogenase, and glycine cleavage system complexes. Special emphasis has been placed on presenting what is currently known about the interconnected paths and loops linking the FAS II-LAS pathway and two other mitochondrial realms, the organellar translation machinery and Fe-S cluster biosynthesis and function.
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Affiliation(s)
- Carol L Dieckmann
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona, USA
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6
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Dohnálek V, Doležal P. Installation of LYRM proteins in early eukaryotes to regulate the metabolic capacity of the emerging mitochondrion. Open Biol 2024; 14:240021. [PMID: 38772414 PMCID: PMC11293456 DOI: 10.1098/rsob.240021] [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: 08/15/2023] [Accepted: 03/13/2024] [Indexed: 05/23/2024] Open
Abstract
Core mitochondrial processes such as the electron transport chain, protein translation and the formation of Fe-S clusters (ISC) are of prokaryotic origin and were present in the bacterial ancestor of mitochondria. In animal and fungal models, a family of small Leu-Tyr-Arg motif-containing proteins (LYRMs) uniformly regulates the function of mitochondrial complexes involved in these processes. The action of LYRMs is contingent upon their binding to the acylated form of acyl carrier protein (ACP). This study demonstrates that LYRMs are structurally and evolutionarily related proteins characterized by a core triplet of α-helices. Their widespread distribution across eukaryotes suggests that 12 specialized LYRMs were likely present in the last eukaryotic common ancestor to regulate the assembly and folding of the subunits that are conserved in bacteria but that lack LYRM homologues. The secondary reduction of mitochondria to anoxic environments has rendered the function of LYRMs and their interaction with acylated ACP dispensable. Consequently, these findings strongly suggest that early eukaryotes installed LYRMs in aerobic mitochondria as orchestrated switches, essential for regulating core metabolism and ATP production.
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Affiliation(s)
- Vít Dohnálek
- Department of Parasitology, Faculty of Science, Charles University, BIOCEV, Vestec252 50, Czech Republic
| | - Pavel Doležal
- Department of Parasitology, Faculty of Science, Charles University, BIOCEV, Vestec252 50, Czech Republic
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7
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Wedan RJ, Longenecker JZ, Nowinski SM. Mitochondrial fatty acid synthesis is an emergent central regulator of mammalian oxidative metabolism. Cell Metab 2024; 36:36-47. [PMID: 38128528 PMCID: PMC10843818 DOI: 10.1016/j.cmet.2023.11.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Revised: 11/27/2023] [Accepted: 11/30/2023] [Indexed: 12/23/2023]
Abstract
Contrary to their well-known functions in nutrient breakdown, mitochondria are also important biosynthetic hubs and express an evolutionarily conserved mitochondrial fatty acid synthesis (mtFAS) pathway. mtFAS builds lipoic acid and longer saturated fatty acids, but its exact products, their ultimate destination in cells, and the cellular significance of the pathway are all active research questions. Moreover, why mitochondria need mtFAS despite their well-defined ability to import fatty acids is still unclear. The identification of patients with inborn errors of metabolism in mtFAS genes has sparked fresh research interest in the pathway. New mammalian models have provided insights into how mtFAS coordinates many aspects of oxidative mitochondrial metabolism and raise questions about its role in diseases such as obesity, diabetes, and heart failure. In this review, we discuss the products of mtFAS, their function, and the consequences of mtFAS impairment across models and in metabolic disease.
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Affiliation(s)
- Riley J Wedan
- Department of Metabolism and Nutritional Programming, The Van Andel Institute, Grand Rapids, MI 49503, USA; College of Human Medicine, Michigan State University, Grand Rapids, MI 49503, USA
| | - Jacob Z Longenecker
- Department of Metabolism and Nutritional Programming, The Van Andel Institute, Grand Rapids, MI 49503, USA
| | - Sara M Nowinski
- Department of Metabolism and Nutritional Programming, The Van Andel Institute, Grand Rapids, MI 49503, USA.
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8
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Fiorini C, Degiorgi A, Cascavilla ML, Tropeano CV, La Morgia C, Battista M, Ormanbekova D, Palombo F, Carbonelli M, Bandello F, Carelli V, Maresca A, Barboni P, Baruffini E, Caporali L. Recessive MECR pathogenic variants cause an LHON-like optic neuropathy. J Med Genet 2023; 61:93-101. [PMID: 37734847 PMCID: PMC10804020 DOI: 10.1136/jmg-2023-109340] [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: 04/17/2023] [Accepted: 08/11/2023] [Indexed: 09/23/2023]
Abstract
BACKGROUND Leber's hereditary optic neuropathy (LHON) is a mitochondrial disorder characterised by complex I defect leading to sudden degeneration of retinal ganglion cells. Although typically associated with pathogenic variants in mitochondrial DNA, LHON was recently described in patients carrying biallelic variants in nuclear genes DNAJC30, NDUFS2 and MCAT. MCAT is part of mitochondrial fatty acid synthesis (mtFAS), as also MECR, the mitochondrial trans-2-enoyl-CoA reductase. MECR mutations lead to a recessive childhood-onset syndromic disorder with dystonia, optic atrophy and basal ganglia abnormalities. METHODS We studied through whole exome sequencing two sisters affected by sudden and painless visual loss at young age, with partial recovery and persistent central scotoma. We modelled the candidate variant in yeast and studied mitochondrial dysfunction in yeast and fibroblasts. We tested protein lipoylation and cell response to oxidative stress in yeast. RESULTS Both sisters carried a homozygous pathogenic variant in MECR (p.Arg258Trp). In yeast, the MECR-R258W mutant showed an impaired oxidative growth, 30% reduction in oxygen consumption rate and 80% decrease in protein levels, pointing to structure destabilisation. Fibroblasts confirmed the reduced amount of MECR protein, but failed to reproduce the OXPHOS defect. Respiratory complexes assembly was normal. Finally, the yeast mutant lacked lipoylation of key metabolic enzymes and was more sensitive to H2O2 treatment. Lipoic Acid supplementation partially rescued the growth defect. CONCLUSION We report the first family with homozygous MECR variant causing an LHON-like optic neuropathy, which pairs the recent MCAT findings, reinforcing the impairment of mtFAS as novel pathogenic mechanism in LHON.
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Affiliation(s)
- Claudio Fiorini
- Programma di Neurogenetica, IRCCS Istituto Delle Scienze Neurologiche di Bologna, Bologna, Italy
| | - Andrea Degiorgi
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parma, Italy
| | - Maria Lucia Cascavilla
- Department of Ophthalmology, University Vita-Salute, IRCCS Ospedale San Raffaele, Milano, Italy
| | | | - Chiara La Morgia
- Programma di Neurogenetica, IRCCS Istituto Delle Scienze Neurologiche di Bologna, Bologna, Italy
- Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Bologna, Italy
| | - Marco Battista
- Department of Ophthalmology, University Vita-Salute, IRCCS Ospedale San Raffaele, Milano, Italy
| | - Danara Ormanbekova
- Programma di Neurogenetica, IRCCS Istituto Delle Scienze Neurologiche di Bologna, Bologna, Italy
| | - Flavia Palombo
- Programma di Neurogenetica, IRCCS Istituto Delle Scienze Neurologiche di Bologna, Bologna, Italy
| | - Michele Carbonelli
- Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Bologna, Italy
| | - Francesco Bandello
- Department of Ophthalmology, University Vita-Salute, IRCCS Ospedale San Raffaele, Milano, Italy
| | - Valerio Carelli
- Programma di Neurogenetica, IRCCS Istituto Delle Scienze Neurologiche di Bologna, Bologna, Italy
- Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Bologna, Italy
| | - Alessandra Maresca
- Programma di Neurogenetica, IRCCS Istituto Delle Scienze Neurologiche di Bologna, Bologna, Italy
| | - Piero Barboni
- Department of Ophthalmology, University Vita-Salute, IRCCS Ospedale San Raffaele, Milano, Italy
| | - Enrico Baruffini
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parma, Italy
| | - Leonardo Caporali
- Programma di Neurogenetica, IRCCS Istituto Delle Scienze Neurologiche di Bologna, Bologna, Italy
- Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Bologna, Italy
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9
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Dutta D, Kanca O, Byeon SK, Marcogliese PC, Zuo Z, Shridharan RV, Park JH, Lin G, Ge M, Heimer G, Kohler JN, Wheeler MT, Kaipparettu BA, Pandey A, Bellen HJ. A defect in mitochondrial fatty acid synthesis impairs iron metabolism and causes elevated ceramide levels. Nat Metab 2023; 5:1595-1614. [PMID: 37653044 PMCID: PMC11151872 DOI: 10.1038/s42255-023-00873-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Accepted: 07/21/2023] [Indexed: 09/02/2023]
Abstract
In most eukaryotic cells, fatty acid synthesis (FAS) occurs in the cytoplasm and in mitochondria. However, the relative contribution of mitochondrial FAS (mtFAS) to the cellular lipidome is not well defined. Here we show that loss of function of Drosophila mitochondrial enoyl coenzyme A reductase (Mecr), which is the enzyme required for the last step of mtFAS, causes lethality, while neuronal loss of Mecr leads to progressive neurodegeneration. We observe a defect in Fe-S cluster biogenesis and increased iron levels in flies lacking mecr, leading to elevated ceramide levels. Reducing the levels of either iron or ceramide suppresses the neurodegenerative phenotypes, indicating an interplay between ceramide and iron metabolism. Mutations in human MECR cause pediatric-onset neurodegeneration, and we show that human-derived fibroblasts display similar elevated ceramide levels and impaired iron homeostasis. In summary, this study identifies a role of mecr/MECR in ceramide and iron metabolism, providing a mechanistic link between mtFAS and neurodegeneration.
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Affiliation(s)
- Debdeep Dutta
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA
| | - Oguz Kanca
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA
| | - Seul Kee Byeon
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA
| | - Paul C Marcogliese
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA
- Department of Biochemistry & Medical Genetics, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Zhongyuan Zuo
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA
| | - Rishi V Shridharan
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA
| | - Jun Hyoung Park
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Guang Lin
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA
| | - Ming Ge
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA
| | - Gali Heimer
- Pediatric Neurology Unit, Edmond and Lily Safra Children's Hospital, Sheba Medical Center, Ramat Gan, Israel
- The Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Jennefer N Kohler
- Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Matthew T Wheeler
- Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Benny A Kaipparettu
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Akhilesh Pandey
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA
- Manipal Academy of Higher Education, Manipal, India
| | - Hugo J Bellen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA.
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10
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Berg JA, Zhou Y, Ouyang Y, Cluntun AA, Waller TC, Conway ME, Nowinski SM, Van Ry T, George I, Cox JE, Wang B, Rutter J. Metaboverse enables automated discovery and visualization of diverse metabolic regulatory patterns. Nat Cell Biol 2023; 25:616-625. [PMID: 37012464 PMCID: PMC10104781 DOI: 10.1038/s41556-023-01117-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Accepted: 02/24/2023] [Indexed: 04/05/2023]
Abstract
Metabolism is intertwined with various cellular processes, including controlling cell fate, influencing tumorigenesis, participating in stress responses and more. Metabolism is a complex, interdependent network, and local perturbations can have indirect effects that are pervasive across the metabolic network. Current analytical and technical limitations have long created a bottleneck in metabolic data interpretation. To address these shortcomings, we developed Metaboverse, a user-friendly tool to facilitate data exploration and hypothesis generation. Here we introduce algorithms that leverage the metabolic network to extract complex reaction patterns from data. To minimize the impact of missing measurements within the network, we introduce methods that enable pattern recognition across multiple reactions. Using Metaboverse, we identify a previously undescribed metabolite signature that correlated with survival outcomes in early stage lung adenocarcinoma patients. Using a yeast model, we identify metabolic responses suggesting an adaptive role of citrate homeostasis during mitochondrial dysfunction facilitated by the citrate transporter, Ctp1. We demonstrate that Metaboverse augments the user's ability to extract meaningful patterns from multi-omics datasets to develop actionable hypotheses.
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Affiliation(s)
- Jordan A Berg
- Department of Biochemistry, University of Utah, Salt Lake City, UT, USA.
- Altos Labs, Redwood City, CA, USA.
| | - Youjia Zhou
- School of Computing, University of Utah, Salt Lake City, UT, USA
- Scientific Computing and Imaging Institute, University of Utah, Salt Lake City, UT, USA
| | - Yeyun Ouyang
- Department of Biochemistry, University of Utah, Salt Lake City, UT, USA
- Altos Labs, Redwood City, CA, USA
| | - Ahmad A Cluntun
- Department of Biochemistry, University of Utah, Salt Lake City, UT, USA
| | - T Cameron Waller
- Division of Computational Biology, Department of Quantitative Health Sciences, Mayo Clinic, Rochester, MN, USA
| | - Megan E Conway
- Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah, Salt Lake City, UT, USA
| | - Sara M Nowinski
- Department of Biochemistry, University of Utah, Salt Lake City, UT, USA
- Department of Metabolism and Nutritional Programming, Van Andel Institute, Grand Rapids, MI, USA
| | - Tyler Van Ry
- Department of Biochemistry, University of Utah, Salt Lake City, UT, USA
- Metabolomics Core Facility, University of Utah, Salt Lake City, UT, USA
- College of Osteopathic Medicine, Michigan State University, East Lansing, MI, USA
| | - Ian George
- Department of Biochemistry, University of Utah, Salt Lake City, UT, USA
| | - James E Cox
- Department of Biochemistry, University of Utah, Salt Lake City, UT, USA
- Metabolomics Core Facility, University of Utah, Salt Lake City, UT, USA
- Diabetes & Metabolism Research Center, University of Utah, Salt Lake City, UT, USA
| | - Bei Wang
- School of Computing, University of Utah, Salt Lake City, UT, USA
- Scientific Computing and Imaging Institute, University of Utah, Salt Lake City, UT, USA
| | - Jared Rutter
- Department of Biochemistry, University of Utah, Salt Lake City, UT, USA.
- Diabetes & Metabolism Research Center, University of Utah, Salt Lake City, UT, USA.
- Howard Hughes Medical Institute, University of Utah, Salt Lake City, UT, USA.
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11
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Rahman MT, Koski MK, Panecka-Hofman J, Schmitz W, Kastaniotis AJ, Wade RC, Wierenga RK, Hiltunen JK, Autio KJ. An engineered variant of MECR reductase reveals indispensability of long-chain acyl-ACPs for mitochondrial respiration. Nat Commun 2023; 14:619. [PMID: 36739436 PMCID: PMC9899272 DOI: 10.1038/s41467-023-36358-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 01/25/2023] [Indexed: 02/06/2023] Open
Abstract
Mitochondrial fatty acid synthesis (mtFAS) is essential for respiratory function. MtFAS generates the octanoic acid precursor for lipoic acid synthesis, but the role of longer fatty acid products has remained unclear. The structurally well-characterized component of mtFAS, human 2E-enoyl-ACP reductase (MECR) rescues respiratory growth and lipoylation defects of a Saccharomyces cerevisiae Δetr1 strain lacking native mtFAS enoyl reductase. To address the role of longer products of mtFAS, we employed in silico molecular simulations to design a MECR variant with a shortened substrate binding cavity. Our in vitro and in vivo analyses indicate that the MECR G165Q variant allows synthesis of octanoyl groups but not long chain fatty acids, confirming the validity of our computational approach to engineer substrate length specificity. Furthermore, our data imply that restoring lipoylation in mtFAS deficient yeast strains is not sufficient to support respiration and that long chain acyl-ACPs generated by mtFAS are required for mitochondrial function.
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Affiliation(s)
- M Tanvir Rahman
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
| | | | - Joanna Panecka-Hofman
- Faculty of Physics, University of Warsaw, Warsaw, Poland
- Molecular and Cellular Modeling Group, Heidelberg Institute for Theoretical Studies (HITS), Heidelberg, Germany
| | - Werner Schmitz
- Faculty of Biochemistry and Molecular Biology, University of Würzburg, Würzburg, Germany
| | | | - Rebecca C Wade
- Molecular and Cellular Modeling Group, Heidelberg Institute for Theoretical Studies (HITS), Heidelberg, Germany
- Zentrum für Molekulare Biologie (ZMBH), DKFZ-ZMBH Alliance and Interdisciplinary Center for Scientific Computing (IWR), Heidelberg University, Heidelberg, Germany
| | - Rik K Wierenga
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
| | - J Kalervo Hiltunen
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
| | - Kaija J Autio
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland.
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12
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Shvetsova A, Masud AJ, Schneider L, Bergmann U, Monteuuis G, Miinalainen IJ, Hiltunen JK, Kastaniotis AJ. A hunt for OM45 synthetic petite interactions in Saccharomyces cerevisiae reveals a role for Miro GTPase Gem1p in cristae structure maintenance. Microbiologyopen 2021; 10:e1238. [PMID: 34713605 PMCID: PMC8501180 DOI: 10.1002/mbo3.1238] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 09/09/2021] [Accepted: 09/09/2021] [Indexed: 11/28/2022] Open
Abstract
Om45 is a major protein of the yeast's outer mitochondrial membrane under respiratory conditions. However, the cellular role of the protein has remained obscure. Previously, deletion mutant phenotypes have not been found, and clear amino acid sequence similarities that would allow inferring its functional role are not available. In this work, we describe synthetic petite mutants of GEM1 and UGO1 that depend on the presence of OM45 for respiratory growth, as well as the identification of several multicopy suppressors of the synthetic petite phenotypes. In the analysis of our mutants, we demonstrate that Om45p and Gem1p have a collaborative role in the maintenance of mitochondrial morphology, cristae structure, and mitochondrial DNA maintenance. A group of multicopy suppressors rescuing the synthetic lethal phenotypes of the mutants on non-fermentable carbon sources additionally supports this result. Our results imply that the synthetic petite phenotypes we observed are due to the disturbance of the inner mitochondrial membrane and point to this mitochondrial sub-compartment as the main target of action of Om45p, Ugo1p, and the yeast Miro GTPase Gem1p.
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Affiliation(s)
- Antonina Shvetsova
- Faculty of Biochemistry and Molecular Medicine and Biocenter OuluUniversity of OuluOuluFinland
| | - Ali J. Masud
- Faculty of Biochemistry and Molecular Medicine and Biocenter OuluUniversity of OuluOuluFinland
| | - Laura Schneider
- Faculty of Biochemistry and Molecular Medicine and Biocenter OuluUniversity of OuluOuluFinland
| | - Ulrich Bergmann
- Faculty of Biochemistry and Molecular Medicine and Biocenter OuluUniversity of OuluOuluFinland
| | - Geoffray Monteuuis
- Faculty of Biochemistry and Molecular Medicine and Biocenter OuluUniversity of OuluOuluFinland
- Present address:
Department of Biochemistry and Developmental BiologyUniversity of HelsinkiHelsinkiFinland
| | - Ilkka J. Miinalainen
- Faculty of Biochemistry and Molecular Medicine and Biocenter OuluUniversity of OuluOuluFinland
| | - J. Kalervo Hiltunen
- Faculty of Biochemistry and Molecular Medicine and Biocenter OuluUniversity of OuluOuluFinland
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13
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Sheraj I, Guray NT, Banerjee S. A pan-cancer transcriptomic study showing tumor specific alterations in central metabolism. Sci Rep 2021; 11:13637. [PMID: 34211032 PMCID: PMC8249409 DOI: 10.1038/s41598-021-93003-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Accepted: 06/11/2021] [Indexed: 02/06/2023] Open
Abstract
Recently, there has been a resurgence of interest in metabolic rewiring of tumors to identify clinically relevant genes. However, most of these studies have had either focused on individual tumors, or are too general, providing a broad outlook on overall changes. In this study, we have first curated an extensive list of genes encoding metabolic enzymes and metabolite transporters relevant to carbohydrate, fatty acid and amino acid oxidation and biosynthesis. Next, we have used publicly available transcriptomic data for 20 different tumor types from The Cancer Genome Atlas Network (TCGA) and focused on differential expression of these genes between tumor and adjacent normal tissue. Our study revealed major transcriptional alterations in genes that are involved in central metabolism. Most tumors exhibit upregulation in carbohydrate and amino acid transporters, increased glycolysis and pentose phosphate pathway, and decreased fatty acid and amino acid oxidation. On the other hand, the expression of genes of the tricarboxylic acid cycle, anaplerotic reactions and electron transport chain differed between tumors. Although most transcriptomic alterations were conserved across many tumor types suggesting the initiation of common regulatory programs, expression changes unique to specific tumors were also identified, which can provide gene expression fingerprints as potential biomarkers or drug targets. Our study also emphasizes the value of transcriptomic data in the deeper understanding of metabolic changes in diseases.
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Affiliation(s)
- Ilir Sheraj
- Department of Biological Sciences, Orta Dogu Teknik Universitesi (ODTU/METU), Ankara, 06800, Turkey
| | - N Tulin Guray
- Department of Biological Sciences, Orta Dogu Teknik Universitesi (ODTU/METU), Ankara, 06800, Turkey
| | - Sreeparna Banerjee
- Department of Biological Sciences, Orta Dogu Teknik Universitesi (ODTU/METU), Ankara, 06800, Turkey.
- Cancer Systems Biology Laboratory (CanSyl), Orta Dogu Teknik Universitesi (ODTU/METU), Ankara, 06800, Turkey.
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14
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Alam J, Rahman FT, Sah-Teli SK, Venkatesan R, Koski MK, Autio KJ, Hiltunen JK, Kastaniotis AJ. Expression and analysis of the SAM-dependent RNA methyltransferase Rsm22 from Saccharomyces cerevisiae. Acta Crystallogr D Struct Biol 2021; 77:840-853. [PMID: 34076597 PMCID: PMC8171064 DOI: 10.1107/s2059798321004149] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Accepted: 04/17/2021] [Indexed: 12/04/2022] Open
Abstract
Rsm22-family proteins are conserved putative SAM-dependent methyltransferases with important functions in mitochondrial translation. Here, the results of a comparative bioinformatics analysis of Rsm22-type proteins are presented, the expression, biophysical characterization and crystallization of Saccharomyces cerevisiae Rsm22 are reported, a low-resolution SAXS structure of the protein is revealed, and SAM-dependent RNA methyl transferase activity of the protein is demonstrated. The Saccharomyces cerevisiae Rsm22 protein (Sc-Rsm22), encoded by the nuclear RSM22 (systematic name YKL155c) gene, is a distant homologue of Rsm22 from Trypanosoma brucei (Tb-Rsm22) and METTL17 from mouse (Mm-METTL17). All three proteins have been shown to be associated with mitochondrial gene expression, and Sc-Rsm22 has been documented to be essential for mitochondrial respiration. The Sc-Rsm22 protein comprises a polypeptide of molecular weight 72.2 kDa that is predicted to harbor an N-terminal mitochondrial targeting sequence. The precise physiological function of Rsm22-family proteins is unknown, and no structural information has been available for Sc-Rsm22 to date. In this study, Sc-Rsm22 was expressed and purified in monomeric and dimeric forms, their folding was confirmed by circular-dichroism analyses and their low-resolution structures were determined using a small-angle X-ray scattering (SAXS) approach. The solution structure of the monomeric form of Sc-Rsm22 revealed an elongated three-domain arrangement, which differs from the shape of Tb-Rsm22 in its complex with the mitochondrial small ribosomal subunit in T. brucei (PDB entry 6sg9). A bioinformatic analysis revealed that the core domain in the middle (Leu117–Asp462 in Sc-Rsm22) resembles the corresponding region in Tb-Rsm22, including a Rossmann-like methyltransferase fold followed by a zinc-finger-like structure. The latter structure is not present in this position in other methyltransferases and is therefore a unique structural motif for this family. The first half of the C-terminal domain is likely to form an OB-fold, which is typically found in RNA-binding proteins and is also seen in the Tb-Rsm22 structure. In contrast, the N-terminal domain of Sc-Rsm22 is predicted to be fully α-helical and shares no sequence similarity with other family members. Functional studies demonstrated that the monomeric variant of Sc-Rsm22 methylates mitochondrial tRNAs in vitro. These data suggest that Sc-Rsm22 is a new and unique member of the RNA methyltransferases that is important for mitochondrial protein synthesis.
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Affiliation(s)
- Jahangir Alam
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Aapistie 7B, FIN-90220 Oulu, Finland
| | - Farah Tazkera Rahman
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Aapistie 7B, FIN-90220 Oulu, Finland
| | - Shiv K Sah-Teli
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Aapistie 7B, FIN-90220 Oulu, Finland
| | - Rajaram Venkatesan
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Aapistie 7B, FIN-90220 Oulu, Finland
| | | | - Kaija J Autio
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Aapistie 7B, FIN-90220 Oulu, Finland
| | - J Kalervo Hiltunen
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Aapistie 7B, FIN-90220 Oulu, Finland
| | - Alexander J Kastaniotis
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Aapistie 7B, FIN-90220 Oulu, Finland
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15
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Altered Metabolic Flexibility in Inherited Metabolic Diseases of Mitochondrial Fatty Acid Metabolism. Int J Mol Sci 2021; 22:ijms22073799. [PMID: 33917608 PMCID: PMC8038842 DOI: 10.3390/ijms22073799] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 04/03/2021] [Accepted: 04/05/2021] [Indexed: 12/14/2022] Open
Abstract
In general, metabolic flexibility refers to an organism's capacity to adapt to metabolic changes due to differing energy demands. The aim of this work is to summarize and discuss recent findings regarding variables that modulate energy regulation in two different pathways of mitochondrial fatty metabolism: β-oxidation and fatty acid biosynthesis. We focus specifically on two diseases: very long-chain acyl-CoA dehydrogenase deficiency (VLCADD) and malonyl-CoA synthetase deficiency (acyl-CoA synthetase family member 3 (ACSF3)) deficiency, which are both characterized by alterations in metabolic flexibility. On the one hand, in a mouse model of VLCAD-deficient (VLCAD-/-) mice, the white skeletal muscle undergoes metabolic and morphologic transdifferentiation towards glycolytic muscle fiber types via the up-regulation of mitochondrial fatty acid biosynthesis (mtFAS). On the other hand, in ACSF3-deficient patients, fibroblasts show impaired mitochondrial respiration, reduced lipoylation, and reduced glycolytic flux, which are compensated for by an increased β-oxidation rate and the use of anaplerotic amino acids to address the energy needs. Here, we discuss a possible co-regulation by mtFAS and β-oxidation in the maintenance of energy homeostasis.
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16
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Zeng M, Xu J, Zhang Z, Zou X, Wang X, Cao K, Lv W, Cui Y, Long J, Feng Z, Liu J. Htd2 deficiency-associated suppression of α-lipoic acid production provokes mitochondrial dysfunction and insulin resistance in adipocytes. Redox Biol 2021; 41:101948. [PMID: 33774475 PMCID: PMC8027779 DOI: 10.1016/j.redox.2021.101948] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 03/03/2021] [Accepted: 03/15/2021] [Indexed: 12/11/2022] Open
Abstract
Mitochondria harbor a unique fatty acid synthesis pathway (mtFAS) with mysterious functions gaining increasing interest, while its involvement in metabolic regulation is essentially unknown. Here we show that 3-Hydroxyacyl-ACP dehydratase (HTD2), a key enzyme in mtFAS pathway was primarily downregulated in adipocytes of mice under metabolic disorders, accompanied by decreased de novo production of lipoic acid, which is the byproduct of mtFAS pathway. Knockdown of Htd2 in 3T3-L1 preadipocytes or differentiated 3T3-L1 mature adipocytes impaired mitochondrial function via suppression of complex I activity, resulting in enhanced oxidative stress and impaired insulin sensitivity, which were all attenuated by supplement of lipoic acid. Moreover, lipidomic study revealed limited lipid alterations in mtFAS deficient cells which primarily presenting accumulation of triglycerides, attributed to mitochondrial dysfunction. Collectively, the present study highlighted the pivotal role of mtFAS pathway in regulating mitochondrial function and adipocytes insulin sensitivity, demonstrating supportive evidence for lipoic acid being potential effective nutrient for improving insulin resistance and related metabolic disorders. 3-Hydroxyacyl-ACP dehydratase is decreased in adipocytes under diabetic condition. Deficient of 3-Hydroxyacyl-ACP dehydratase (HTD2) triggers mitochondrial dysfunction. Deficient of HTD2 promotes insulin resistance in adipocytes. Supplement of lipoic acid ameliorates deleterious effects of HTD2 deficiency.
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Affiliation(s)
- Mengqi Zeng
- Center for Mitochondrial Biology and Medicine, The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi, 710049, China
| | - Jie Xu
- Center for Mitochondrial Biology and Medicine, The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi, 710049, China
| | - Zhengyi Zhang
- Center for Mitochondrial Biology and Medicine, The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi, 710049, China
| | - Xuan Zou
- National & Local Joint Engineering Research Center of Biodiagnosis and Biotherapy, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shannxi, 710004, China
| | - Xueqiang Wang
- Center for Mitochondrial Biology and Medicine, The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi, 710049, China
| | - Ke Cao
- Center for Mitochondrial Biology and Medicine, The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi, 710049, China
| | - Weiqiang Lv
- Center for Mitochondrial Biology and Medicine, The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi, 710049, China
| | - Yuting Cui
- Center for Mitochondrial Biology and Medicine, The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi, 710049, China
| | - Jiangang Long
- Center for Mitochondrial Biology and Medicine, The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi, 710049, China
| | - Zhihui Feng
- Center for Mitochondrial Biology and Medicine, The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi, 710049, China; Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi, 710049, China.
| | - Jiankang Liu
- Center for Mitochondrial Biology and Medicine, The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi, 710049, China; National & Local Joint Engineering Research Center of Biodiagnosis and Biotherapy, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shannxi, 710004, China; Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi, 710049, China.
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17
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Pietikäinen LP, Rahman MT, Hiltunen JK, Dieckmann CL, Kastaniotis AJ. Genetic dissection of the mitochondrial lipoylation pathway in yeast. BMC Biol 2021; 19:14. [PMID: 33487163 PMCID: PMC7831266 DOI: 10.1186/s12915-021-00951-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 01/06/2021] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Lipoylation of 2-ketoacid dehydrogenases is essential for mitochondrial function in eukaryotes. While the basic principles of the lipoylation processes have been worked out, we still lack a thorough understanding of the details of this important post-translational modification pathway. Here we used yeast as a model organism to characterize substrate usage by the highly conserved eukaryotic octanoyl/lipoyl transferases in vivo and queried how amenable the lipoylation system is to supplementation with exogenous substrate. RESULTS We show that the requirement for mitochondrial fatty acid synthesis to provide substrates for lipoylation of the 2-ketoacid dehydrogenases can be bypassed by supplying the cells with free lipoic acid (LA) or octanoic acid (C8) and a mitochondrially targeted fatty acyl/lipoyl activating enzyme. We also provide evidence that the S. cerevisiae lipoyl transferase Lip3, in addition to transferring LA from the glycine cleavage system H protein to the pyruvate dehydrogenase (PDH) and α-ketoglutarate dehydrogenase (KGD) E2 subunits, can transfer this cofactor from the PDH complex to the KGD complex. In support of yeast as a model system for human metabolism, we demonstrate that the human octanoyl/lipoyl transferases can substitute for their counterparts in yeast to support respiratory growth and protein lipoylation. Like the wild-type yeast enzyme, the human lipoyl transferase LIPT1 responds to LA supplementation in the presence of the activating enzyme LplA. CONCLUSIONS In the yeast model system, the eukaryotic lipoylation pathway can use free LA and C8 as substrates when fatty/lipoic acid activating enzymes are targeted to mitochondria. Lip3 LA transferase has a wider substrate specificity than previously recognized. We show that these features of the lipoylation mechanism in yeast are conserved in mammalian mitochondria. Our findings have important implications for the development of effective therapies for the treatment of LA or mtFAS deficiency-related disorders.
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Affiliation(s)
- Laura P Pietikäinen
- Faculty of Biochemistry and Molecular Medicine and Biocenter Oulu, University of Oulu, PO Box 5400, FI-90014, Oulu, Finland
| | - M Tanvir Rahman
- Faculty of Biochemistry and Molecular Medicine and Biocenter Oulu, University of Oulu, PO Box 5400, FI-90014, Oulu, Finland
| | - J Kalervo Hiltunen
- Faculty of Biochemistry and Molecular Medicine and Biocenter Oulu, University of Oulu, PO Box 5400, FI-90014, Oulu, Finland
| | - Carol L Dieckmann
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ, 85721, USA
| | - Alexander J Kastaniotis
- Faculty of Biochemistry and Molecular Medicine and Biocenter Oulu, University of Oulu, PO Box 5400, FI-90014, Oulu, Finland.
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18
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Liu Z, Shimura M, Zhang L, Zhang W, Wang J, Ogawa-Tominaga M, Wang J, Wang X, Lv J, Shi W, Zhang VW, Murayama K, Fang F. Whole exome sequencing identifies a novel homozygous MECR mutation in a Chinese patient with childhood-onset dystonia and basal ganglia abnormalities, without optic atrophy. Mitochondrion 2021; 57:222-229. [PMID: 33401012 DOI: 10.1016/j.mito.2020.12.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2020] [Revised: 12/23/2020] [Accepted: 12/30/2020] [Indexed: 12/01/2022]
Abstract
Childhood-onset dystonia with optic atrophy and basal ganglia abnormalities is an extremely rare autosomal recessive mitochondrial disease caused by biallelic mutations in MECR. Using whole-exome sequencing, we identified a novel homozygous MECR mutation (c.910G > T, p.Asp304Tyr) in a Chinese patient with childhood-onset dystonia and basal ganglia abnormalities, without optic atrophy. With lipoic acid treatment, the disease progression was under control, and neither visual impairment nor optic atrophy was observed. To our knowledge, this is the first study about MECR-related mitochondrial disease in a Chinese patient and the first to report that supplementation with lipoic acid is a possible effective therapeutic strategy for this disease.
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Affiliation(s)
- Zhimei Liu
- Department of Neurology, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing 100045, China
| | - Masaru Shimura
- Center for Medical Genetics and Department of Metabolism, Chiba Children's Hospital, Chiba 2660007, Japan
| | - Li Zhang
- Center for Bioinformatics and Computational Biology, and the Institute of Biomedical Sciences, School of Life Sciences, East China Normal University, Shanghai 200241, China
| | - Weihua Zhang
- Department of Neurology, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing 100045, China
| | - Jianing Wang
- College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Minako Ogawa-Tominaga
- Center for Medical Genetics and Department of Metabolism, Chiba Children's Hospital, Chiba 2660007, Japan
| | - Junling Wang
- Department of Neurology, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing 100045, China
| | - Xiaohui Wang
- Department of Neurology, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing 100045, China
| | - Junlan Lv
- Department of Neurology, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing 100045, China
| | - Wei Shi
- Department of Ophthalmology, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing 100045, China
| | | | - Kei Murayama
- Center for Medical Genetics and Department of Metabolism, Chiba Children's Hospital, Chiba 2660007, Japan.
| | - Fang Fang
- Department of Neurology, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing 100045, China.
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19
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Nowinski SM, Solmonson A, Rusin SF, Maschek JA, Bensard CL, Fogarty S, Jeong MY, Lettlova S, Berg JA, Morgan JT, Ouyang Y, Naylor BC, Paulo JA, Funai K, Cox JE, Gygi SP, Winge DR, DeBerardinis RJ, Rutter J. Mitochondrial fatty acid synthesis coordinates oxidative metabolism in mammalian mitochondria. eLife 2020; 9:58041. [PMID: 32804083 PMCID: PMC7470841 DOI: 10.7554/elife.58041] [Citation(s) in RCA: 54] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 08/15/2020] [Indexed: 12/13/2022] Open
Abstract
Cells harbor two systems for fatty acid synthesis, one in the cytoplasm (catalyzed by fatty acid synthase, FASN) and one in the mitochondria (mtFAS). In contrast to FASN, mtFAS is poorly characterized, especially in higher eukaryotes, with the major product(s), metabolic roles, and cellular function(s) being essentially unknown. Here we show that hypomorphic mtFAS mutant mouse skeletal myoblast cell lines display a severe loss of electron transport chain (ETC) complexes and exhibit compensatory metabolic activities including reductive carboxylation. This effect on ETC complexes appears to be independent of protein lipoylation, the best characterized function of mtFAS, as mutants lacking lipoylation have an intact ETC. Finally, mtFAS impairment blocks the differentiation of skeletal myoblasts in vitro. Together, these data suggest that ETC activity in mammals is profoundly controlled by mtFAS function, thereby connecting anabolic fatty acid synthesis with the oxidation of carbon fuels.
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Affiliation(s)
| | - Ashley Solmonson
- Children's Medical Center Research Institute, University of Texas Southwestern Medical Center, Dallas, United States
| | - Scott F Rusin
- Department of Cell Biology, Harvard University School of Medicine, Boston, United States
| | - J Alan Maschek
- Diabetes & Metabolism Research Center, Salt Lake City, United States.,Department of Nutrition and Integrative Physiology, Salt Lake City, United States.,Metabolomics, Proteomics and Mass Spectrometry Core Research Facilities University of Utah, Salt Lake City, United States
| | | | - Sarah Fogarty
- Department of Biochemistry, Salt Lake City, United States.,Howard Hughes Medical Institute, Salt Lake City, United States
| | - Mi-Young Jeong
- Department of Biochemistry, Salt Lake City, United States
| | | | - Jordan A Berg
- Department of Biochemistry, Salt Lake City, United States
| | - Jeffrey T Morgan
- Department of Biochemistry, Salt Lake City, United States.,Howard Hughes Medical Institute, Salt Lake City, United States
| | - Yeyun Ouyang
- Department of Biochemistry, Salt Lake City, United States
| | - Bradley C Naylor
- Metabolomics, Proteomics and Mass Spectrometry Core Research Facilities University of Utah, Salt Lake City, United States
| | - Joao A Paulo
- Department of Cell Biology, Harvard University School of Medicine, Boston, United States
| | - Katsuhiko Funai
- Diabetes & Metabolism Research Center, Salt Lake City, United States
| | - James E Cox
- Department of Biochemistry, Salt Lake City, United States.,Diabetes & Metabolism Research Center, Salt Lake City, United States.,Metabolomics, Proteomics and Mass Spectrometry Core Research Facilities University of Utah, Salt Lake City, United States
| | - Steven P Gygi
- Department of Cell Biology, Harvard University School of Medicine, Boston, United States
| | - Dennis R Winge
- Department of Biochemistry, Salt Lake City, United States.,Diabetes & Metabolism Research Center, Salt Lake City, United States.,Department of Internal Medicine, Salt Lake City, United States
| | - Ralph J DeBerardinis
- Children's Medical Center Research Institute, University of Texas Southwestern Medical Center, Dallas, United States.,Howard Hughes Medical Institute, Salt Lake City, United States
| | - Jared Rutter
- Department of Biochemistry, Salt Lake City, United States.,Diabetes & Metabolism Research Center, Salt Lake City, United States.,Howard Hughes Medical Institute, Salt Lake City, United States
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20
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Altinoz MA, Ozpinar A, Seyfried TN. Caprylic (Octanoic) Acid as a Potential Fatty Acid Chemotherapeutic for Glioblastoma. Prostaglandins Leukot Essent Fatty Acids 2020; 159:102142. [PMID: 32512365 DOI: 10.1016/j.plefa.2020.102142] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 05/01/2020] [Accepted: 05/25/2020] [Indexed: 12/18/2022]
Abstract
High grade glial tumors (HGGs) including anaplastic astrocytoma (WHO Grade-III) and glioblastoma multiforme (GBM, WHO Grade-IV) are among the most malignant cancers known to man. Due to their defective mitochondria, HGG cells consume glucose via glycolysis even in the presence of oxygen. Overall survival is worse in HGG patients that are hyperglycemic. Unlike normal neural cells, HGG cells cannot efficiently metabolize ketone bodies for energy. Thus, a metabolic treatment based on therapeutic ketosis (reduced glucose with elevated ketone bodies) was proposed to treat GBM and was supoported from preclinical studies. Caprylic (octanoic) acid, a monocarboxylated saturated fatty acid, is among the best producers of ketone bodies and induces necrosis of experimental tumors at high dose. Caprylic acid is enriched in coconut and in goat's milk. It is also a posttranslational modifier of the ghrelin hormone and is produced in trace amounts in human tissues. Caprylic acid is a straight-chain isomer of the antiepileptic valproic acid, which is used in treatment of HGG-associated seizures and which may increase survival in GBM patients according to epidemiological observations. Among the valproic acids analogs tested, caprylic acid is the most potent molecule to block C6 astrocytoma cell growth in vitro and accumulates selectively within glial cells as shown by Positron Emission Tomography in vivo. Caprylic acid blocks glycolysis both in healthy liver and in malignant liver cells, which is more prominent in the latter and also lowers blood glucose. Noteworthy, caprylic acid exerts neuroprotective- and mitochondria-protective effects in several models of neurodegenerative diseases. Boost injections of caprylic acid at non-toxic levels during classical ketogenic metabolic therapy may fortify antitumor actions and reduce systemic toxicity by differential programming of mitochondrial and other metabolic pathways.
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Affiliation(s)
- Meric A Altinoz
- Department of Biochemistry, Acibadem University, Istanbul, Turkey; Department of Psychiatry, Maastricht University, Maastricht, Holland.
| | - Aysel Ozpinar
- Department of Biochemistry, Acibadem University, Istanbul, Turkey
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21
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Kastaniotis AJ, Autio KJ, R Nair R. Mitochondrial Fatty Acids and Neurodegenerative Disorders. Neuroscientist 2020; 27:143-158. [PMID: 32644907 DOI: 10.1177/1073858420936162] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Fatty acids in mitochondria, in sensu stricto, arise either as β-oxidation substrates imported via the carnitine shuttle or through de novo synthesis by the mitochondrial fatty acid synthesis (mtFAS) pathway. Defects in mtFAS or processes involved in the generation of the mtFAS product derivative lipoic acid (LA), including iron-sulfur cluster synthesis required for functional LA synthase, have emerged only recently as etiology for neurodegenerative disease. Intriguingly, mtFAS deficiencies very specifically affect CNS function, while LA synthesis and attachment defects have a pleiotropic presentation beyond neurodegeneration. Typical mtFAS defect presentations include optical atrophy, as well as basal ganglia defects associated with dystonia. The phenotype display of patients with mtFAS defects can resemble the presentation of disorders associated with coenzyme A (CoA) synthesis. A recent publication links these processes together based on the requirement of CoA for acyl carrier protein maturation. MtFAS defects, CoA synthesis- as well as Fe-S cluster-deficiencies share lack of LA as a common symptom.
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Affiliation(s)
| | - Kaija J Autio
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
| | - Remya R Nair
- Mammalian Genetics Unit, MRC Harwell Institute, Oxfordshire, UK
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22
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Abstract
Biology students today are taught that mitochondria are 'the powerhouse of the cell'. This gross over-simplification of their cellular role has arguably led to a paucity of knowledge concerning the many other tasks carried out by this multifunctional organelle. Mitochondrial fatty acid synthesis (mtFAS) is one such under-appreciated pathway that is crucial for mitochondrial function, although even mitochondrial experts are often surprised to learn of its existence. For many years, the only function of mtFAS was thought to be the production of lipoic acid, an important co-factor for several mitochondrial enzymes. However, recent advances have revealed a far wider role for mtFAS in mitochondrial physiology. The discovery of human patients with mutations in mtFAS enzymes has brought renewed interest in understanding the full significance of this novel mode of mitochondrial metabolic regulation. We now appreciate that mtFAS is a nutrient-sensitive pathway that provides an elegant mechanism whereby acetyl-CoA regulates its own consumption via coordination of lipoic acid synthesis and tricarboxylic acid (TCA) cycle activity, iron-sulfur (FeS) cluster biogenesis, assembly of oxidative phosphorylation complexes, and mitochondrial translation. In this minireview, we describe and build upon the important discoveries that led to our current understanding of this elegant mechanism of coordination of nutrient status and metabolism.
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Jeong SY, Hogarth P, Placzek A, Gregory AM, Fox R, Zhen D, Hamada J, van der Zwaag M, Lambrechts R, Jin H, Nilsen A, Cobb J, Pham T, Gray N, Ralle M, Duffy M, Schwanemann L, Rai P, Freed A, Wakeman K, Woltjer RL, Sibon OCM, Hayflick SJ. 4'-Phosphopantetheine corrects CoA, iron, and dopamine metabolic defects in mammalian models of PKAN. EMBO Mol Med 2019; 11:e10489. [PMID: 31660701 PMCID: PMC6895607 DOI: 10.15252/emmm.201910489] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 08/07/2019] [Accepted: 08/14/2019] [Indexed: 11/19/2022] Open
Abstract
Pantothenate kinase-associated neurodegeneration (PKAN) is an inborn error of CoA metabolism causing dystonia, parkinsonism, and brain iron accumulation. Lack of a good mammalian model has impeded studies of pathogenesis and development of rational therapeutics. We took a new approach to investigating an existing mouse mutant of Pank2 and found that isolating the disease-vulnerable brain revealed regional perturbations in CoA metabolism, iron homeostasis, and dopamine metabolism and functional defects in complex I and pyruvate dehydrogenase. Feeding mice a CoA pathway intermediate, 4'-phosphopantetheine, normalized levels of the CoA-, iron-, and dopamine-related biomarkers as well as activities of mitochondrial enzymes. Human cell changes also were recovered by 4'-phosphopantetheine. We can mechanistically link a defect in CoA metabolism to these secondary effects via the activation of mitochondrial acyl carrier protein, which is essential to oxidative phosphorylation, iron-sulfur cluster biogenesis, and mitochondrial fatty acid synthesis. We demonstrate the fidelity of our model in recapitulating features of the human disease. Moreover, we identify pharmacodynamic biomarkers, provide insights into disease pathogenesis, and offer evidence for 4'-phosphopantetheine as a candidate therapeutic for PKAN.
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Affiliation(s)
- Suh Young Jeong
- Department of Molecular & Medical GeneticsOregon Health & Science UniversityPortlandORUSA
| | - Penelope Hogarth
- Department of Molecular & Medical GeneticsOregon Health & Science UniversityPortlandORUSA
- Department of NeurologyOregon Health & Science UniversityPortlandORUSA
| | - Andrew Placzek
- Medicinal Chemistry CoreOregon Health & Science UniversityPortlandORUSA
| | - Allison M Gregory
- Department of Molecular & Medical GeneticsOregon Health & Science UniversityPortlandORUSA
| | - Rachel Fox
- Department of Molecular & Medical GeneticsOregon Health & Science UniversityPortlandORUSA
| | - Dolly Zhen
- Department of Molecular & Medical GeneticsOregon Health & Science UniversityPortlandORUSA
| | - Jeffrey Hamada
- Department of Molecular & Medical GeneticsOregon Health & Science UniversityPortlandORUSA
| | | | - Roald Lambrechts
- Department of Cell BiologyUniversity Medical Center GroningenGroningenthe Netherlands
| | - Haihong Jin
- Medicinal Chemistry CoreOregon Health & Science UniversityPortlandORUSA
| | - Aaron Nilsen
- Medicinal Chemistry CoreOregon Health & Science UniversityPortlandORUSA
| | - Jared Cobb
- Department of PathologyOregon Health & Science UniversityPortlandORUSA
| | - Thao Pham
- Department of PathologyOregon Health & Science UniversityPortlandORUSA
| | - Nora Gray
- Department of NeurologyOregon Health & Science UniversityPortlandORUSA
| | - Martina Ralle
- Department of Molecular & Medical GeneticsOregon Health & Science UniversityPortlandORUSA
| | - Megan Duffy
- Department of Molecular & Medical GeneticsOregon Health & Science UniversityPortlandORUSA
| | - Leila Schwanemann
- Department of Molecular & Medical GeneticsOregon Health & Science UniversityPortlandORUSA
| | - Puneet Rai
- Department of Molecular & Medical GeneticsOregon Health & Science UniversityPortlandORUSA
| | - Alison Freed
- Department of Molecular & Medical GeneticsOregon Health & Science UniversityPortlandORUSA
| | - Katrina Wakeman
- Department of Molecular & Medical GeneticsOregon Health & Science UniversityPortlandORUSA
| | - Randall L Woltjer
- Department of PathologyOregon Health & Science UniversityPortlandORUSA
| | - Ody CM Sibon
- Department of Cell BiologyUniversity Medical Center GroningenGroningenthe Netherlands
| | - Susan J Hayflick
- Department of Molecular & Medical GeneticsOregon Health & Science UniversityPortlandORUSA
- Department of NeurologyOregon Health & Science UniversityPortlandORUSA
- Department of PediatricsOregon Health & Science UniversityPortlandORUSA
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24
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Masud AJ, Kastaniotis AJ, Rahman MT, Autio KJ, Hiltunen JK. Mitochondrial acyl carrier protein (ACP) at the interface of metabolic state sensing and mitochondrial function. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2019; 1866:118540. [PMID: 31473256 DOI: 10.1016/j.bbamcr.2019.118540] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 08/23/2019] [Accepted: 08/27/2019] [Indexed: 12/20/2022]
Abstract
Acyl carrier protein (ACP) is a principal partner in the cytosolic and mitochondrial fatty acid synthesis (FAS) pathways. The active form holo-ACP serves as FAS platform, using its 4'-phosphopantetheine group to present covalently attached FAS intermediates to the enzymes responsible for the acyl chain elongation process. Mitochondrial unacylated holo-ACP is a component of mammalian mitoribosomes, and acylated ACP species participate as interaction partners in several ACP-LYRM (leucine-tyrosine-arginine motif)-protein heterodimers that act either as assembly factors or subunits of the electron transport chain and Fe-S cluster assembly complexes. Moreover, octanoyl-ACP provides the C8 backbone for endogenous lipoic acid synthesis. Accumulating evidence suggests that mtFAS-generated acyl-ACPs act as signaling molecules in an intramitochondrial metabolic state sensing circuit, coordinating mitochondrial acetyl-CoA levels with mitochondrial respiration, Fe-S cluster biogenesis and protein lipoylation.
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Affiliation(s)
- Ali J Masud
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
| | | | - M Tanvir Rahman
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
| | - Kaija J Autio
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
| | - J Kalervo Hiltunen
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland.
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25
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Wehbe Z, Behringer S, Alatibi K, Watkins D, Rosenblatt D, Spiekerkoetter U, Tucci S. The emerging role of the mitochondrial fatty-acid synthase (mtFASII) in the regulation of energy metabolism. Biochim Biophys Acta Mol Cell Biol Lipids 2019; 1864:1629-1643. [PMID: 31376476 DOI: 10.1016/j.bbalip.2019.07.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 07/17/2019] [Accepted: 07/28/2019] [Indexed: 11/30/2022]
Abstract
Malonyl-CoA synthetase (ACSF3) catalyzes the first step of the mitochondrial fatty acid biosynthesis (mtFASII). Mutations in ACSF3 cause CMAMMA a rare inborn error of metabolism. The clinical phenotype is very heterogeneous, with some patients presenting with neurologic manifestations. In some children, presenting symptoms such as coma, ketoacidosis and hypoglycemia are suggestive of an intermediary metabolic disorder. The overall pathophysiological mechanisms are not understood. In order to study the role of mtFASII in the regulation of energy metabolism we performed a comprehensive metabolic phenotyping with Seahorse technology proteomics in fibroblasts from healthy controls and ACSF3 patients. SILAC-based proteomics and lipidomic analysis were performed to investigate the effects of hypofunctional mtFASII on proteome and lipid homeostasis of complex lipids. Our data clearly confirmed an impaired mitochondrial flexibility characterized by reduced mitochondrial respiration and glycolytic flux due to a lower lipoylation degree. These findings were accompanied by the adaptational upregulation of β-oxidation and by the reduction of anaplerotic amino acids as compensatory mechanism to address the required energy need. Finally, lipidomic analysis demonstrated that the content of the bioactive lipids sphingomyelins and cardiolipins was strongly increased. Our data clearly demonstrate the role of mtFASII in metabolic regulation. Moreover, we show that mtFASII acts as mediator in the lipid-mediated signaling processes in the regulation of energy homeostasis and metabolic flexibility.
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Affiliation(s)
- Zeinab Wehbe
- Department of General Pediatrics, Center for Pediatrics and Adolescent Medicine, Faculty of Medicine and Medical Centre, University of Freiburg, 79106 Freiburg, Germany; University of Freiburg, Faculty of Biology, Schaenzlestrasse 1, D-79104 Freiburg, Germany
| | - Sidney Behringer
- Department of General Pediatrics, Center for Pediatrics and Adolescent Medicine, Faculty of Medicine and Medical Centre, University of Freiburg, 79106 Freiburg, Germany
| | - Khaled Alatibi
- Department of General Pediatrics, Center for Pediatrics and Adolescent Medicine, Faculty of Medicine and Medical Centre, University of Freiburg, 79106 Freiburg, Germany; University of Freiburg, Faculty of Biology, Schaenzlestrasse 1, D-79104 Freiburg, Germany
| | - David Watkins
- Department of Human Genetics, McGill University and Research Institute McGill University Health Centre, H4A 3J1 Montreal, Quebec, Canada
| | - David Rosenblatt
- Department of Human Genetics, McGill University and Research Institute McGill University Health Centre, H4A 3J1 Montreal, Quebec, Canada
| | - Ute Spiekerkoetter
- Department of General Pediatrics, Center for Pediatrics and Adolescent Medicine, Faculty of Medicine and Medical Centre, University of Freiburg, 79106 Freiburg, Germany
| | - Sara Tucci
- Department of General Pediatrics, Center for Pediatrics and Adolescent Medicine, Faculty of Medicine and Medical Centre, University of Freiburg, 79106 Freiburg, Germany.
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26
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Guedes-Monteiro RF, Franco LV, Moda BS, Tzagoloff A, Barros MH. 5′ processing of Saccharomyces cerevisiae mitochondrial tRNAs requires expression of multiple genes. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2019; 1866:806-818. [DOI: 10.1016/j.bbamcr.2019.02.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Revised: 01/31/2019] [Accepted: 02/03/2019] [Indexed: 01/02/2023]
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ACP Acylation Is an Acetyl-CoA-Dependent Modification Required for Electron Transport Chain Assembly. Mol Cell 2019; 71:567-580.e4. [PMID: 30118679 DOI: 10.1016/j.molcel.2018.06.039] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Revised: 06/08/2018] [Accepted: 06/25/2018] [Indexed: 01/28/2023]
Abstract
The electron transport chain (ETC) is an important participant in cellular energy conversion, but its biogenesis presents the cell with numerous challenges. To address these complexities, the cell utilizes ETC assembly factors, which include the LYR protein family. Each member of this family interacts with the mitochondrial acyl carrier protein (ACP), the scaffold protein upon which the mitochondrial fatty acid synthesis (mtFAS) pathway builds fatty acyl chains from acetyl-CoA. We demonstrate that the acylated form of ACP is an acetyl-CoA-dependent allosteric activator of the LYR protein family used to stimulate ETC biogenesis. By tuning ETC assembly to the abundance of acetyl-CoA, which is the major fuel of the TCA cycle and ETC, this system could provide an elegant mechanism for coordinating the assembly of ETC complexes with one another and with substrate availability.
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28
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Lourencetti NMS, Wolf IR, Lacerda MPF, Valente GT, Zanelli CF, Santoni MM, Mendes-Giannini MJS, Enguita FJ, Fusco-Almeida AM. Transcriptional profile of a bioethanol production contaminant Candida tropicalis. AMB Express 2018; 8:166. [PMID: 30311091 PMCID: PMC6182018 DOI: 10.1186/s13568-018-0693-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 09/26/2018] [Indexed: 11/26/2022] Open
Abstract
The fermentation process is widely used in the industry for bioethanol production. Even though it is widely used, microbial contamination is unpredictable and difficult to control. The problem of reduced productivity is directly linked to competition for nutrients during contamination. Yeasts representing the Candida species are frequently isolated contaminants. Elucidating the behavior of a contaminant during the fermentation cycle is essential for combatting the contamination. Consequently, the aim of the current study was to better understand the functional and transcriptional behavior of a contaminating yeast Candida tropicalis. We used a global RNA sequencing approach (RNA-seq/MiSeq) to analyze gene expression. Genes with significantly repressed or induced expression, and related to the fermentations process, such as sugar transport, pyruvate decarboxylase, amino acid metabolism, membrane, tolerance to high concentrations of ethanol and temperatures, nutrient suppression), and transcription-linked processes, were identified. The expression pattern suggested that the functional and transcriptional behavior of the contaminating yeast during fermentation for bioethanol production is similar to that of the standard yeast Saccharomyces cerevisiae. In addition, the analysis confirmed that C. tropicalis is an important contaminant of the alcoholic fermentation process, generating bioethanol and viability through its tolerance to all the adversities of a fermentation process essential for the production of bioethanol. According on the gene expression profile, many of these mechanisms are similar to those of S. cerevisiae strains currently used for bioethanol production. These mechanisms can inform studies on antimicrobials, to combat yeast contamination during industrial bioethanol production.
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29
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Impaired Mitochondrial Fatty Acid Synthesis Leads to Neurodegeneration in Mice. J Neurosci 2018; 38:9781-9800. [PMID: 30266742 DOI: 10.1523/jneurosci.3514-17.2018] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Revised: 08/31/2018] [Accepted: 09/19/2018] [Indexed: 01/07/2023] Open
Abstract
There has been a growing interest toward mitochondrial fatty acid synthesis (mtFAS) since the recent discovery of a neurodegenerative human disorder termed MEPAN (mitochondrial enoyl reductase protein associated neurodegeneration), which is caused by mutations in the mitochondrial enoyl-CoA/ACP (acyl carrier protein) reductase (MECR) carrying out the last step of mtFAS. We show here that MECR protein is highly expressed in mouse Purkinje cells (PCs). To elucidate mtFAS function in neural tissue, here, we generated a mouse line with a PC-specific knock-out (KO) of Mecr, leading to inactivation of mtFAS confined to this cell type. Both sexes were studied. The mitochondria in KO PCs displayed abnormal morphology, loss of protein lipoylation, and reduced respiratory chain enzymatic activities by the time these mice were 6 months of age, followed by nearly complete loss of PCs by 9 months of age. These animals exhibited balancing difficulties ∼7 months of age and ataxic symptoms were evident from 8-9 months of age on. Our data show that impairment of mtFAS results in functional and ultrastructural changes in mitochondria followed by death of PCs, mimicking aspects of the clinical phenotype. This KO mouse represents a new model for impaired mitochondrial lipid metabolism and cerebellar ataxia with a distinct and well trackable cellular phenotype. This mouse model will allow the future investigation of the feasibility of metabolite supplementation approaches toward the prevention of neurodegeneration due to dysfunctional mtFAS.SIGNIFICANCE STATEMENT We have recently reported a novel neurodegenerative disorder in humans termed MEPAN (mitochondrial enoyl reductase protein associated neurodegeneration) (Heimer et al., 2016). The cause of neuron degeneration in MEPAN patients is the dysfunction of the highly conserved mitochondrial fatty acid synthesis (mtFAS) pathway due to mutations in MECR, encoding mitochondrial 2-enoyl-CoA/ACP reductase. The report presented here describes the analysis of the first mouse model suffering from mtFAS-defect-induced neurodegenerative changes due to specific disruption of the Mecr gene in Purkinje cells. Our work sheds a light on the mechanisms of neurodegeneration caused by mtFAS deficiency and provides a test bed for future treatment approaches.
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30
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A conserved mammalian mitochondrial isoform of acetyl-CoA carboxylase ACC1 provides the malonyl-CoA essential for mitochondrial biogenesis in tandem with ACSF3. Biochem J 2017; 474:3783-3797. [PMID: 28986507 DOI: 10.1042/bcj20170416] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Revised: 09/29/2017] [Accepted: 10/03/2017] [Indexed: 01/06/2023]
Abstract
Mitochondrial fatty acid synthesis (mtFAS) is a highly conserved pathway essential for mitochondrial biogenesis. The mtFAS process is required for mitochondrial respiratory chain assembly and function, synthesis of the lipoic acid cofactor indispensable for the function of several mitochondrial enzyme complexes and essential for embryonic development in mice. Mutations in human mtFAS have been reported to lead to neurodegenerative disease. The source of malonyl-CoA for mtFAS in mammals has remained unclear. We report the identification of a conserved vertebrate mitochondrial isoform of ACC1 expressed from an ACACA transcript splicing variant. A specific knockdown (KD) of the corresponding transcript in mouse cells, or CRISPR/Cas9-mediated inactivation of the putative mitochondrial targeting sequence in human cells, leads to decreased lipoylation and mitochondrial fragmentation. Simultaneous KD of ACSF3, encoding a mitochondrial malonyl-CoA synthetase previously implicated in the mtFAS process, resulted in almost complete ablation of protein lipoylation, indicating that these enzymes have a redundant function in mtFAS. The discovery of a mitochondrial isoform of ACC1 required for lipoic acid synthesis has intriguing consequences for our understanding of mitochondrial disorders, metabolic regulation of mitochondrial biogenesis and cancer.
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31
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Angerer H, Schönborn S, Gorka J, Bahr U, Karas M, Wittig I, Heidler J, Hoffmann J, Morgner N, Zickermann V. Acyl modification and binding of mitochondrial ACP to multiprotein complexes. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2017; 1864:1913-1920. [PMID: 28802701 DOI: 10.1016/j.bbamcr.2017.08.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Revised: 08/03/2017] [Accepted: 08/08/2017] [Indexed: 01/06/2023]
Abstract
The mitochondrial acyl carrier protein (ACPM/NDUFAB1) is a central element of the mitochondrial fatty acid synthesis type II machinery. Originally ACPM was detected as a subunit of respiratory complex I but the reason for the association with the large enzyme complex remained elusive. Complex I from the aerobic yeast Yarrowia lipolytica comprises two different ACPMs, ACPM1 and ACPM2. They are anchored to the protein complex by LYR (leucine-tyrosine-arginine) motif containing protein (LYRM) subunits LYRM3 (NDUFB9) and LYRM6 (NDUFA6). The ACPM1-LYRM6 and ACPM2-LYRM3 modules are essential for complex I activity and assembly/stability, respectively. We show that in addition to the complex I bound fraction, ACPM1 is present as a free matrix protein and in complex with the soluble LYRM4(ISD11)/NFS1 complex implicated in Fe-S cluster biogenesis. We show that the presence of a long acyl chain bound to the phosphopantetheine cofactor is important for docking ACPMs to protein complexes and we propose that association of ACPMs and LYRMs is universally based on a new protein-protein interaction motif.
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Affiliation(s)
- Heike Angerer
- Goethe University Frankfurt, Medical School, Institute of Biochemistry II, Structural Bioenergetics Group, Max-von-Laue Str. 9, 60438 Frankfurt, Germany.
| | - Stefan Schönborn
- Goethe University Frankfurt, Institute of Pharmaceutical Chemistry, Max-von-Laue Str. 9, 60438 Frankfurt, Germany
| | - Jan Gorka
- Goethe University Frankfurt, Institute of Pharmaceutical Chemistry, Max-von-Laue Str. 9, 60438 Frankfurt, Germany
| | - Ute Bahr
- Goethe University Frankfurt, Institute of Pharmaceutical Chemistry, Max-von-Laue Str. 9, 60438 Frankfurt, Germany
| | - Michael Karas
- Goethe University Frankfurt, Institute of Pharmaceutical Chemistry, Max-von-Laue Str. 9, 60438 Frankfurt, Germany
| | - Ilka Wittig
- Functional Proteomics, SFB 815 core unit, Goethe-University Frankfurt, Medical School, Theodor-Stern-Kai 7, 60590 Frankfurt, Germany
| | - Juliana Heidler
- Functional Proteomics, SFB 815 core unit, Goethe-University Frankfurt, Medical School, Theodor-Stern-Kai 7, 60590 Frankfurt, Germany
| | - Jan Hoffmann
- Goethe University Frankfurt, Institute of Physical and Theoretical Chemistry, Max-von-Laue Str. 9, 60438 Frankfurt, Germany
| | - Nina Morgner
- Goethe University Frankfurt, Institute of Physical and Theoretical Chemistry, Max-von-Laue Str. 9, 60438 Frankfurt, Germany
| | - Volker Zickermann
- Goethe University Frankfurt, Medical School, Institute of Biochemistry II, Structural Bioenergetics Group, Max-von-Laue Str. 9, 60438 Frankfurt, Germany; Cluster of Excellence Macromolecular Complexes, Goethe University Frankfurt, Germany.
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32
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Cory SA, Van Vranken JG, Brignole EJ, Patra S, Winge DR, Drennan CL, Rutter J, Barondeau DP. Structure of human Fe-S assembly subcomplex reveals unexpected cysteine desulfurase architecture and acyl-ACP-ISD11 interactions. Proc Natl Acad Sci U S A 2017; 114:E5325-E5334. [PMID: 28634302 PMCID: PMC5502623 DOI: 10.1073/pnas.1702849114] [Citation(s) in RCA: 108] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
In eukaryotes, sulfur is mobilized for incorporation into multiple biosynthetic pathways by a cysteine desulfurase complex that consists of a catalytic subunit (NFS1), LYR protein (ISD11), and acyl carrier protein (ACP). This NFS1-ISD11-ACP (SDA) complex forms the core of the iron-sulfur (Fe-S) assembly complex and associates with assembly proteins ISCU2, frataxin (FXN), and ferredoxin to synthesize Fe-S clusters. Here we present crystallographic and electron microscopic structures of the SDA complex coupled to enzyme kinetic and cell-based studies to provide structure-function properties of a mitochondrial cysteine desulfurase. Unlike prokaryotic cysteine desulfurases, the SDA structure adopts an unexpected architecture in which a pair of ISD11 subunits form the dimeric core of the SDA complex, which clarifies the critical role of ISD11 in eukaryotic assemblies. The different quaternary structure results in an incompletely formed substrate channel and solvent-exposed pyridoxal 5'-phosphate cofactor and provides a rationale for the allosteric activator function of FXN in eukaryotic systems. The structure also reveals the 4'-phosphopantetheine-conjugated acyl-group of ACP occupies the hydrophobic core of ISD11, explaining the basis of ACP stabilization. The unexpected architecture for the SDA complex provides a framework for understanding interactions with acceptor proteins for sulfur-containing biosynthetic pathways, elucidating mechanistic details of eukaryotic Fe-S cluster biosynthesis, and clarifying how defects in Fe-S cluster assembly lead to diseases such as Friedreich's ataxia. Moreover, our results support a lock-and-key model in which LYR proteins associate with acyl-ACP as a mechanism for fatty acid biosynthesis to coordinate the expression, Fe-S cofactor maturation, and activity of the respiratory complexes.
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Affiliation(s)
- Seth A Cory
- Department of Chemistry, Texas A&M University, College Station, TX 77842
| | - Jonathan G Van Vranken
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112
| | - Edward J Brignole
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139
- Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Shachin Patra
- Department of Chemistry, Texas A&M University, College Station, TX 77842
| | - Dennis R Winge
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112
- Department of Medicine, University of Utah School of Medicine, Salt Lake City, UT 84132
| | - Catherine L Drennan
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139
- Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02139
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Jared Rutter
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112
- Howard Hughes Medical Institute, University of Utah School of Medicine, Salt Lake City, UT 84132
| | - David P Barondeau
- Department of Chemistry, Texas A&M University, College Station, TX 77842;
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33
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Nair RR, Kerätär JM, Autio KJ, Masud AJ, Finnilä MA, Autio-Harmainen HI, Miinalainen IJ, Nieminen PA, Hiltunen JK, Kastaniotis AJ. Genetic modifications of Mecr reveal a role for mitochondrial 2-enoyl-CoA/ACP reductase in placental development in mice. Hum Mol Genet 2017; 26:2104-2117. [DOI: 10.1093/hmg/ddx105] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Accepted: 03/13/2017] [Indexed: 01/23/2023] Open
Affiliation(s)
- Remya R. Nair
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, FI-90014 Oulu, Finland
| | - Juha M. Kerätär
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, FI-90014 Oulu, Finland
| | - Kaija J. Autio
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, FI-90014 Oulu, Finland
| | - Ali J. Masud
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, FI-90014 Oulu, Finland
| | - Mikko A.J. Finnilä
- Department of Applied Physics, University of Eastern Finland, FI-70211 Kuopio, Finland
- Research Unit of Medical Imaging, Physics and Technology, Faculty of Medicine, University of Oulu, FI-90014 Oulu, Finland
| | - Helena I. Autio-Harmainen
- Department of Pathology and Medical Research Center Oulu, Oulu University Hospital, FI-90220 Oulu, Finland
| | - Ilkka J. Miinalainen
- Electron Microscopy Core Facility, Biocenter Oulu, University of Oulu, FI-90014 Oulu, Finland
| | - Pentti A. Nieminen
- Medical Informatics and Statistics Research group, University of Oulu, FI-90014 Oulu, Finland
| | - J. Kalervo Hiltunen
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, FI-90014 Oulu, Finland
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Esteban-Torres M, Reverón I, Plaza-Vinuesa L, de las Rivas B, Muñoz R, López de Felipe F. Transcriptional Reprogramming at Genome-Scale of Lactobacillus plantarum WCFS1 in Response to Olive Oil Challenge. Front Microbiol 2017; 8:244. [PMID: 28261192 PMCID: PMC5313477 DOI: 10.3389/fmicb.2017.00244] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Accepted: 02/03/2017] [Indexed: 12/16/2022] Open
Abstract
Dietary fats may exert selective pressures on Lactobacillus species, however, knowledge on the mechanisms of adaptation to fat stress in these organisms is still fragmentary. This study was undertaken to gain insight into the mechanisms of adaptation of Lactobacillus plantarum WCFS1 to olive oil challenge by whole genome transcriptional profiling using DNA microarrays. A set of 230 genes were differentially expressed by L. plantarum WCFS1 to respond to this vegetable oil. This response involved elements typical of the stringent response, as indicated by the induction of genes involved in stress-related pathways and downregulation of genes related to processes associated with rapid growth. A set of genes involved in the transport and metabolism of compatible solutes were downregulated, indicating that this organism does not require osmoprotective mechanisms in presence of olive oil. The fatty acid biosynthetic pathway was thoroughly downregulated at the transcriptional level, which coincided with a diminished expression of genes controlled by this pathway in other organisms and that are required for the respiratory function, pyruvate dehydrogenase activity, RNA processing and cell size setting. Finally, a set of genes involved in host-cell signaling by L. plantarum were differentially regulated indicating that olive oil can influence the expression of metabolic traits involved in the crosstalk between this bacterium and the host.
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Affiliation(s)
| | | | | | | | | | - Félix López de Felipe
- Laboratorio de Biotecnología Bacteriana, Instituto de Ciencia y Tecnología de los Alimentos y Nutrición – Consejo Superior de Investigaciones CientificasMadrid, Spain
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Heimer G, Kerätär J, Riley L, Balasubramaniam S, Eyal E, Pietikäinen L, Hiltunen JK, Marek-Yagel D, Hamada J, Gregory A, Rogers C, Hogarth P, Nance MA, Shalva N, Veber A, Tzadok M, Nissenkorn A, Tonduti D, Renaldo F, Kraoua I, Panteghini C, Valletta L, Garavaglia B, Cowley MJ, Gayevskiy V, Roscioli T, Silberstein JM, Hoffmann C, Raas-Rothschild A, Tiranti V, Anikster Y, Christodoulou J, Kastaniotis AJ, Ben-Zeev B, Hayflick SJ, Bamshad M, Leal S, Nickerson D, Anderson P, Annable M, Blue E, Buckingham K, Chin J, Chong J, Cornejo R, Davis C, Frazar C, He Z, Jarvik G, Jimenez G, Johanson E, Kolar T, Krauter S, Luksic D, Marvin C, McGee S, McGoldrick D, Patterson K, Perez M, Phillips S, Pijoan J, Robertson P, Santos-Cortez R, Shankar A, Slattery K, Shively K, Siegel D, Smith J, Tackett M, Wang G, Wegener M, Weiss J, Wernick R, Wheeler M, Yi Q. MECR Mutations Cause Childhood-Onset Dystonia and Optic Atrophy, a Mitochondrial Fatty Acid Synthesis Disorder. Am J Hum Genet 2016; 99:1229-1244. [PMID: 27817865 DOI: 10.1016/j.ajhg.2016.09.021] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Accepted: 09/26/2016] [Indexed: 11/24/2022] Open
Abstract
Mitochondrial fatty acid synthesis (mtFAS) is an evolutionarily conserved pathway essential for the function of the respiratory chain and several mitochondrial enzyme complexes. We report here a unique neurometabolic human disorder caused by defective mtFAS. Seven individuals from five unrelated families presented with childhood-onset dystonia, optic atrophy, and basal ganglia signal abnormalities on MRI. All affected individuals were found to harbor recessive mutations in MECR encoding the mitochondrial trans-2-enoyl-coenzyme A-reductase involved in human mtFAS. All six mutations are extremely rare in the general population, segregate with the disease in the families, and are predicted to be deleterious. The nonsense c.855T>G (p.Tyr285∗), c.247_250del (p.Asn83Hisfs∗4), and splice site c.830+2_830+3insT mutations lead to C-terminal truncation variants of MECR. The missense c.695G>A (p.Gly232Glu), c.854A>G (p.Tyr285Cys), and c.772C>T (p.Arg258Trp) mutations involve conserved amino acid residues, are located within the cofactor binding domain, and are predicted by structural analysis to have a destabilizing effect. Yeast modeling and complementation studies validated the pathogenicity of the MECR mutations. Fibroblast cell lines from affected individuals displayed reduced levels of both MECR and lipoylated proteins as well as defective respiration. These results suggest that mutations in MECR cause a distinct human disorder of the mtFAS pathway. The observation of decreased lipoylation raises the possibility of a potential therapeutic strategy.
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Kastaniotis AJ, Autio KJ, Kerätär JM, Monteuuis G, Mäkelä AM, Nair RR, Pietikäinen LP, Shvetsova A, Chen Z, Hiltunen JK. Mitochondrial fatty acid synthesis, fatty acids and mitochondrial physiology. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1862:39-48. [PMID: 27553474 DOI: 10.1016/j.bbalip.2016.08.011] [Citation(s) in RCA: 89] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2016] [Revised: 07/20/2016] [Accepted: 08/17/2016] [Indexed: 02/07/2023]
Abstract
Mitochondria and fatty acids are tightly connected to a multiplicity of cellular processes that go far beyond mitochondrial fatty acid metabolism. In line with this view, there is hardly any common metabolic disorder that is not associated with disturbed mitochondrial lipid handling. Among other aspects of mitochondrial lipid metabolism, apparently all eukaryotes are capable of carrying out de novo fatty acid synthesis (FAS) in this cellular compartment in an acyl carrier protein (ACP)-dependent manner. The dual localization of FAS in eukaryotic cells raises the questions why eukaryotes have maintained the FAS in mitochondria in addition to the "classic" cytoplasmic FAS and what the products are that cannot be substituted by delivery of fatty acids of extramitochondrial origin. The current evidence indicates that mitochondrial FAS is essential for cellular respiration and mitochondrial biogenesis. Although both β-oxidation and FAS utilize thioester chemistry, CoA acts as acyl-group carrier in the breakdown pathway whereas ACP assumes this role in the synthetic direction. This arrangement metabolically separates these two pathways running towards opposite directions and prevents futile cycling. A role of this pathway in mitochondrial metabolic sensing has recently been proposed. This article is part of a Special Issue entitled: Lipids of Mitochondria edited by Guenther Daum.
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Affiliation(s)
- Alexander J Kastaniotis
- Faculty of Biochemistry and Molecular Medicine, Biocenter Oulu, University of Oulu, Oulu, Finland.
| | - Kaija J Autio
- Faculty of Biochemistry and Molecular Medicine, Biocenter Oulu, University of Oulu, Oulu, Finland
| | - Juha M Kerätär
- Faculty of Biochemistry and Molecular Medicine, Biocenter Oulu, University of Oulu, Oulu, Finland
| | - Geoffray Monteuuis
- Faculty of Biochemistry and Molecular Medicine, Biocenter Oulu, University of Oulu, Oulu, Finland
| | - Anne M Mäkelä
- Faculty of Biochemistry and Molecular Medicine, Biocenter Oulu, University of Oulu, Oulu, Finland
| | - Remya R Nair
- Faculty of Biochemistry and Molecular Medicine, Biocenter Oulu, University of Oulu, Oulu, Finland
| | - Laura P Pietikäinen
- Faculty of Biochemistry and Molecular Medicine, Biocenter Oulu, University of Oulu, Oulu, Finland
| | - Antonina Shvetsova
- Faculty of Biochemistry and Molecular Medicine, Biocenter Oulu, University of Oulu, Oulu, Finland
| | - Zhijun Chen
- State Key Laboratory of Supramolecular Structure and Materials and Institute of Theoretical Chemistry, Jilin University, 2699 Qianjin Street, Changchun 130012, PR China
| | - J Kalervo Hiltunen
- Faculty of Biochemistry and Molecular Medicine, Biocenter Oulu, University of Oulu, Oulu, Finland; State Key Laboratory of Supramolecular Structure and Materials and Institute of Theoretical Chemistry, Jilin University, 2699 Qianjin Street, Changchun 130012, PR China.
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37
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van Rossum HM, Kozak BU, Niemeijer MS, Duine HJ, Luttik MAH, Boer VM, Kötter P, Daran JMG, van Maris AJA, Pronk JT. Alternative reactions at the interface of glycolysis and citric acid cycle in Saccharomyces cerevisiae. FEMS Yeast Res 2016; 16:fow017. [PMID: 26895788 PMCID: PMC5815053 DOI: 10.1093/femsyr/fow017] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/16/2016] [Indexed: 11/14/2022] Open
Abstract
Pyruvate and acetyl-coenzyme A, located at the interface between glycolysis and TCA cycle, are important intermediates in yeast metabolism and key precursors for industrially relevant products. Rational engineering of their supply requires knowledge of compensatory reactions that replace predominant pathways when these are inactivated. This study investigates effects of individual and combined mutations that inactivate the mitochondrial pyruvate-dehydrogenase (PDH) complex, extramitochondrial citrate synthase (Cit2) and mitochondrial CoA-transferase (Ach1) in Saccharomyces cerevisiae. Additionally, strains with a constitutively expressed carnitine shuttle were constructed and analyzed. A predominant role of the PDH complex in linking glycolysis and TCA cycle in glucose-grown batch cultures could be functionally replaced by the combined activity of the cytosolic PDH bypass and Cit2. Strongly impaired growth and a high incidence of respiratory deficiency in pda1Δ ach1Δ strains showed that synthesis of intramitochondrial acetyl-CoA as a metabolic precursor requires activity of either the PDH complex or Ach1. Constitutive overexpression of AGP2, HNM1, YAT2, YAT1, CRC1 and CAT2 enabled the carnitine shuttle to efficiently link glycolysis and TCA cycle in l-carnitine-supplemented, glucose-grown batch cultures. Strains in which all known reactions at the glycolysis-TCA cycle interface were inactivated still grew slowly on glucose, indicating additional flexibility at this key metabolic junction.
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Affiliation(s)
- Harmen M van Rossum
- Department of Biotechnology, Delft University of Technology, Julianalaan 67, NL-2628 BC Delft, The Netherlands
| | - Barbara U Kozak
- Department of Biotechnology, Delft University of Technology, Julianalaan 67, NL-2628 BC Delft, The Netherlands
| | - Matthijs S Niemeijer
- Department of Biotechnology, Delft University of Technology, Julianalaan 67, NL-2628 BC Delft, The Netherlands
| | - Hendrik J Duine
- Department of Biotechnology, Delft University of Technology, Julianalaan 67, NL-2628 BC Delft, The Netherlands
| | - Marijke A H Luttik
- Department of Biotechnology, Delft University of Technology, Julianalaan 67, NL-2628 BC Delft, The Netherlands
| | - Viktor M Boer
- DSM Biotechnology Center, Alexander Fleminglaan 1, NL-2613 AX Delft, The Netherlands
| | - Peter Kötter
- Institute for Molecular Bio Sciences, Goethe University, Max-von-Laue-Straße 9, D-60438 Frankfurt, Germany
| | - Jean-Marc G Daran
- Department of Biotechnology, Delft University of Technology, Julianalaan 67, NL-2628 BC Delft, The Netherlands
| | - Antonius J A van Maris
- Department of Biotechnology, Delft University of Technology, Julianalaan 67, NL-2628 BC Delft, The Netherlands
| | - Jack T Pronk
- Department of Biotechnology, Delft University of Technology, Julianalaan 67, NL-2628 BC Delft, The Netherlands
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38
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Singh N, Yadav KK, Rajasekharan R. ZAP1-mediated modulation of triacylglycerol levels in yeast by transcriptional control of mitochondrial fatty acid biosynthesis. Mol Microbiol 2016; 100:55-75. [PMID: 26711224 DOI: 10.1111/mmi.13298] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/01/2015] [Indexed: 02/03/2023]
Abstract
The transcriptional activator Zap1p maintains zinc homeostasis in Saccharomyces cerevisiae. In this study, we examined the role of Zap1p in triacylglycerol (TAG) metabolism. The expression of ETR1 is reduced in zap1Δ. The altered expression of ETR1 results in reduced mitochondrial fatty acid biosynthesis and reduction in lipoic acid content in zap1Δ. The transcription factor Zap1 positively regulates ETR1 expression. Deletion of ETR1 also causes the accumulation of TAG, and the introduction of ETR1 in zap1Δ strain rescues the TAG level. These results demonstrated that the compromised mitochondrial fatty acid biosynthesis causes a reduction in lipoic acid and loss of mitochondrial function in zap1Δ. Functional mitochondria are required for the ATP production and defect in mitochondria slow down the process which may channeled carbon towards lipid biosynthesis and stored in the form of TAG.
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Affiliation(s)
- Neelima Singh
- Lipidomic Centre, Department of Lipid Science, CSIR-Central Food Technological Research Institute (CFTRI), Karnataka, Mysore, 570020, India.,Academy of Scientific & Innovative Research, CSIR-CFTRI, Mysore, India
| | - Kamlesh Kumar Yadav
- Lipidomic Centre, Department of Lipid Science, CSIR-Central Food Technological Research Institute (CFTRI), Karnataka, Mysore, 570020, India.,Academy of Scientific & Innovative Research, CSIR-CFTRI, Mysore, India
| | - Ram Rajasekharan
- Lipidomic Centre, Department of Lipid Science, CSIR-Central Food Technological Research Institute (CFTRI), Karnataka, Mysore, 570020, India.,Academy of Scientific & Innovative Research, CSIR-CFTRI, Mysore, India
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39
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Tomàs-Gamisans M, Ferrer P, Albiol J. Integration and Validation of the Genome-Scale Metabolic Models of Pichia pastoris: A Comprehensive Update of Protein Glycosylation Pathways, Lipid and Energy Metabolism. PLoS One 2016; 11:e0148031. [PMID: 26812499 PMCID: PMC4734642 DOI: 10.1371/journal.pone.0148031] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Accepted: 01/12/2016] [Indexed: 01/21/2023] Open
Abstract
Motivation Genome-scale metabolic models (GEMs) are tools that allow predicting a phenotype from a genotype under certain environmental conditions. GEMs have been developed in the last ten years for a broad range of organisms, and are used for multiple purposes such as discovering new properties of metabolic networks, predicting new targets for metabolic engineering, as well as optimizing the cultivation conditions for biochemicals or recombinant protein production. Pichia pastoris is one of the most widely used organisms for heterologous protein expression. There are different GEMs for this methylotrophic yeast of which the most relevant and complete in the published literature are iPP668, PpaMBEL1254 and iLC915. However, these three models differ regarding certain pathways, terminology for metabolites and reactions and annotations. Moreover, GEMs for some species are typically built based on the reconstructed models of related model organisms. In these cases, some organism-specific pathways could be missing or misrepresented. Results In order to provide an updated and more comprehensive GEM for P. pastoris, we have reconstructed and validated a consensus model integrating and merging all three existing models. In this step a comprehensive review and integration of the metabolic pathways included in each one of these three versions was performed. In addition, the resulting iMT1026 model includes a new description of some metabolic processes. Particularly new information described in recently published literature is included, mainly related to fatty acid and sphingolipid metabolism, glycosylation and cell energetics. Finally the reconstructed model was tested and validated, by comparing the results of the simulations with available empirical physiological datasets results obtained from a wide range of experimental conditions, such as different carbon sources, distinct oxygen availability conditions, as well as producing of two different recombinant proteins. In these simulations, the iMT1026 model has shown a better performance than the previous existing models.
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Affiliation(s)
- Màrius Tomàs-Gamisans
- Departament d'Enginyeria Química, Biològica i Ambiental, Universitat Autònoma de Barcelona, 08193 Bellaterra (Cerdanyola del Vallès), Barcelona, Spain
| | - Pau Ferrer
- Departament d'Enginyeria Química, Biològica i Ambiental, Universitat Autònoma de Barcelona, 08193 Bellaterra (Cerdanyola del Vallès), Barcelona, Spain
| | - Joan Albiol
- Departament d'Enginyeria Química, Biològica i Ambiental, Universitat Autònoma de Barcelona, 08193 Bellaterra (Cerdanyola del Vallès), Barcelona, Spain
- * E-mail:
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40
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Chen L, Zhang YH, Huang T, Cai YD. Identifying novel protein phenotype annotations by hybridizing protein-protein interactions and protein sequence similarities. Mol Genet Genomics 2016; 291:913-34. [PMID: 26728152 DOI: 10.1007/s00438-015-1157-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Accepted: 12/08/2015] [Indexed: 01/18/2023]
Abstract
Studies of protein phenotypes represent a central challenge of modern genetics in the post-genome era because effective and accurate investigation of protein phenotypes is one of the most critical procedures to identify functional biological processes in microscale, which involves the analysis of multifactorial traits and has greatly contributed to the development of modern biology in the post genome era. Therefore, we have developed a novel computational method that identifies novel proteins associated with certain phenotypes in yeast based on the protein-protein interaction network. Unlike some existing network-based computational methods that identify the phenotype of a query protein based on its direct neighbors in the local network, the proposed method identifies novel candidate proteins for a certain phenotype by considering all annotated proteins with this phenotype on the global network using a shortest path (SP) algorithm. The identified proteins are further filtered using both a permutation test and their interactions and sequence similarities to annotated proteins. We compared our method with another widely used method called random walk with restart (RWR). The biological functions of proteins for each phenotype identified by our SP method and the RWR method were analyzed and compared. The results confirmed a large proportion of our novel protein phenotype annotation, and the RWR method showed a higher false positive rate than the SP method. Our method is equally effective for the prediction of proteins involving in all the eleven clustered yeast phenotypes with a quite low false positive rate. Considering the universality and generalizability of our supporting materials and computing strategies, our method can further be applied to study other organisms and the new functions we predicted can provide pertinent instructions for the further experimental verifications.
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Affiliation(s)
- Lei Chen
- School of Life Sciences, Shanghai University, Shanghai, 200444, People's Republic of China. .,College of Information Engineering, Shanghai Maritime University, Shanghai, 201306, People's Republic of China.
| | - Yu-Hang Zhang
- Institute of Health Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200031, People's Republic of China
| | - Tao Huang
- Institute of Health Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200031, People's Republic of China
| | - Yu-Dong Cai
- School of Life Sciences, Shanghai University, Shanghai, 200444, People's Republic of China.
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41
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Guan X, Chen H, Abramson A, Man H, Wu J, Yu O, Nikolau BJ. A phosphopantetheinyl transferase that is essential for mitochondrial fatty acid biosynthesis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2015; 84:718-32. [PMID: 26402847 DOI: 10.1111/tpj.13034] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Revised: 09/10/2015] [Accepted: 09/14/2015] [Indexed: 05/23/2023]
Abstract
In this study we report the molecular genetic characterization of the Arabidopsis mitochondrial phosphopantetheinyl transferase (mtPPT), which catalyzes the phosphopantetheinylation and thus activation of mitochondrial acyl carrier protein (mtACP) of mitochondrial fatty acid synthase (mtFAS). This catalytic capability of the purified mtPPT protein (encoded by AT3G11470) was directly demonstrated in an in vitro assay that phosphopantetheinylated mature Arabidopsis apo-mtACP isoforms. The mitochondrial localization of the AT3G11470-encoded proteins was validated by the ability of their N-terminal 80-residue leader sequence to guide a chimeric GFP protein to this organelle. A T-DNA-tagged null mutant mtppt-1 allele shows an embryo-lethal phenotype, illustrating a crucial role of mtPPT for embryogenesis. Arabidopsis RNAi transgenic lines with reduced mtPPT expression display typical phenotypes associated with a deficiency in the mtFAS system, namely miniaturized plant morphology, slow growth, reduced lipoylation of mitochondrial proteins, and the hyperaccumulation of photorespiratory intermediates, glycine and glycolate. These morphological and metabolic alterations are reversed when these plants are grown in a non-photorespiratory condition (i.e. 1% CO2 atmosphere), demonstrating that they are a consequence of a deficiency in photorespiration due to the reduced lipoylation of the photorespiratory glycine decarboxylase.
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Affiliation(s)
- Xin Guan
- Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, IA, 50011, USA
- The NSF Engineering Research Center for Biorenewable Chemicals (CBiRC), Iowa State University, Ames, IA, 50011, USA
| | - Hui Chen
- Donald Danforth Plant Science Center, St. Louis, MO, 63132, USA
- Conagen Inc., Bedford, MA, 01730, USA
| | - Alex Abramson
- The NSF Engineering Research Center for Biorenewable Chemicals (CBiRC), Iowa State University, Ames, IA, 50011, USA
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Huimin Man
- Donald Danforth Plant Science Center, St. Louis, MO, 63132, USA
- Conagen Inc., Bedford, MA, 01730, USA
| | - Jinxia Wu
- Donald Danforth Plant Science Center, St. Louis, MO, 63132, USA
- Institute of Biotechnology, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
| | - Oliver Yu
- Donald Danforth Plant Science Center, St. Louis, MO, 63132, USA
- Wuxi NewWay Biotech Co., Ltd., Wuxi, Jiangsu, 214043, China
| | - Basil J Nikolau
- Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, IA, 50011, USA
- The NSF Engineering Research Center for Biorenewable Chemicals (CBiRC), Iowa State University, Ames, IA, 50011, USA
- Center for Metabolic Biology, Iowa State University, Ames, IA, 50011, USA
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42
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Mayr JA. Lipid metabolism in mitochondrial membranes. J Inherit Metab Dis 2015; 38:137-44. [PMID: 25082432 DOI: 10.1007/s10545-014-9748-x] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Revised: 07/10/2014] [Accepted: 07/15/2014] [Indexed: 12/26/2022]
Abstract
Mitochondrial membranes have a unique lipid composition necessary for proper shape and function of the organelle. Mitochondrial lipid metabolism involves biosynthesis of the phospholipids phosphatidylethanolamine, cardiolipin and phosphatidylglycerol, the latter is a precursor of the late endosomal lipid bis(monoacylglycero)phosphate. It also includes mitochondrial fatty acid synthesis necessary for the formation of the lipid cofactor lipoic acid. Furthermore the synthesis of coenzyme Q takes place in mitochondria as well as essential parts of the steroid and vitamin D metabolism. Lipid transport and remodelling, which are necessary for tailoring and maintaining specific membrane properties, are just partially unravelled. Mitochondrial lipids are involved in organelle maintenance, fission and fusion, mitophagy and cytochrome c-mediated apoptosis. Mutations in TAZ, SERAC1 and AGK affect mitochondrial phospholipid metabolism and cause Barth syndrome, MEGDEL and Sengers syndrome, respectively. In these disorders an abnormal mitochondrial energy metabolism was found, which seems to be due to disturbed protein-lipid interactions, affecting especially enzymes of the oxidative phosphorylation. Since a growing number of enzymes and transport processes are recognised as parts of the mitochondrial lipid metabolism, a further increase of lipid-related disorders can be expected.
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Affiliation(s)
- Johannes A Mayr
- Department of Paediatrics, Paracelsus Medical University Salzburg, Salzburg, 5020, Austria,
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Suomi F, Menger KE, Monteuuis G, Naumann U, Kursu VAS, Shvetsova A, Kastaniotis AJ. Expression and evolution of the non-canonically translated yeast mitochondrial acetyl-CoA carboxylase Hfa1p. PLoS One 2014; 9:e114738. [PMID: 25503745 PMCID: PMC4263661 DOI: 10.1371/journal.pone.0114738] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Accepted: 11/13/2014] [Indexed: 12/16/2022] Open
Abstract
The Saccharomyces cerevisiae genome encodes two sequence related acetyl-CoA carboxylases, the cytosolic Acc1p and the mitochondrial Hfa1p, required for respiratory function. Several aspects of expression of the HFA1 gene and its evolutionary origin have remained unclear. Here, we determined the HFA1 transcription initiation sites by 5' RACE analysis. Using a novel "Stop codon scanning" approach, we mapped the location of the HFA1 translation initiation site to an upstream AUU codon at position -372 relative to the annotated start codon. This upstream initiation leads to production of a mitochondrial targeting sequence preceding the ACC domains of the protein. In silico analyses of fungal ACC genes revealed conserved "cryptic" upstream mitochondrial targeting sequences in yeast species that have not undergone a whole genome duplication. Our Δhfa1 baker's yeast mutant phenotype rescue studies using the protoploid Kluyveromyces lactis ACC confirmed functionality of the cryptic upstream mitochondrial targeting signal. These results lend strong experimental support to the hypothesis that the mitochondrial and cytosolic acetyl-CoA carboxylases in S. cerevisiae have evolved from a single gene encoding both the mitochondrial and cytosolic isoforms. Leaning on a cursory survey of a group of genes of our interest, we propose that cryptic 5' upstream mitochondrial targeting sequences may be more abundant in eukaryotes than anticipated thus far.
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Affiliation(s)
- Fumi Suomi
- Faculty of Biochemistry and Molecular Medicine and Biocenter Oulu, University of Oulu, Oulu, Finland
| | - Katja E Menger
- Faculty of Biochemistry and Molecular Medicine and Biocenter Oulu, University of Oulu, Oulu, Finland
| | - Geoffray Monteuuis
- Faculty of Biochemistry and Molecular Medicine and Biocenter Oulu, University of Oulu, Oulu, Finland
| | - Uta Naumann
- Faculty of Biochemistry and Molecular Medicine and Biocenter Oulu, University of Oulu, Oulu, Finland
| | - V A Samuli Kursu
- Faculty of Biochemistry and Molecular Medicine and Biocenter Oulu, University of Oulu, Oulu, Finland
| | - Antonina Shvetsova
- Faculty of Biochemistry and Molecular Medicine and Biocenter Oulu, University of Oulu, Oulu, Finland
| | - Alexander J Kastaniotis
- Faculty of Biochemistry and Molecular Medicine and Biocenter Oulu, University of Oulu, Oulu, Finland
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Venkatesan R, Sah-Teli SK, Awoniyi LO, Jiang G, Prus P, Kastaniotis AJ, Hiltunen JK, Wierenga RK, Chen Z. Insights into mitochondrial fatty acid synthesis from the structure of heterotetrameric 3-ketoacyl-ACP reductase/3R-hydroxyacyl-CoA dehydrogenase. Nat Commun 2014; 5:4805. [DOI: 10.1038/ncomms5805] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Accepted: 07/24/2014] [Indexed: 12/19/2022] Open
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45
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Mayr JA, Feichtinger RG, Tort F, Ribes A, Sperl W. Lipoic acid biosynthesis defects. J Inherit Metab Dis 2014; 37:553-63. [PMID: 24777537 DOI: 10.1007/s10545-014-9705-8] [Citation(s) in RCA: 155] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Revised: 03/11/2014] [Accepted: 03/12/2014] [Indexed: 01/10/2023]
Abstract
Lipoate is a covalently bound cofactor essential for five redox reactions in humans: in four 2-oxoacid dehydrogenases and the glycine cleavage system (GCS). Two enzymes are from the energy metabolism, α-ketoglutarate dehydrogenase and pyruvate dehydrogenase; and three are from the amino acid metabolism, branched-chain ketoacid dehydrogenase, 2-oxoadipate dehydrogenase, and the GCS. All these enzymes consist of multiple subunits and share a similar architecture. Lipoate synthesis in mitochondria involves mitochondrial fatty acid synthesis up to octanoyl-acyl-carrier protein; and three lipoate-specific steps, including octanoic acid transfer to glycine cleavage H protein by lipoyl(octanoyl) transferase 2 (putative) (LIPT2), lipoate synthesis by lipoic acid synthetase (LIAS), and lipoate transfer by lipoyltransferase 1 (LIPT1), which is necessary to lipoylate the E2 subunits of the 2-oxoacid dehydrogenases. The reduced form dihydrolipoate is reactivated by dihydrolipoyl dehydrogenase (DLD). Mutations in LIAS have been identified that result in a variant form of nonketotic hyperglycinemia with early-onset convulsions combined with a defect in mitochondrial energy metabolism with encephalopathy and cardiomyopathy. LIPT1 deficiency spares the GCS, and resulted in a combined 2-oxoacid dehydrogenase deficiency and early death in one patient and in a less severely affected individual with a Leigh-like phenotype. As LIAS is an iron-sulphur-cluster-dependent enzyme, a number of recently identified defects in mitochondrial iron-sulphur cluster synthesis, including NFU1, BOLA3, IBA57, GLRX5 presented with deficiency of LIAS and a LIAS-like phenotype. As in DLD deficiency, a broader clinical spectrum can be anticipated for lipoate synthesis defects depending on which of the affected enzymes is most rate limiting.
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Affiliation(s)
- Johannes A Mayr
- Department of Paediatrics, Paracelsus Medical University Salzburg, Salzburg, 5020, Austria,
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Abstract
UNLABELLED Mammary gland (MG) de novo lipogenesis contributes significantly to milk fat in animals but little is known in humans. OBJECTIVE To test the hypothesis that the incorporation of (13)C carbons from [U-(13)C]glucose into fatty acids (FA) and glycerol in triglycerides (TG) will be greater: 1) in milk than plasma TG, 2) during a high-carbohydrate (H-CHO) diet than high-fat (H-FAT) diet, and 3) during feeding than fasting. Seven healthy, lactating women were studied on two isocaloric, isonitrogenous diets. On one occasion, subjects received diets containing H-FAT or H-CHO diet for 1 wk. Incorporation of (13)C from infused [U-(13)C]glucose into FA and glycerol was measured using GC-MS and gene expression in RNA isolated from milk fat globule using microarrays. Incorporation of (13)C2 into milk FA increased with increased FA chain length from C2:0 to C12:0 but progressively declined in C14:0 and C16:0 and was not detected in FA>C16. During feeding, regardless of diets, enrichment of (13)C2 in milk FA and (13)C3 in milk glycerol were ∼ 3- and ∼ 7-fold higher compared with plasma FA and glycerol, respectively. Following an overnight fast during H-CHO and H-FAT diets, 25 and 6%, respectively, of medium-chain FA (MCFA, C6-C12) in milk were derived from glucose but increased to 75 and 25% with feeding. Expression of genes involved in FA or glycerol synthesis was unchanged regardless of diet or fast/fed conditions. The human MG is capable of de novo lipogenesis of primarily MCFA and glycerol, which is influenced by the macronutrient composition of the maternal diet.
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Affiliation(s)
- Mahmoud A Mohammad
- Department of Pediatrics, Children's Nutrition Research Center, US Department of Agriculture/Agricultural Research Service, Baylor College of Medicine, Houston, Texas
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