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Leo G, Leone P, Ataie Kachoie E, Tolomeo M, Galluccio M, Indiveri C, Barile M, Capaldi S. Structural insights into the bifunctional enzyme human FAD synthase. Structure 2024:S0969-2126(24)00132-1. [PMID: 38688286 DOI: 10.1016/j.str.2024.04.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2024] [Revised: 03/20/2024] [Accepted: 04/03/2024] [Indexed: 05/02/2024]
Abstract
Human flavin adenine dinucleotide synthase (hFADS) is a bifunctional, multi-domain enzyme that exhibits both flavin mononucleotide adenylyltransferase and pyrophosphatase activities. Here we report the crystal structure of full-length hFADS2 and its C-terminal PAPS domain in complex with flavin adenine dinucleotide (FAD), and dissect the structural determinants underlying the contribution of each individual domain, within isoforms 1 and 2, to each of the two enzymatic activities. Structural and functional characterization performed on complete or truncated constructs confirmed that the C-terminal domain tightly binds FAD and catalyzes its synthesis, while the combination of the N-terminal molybdopterin-binding and KH domains is the minimal essential substructure required for the hydrolysis of FAD and other ADP-containing dinucleotides. hFADS2 associates in a stable C2-symmetric dimer, in which the packing of the KH domain of one protomer against the N-terminal domain of the other creates the adenosine-specific active site responsible for the hydrolytic activity.
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Affiliation(s)
- Giulia Leo
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134 Verona, Italy
| | - Piero Leone
- Department of Biosciences, Biotechnology and Environment, University of Bari, via Orabona 4, 70126 Bari, Italy
| | - Elham Ataie Kachoie
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134 Verona, Italy
| | - Maria Tolomeo
- Department of Biosciences, Biotechnology and Environment, University of Bari, via Orabona 4, 70126 Bari, Italy; Department of Biology, Ecology and Earth Sciences (DiBEST), Laboratory of Biochemistry, Molecular Biotechnology, and Molecular Biology, University of Calabria, via P. Bucci 4c, 6c, 87036 Arcavacata di Rende, Italy
| | - Michele Galluccio
- Department of Biology, Ecology and Earth Sciences (DiBEST), Laboratory of Biochemistry, Molecular Biotechnology, and Molecular Biology, University of Calabria, via P. Bucci 4c, 6c, 87036 Arcavacata di Rende, Italy
| | - Cesare Indiveri
- Department of Biology, Ecology and Earth Sciences (DiBEST), Laboratory of Biochemistry, Molecular Biotechnology, and Molecular Biology, University of Calabria, via P. Bucci 4c, 6c, 87036 Arcavacata di Rende, Italy; National Research Council (CNR), Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies (IBIOM), via Amendola 122/O, 70126 Bari, Italy
| | - Maria Barile
- Department of Biosciences, Biotechnology and Environment, University of Bari, via Orabona 4, 70126 Bari, Italy.
| | - Stefano Capaldi
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134 Verona, Italy.
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2
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Nisco A, Carvalho TMA, Tolomeo M, Di Molfetta D, Leone P, Galluccio M, Medina M, Indiveri C, Reshkin SJ, Cardone RA, Barile M. Increased demand for FAD synthesis in differentiated and stem pancreatic cancer cells is accomplished by modulating FLAD1 gene expression: the inhibitory effect of Chicago Sky Blue. FEBS J 2023; 290:4679-4694. [PMID: 37254652 DOI: 10.1111/febs.16881] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Revised: 03/31/2023] [Accepted: 05/30/2023] [Indexed: 06/01/2023]
Abstract
FLAD1, along with its FAD synthase (FADS, EC 2.7.7.2) product, is crucial for flavin homeostasis and, due to its role in the mitochondrial respiratory chain and nuclear epigenetics, is closely related to cellular metabolism. Therefore, it is not surprising that it could be correlated with cancer. To our knowledge, no previous study has investigated FLAD1 prognostic significance in pancreatic ductal adenocarcinoma (PDAC). Thus, in the present work, the FAD synthesis process was evaluated in two PDAC cell lines: (a) PANC-1- and PANC-1-derived cancer stem cells (CSCs), presenting the R273H mutation in the oncosuppressor p53, and (b) MiaPaca2 and MiaPaca2-derived CSCs, presenting the R248W mutation in p53. As a control, HPDE cells expressing wt-p53 were used. FADS expression/activity increase was found with malignancy and even more with stemness. An increased FAD synthesis rate in cancer cell lines is presumably demanded by the increase in the FAD-dependent lysine demethylase 1 protein amount as well as by the increased expression levels of the flavoprotein subunit of complex II of the mitochondrial respiratory chain, namely succinate dehydrogenase. With the aim of proposing FADS as a novel target for cancer therapy, the inhibitory effect of Chicago Sky Blue on FADS enzymatic activity was tested on the recombinant 6His-hFADS2 (IC50 = 1.2 μm) and PANC-1-derived CSCs' lysate (IC50 = 2-10 μm). This molecule was found effective in inhibiting the growth of PANC-1 and even more of its derived CSC line, thus assessing its role as a potential chemotherapeutic drug.
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Affiliation(s)
- Alessia Nisco
- Department of Biosciences, Biotechnologies, and Environment, University of Bari Aldo Moro, Italy
| | - Tiago M A Carvalho
- Department of Biosciences, Biotechnologies, and Environment, University of Bari Aldo Moro, Italy
| | - Maria Tolomeo
- Department of Biosciences, Biotechnologies, and Environment, University of Bari Aldo Moro, Italy
- Department of DiBEST (Biologia, Ecologia e Scienze della Terra), University of Calabria, Arcavacata di Rende, Italy
| | - Daria Di Molfetta
- Department of Biosciences, Biotechnologies, and Environment, University of Bari Aldo Moro, Italy
| | - Piero Leone
- Department of Biosciences, Biotechnologies, and Environment, University of Bari Aldo Moro, Italy
| | - Michele Galluccio
- Department of DiBEST (Biologia, Ecologia e Scienze della Terra), University of Calabria, Arcavacata di Rende, Italy
| | - Milagros Medina
- Departamento de Bioquímica y Biología Molecular y Celular, Facultad de Ciencias, Instituto de Biocomputación y Física de Sistemas Complejos (BIFI) (GBsC-CSIC Joint Unit), University of Zaragoza, Spain
| | - Cesare Indiveri
- Department of DiBEST (Biologia, Ecologia e Scienze della Terra), University of Calabria, Arcavacata di Rende, Italy
- CNR Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies (IBIOM), Bari, Italy
| | - Stephan Joel Reshkin
- Department of Biosciences, Biotechnologies, and Environment, University of Bari Aldo Moro, Italy
| | - Rosa Angela Cardone
- Department of Biosciences, Biotechnologies, and Environment, University of Bari Aldo Moro, Italy
| | - Maria Barile
- Department of Biosciences, Biotechnologies, and Environment, University of Bari Aldo Moro, Italy
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3
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Lynch JH, Roje S. A higher plant FAD synthetase is fused to an inactivated FAD pyrophosphatase. J Biol Chem 2022; 298:102626. [PMID: 36273586 PMCID: PMC9678776 DOI: 10.1016/j.jbc.2022.102626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 10/16/2022] [Accepted: 10/17/2022] [Indexed: 11/05/2022] Open
Abstract
The riboflavin derivatives FMN and flavin adenine dinucleotide (FAD) are critical cofactors for wide-ranging biological processes across all kingdoms of life. Although it is well established that these flavins can be readily interconverted, in plants, the responsible catalysts and regulatory mechanisms remain poorly understood. Here, we report the cloning and biochemical characterization of an FAD synthetase encoded by the gene At5g03430, which we have designated AtFADS1 (A. thaliana FADS1). The catalytic properties of the FAD synthetase activity are similar to those reported for other FAD synthetases, except that we observed maximum activity with Zn2+ as the associated divalent metal cation. Like human FAD synthetase, AtFADS1 exists as an apparent fusion with an ancestral FAD pyrophosphatase, a feature that is conserved across plants. However, we detected no pyrophosphatase activity with AtFADS1, consistent with an observed loss of a key catalytic residue in higher plant evolutionary history. In contrast, we determined that algal FADS1 retains both FAD synthetase and pyrophosphatase activity. We discuss the implications, including the potential for yet-unstudied biologically relevant noncatalytic functions, and possible evolutionary pressures that have led to the loss of FAD pyrophosphatase activity, yet universal retention of an apparently nonfunctional domain in FADS of land plants.
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Affiliation(s)
- Joseph H Lynch
- Institute of Biological Chemistry, Washington State University, Pullman, Washington, USA
| | - Sanja Roje
- Institute of Biological Chemistry, Washington State University, Pullman, Washington, USA.
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Arib C, Liu H, Liu Q, Cieutat AM, Paleni D, Li X, Spadavecchia J. A Pegylated Flavin Adenine Dinucleotide PEG Complex to Boost Immunogenic and Therapeutic Effects in a Liver Cancer Model. Nanotheranostics 2021; 5:405-416. [PMID: 33912380 PMCID: PMC8077970 DOI: 10.7150/ntno.59290] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2021] [Accepted: 04/03/2021] [Indexed: 01/10/2023] Open
Abstract
Flavin adenine dinucleotide (FAD) is engaged in several metabolic diseases. Its main role is being a cofactor essential for the activity of many flavoproteins, which play a crucial role in electron transport pathways in living systems. The aim of this study was to apply a pegylated flavins formulation named FAD-PEG diacide complex as theranostic pathway in cancer therapy. For this purpose, a mouse liver cancer model induced by Hepa1-6 cells was used to evaluate the therapeutic efficacy of FAD (named NP1) and FAD-PEG diacide complex (named NP2). The cytokines were applied to screen the serum inflammatory factors, to establish the blood cell content of different groups of nude mice. The highlights follows that FAD formulations (NP1; NP2) significantly suppressed the tumor growth and reduced the tumor index without effects on the body weight of mice. Furthermore, NP2 significantly reduced the serum levels of cytokines IL-6, TNF-α and IL-12 (P70). The reported results provide the proof-of-concept for the synthesis of a smart adjuvant for liver cancer therapy and support their further development in the field of nanomedicine.
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Affiliation(s)
- Celia Arib
- CNRS, UMR 7244, NBD-CSPBAT, Laboratoire de Chimie, Structures et Propriétés de Biomatériaux et d'Agents Thérapeutiques Université Paris 13, Sorbonne Paris Nord, Bobigny, France
| | - Hui Liu
- Department of Hepatobiliary Surgery, Guangdong Provincial Key Laboratory of Regional Immunity and Diseases & Carson International Cancer Center, Shenzhen University General Hospital & Shenzhen University Clinical Medical Academy Center, Shenzhen University, Shenzhen, China
| | - Qiqian Liu
- CNRS, UMR 7244, NBD-CSPBAT, Laboratoire de Chimie, Structures et Propriétés de Biomatériaux et d'Agents Thérapeutiques Université Paris 13, Sorbonne Paris Nord, Bobigny, France
| | - Anne-Marie Cieutat
- CNRS, UMR 7244, NBD-CSPBAT, Laboratoire de Chimie, Structures et Propriétés de Biomatériaux et d'Agents Thérapeutiques Université Paris 13, Sorbonne Paris Nord, Bobigny, France
| | - Didier Paleni
- BioEVEN start-up, 75 rue de Lourmel 75015 Paris, France
| | - Xiaowu Li
- Department of Hepatobiliary Surgery, Guangdong Provincial Key Laboratory of Regional Immunity and Diseases & Carson International Cancer Center, Shenzhen University General Hospital & Shenzhen University Clinical Medical Academy Center, Shenzhen University, Shenzhen, China
| | - Jolanda Spadavecchia
- CNRS, UMR 7244, NBD-CSPBAT, Laboratoire de Chimie, Structures et Propriétés de Biomatériaux et d'Agents Thérapeutiques Université Paris 13, Sorbonne Paris Nord, Bobigny, France.,Department of Hepatobiliary Surgery, Guangdong Provincial Key Laboratory of Regional Immunity and Diseases & Carson International Cancer Center, Shenzhen University General Hospital & Shenzhen University Clinical Medical Academy Center, Shenzhen University, Shenzhen, China
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Leone P, Tolomeo M, Barile M. Continuous and Discontinuous Approaches to Study FAD Synthesis and Degradation Catalyzed by Purified Recombinant FAD Synthase or Cellular Fractions. Methods Mol Biol 2021; 2280:87-116. [PMID: 33751431 DOI: 10.1007/978-1-0716-1286-6_7] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Riboflavin, or vitamin B2, is the precursor of flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), essential redox (and sometimes non-redox) cofactors of a large number of flavoenzymes involved in energetic metabolism, protein folding, apoptosis, chromatin remodeling, and a number of other cell regulatory processes.The cellular and subcellular steady-state concentrations of flavin cofactors, which are available for flavoprotein biogenesis and assembly, depend on carrier-mediated transport processes and on coordinated synthesizing/destroying enzymatic activities, catalyzed by enzymes whose catalytic and structural properties are still matter of investigation.Alteration of flavin homeostasis has been recently correlated to human pathological conditions, such as neuromuscular disorders and cancer, and therefore we propose here protocols useful to detect metabolic processes involved in FAD forming and destroying.Our protocols exploit the chemical-structural differences between riboflavin, FMN , and FAD , which are responsible for differences in the spectroscopic properties (mainly fluorescence) of the two cofactors (FMN and FAD); therefore, in our opinion, when applicable measurements of fluorescence changes in continuo represent the elective techniques to follow FAD synthesis and degradation. Thus, after procedures able to calibrate flavin concentrations (Subheading 3.1), we describe simple continuous and rapid procedures, based on the peculiar optical properties of free flavins, useful to determine the rate of cofactor metabolism catalyzed by either recombinant enzymes or natural enzymes present in cellular lysates/subfractions (Subheading 3.2).Fluorescence properties of free flavins can also be useful in analytical determinations of the three molecular flavin forms, based on HPLC separation, with a quite high sensitivity. Assaying at different incubation times the molecular composition of the reaction mixture is a discontinuous experimental approach to measure the rate of FAD synthesis/degradation catalyzed by cell lysates or recombinant FAD synthase (Subheading 3.3). Continuous and discontinuous approaches can, when necessary, be performed in parallel.
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Affiliation(s)
- Piero Leone
- Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari "A. Moro", Bari, Italy
| | - Maria Tolomeo
- Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari "A. Moro", Bari, Italy
| | - Maria Barile
- Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari "A. Moro", Bari, Italy.
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Tolomeo M, Nisco A, Leone P, Barile M. Development of Novel Experimental Models to Study Flavoproteome Alterations in Human Neuromuscular Diseases: The Effect of Rf Therapy. Int J Mol Sci 2020; 21:ijms21155310. [PMID: 32722651 PMCID: PMC7432027 DOI: 10.3390/ijms21155310] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2020] [Revised: 07/20/2020] [Accepted: 07/21/2020] [Indexed: 02/07/2023] Open
Abstract
Inborn errors of Riboflavin (Rf) transport and metabolism have been recently related to severe human neuromuscular disorders, as resulting in profound alteration of human flavoproteome and, therefore, of cellular bioenergetics. This explains why the interest in studying the “flavin world”, a topic which has not been intensively investigated before, has increased much over the last few years. This also prompts basic questions concerning how Rf transporters and FAD (flavin adenine dinucleotide) -forming enzymes work in humans, and how they can create a coordinated network ensuring the maintenance of intracellular flavoproteome. The concept of a coordinated cellular “flavin network”, introduced long ago studying humans suffering for Multiple Acyl-CoA Dehydrogenase Deficiency (MADD), has been, later on, addressed in model organisms and more recently in cell models. In the frame of the underlying relevance of a correct supply of Rf in humans and of a better understanding of the molecular rationale of Rf therapy in patients, this review wants to deal with theories and existing experimental models in the aim to potentiate possible therapeutic interventions in Rf-related neuromuscular diseases.
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Leone P, Galluccio M, Quarta S, Anoz-Carbonell E, Medina M, Indiveri C, Barile M. Mutation of Aspartate 238 in FAD Synthase Isoform 6 Increases the Specific Activity by Weakening the FAD Binding. Int J Mol Sci 2019; 20:ijms20246203. [PMID: 31835305 PMCID: PMC6941110 DOI: 10.3390/ijms20246203] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Revised: 12/04/2019] [Accepted: 12/06/2019] [Indexed: 02/07/2023] Open
Abstract
FAD synthase (FADS, or FMN:ATP adenylyl transferase) coded by the FLAD1 gene is the last enzyme in the pathway of FAD synthesis. The mitochondrial isoform 1 and the cytosolic isoform 2 are characterized by the following two domains: the C-terminal PAPS domain (FADSy) performing FAD synthesis and pyrophosphorolysis; the N-terminal molybdopterin-binding domain (FADHy) performing a Co++/K+-dependent FAD hydrolysis. Mutations in FLAD1 gene are responsible for riboflavin responsive and non-responsive multiple acyl-CoA dehydrogenases and combined respiratory chain deficiency. In patients harboring frameshift mutations, a shorter isoform (hFADS6) containing the sole FADSy domain is produced representing an emergency protein. With the aim to ameliorate its function we planned to obtain an engineered more efficient hFADS6. Thus, the D238A mutant, resembling the D181A FMNAT “supermutant” of C. glabrata, was overproduced and purified. Kinetic analysis of this enzyme highlighted a general increase of Km, while the kcat was two-fold higher than that of WT. The data suggest that the FAD synthesis rate can be increased. Additional modifications could be performed to further improve the synthesis of FAD. These results correlate with previous data produced in our laboratory, and point towards the following proposals (i) FAD release is the rate limiting step of the catalytic cycle and (ii) ATP and FMN binding sites are synergistically connected.
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Affiliation(s)
- Piero Leone
- Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari, via Orabona 4–, 70126 Bari, Italy; (P.L.); (S.Q.)
- Department of Biology, Ecology and Earth Sciences (DiBEST), Unit of Biochemistry and Molecular Biotechnology, University of Calabria, via P. Bucci 4c, 87036 Arcavacata di Rende, Italy; (M.G.); (C.I.)
| | - Michele Galluccio
- Department of Biology, Ecology and Earth Sciences (DiBEST), Unit of Biochemistry and Molecular Biotechnology, University of Calabria, via P. Bucci 4c, 87036 Arcavacata di Rende, Italy; (M.G.); (C.I.)
| | - Stefano Quarta
- Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari, via Orabona 4–, 70126 Bari, Italy; (P.L.); (S.Q.)
| | - Ernesto Anoz-Carbonell
- Departamento de Bioquímica y Biología Molecular y Celular, Facultad de Ciencias, Instituto de Biocomputación y Física de Sistemas Complejos (GBsC-CSIC and BIFI-IQFR Joint Units), Universidad de Zaragoza, 50009 Zaragoza, Spain; (E.A.-C.); (M.M.)
| | - Milagros Medina
- Departamento de Bioquímica y Biología Molecular y Celular, Facultad de Ciencias, Instituto de Biocomputación y Física de Sistemas Complejos (GBsC-CSIC and BIFI-IQFR Joint Units), Universidad de Zaragoza, 50009 Zaragoza, Spain; (E.A.-C.); (M.M.)
| | - Cesare Indiveri
- Department of Biology, Ecology and Earth Sciences (DiBEST), Unit of Biochemistry and Molecular Biotechnology, University of Calabria, via P. Bucci 4c, 87036 Arcavacata di Rende, Italy; (M.G.); (C.I.)
| | - Maria Barile
- Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari, via Orabona 4–, 70126 Bari, Italy; (P.L.); (S.Q.)
- Correspondence:
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Leone P, Galluccio M, Brizio C, Barbiroli A, Iametti S, Indiveri C, Barile M. The hidden side of the human FAD synthase 2. Int J Biol Macromol 2019; 138:986-995. [PMID: 31351152 DOI: 10.1016/j.ijbiomac.2019.07.138] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Revised: 07/22/2019] [Accepted: 07/23/2019] [Indexed: 11/16/2022]
Abstract
FAD synthase, the last enzyme of the pathway converting riboflavin to FAD, exists in humans in different isoforms, with isoforms 1, 2 and 6 being characterized at the functional and molecular levels. Isoform 2, the cytosolic and most abundant FADS, consists of two domains: a PAPS reductase C-terminus domain (here named FADSy) responsible for FAD synthesis, and an N-terminus molybdopterin-binding resembling domain (MPTb - here named FADHy), whose FAD hydrolytic activity is hidden unless both Co2+ and chemical mercurial reagents are added to the enzyme. To investigate the hFADS2 hydrolytic function under conditions closer to the physiological context, the hydrolytic activity was further characterized. Co2+ induced FAD hydrolysis was strongly stimulated in the presence of K+, reaching a Vmax higher than that of FAD synthesis. The pH dependence together with the inhibition of the hydrolysis by NaF and KI allow excluding that the reaction occurs via a NUDIX type catalysis. The K0.5 for K+ or Co2+ was 7.2 or 0.035 mM, respectively. Other monovalent or divalent cations can partially substitute K+ or Co2+. Reduced glutathione stimulated whereas NADH inhibited the hydrolytic activity. The latter aspects correlate with an interconnection of the homeostasis of NAD and FAD.
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Affiliation(s)
- Piero Leone
- Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari, via Orabona 4 -, 70126 Bari, Italy; Department of Biology, Ecology and Earth Sciences (DiBEST), Unit of Biochemistry and Molecular Biotechnology, University of Calabria, via P. Bucci 4c, , 87036 Arcavacata di Rende, Italy
| | - Michele Galluccio
- Department of Biology, Ecology and Earth Sciences (DiBEST), Unit of Biochemistry and Molecular Biotechnology, University of Calabria, via P. Bucci 4c, , 87036 Arcavacata di Rende, Italy
| | - Carmen Brizio
- Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari, via Orabona 4 -, 70126 Bari, Italy
| | - Alberto Barbiroli
- Dipartimento di Scienze per gli Alimenti, la Nutrizione e l'Ambiente (DeFENS), Università degli Studi di Milano, via Celoria 2, I-20133 Milano, Italy
| | - Stefania Iametti
- Dipartimento di Scienze per gli Alimenti, la Nutrizione e l'Ambiente (DeFENS), Università degli Studi di Milano, via Celoria 2, I-20133 Milano, Italy
| | - Cesare Indiveri
- Department of Biology, Ecology and Earth Sciences (DiBEST), Unit of Biochemistry and Molecular Biotechnology, University of Calabria, via P. Bucci 4c, , 87036 Arcavacata di Rende, Italy; Institute of Biomembranes, Bioenergetics and Molecular Biotechnology (IBIOM) - CNR, via Giovanni Amendola 165/A, 70126 Bari, Italy
| | - Maria Barile
- Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari, via Orabona 4 -, 70126 Bari, Italy.
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Frolova MS, Marchenkov VV, Vekshin NL. Disruption of flavin homeostasis in isolated rat liver mitochondria. Biochem Biophys Res Commun 2019; 516:1211-1215. [PMID: 31300198 DOI: 10.1016/j.bbrc.2019.07.021] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Accepted: 07/05/2019] [Indexed: 12/16/2022]
Abstract
It has been shown that spontaneous release of non-covalent flavins (from flavoenzymes) begins after isolation of mitochondria from rat liver, which is hydrolyzed to riboflavin. This process is stopped by 1 mM EDTA in the incubation medium. In the presence of NADH, deflavinization of flavoproteins leads to formation of superoxide by at least of three processes. The first of these occurs in complex I as a result of the spontaneous release of FMN from the active center. This process is inhibited by adenosine and guanosine phosphates, as well as NAD, but amplified by nicotinamide. The second process is associated with enzymatic hydrolysis of FAD and FMN to riboflavin; it is blocked by EDTA, AMP, NA, NAD. The third process is associated with non-enzymatic hydrolysis of FAD by iron ions in matrix; it is blocked by EDTA and AMP.
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Affiliation(s)
- M S Frolova
- Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Russia.
| | - V V Marchenkov
- Institute of Protein Research, Russian Academy of Sciences, Pushchino, Russia
| | - N L Vekshin
- Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Russia
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10
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Lynch JH, Sa N, Saeheng S, Raffaelli N, Roje S. Characterization of a non-nudix pyrophosphatase points to interplay between flavin and NAD(H) homeostasis in Saccharomyces cerevisiae. PLoS One 2018; 13:e0198787. [PMID: 29902190 PMCID: PMC6002036 DOI: 10.1371/journal.pone.0198787] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Accepted: 05/28/2018] [Indexed: 12/11/2022] Open
Abstract
The flavin cofactors FMN and FAD are required for a wide variety of biological processes, however, little is known about their metabolism. Here, we report the cloning and biochemical characterization of the Saccharomyces cerevisiae pyrophosphatase Fpy1p. Genetic and functional studies suggest that Fpy1p may play a key role in flavin metabolism and is the first-reported non-Nudix superfamily enzyme to display FAD pyrophosphatase activity. Characterization of mutant yeast strains found that deletion of fpy1 counteracts the adverse effects that are caused by deletion of flx1, a known mitochondrial FAD transporter. We show that Fpy1p is capable of hydrolyzing FAD, NAD(H), and ADP-ribose. The enzymatic activity of Fpy1p is dependent upon the presence of K+ and divalent metal cations, with similar kinetic parameters to those that have been reported for Nudix FAD pyrophosphatases. In addition, we report that the deletion of fpy1 intensifies the FMN-dependence of null mutants of the riboflavin kinase Fmn1p, demonstrate that fpy1 mutation abolishes the decreased fitness resulting from the deletion of the flx1 ORF, and offer a possible mechanism for the genetic interplay between fpy1, flx1 and fmn1.
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Affiliation(s)
- Joseph H. Lynch
- Institute of Biological Chemistry, Washington State University, Pullman, WA, United States of America
| | - Na Sa
- Institute of Biological Chemistry, Washington State University, Pullman, WA, United States of America
| | - Sompop Saeheng
- Institute of Biological Chemistry, Washington State University, Pullman, WA, United States of America
| | - Nadia Raffaelli
- Dipartimento di Scienze Agrarie, Alimentari e Ambientali, Università Politecnica delle Marche, Ancona, Italy
| | - Sanja Roje
- Institute of Biological Chemistry, Washington State University, Pullman, WA, United States of America
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Leone P, Galluccio M, Barbiroli A, Eberini I, Tolomeo M, Vrenna F, Gianazza E, Iametti S, Bonomi F, Indiveri C, Barile M. Bacterial Production, Characterization and Protein Modeling of a Novel Monofuctional Isoform of FAD Synthase in Humans: An Emergency Protein? Molecules 2018; 23:E116. [PMID: 29316637 DOI: 10.3390/molecules23010116] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2017] [Revised: 12/30/2017] [Accepted: 01/04/2018] [Indexed: 12/13/2022] Open
Abstract
FAD synthase (FADS, EC 2.7.7.2) is the last essential enzyme involved in the pathway of biosynthesis of Flavin cofactors starting from Riboflavin (Rf). Alternative splicing of the human FLAD1 gene generates different isoforms of the enzyme FAD synthase. Besides the well characterized isoform 1 and 2, other FADS isoforms with different catalytic domains have been detected, which are splice variants. We report the characterization of one of these novel isoforms, a 320 amino acid protein, consisting of the sole C-terminal 3′-phosphoadenosine 5′-phosphosulfate (PAPS) reductase domain (named FADS6). This isoform has been previously detected in Riboflavin-Responsive (RR-MADD) and Non-responsive Multiple Acyl-CoA Dehydrogenase Deficiency (MADD) patients with frameshift mutations of FLAD1 gene. To functionally characterize the hFADS6, it has been over-expressed in Escherichia coli and purified with a yield of 25 mg·L−1 of cell culture. The protein has a monomeric form, it binds FAD and is able to catalyze FAD synthesis (kcat about 2.8 min−1), as well as FAD pyrophosphorolysis in a strictly Mg2+-dependent manner. The synthesis of FAD is inhibited by HgCl2. The enzyme lacks the ability to hydrolyze FAD. It behaves similarly to PAPS. Combining threading and ab-initio strategy a 3D structural model for such isoform has been built. The relevance to human physio-pathology of this FADS isoform is discussed.
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Barile M, Giancaspero TA, Leone P, Galluccio M, Indiveri C. Riboflavin transport and metabolism in humans. J Inherit Metab Dis 2016; 39:545-57. [PMID: 27271694 DOI: 10.1007/s10545-016-9950-0] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2016] [Revised: 05/12/2016] [Accepted: 05/19/2016] [Indexed: 12/17/2022]
Abstract
Recent studies elucidated how riboflavin transporters and FAD forming enzymes work in humans and create a coordinated flavin network ensuring the maintenance of cellular flavoproteome. Alteration of this network may be causative of severe metabolic disorders such as multiple acyl-CoA dehydrogenase deficiency (MADD) or Brown-Vialetto-van Laere syndrome. A crucial step in the maintenance of FAD homeostasis is riboflavin uptake by plasma and mitochondrial membranes. Therefore, studies on recently identified human plasma membrane riboflavin transporters are presented, together with those in which still unidentified mitochondrial riboflavin transporter(s) have been described. A main goal of future research is to fill the gaps still existing as for some transcriptional, functional and structural details of human FAD synthases (FADS) encoded by FLAD1 gene, a novel "redox sensing" enzyme. In the frame of the hypothesis that FADS, acting as a "FAD chaperone", could play a crucial role in the biogenesis of mitochondrial flavo-proteome, several basic functional aspects of flavin cofactor delivery to cognate apo-flavoenzyme are also briefly dealt with. The establishment of model organisms performing altered FAD homeostasis will improve the molecular description of human pathologies. The molecular and functional studies of transporters and enzymes herereported, provide guidelines for improving therapies which may have beneficial effects on the altered metabolism.
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Affiliation(s)
- Maria Barile
- Dipartimento di Bioscienze, Biotecnologie e Biofarmaceutica, Università degli Studi di Bari "Aldo Moro", via Orabona 4, I-70126, Bari, Italy.
| | - Teresa Anna Giancaspero
- Dipartimento di Bioscienze, Biotecnologie e Biofarmaceutica, Università degli Studi di Bari "Aldo Moro", via Orabona 4, I-70126, Bari, Italy
| | - Piero Leone
- Dipartimento di Bioscienze, Biotecnologie e Biofarmaceutica, Università degli Studi di Bari "Aldo Moro", via Orabona 4, I-70126, Bari, Italy
| | - Michele Galluccio
- Dipartimento DiBEST (Biologia, Ecologia, Scienze della Terra), Unità di Biochimica e Biotecnologie Molecolari, Università della Calabria, via Bucci 4c, I-87036, Arcavacata di Rende, Italy
| | - Cesare Indiveri
- Dipartimento DiBEST (Biologia, Ecologia, Scienze della Terra), Unità di Biochimica e Biotecnologie Molecolari, Università della Calabria, via Bucci 4c, I-87036, Arcavacata di Rende, Italy
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Yoshida A, Shiotsu-Ogura Y, Wada-Takahashi S, Takahashi SS, Toyama T, Yoshino F. Blue light irradiation-induced oxidative stress in vivo via ROS generation in rat gingival tissue. Journal of Photochemistry and Photobiology B: Biology 2015; 151:48-53. [DOI: 10.1016/j.jphotobiol.2015.07.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Revised: 06/30/2015] [Accepted: 07/02/2015] [Indexed: 10/23/2022]
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Giancaspero TA, Galluccio M, Miccolis A, Leone P, Eberini I, Iametti S, Indiveri C, Barile M. Human FAD synthase is a bi-functional enzyme with a FAD hydrolase activity in the molybdopterin binding domain. Biochem Biophys Res Commun 2015; 465:443-9. [PMID: 26277395 DOI: 10.1016/j.bbrc.2015.08.035] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Accepted: 08/09/2015] [Indexed: 02/05/2023]
Abstract
FAD synthase (FMN:ATP adenylyl transferase, FMNAT or FADS, EC 2.7.7.2) is involved in the biochemical pathway for converting riboflavin into FAD. Human FADS exists in different isoforms. Two of these have been characterized and are localized in different subcellular compartments. hFADS2 containing 490 amino acids shows a two domain organization: the 3'-phosphoadenosine-5'-phosphosulfate (PAPS) reductase domain, that is the FAD-forming catalytic domain, and a resembling molybdopterin-binding (MPTb) domain. By a multialignment of hFADS2 with other MPTb containing proteins of various organisms from bacteria to plants, the critical residues for hydrolytic function were identified. A homology model of the MPTb domain of hFADS2 was built, using as template the solved structure of a T. acidophilum enzyme. The capacity of hFADS2 to catalyse FAD hydrolysis was revealed. The recombinant hFADS2 was able to hydrolyse added FAD in a Co(2+) and mersalyl dependent reaction. The recombinant PAPS reductase domain is not able to perform the same function. The mutant C440A catalyses the same hydrolytic function of WT with no essential requirement for mersalyl, thus indicating the involvement of C440 in the control of hydrolysis switch. The enzyme C440A is also able to catalyse hydrolysis of FAD bound to the PAPS reductase domain, which is quantitatively converted into FMN.
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Affiliation(s)
- Teresa Anna Giancaspero
- Dipartimento di Bioscienze, Biotecnologie e Biofarmaceutica, Università degli Studi di Bari "A. Moro", via Orabona 4, I-70126, Bari, Italy.
| | - Michele Galluccio
- Dipartimento DiBEST, Biologia, Ecologia, Scienze della Terra, Unità di Biochimica e Biotecnologie Molecolari, Università della Calabria, via Bucci 4c, I-87036, Arcavacata di Rende, Italy.
| | - Angelica Miccolis
- Dipartimento di Bioscienze, Biotecnologie e Biofarmaceutica, Università degli Studi di Bari "A. Moro", via Orabona 4, I-70126, Bari, Italy.
| | - Piero Leone
- Dipartimento di Bioscienze, Biotecnologie e Biofarmaceutica, Università degli Studi di Bari "A. Moro", via Orabona 4, I-70126, Bari, Italy.
| | - Ivano Eberini
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, via Balzaretti 9, I-20133, Milano, Italy.
| | - Stefania Iametti
- Dipartimento di Scienze per gli Alimenti, la Nutrizione e l'Ambiente, Università degli Studi di Milano, via Celoria 2, I-20133, Milano, Italy.
| | - Cesare Indiveri
- Dipartimento DiBEST, Biologia, Ecologia, Scienze della Terra, Unità di Biochimica e Biotecnologie Molecolari, Università della Calabria, via Bucci 4c, I-87036, Arcavacata di Rende, Italy.
| | - Maria Barile
- Dipartimento di Bioscienze, Biotecnologie e Biofarmaceutica, Università degli Studi di Bari "A. Moro", via Orabona 4, I-70126, Bari, Italy.
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Taniguchi H, Wendisch VF. Exploring the role of sigma factor gene expression on production by Corynebacterium glutamicum: sigma factor H and FMN as example. Front Microbiol 2015; 6:740. [PMID: 26257719 PMCID: PMC4510997 DOI: 10.3389/fmicb.2015.00740] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Accepted: 07/06/2015] [Indexed: 12/25/2022] Open
Abstract
Bacteria are known to cope with environmental changes by using alternative sigma factors binding to RNA polymerase core enzyme. Sigma factor is one of the targets to modify transcription regulation in bacteria and to influence production capacities. In this study, the effect of overexpressing each annotated sigma factor gene in Corynebacterium glutamicum WT was assayed using an IPTG inducible plasmid system and different IPTG concentrations. It was revealed that growth was severely decreased when sigD or sigH were overexpressed with IPTG concentrations higher than 50 μM. Overexpression of sigH led to an obvious phenotypic change, a yellow-colored supernatant. High performance liquid chromatography analysis revealed that riboflavin was excreted to the medium when sigH was overexpressed and DNA microarray analysis confirmed increased expression of riboflavin biosynthesis genes. In addition, genes for enzymes related to the pentose phosphate pathway and for enzymes dependent on flavin mononucleotide (FMN), flavin adenine dinucleotide (FAD), or NADPH as cofactor were upregulated when sigH was overexpressed. To test if sigH overexpression can be exploited for production of riboflavin-derived FMN or FAD, the endogenous gene for bifunctional riboflavin kinase/FMN adenyltransferase was co-expressed with sigH from a plasmid. Balanced expression of sigH and ribF improved accumulation of riboflavin (19.8 ± 0.3 μM) and allowed for its conversion to FMN (33.1 ± 1.8 μM) in the supernatant. While a proof-of-concept was reached, conversion was not complete and titers were not high. This study revealed that inducible and gradable overexpression of sigma factor genes is an interesting approach to switch gene expression profiles and to discover untapped potential of bacteria for chemical production.
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Affiliation(s)
- Hironori Taniguchi
- Genetics of Prokaryotes, Faculty of Biology and Center for Biotechnology, Bielefeld University Bielefeld, Germany
| | - Volker F Wendisch
- Genetics of Prokaryotes, Faculty of Biology and Center for Biotechnology, Bielefeld University Bielefeld, Germany
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Giancaspero TA, Colella M, Brizio C, Difonzo G, Fiorino GM, Leone P, Brandsch R, Bonomi F, Iametti S, Barile M. Remaining challenges in cellular flavin cofactor homeostasis and flavoprotein biogenesis. Front Chem 2015; 3:30. [PMID: 25954742 PMCID: PMC4406087 DOI: 10.3389/fchem.2015.00030] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Accepted: 04/05/2015] [Indexed: 12/27/2022] Open
Abstract
The primary role of the water-soluble vitamin B2 (riboflavin) in cell biology is connected with its conversion into FMN and FAD, the cofactors of a large number of dehydrogenases, oxidases and reductases involved in a broad spectrum of biological activities, among which energetic metabolism and chromatin remodeling. Subcellular localisation of FAD synthase (EC 2.7.7.2, FADS), the second enzyme in the FAD forming pathway, is addressed here in HepG2 cells by confocal microscopy, in the frame of its relationships with kinetics of FAD synthesis and delivery to client apo-flavoproteins. FAD synthesis catalyzed by recombinant isoform 2 of FADS occurs via an ordered bi-bi mechanism in which ATP binds prior to FMN, and pyrophosphate is released before FAD. Spectrophotometric continuous assays of the reconstitution rate of apo-D-aminoacid oxidase with its cofactor, allowed us to propose that besides its FAD synthesizing activity, hFADS is able to operate as a FAD “chaperone.” The physical interaction between FAD forming enzyme and its clients was further confirmed by dot blot and immunoprecipitation experiments carried out testing as a client either a nuclear lysine-specific demethylase 1 (LSD1) or a mitochondrial dimethylglycine dehydrogenase (Me2GlyDH, EC 1.5.8.4). Both enzymes carry out similar reactions of oxidative demethylation, in which tetrahydrofolate is converted into 5,10-methylene-tetrahydrofolate. A direct transfer of the cofactor from hFADS2 to apo-dimethyl glycine dehydrogenase was also demonstrated. Thus, FAD synthesis and delivery to these enzymes are crucial processes for bioenergetics and nutri-epigenetics of liver cells.
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Affiliation(s)
- Teresa A Giancaspero
- Dipartimento di Bioscienze, Biotecnologie e Biofarmaceutica, Università degli Studi di Bari Aldo Moro Bari, Italy
| | - Matilde Colella
- Dipartimento di Bioscienze, Biotecnologie e Biofarmaceutica, Università degli Studi di Bari Aldo Moro Bari, Italy
| | - Carmen Brizio
- Dipartimento di Bioscienze, Biotecnologie e Biofarmaceutica, Università degli Studi di Bari Aldo Moro Bari, Italy
| | - Graziana Difonzo
- Dipartimento di Bioscienze, Biotecnologie e Biofarmaceutica, Università degli Studi di Bari Aldo Moro Bari, Italy
| | - Giuseppina M Fiorino
- Dipartimento di Bioscienze, Biotecnologie e Biofarmaceutica, Università degli Studi di Bari Aldo Moro Bari, Italy
| | - Piero Leone
- Dipartimento di Bioscienze, Biotecnologie e Biofarmaceutica, Università degli Studi di Bari Aldo Moro Bari, Italy
| | - Roderich Brandsch
- Institut für Biochemie und Molekularbiologie, Universität Freiburg Freiburg, Germany
| | - Francesco Bonomi
- Dipartimento di Scienze per gli Alimenti, la Nutrizione e l'Ambiente, Università degli Studi di Milano Milano, Italy
| | - Stefania Iametti
- Dipartimento di Scienze per gli Alimenti, la Nutrizione e l'Ambiente, Università degli Studi di Milano Milano, Italy
| | - Maria Barile
- Dipartimento di Bioscienze, Biotecnologie e Biofarmaceutica, Università degli Studi di Bari Aldo Moro Bari, Italy ; Dipartimento di Scienze della Vita, Istituto di Biomembrane e Bioenergetica, CNR Bari, Italy
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Miccolis A, Galluccio M, Nitride C, Giancaspero TA, Ferranti P, Iametti S, Indiveri C, Bonomi F, Barile M. Significance of redox-active cysteines in human FAD synthase isoform 2. Biochim Biophys Acta 2014; 1844:2086-95. [PMID: 25135855 DOI: 10.1016/j.bbapap.2014.08.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Revised: 07/30/2014] [Accepted: 08/08/2014] [Indexed: 11/22/2022]
Abstract
FAD synthase (FMN:ATP adenylyl transferase, FMNAT or FADS, EC 2.7.7.2) is the last enzyme in the pathway converting riboflavin into FAD. In humans, FADS is localized in different subcellular compartments and exists in different isoforms. Isoform 2 (490-amino acids) is organized in two domains: the 3'-phosphoadenosine-5'-phosphosulfate (PAPS) reductase domain, that is the FAD-forming catalytic domain, and one resembling a molybdopterin-binding (MPTb) domain, with a hypothetical regulatory role. hFADS2 contains ten Cys residues, seven of which located in the PAPS reductase domain, with a possible involvement either in FAD synthesis or in FAD delivery to cognate apo-flavoproteins. A homology model of the PAPS reductase domain of hFADS2 revealed a co-ordinated network among the Cys residues in this domain. In this model, C312 and C303 are very close to the flavin substrate, consistent with a significantly lowered FAD synthesis rate in C303A and C312A mutants. FAD synthesis is also inhibited by thiol-blocking reagents, suggesting the involvement of free cysteines in the hFADS2 catalytic cycle. Mass spectrometry measurements and titration with thiol reagents on wt hFADS2 and on several individual cysteine/alanine mutants allowed us to detect two stably reduced cysteines (C139 and C241, one for each protein domain), two stable disulfide bridges (C399-C402, C303-C312, both in the PAPS domain), and two unstable disulfides (C39-C50; C440-C464). Whereas the C39-C50 unstable disulfide is located in the MPTb domain and appears to have no catalytic relevance, a cysteine-based redox switch may involve formation and breakdown of a disulfide between C440 and C464 in the PAPS domain.
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Abstract
Flavin-dependent monooxygenases and oxidoreductases are located at critical branch points in the biosynthesis and metabolism of cholesterol and vitamin D. These flavoproteins function as obligatory intermediates that accept 2 electrons from NAD(P)H with subsequent 1-electron transfers to a variety of cytochrome P450 (CYP) heme proteins within the mitochondria matrix (type I) and the (microsomal) endoplasmic reticulum (type II). The mode of electron transfer in these systems differs slightly in the number and form of the flavin prosthetic moiety. In the type I mitochondrial system, FAD-adrenodoxin reductase interfaces with adrenodoxin before electron transfer to CYP heme proteins. In the microsomal type II system, a diflavin (FAD/FMN)-dependent cytochrome P450 oxidoreductase [NAD(P)H-cytochrome P450 reductase (CPR)] donates electrons to a multitude of heme oxygenases. Both flavoenzyme complexes exhibit a commonality of function with all CYP enzymes and are crucial for maintaining a balance of cholesterol and vitamin D metabolites. Deficits in riboflavin availability, imbalances in the intracellular ratio of FAD to FMN, and mutations that affect flavin binding domains and/or interactions with client proteins result in marked structural alterations within the skeletal and central nervous systems similar to those of disorders (inborn errors) in the biosynthetic pathways that lead to cholesterol, steroid hormones, and vitamin D and their metabolites. Studies of riboflavin deficiency during embryonic development demonstrate congenital malformations similar to those associated with genetic alterations of the flavoenzymes in these pathways. Overall, a deeper understanding of the role of riboflavin in these pathways may prove essential to targeted therapeutic designs aimed at cholesterol and vitamin D metabolism.
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Giancaspero TA, Locato V, Barile M. A regulatory role of NAD redox status on flavin cofactor homeostasis in S. cerevisiae mitochondria. Oxid Med Cell Longev 2013; 2013:612784. [PMID: 24078860 PMCID: PMC3774037 DOI: 10.1155/2013/612784] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Accepted: 07/18/2013] [Indexed: 01/18/2023]
Abstract
Flavin adenine dinucleotide (FAD) and nicotinamide adenine dinucleotide (NAD) are two redox cofactors of pivotal importance for mitochondrial functionality and cellular redox balance. Despite their relevance, the mechanism by which intramitochondrial NAD(H) and FAD levels are maintained remains quite unclear in Saccharomyces cerevisiae. We investigated here the ability of isolated mitochondria to degrade externally added FAD and NAD (in both its reduced and oxidized forms). A set of kinetic experiments demonstrated that mitochondrial FAD and NAD(H) destroying enzymes are different from each other and from the already characterized NUDIX hydrolases. We studied here, in some detail, FAD pyrophosphatase (EC 3.6.1.18), which is inhibited by NAD(+) and NADH according to a noncompetitive inhibition, with Ki values that differ from each other by an order of magnitude. These findings, together with the ability of mitochondrial FAD pyrophosphatase to metabolize endogenous FAD, presumably deriving from mitochondrial holoflavoproteins destined to degradation, allow for proposing a novel possible role of mitochondrial NAD redox status in regulating FAD homeostasis and/or flavoprotein degradation in S. cerevisiae.
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Affiliation(s)
| | - Vittoria Locato
- Centro Integrato di Ricerca, Università Campus Bio-Medico di Roma, Via Alvaro del Portillo 21, 00128 Roma, Italy
| | - Maria Barile
- Istituto di Biomembrane e Bioenergetica, CNR, Via Orabona 4, 70126 Bari, Italy
- Dipartimento di Bioscienze, Biotecnologie e Biofarmaceutica, Università degli Studi di Bari “Aldo Moro”, Via Orabona 4, 70126 Bari, Italy
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Giancaspero TA, Busco G, Panebianco C, Carmone C, Miccolis A, Liuzzi GM, Colella M, Barile M. FAD synthesis and degradation in the nucleus create a local flavin cofactor pool. J Biol Chem 2013; 288:29069-80. [PMID: 23946482 DOI: 10.1074/jbc.m113.500066] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
FAD is a redox cofactor ensuring the activity of many flavoenzymes mainly located in mitochondria but also relevant for nuclear redox activities. The last enzyme in the metabolic pathway producing FAD is FAD synthase (EC 2.7.7.2), a protein known to be localized both in cytosol and in mitochondria. FAD degradation to riboflavin occurs via still poorly characterized enzymes, possibly belonging to the NUDIX hydrolase family. By confocal microscopy and immunoblotting experiments, we demonstrate here the existence of FAD synthase in the nucleus of different experimental rat models. HPLC experiments demonstrated that isolated rat liver nuclei contain ∼300 pmol of FAD·mg(-1) protein, which was mainly protein-bound FAD. A mean FAD synthesis rate of 18.1 pmol·min(-1)·mg(-1) protein was estimated by both HPLC and continuous coupled enzymatic spectrophotometric assays. Rat liver nuclei were also shown to be endowed with a FAD pyrophosphatase that hydrolyzes FAD with an optimum at alkaline pH and is significantly inhibited by adenylate-containing nucleotides. The coordinate activity of these FAD forming and degrading enzymes provides a potential mechanism by which a dynamic pool of flavin cofactor is created in the nucleus. These data, which significantly add to the biochemical comprehension of flavin metabolism and its subcellular compartmentation, may also provide the basis for a more detailed comprehension of the role of flavin homeostasis in biologically and clinically relevant epigenetic events.
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Deka RK, Brautigam CA, Liu WZ, Tomchick DR, Norgard MV. The TP0796 lipoprotein of Treponema pallidum is a bimetal-dependent FAD pyrophosphatase with a potential role in flavin homeostasis. J Biol Chem 2013; 288:11106-21. [PMID: 23447540 DOI: 10.1074/jbc.m113.449975] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Treponema pallidum, an obligate parasite of humans and the causative agent of syphilis, has evolved the capacity to exploit host-derived metabolites for its survival. Flavin-containing compounds are essential cofactors that are required for metabolic processes in all living organisms, and riboflavin is a direct precursor of the cofactors FMN and FAD. Unlike many pathogenic bacteria, Treponema pallidum cannot synthesize riboflavin; we recently described a flavin-uptake mechanism composed of an ABC-type transporter. However, there is a paucity of information about flavin utilization in bacterial periplasms. Using a discovery-driven approach, we have identified the TP0796 lipoprotein as a previously uncharacterized Mg(2+)-dependent FAD pyrophosphatase within the ApbE superfamily. TP0796 probably plays a central role in flavin turnover by hydrolyzing exogenously acquired FAD, yielding AMP and FMN. Biochemical and structural investigations revealed that the enzyme has a unique bimetal Mg(2+) catalytic center. Furthermore, the pyrophosphatase activity is product-inhibited by AMP, indicating a possible role for this molecule in modulating FMN and FAD levels in the treponemal periplasm. The ApbE superfamily was previously thought to be involved in thiamine biosynthesis, but our characterization of TP0796 prompts a renaming of this superfamily as a periplasmic flavin-trafficking protein (Ftp). TP0796 is the first structurally and biochemically characterized FAD pyrophosphate enzyme in bacteria. This new paradigm for a bacterial flavin utilization pathway may prove to be useful for future inhibitor design.
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Affiliation(s)
- Ranjit K Deka
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
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Miccolis A, Galluccio M, Giancaspero TA, Indiveri C, Barile M. Bacterial over-expression and purification of the 3'phosphoadenosine 5'phosphosulfate (PAPS) reductase domain of human FAD synthase: functional characterization and homology modeling. Int J Mol Sci 2012; 13:16880-98. [PMID: 23443125 DOI: 10.3390/ijms131216880] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2012] [Revised: 11/14/2012] [Accepted: 11/20/2012] [Indexed: 11/16/2022] Open
Abstract
FAD synthase (FADS, EC 2.7.7.2) is a key enzyme in the metabolic pathway that converts riboflavin into the redox cofactor, FAD. Human FADS is organized in two domains: -the 3′phosphoadenosine 5′phosphosulfate (PAPS) reductase domain, similar to yeast Fad1p, at the C-terminus, and -the resembling molybdopterin-binding domain at the N-terminus. To understand whether the PAPS reductase domain of hFADS is sufficient to catalyze FAD synthesis, per se, and to investigate the role of the molybdopterin-binding domain, a soluble “truncated” form of hFADS lacking the N-terminal domain (Δ1-328-hFADS) has been over-produced and purified to homogeneity as a recombinant His-tagged protein. The recombinant Δ1-328-hFADS binds one mole of FAD product very tightly as the wild-type enzyme. Under turnover conditions, it catalyzes FAD assembly from ATP and FMN and, at a much lower rate, FAD pyrophosphorolytic hydrolysis. The Δ1-328-hFADS enzyme shows a slight, but not significant, change of Km values (0.24 and 6.23 μM for FMN and ATP, respectively) and of kcat (4.2 × 10−2 s−1) compared to wild-type protein in the forward direction. These results demonstrate that the molybdopterin-binding domain is not strictly required for catalysis. Its regulatory role is discussed in light of changes in divalent cations sensitivity of the Δ1-328-hFADS versus wild-type protein.
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Maruta T, Yoshimoto T, Ito D, Ogawa T, Tamoi M, Yoshimura K, Shigeoka S. An Arabidopsis FAD pyrophosphohydrolase, AtNUDX23, is involved in flavin homeostasis. Plant Cell Physiol 2012; 53:1106-16. [PMID: 22505691 DOI: 10.1093/pcp/pcs054] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Although flavins, riboflavin (RF), FMN and FAD, are essential for primary and secondary metabolism in plants, the metabolic regulation of flavins is still largely unknown. Recently, we found that an Arabidopsis Nudix hydrolase, AtNUDX23, has FAD pyrophosphohydrolase activity and is distributed in plastids. Levels of RF and FAD but not FMN in Arabidopsis leaves significantly increased under continuous light and decreased in the dark. The transcript levels of AtNUDX23 as well as genes involved in flavin metabolism (AtFADS, AtRibF1, AtRibF2, AtFMN/FHy, LS and AtRibA) significantly increased under continuous light. The pyrophosphohydrolase activity toward FAD was enhanced in AtNUDX23-overexpressing (OX-NUDX23) plants and reduced in AtNUDX23-suppressed (KD-nudx23) plants, compared with the control plants. Interestingly intracellular levels of RF, FMN and FAD significantly decreased in not only OX-NUDX23 but also KD-nudx23 plants. The transcript levels of the flavin metabolic genes also decreased in both plants. Similarly, the increase in intracellular levels on treatment with flavins caused a reduction in the transcript levels of genes involved in flavin metabolism. These results suggest that negative feedback regulation of the metabolism of flavins through the hydrolysis of FAD by AtNUDX23 in plastids is involved in flavin homeostasis in plant cells.
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Affiliation(s)
- Takanori Maruta
- Department of Advanced Bioscience, Faculty of Agriculture, Kinki University, Nakamachi, Nara, 631-8505 Japan
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Liuzzi VC, Giancaspero TA, Gianazza E, Banfi C, Barile M, De Giorgi C. Silencing of FAD synthase gene in Caenorhabditis elegans upsets protein homeostasis and impacts on complex behavioral patterns. Biochim Biophys Acta Gen Subj 2012; 1820:521-31. [PMID: 22306247 DOI: 10.1016/j.bbagen.2012.01.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2011] [Revised: 01/18/2012] [Accepted: 01/22/2012] [Indexed: 12/29/2022]
Abstract
BACKGROUND FAD synthase is a ubiquitous enzyme that catalyses the last step of FAD biosynthesis, allowing for the biogenesis of several flavoproteins. In humans different isoforms are generated by alternative splicing, isoform 1 being localized in mitochondria. Homology searching in Caenorabditis elegans leads to the identification of two human FAD synthase homologues, coded by the single copy gene R53.1. METHODS The C. elegans R53.1 gene was silenced by feeding. The expression level of transcripts was established by semi-quantitative RT-PCR. Overall protein composition was evaluated by two-dimensional electrophoresis. Enzymatic activities were measured by spectrophotometry and oxygen consumption by polarography on isolated mitochondria. RESULTS From R53.1 two transcripts are generated by trans-splicing. Reducing by 50% the transcription efficiency of R53.1 by RNAi results in a 50% reduction in total flavin with decrease in ATP content and increase in ROS level. Significant phenotypical changes are noticed in knock-down nematodes. Among them, a significant impairment in locomotion behaviour possibly due to altered cholinergic transmission. At biochemical level, impairment of flavoenzyme activities and of some KCN-insensitive oxygen-consuming enzymes is detected. At proteomic level, at least 15 abundant proteins are affected by R53.1 gene silencing, among which superoxide dismutases. CONCLUSION AND GENERAL SIGNIFICANCE For the first time we addressed the existence of different isoforms of FAD-metabolizing enzymes in nematodes. A correlation between FAD synthase silencing and flavoenzyme derangement, energy shortage and redox balance impairment is apparent. In this aspect R53.1-interfered nematodes could provide an animal model system for studying human pathologies with alteration in flavin homeostasis/flavoenzyme biogenesis.
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Rawat R, Sandoval FJ, Wei Z, Winkler R, Roje S. An FMN hydrolase of the haloacid dehalogenase superfamily is active in plant chloroplasts. J Biol Chem 2011; 286:42091-42098. [PMID: 22002057 PMCID: PMC3234908 DOI: 10.1074/jbc.m111.260885] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2011] [Revised: 10/13/2011] [Indexed: 11/06/2022] Open
Abstract
FMN hydrolases catalyze dephosphorylation of FMN to riboflavin. Although these enzymes have been described in many organisms, few had their corresponding genes cloned and their recombinant proteins biochemically characterized, and none had their physiological roles determined. We found previously that FMN hydrolase activity in pea chloroplasts is Mg(2+)-dependent, suggesting an enzyme of the haloacid dehalogenase (HAD) superfamily. In this study, a new FMN hydrolase was purified by multistep chromatography after ammonium sulfate precipitation. The molecular weight of the native protein was estimated at ∼59,400, a dimer of about twice the predicted molecular weight of most HAD superfamily phosphatases. After SDS-PAGE of the partially purified material, two separate protein bands within 25-30 kDa were extracted from the gel and analyzed by nanoLC-MS/MS. Peptide sequence matching to the protein samples suggested the presence of three HAD-like hydrolases. cDNAs for sequence homologs from Arabidopsis thaliana of these proteins were expressed in Escherichia coli. Activity screening of the encoded proteins showed that the At1g79790 gene encodes an FMN hydrolase (AtcpFHy1). Plastid localization of AtcpFHy1 was confirmed using fluorescence microscopy of A. thaliana protoplasts transiently expressing the N-terminal fusion of AtcpFHy1 to enhanced green fluorescent protein. Phosphatase activity of AtcpFHy1 is FMN-specific, as assayed with 19 potential substrates. Kinetic parameters and pH and temperature optima for AtcpFHy1 were determined. A phylogenetic analysis of putative phosphatases of the HAD superfamily suggested distinct evolutionary origins for the plastid AtcpFHy1 and the cytosolic FMN hydrolase characterized previously.
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Affiliation(s)
- Renu Rawat
- Institute of Biological Chemistry, Washington State University, Pullman, Washington 99164
| | - Francisco J Sandoval
- Institute of Biological Chemistry, Washington State University, Pullman, Washington 99164
| | - Zhaoyang Wei
- Institute of Biological Chemistry, Washington State University, Pullman, Washington 99164
| | - Robert Winkler
- Departamento de Biotecnología y Tecnología de Alimentos, Instituto Tecnológico y de Estudios Superiores de Monterrey, 64849 Monterrey, Nuevo León, Mexico
| | - Sanja Roje
- Institute of Biological Chemistry, Washington State University, Pullman, Washington 99164.
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Nakane S, Wakamatsu T, Masui R, Kuramitsu S, Fukui K. In vivo, in vitro, and x-ray crystallographic analyses suggest the involvement of an uncharacterized triose-phosphate isomerase (TIM) barrel protein in protection against oxidative stress. J Biol Chem 2011; 286:41636-41646. [PMID: 21984829 PMCID: PMC3308873 DOI: 10.1074/jbc.m111.293886] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2011] [Revised: 10/06/2011] [Indexed: 11/06/2022] Open
Abstract
Accumulating genome sequences have revealed the existence of a large number of conserved hypothetical proteins. Characterization of these proteins is considered essential in the elucidation of intracellular biological pathways. Our previous transcriptomic analysis suggested that, in Thermus thermophilus HB8, loss of an oxidized DNA-repairing activity leads to the up-regulation of a function-unknown gene, tthb071, which is conserved in a wide range of bacteria. Interestingly, the tthb071 gene product, TTHB071, showed a significant primary structure similarity to apurinic/apyrimidinic (AP) endonucleases, which are required for the repair of oxidized DNA. In the present study, we observed that disruption of tthb071 increases the H(2)O(2) sensitivity in T. thermophilus HB8, suggesting the involvement of tthb071 in a protection mechanism against oxidative stress. However, purified TTHB071 exhibited no AP endonuclease or DNA-binding activities, indicating that TTHB071 plays no major role in repairing oxidative DNA damage. Then we determined the three-dimensional structure of TTHB071 complexed with zinc ions by x-ray crystallography. In addition to the overall structural similarity, the zinc-binding fashion was almost identical to that of the phosphatase active site of an AP endonuclease, implying that TTHB071 possesses a phosphatase activity. Based on the structural information around the zinc-binding site, we investigated the binding of TTHB071 to 14 different compounds. As a result, TTHB071 favorably bound FMN and pyridoxal phosphate in a zinc ion-mediated manner. Our results suggest that TTHB071 protects the cell from oxidative stress, through controlling the metabolism of FMN, pyridoxal phosphate, or an analogous compound.
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Affiliation(s)
- Shuhei Nakane
- Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan
| | - Taisuke Wakamatsu
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Ryoji Masui
- Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan; RIKEN SPring-8 Center, Harima Institute, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan
| | - Seiki Kuramitsu
- Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan; Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan; RIKEN SPring-8 Center, Harima Institute, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan
| | - Kenji Fukui
- RIKEN SPring-8 Center, Harima Institute, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan.
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Torchetti EM, Bonomi F, Galluccio M, Gianazza E, Giancaspero TA, Iametti S, Indiveri C, Barile M. Human FAD synthase (isoform 2): a component of the machinery that delivers FAD to apo-flavoproteins. FEBS J 2011; 278:4434-49. [PMID: 21951714 DOI: 10.1111/j.1742-4658.2011.08368.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
A soluble form of human FAD synthase (isoform 2; hFADS2) was produced and purified to homogeneity as a recombinant His-tagged protein. The enzyme binds 1 mole of the FAD product very tightly, although noncovalently. Complete release of FAD from the 'as isolated' protein requires extensive denaturation. A 75 : 25 mixture of apo/holoprotein could be prepared by treatment with mild chaotropes, allowing estimatation of the contribution made by bound FAD to the protein stability and evaluatation of whether structural rearrangements may be required for FAD release. Under turnover conditions, the enzyme catalyzes FAD assembly from ATP and FMN and, at a much lower rate, the pyrophosphorolytic hydrolysis of FAD. Several mechanistic features of both reactions were investigated in detail, along with their dependence on environmental conditions (pH, temperature, dependence on metals). Our data indicate that FAD release may represent the rate-limiting step of the whole catalytic cycle and that the process leading to FAD synthesis, and delivery to client apoproteins may be tightly controlled.
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Affiliation(s)
- Enza M Torchetti
- Dipartimento di Biochimica e Biologia Molecolare E. Quagliariello (DBBM), Università degli Studi di Bari, Bari, Italy
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Pallotta ML. Evidence for the presence of a FAD pyrophosphatase and a FMN phosphohydrolase in yeast mitochondria: a possible role in flavin homeostasis. Yeast 2011; 28:693-705. [PMID: 21915900 DOI: 10.1002/yea.1897] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2011] [Accepted: 07/10/2011] [Indexed: 12/20/2022] Open
Abstract
Despite the crucial roles of flavin cofactors in metabolism, we know little about the enzymes responsible for the turnover of flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) and their subcellular localization. The mechanism by which mitochondria obtain their own flavin cofactors is an interesting point of investigation, because FMN and FAD are mainly located in mitochondria, where they act as redox cofactors of a number of dehydrogenases and oxidases that play a crucial function in both bioenergetics and cellular regulation. In this context, the capability of yeast mitochondria to metabolize externally added and endogenous FAD and FMN was investigated and use was made of purified and bioenergetically active mitochondria prepared starting from the Saccharomyces cerevisiae cell. To determine whether flavin metabolism can occur, the amounts of flavins in aliquots of neutralized perchloric extracts of both spheroplasts and mitochondria were measured by HPLC, and the competence of S. cerevisiae mitochondria to metabolize FAD and FMN was investigated both spectroscopically and via HPLC. FAD deadenylation and FMN dephosphorylation were studied with respect to dependence on substrate concentration, pH profile and inhibitor sensitivity. The existence of two novel mitochondrial FAD pyrophosphatase (diphosphatase) (EC 3.6.1.18) and FMN phosphohydrolase (EC 3.1.3.2) activities, which catalyse the reactions FAD + H₂O → FMN + AMP and FMN + H₂O → riboflavin + Pi respectively, is here shown by fractionation studies. Considering cytosolic riboflavin, FMN and FAD concentrations, as calculated by measuring both spheroplast and mitochondrial contents via HPLC, probably mitochondria play a major role in regulating the flavin pool in yeast and in relation to flavin homeostasis.
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Abbas CA, Sibirny AA. Genetic control of biosynthesis and transport of riboflavin and flavin nucleotides and construction of robust biotechnological producers. Microbiol Mol Biol Rev 2011; 75:321-60. [PMID: 21646432 PMCID: PMC3122625 DOI: 10.1128/mmbr.00030-10] [Citation(s) in RCA: 234] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Riboflavin [7,8-dimethyl-10-(1'-d-ribityl)isoalloxazine, vitamin B₂] is an obligatory component of human and animal diets, as it serves as the precursor of flavin coenzymes, flavin mononucleotide, and flavin adenine dinucleotide, which are involved in oxidative metabolism and other processes. Commercially produced riboflavin is used in agriculture, medicine, and the food industry. Riboflavin synthesis starts from GTP and ribulose-5-phosphate and proceeds through pyrimidine and pteridine intermediates. Flavin nucleotides are synthesized in two consecutive reactions from riboflavin. Some microorganisms and all animal cells are capable of riboflavin uptake, whereas many microorganisms have distinct systems for riboflavin excretion to the medium. Regulation of riboflavin synthesis in bacteria occurs by repression at the transcriptional level by flavin mononucleotide, which binds to nascent noncoding mRNA and blocks further transcription (named the riboswitch). In flavinogenic molds, riboflavin overproduction starts at the stationary phase and is accompanied by derepression of enzymes involved in riboflavin synthesis, sporulation, and mycelial lysis. In flavinogenic yeasts, transcriptional repression of riboflavin synthesis is exerted by iron ions and not by flavins. The putative transcription factor encoded by SEF1 is somehow involved in this regulation. Most commercial riboflavin is currently produced or was produced earlier by microbial synthesis using special selected strains of Bacillus subtilis, Ashbya gossypii, and Candida famata. Whereas earlier RF overproducers were isolated by classical selection, current producers of riboflavin and flavin nucleotides have been developed using modern approaches of metabolic engineering that involve overexpression of structural and regulatory genes of the RF biosynthetic pathway as well as genes involved in the overproduction of the purine precursor of riboflavin, GTP.
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Affiliation(s)
| | - Andriy A. Sibirny
- Institute of Cell Biology, NAS of Ukraine, Lviv 79005, Ukraine
- University of Rzeszow, Rzeszow 35-601, Poland
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Simmen T, Lynes EM, Gesson K, Thomas G. Oxidative protein folding in the endoplasmic reticulum: tight links to the mitochondria-associated membrane (MAM). Biochim Biophys Acta 2010; 1798:1465-73. [PMID: 20430008 DOI: 10.1016/j.bbamem.2010.04.009] [Citation(s) in RCA: 142] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2010] [Revised: 04/15/2010] [Accepted: 04/16/2010] [Indexed: 12/18/2022]
Abstract
The production of secretory proteins at the ER (endoplasmic reticulum) depends on a ready supply of energy and metabolites as well as the close monitoring of the chemical conditions that favor oxidative protein folding. ER oxidoreductases and chaperones fold nascent proteins into their export-competent three-dimensional structure. Interference with these protein folding enzymes leads to the accumulation of unfolded proteins within the ER lumen, causing an acute organellar stress that triggers the UPR (unfolded protein response). The UPR increases the transcription of ER chaperones commensurate with the load of newly synthesized proteins and can protect the cell from ER stress. Persistant stress, however, can force the UPR to commit cells to undergo apoptotic cell death, which requires the emptying of ER calcium stores. Conversely, a continuous ebb and flow of calcium occurs between the ER and mitochondria during resting conditions on a domain of the ER that forms close contacts with mitochondria, the MAM (mitochondria-associated membrane). On the MAM, ER folding chaperones such as calnexin and calreticulin and oxidoreductases such as ERp44, ERp57 and Ero1alpha regulate calcium flux from the ER through reversible, calcium and redox-dependent interactions with IP3Rs (inositol 1,4,5-trisphophate receptors) and with SERCAs (sarcoplasmic/endoplasmic reticulum calcium ATPases). During apoptosis progression and depending on the identity of the ER chaperone and oxidoreductase, these interactions increase or decrease, suggesting that the extent of MAM targeting of ER chaperones and oxidoreductases could shift the readout of ER-mitochondria calcium exchange from housekeeping to apoptotic. However, little is known about the cytosolic factors that mediate the on/off interactions between ER chaperones and oxidoreductases with ER calcium channels and pumps. One candidate regulator is the multi-functional molecule PACS-2 (phosphofurin acidic cluster sorting protein-2). Recent studies suggest that PACS-2 mediates localization of a mobile pool of calnexin to the MAM in addition to regulating homeostatic ER calcium signaling as well as MAM integrity. Together, these findings suggest that cytosolic, membrane and lumenal proteins combine to form a two-way switch that determines the rate of protein secretion by providing ions and metabolites and that appears to participate in the pro-apoptotic ER-mitochondria calcium transfer.
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Affiliation(s)
- Thomas Simmen
- Faculty of Medicine and Dentistry, School of Molecular and Systems Medicine, Department of Cell Biology, University of Alberta, Edmonton, Alberta, Canada.
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31
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de Bari L, Valenti D, Atlante A, Passarella S. L-lactate generates hydrogen peroxide in purified rat liver mitochondria due to the putative L-lactate oxidase localized in the intermembrane space. FEBS Lett 2010; 584:2285-90. [PMID: 20350544 DOI: 10.1016/j.febslet.2010.03.038] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2010] [Accepted: 03/24/2010] [Indexed: 12/30/2022]
Abstract
In order to ascertain whether and how mitochondria can produce hydrogen peroxide (H(2)O(2)) as a result of L-lactate addition, we monitored H(2)O(2) generation in rat liver mitochondria and in submitochondrial fractions free of peroxisomal and cytosolic contamination. We found that H(2)O(2) is produced independently on the respiratory chain with 1:1 stoichiometry with pyruvate, due to a putative flavine-dependent L-lactate oxidase restricted to the intermembrane space. The L-lactate oxidase reaction shows a hyperbolic dependence on L-lactate concentration and is inhibited by NAD(+) in a competitive manner, being the enzyme different from the L-lactate dehydrogenase isoenzymes as shown by their pH profiles.
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Affiliation(s)
- Lidia de Bari
- Istituto di Biomembrane e Bioenergetica (IBBE), CNR, Bari, Italy
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32
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Torchetti EM, Brizio C, Colella M, Galluccio M, Giancaspero TA, Indiveri C, Roberti M, Barile M. Mitochondrial localization of human FAD synthetase isoform 1. Mitochondrion 2010; 10:263-73. [PMID: 20060505 DOI: 10.1016/j.mito.2009.12.149] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2009] [Revised: 12/14/2009] [Accepted: 12/22/2009] [Indexed: 10/20/2022]
Abstract
FAD synthetase or ATP:FMN adenylyl transferase (FADS or FMNAT, EC 2.7.7.2) is a key enzyme in the metabolic pathway that converts riboflavin into the redox cofactor FAD. We face here the still controversial sub-cellular localization of FADS in eukaryotes. First, by western blotting experiments, we confirm the existence in rat liver of different FADS isoforms which are distinct for molecular mass and sub-cellular localization. A cross-reactive band with an apparent molecular mass of 60 kDa on SDS-PAGE is localized in the internal compartments of freshly isolated purified rat liver mitochondria. Recently we have identified two isoforms of FADS in humans, that differ for an extra-sequence of 97 amino acids at the N-terminus, present only in isoform 1 (hFADS1). The first 17 residues of hFADS1 represent a cleavable mitochondrial targeting sequence (by Target-P prediction). The recombinant hFADS1 produced in Escherichia coli showed apparent K(m) and V(max) values for FMN equal to 1.3+/-0.7 microM and 4.4+/-1.3 nmol x min(-1) x mg protein(-1), respectively, and was inhibited by FMN at concentration higher than 1.5 microM. The in vitro synthesized hFADS1, but not hFADS2, is imported into rat liver mitochondria and processed into a lower molecular mass protein product. Immunofluorescence confocal microscopy performed on BHK-21 and Caco-2 cell lines transiently expressing the two human isoforms, definitively confirmed that hFADS1, but not hFADS2, localizes in mitochondria.
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Affiliation(s)
- Enza Maria Torchetti
- Dipartimento di Biochimica e Biologia Molecolare E. Quagliariello, Università degli Studi di Bari, Via Orabona 4, I-70126 Bari, Italy.
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Giancaspero TA, Locato V, de Pinto MC, De Gara L, Barile M. The occurrence of riboflavin kinase and FAD synthetase ensures FAD synthesis in tobacco mitochondria and maintenance of cellular redox status. FEBS J 2009; 276:219-31. [PMID: 19049514 DOI: 10.1111/j.1742-4658.2008.06775.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Intact mitochondria isolated from Nicotiana tabacum cv. Bright Yellow 2 (TBY-2) cells can take up riboflavin via carrier-mediated systems that operate at different concentration ranges and have different uptake efficiencies. Once inside mitochondria, riboflavin is converted into catalytically active cofactors, FMN and FAD, due to the existence of a mitochondrial riboflavin kinase (EC 2.7.1.26) and an FAD synthetase (EC 2.7.7.2). Newly synthesized FAD can be exported from intact mitochondria via a putative FAD exporter. The dependence of FMN synthesis rate on riboflavin concentration shows saturation kinetics with a sigmoidal shape (S(0.5), V(max) and Hill coefficient values 0.32+/-0.12 microm, 1.4 nmol x min(-1) x mg(-1) protein and 3.1, respectively). The FAD-forming enzymes are both activated by MgCl(2), and reside in two distinct monofunctional enzymes, which can be physically separated in mitochondrial soluble and membrane-enriched fractions, respectively.
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Affiliation(s)
- Teresa A Giancaspero
- Dipartimento di Biochimica e Biologia Molecolare E. Quagliariello, Università degli Studi di Bari, Bari, Italy
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Sandoval FJ, Zhang Y, Roje S. Flavin nucleotide metabolism in plants: monofunctional enzymes synthesize fad in plastids. J Biol Chem 2008; 283:30890-900. [PMID: 18713732 PMCID: PMC2662166 DOI: 10.1074/jbc.m803416200] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2008] [Revised: 07/30/2008] [Indexed: 11/06/2022] Open
Abstract
FAD synthetases (EC 2.7.7.2) catalyze biosynthesis of FAD from FMN and ATP. Monofunctional FAD synthetases are known to exist in mammals and yeast; bifunctional enzymes also catalyzing phosphorylation of riboflavin to FMN are known to exist in bacteria. Previously known eukaryotic enzymes with FAD synthetase activity have no sequence similarity to prokaryotic enzymes with riboflavin kinase and FAD synthetase activities. Proteins homologous to bacterial bifunctional FAD synthetases, yet shorter and lacking amino acid motifs at the C terminus, were found by bioinformatic analyses in vascular plant genomes, suggesting that plants contain a type of FAD synthetase previously known to exist only in prokaryotes. The Arabidopsis thaliana genome encodes two of such proteins. Both proteins, which we named AtRibF1 and AtRibF2, carry N-terminal extensions with characteristics of organellar targeting peptides. AtRibF1 and AtRibF2 cDNAs were cloned by reverse transcription-PCR. Only FAD synthetase activity was detected in the recombinant enzymes produced in Escherichia coli. FMN and ATP inhibited both enzymes. Kinetic parameters of AtRibF1 and AtRibF2 for the two substrates were similar. Confocal microscopy of protoplasts transformed with enhanced green fluorescence protein-fused proteins showed that AtRibF1 and AtRibF2 are targeted to plastids. In agreement with subcellular localization to plastids, Percoll-isolated chloroplasts from pea (Pisum sativum) synthesized FAD from imported riboflavin. Riboflavin kinase, FMN hydrolase, and FAD pyrophosphatase activities were detected in Percoll-isolated chloroplasts and mitochondria from pea. We propose from these new findings a model for subcellular distribution of enzymes that synthesize and hydrolyze flavin nucleotides in plants.
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Affiliation(s)
- Francisco J Sandoval
- Institute of Biological Chemistry, Washingon State University, Pullman, WA 99164, USA
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Wakamatsu T, Nakagawa N, Kuramitsu S, Masui R. Structural basis for different substrate specificities of two ADP-ribose pyrophosphatases from Thermus thermophilus HB8. J Bacteriol 2008; 190:1108-17. [PMID: 18039767 PMCID: PMC2223557 DOI: 10.1128/jb.01522-07] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2007] [Accepted: 11/12/2007] [Indexed: 11/20/2022] Open
Abstract
ADP-ribose (ADPR) is one of the main substrates of Nudix proteins. Among the eight Nudix proteins of Thermus thermophilus HB8, we previously determined the crystal structure of Ndx4, an ADPR pyrophosphatase (ADPRase). In this study we show that Ndx2 of T. thermophilus also preferentially hydrolyzes ADPR and flavin adenine dinucleotide and have determined its crystal structure. We have determined the structures of Ndx2 alone and in complex with Mg2+, with Mg2+ and AMP, and with Mg2+ and a nonhydrolyzable ADPR analogue. Although Ndx2 recognizes the AMP moiety in a manner similar to those for other ADPRases, it recognizes the terminal ribose in a distinct manner. The residues responsible for the recognition of the substrate in Ndx2 are not conserved among ADPRases. This may reflect the diversity in substrate specificity among ADPRases. Based on these results, we propose the classification of ADPRases into two types: ADPRase-I enzymes, which exhibit high specificity for ADPR; and ADPRase-II enzymes, which exhibit low specificity for ADPR. In the active site of the ternary complexes, three Mg2+ ions are coordinated to the side chains of conserved glutamate residues and water molecules. Substitution of Glu90 and Glu94 with glutamine suggests that these residues are essential for catalysis. These results suggest that ADPRase-I and ADPRase-II enzymes have nearly identical catalytic mechanisms but different mechanisms of substrate recognition.
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Affiliation(s)
- Taisuke Wakamatsu
- Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka 565-0871, Japan
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36
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Akimoto M, Sato Y, Nemoto E, Todo H, Hasegawa T, Sugibayashi K. Pharmacokinetic Profile of Flavin Adenine Dinucleotide, Flavin Mononucleotide and Riboflavin Following Intravenous Administration of Riboflavin or Its Coenzymes in Rats. ACTA ACUST UNITED AC 2007. [DOI: 10.1248/jhs.53.332] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Masayuki Akimoto
- Faculty of Pharmaceutical Science, Josai International University
| | - Yuko Sato
- Faculty of Pharmaceutical Science, Josai International University
| | - Eiichi Nemoto
- Faculty of Pharmaceutical Science, Josai International University
| | - Hiroaki Todo
- Faculty of Pharmaceutical Sciences, Josai University
| | - Tetsuya Hasegawa
- Faculty of Pharmaceutical Science, Josai International University
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37
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Akimoto M, Sato Y, Okubo T, Todo H, Hasegawa T, Sugibayashi K. Conversion of FAD to FMN and riboflavin in plasma: effects of measuring method. Biol Pharm Bull 2006; 29:1779-82. [PMID: 16880644 DOI: 10.1248/bpb.29.1779] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The stability of flavin adenin dinucleotide (FAD) in plasma was studied under a low-intensity light and FAD was found to be converted to flavin mononucleotide (FMN) and riboflavin (RF) in both human and rat plasma. The hydrolysis rates of FAD in plasma at 4 degrees C were lower than those at 37 degrees C. In addition, the hydrolysis rates were markedly inhibited when EDTA, known as an anticoagulant, was added to plasma. These results indicated that plasma samples in pharmacokinetic studies should be pretreated with EDTA, extracted at the earliest convenience and lower temperature like 4 degrees C to keep a high stability. The pharmacokinetic study after intravenous administration of FAD at a dose of 500 nmol/kg as FAD in rats was performed with plasma samples after addition of EDTA under strict light and temperature control. A measurable amount of FAD in plasma together with rapid conversions of FAD to FMN and RF were observed in rat plasma. The AUC values (mean+/-S.D. of 4 rats) for FAD, FMN and RF were 707+/-378, 3643+/-958 and 30095+/-3544 nmol x min/l, respectively. Using excess EDTA under strict temperature and light control may be useful for assessment of vitamin B2 in the in vivo study.
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Affiliation(s)
- Masayuki Akimoto
- Faculty of Pharmaceutical Science, Josai International University, Japan.
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38
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Gianazza E, Vergani L, Wait R, Brizio C, Brambilla D, Begum S, Giancaspero TA, Conserva F, Eberini I, Bufano D, Angelini C, Pegoraro E, Tramontano A, Barile M. Coordinated and reversible reduction of enzymes involved in terminal oxidative metabolism in skeletal muscle mitochondria from a riboflavin-responsive, multiple acyl-CoA dehydrogenase deficiency patient. Electrophoresis 2006; 27:1182-98. [PMID: 16470778 DOI: 10.1002/elps.200500687] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
In this case report we studied alterations in mitochondrial proteins in a patient suffering from recurrent profound muscle weakness, associated with ethylmalonic-adipic aciduria, who had benefited from high dose of riboflavin treatment. Morphological and biochemical alterations included muscle lipid accumulation, low muscle carnitine content, reduction in fatty acid beta-oxidation and reduced activity of complexes I and II of the respiratory chain. Riboflavin therapy partially or totally reversed these symptoms and increased the level of muscle flavin adenine dinucleotide, suggesting that aberrant flavin cofactor metabolism accounted for the disease. Proteomic investigation of muscle mitochondria revealed decrease or absence of several flavoenzymes, enzymes related to flavin cofactor-dependent mitochondrial pathways and mitochondrial or mitochondria-associated calcium-binding proteins. All these deficiencies were completely rescued after riboflavin treatment. This study indicates for the first time a profound involvement of riboflavin/flavin cofactors in modulating the level of a number of functionally coordinated polypeptides involved in fatty acyl-CoA and amino acid metabolism, extending the number of enzymatic pathways altered in riboflavin-responsive multiple acyl-CoA dehydrogenase deficiency.
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Affiliation(s)
- Elisabetta Gianazza
- Dipartimento di Scienze Farmacologiche, Gruppo di Studio per la Proteomica e la Struttura delle Proteine, Università degli Studi, Milano, Italy
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39
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Brizio C, Galluccio M, Wait R, Torchetti EM, Bafunno V, Accardi R, Gianazza E, Indiveri C, Barile M. Over-expression in Escherichia coli and characterization of two recombinant isoforms of human FAD synthetase. Biochem Biophys Res Commun 2006; 344:1008-16. [PMID: 16643857 DOI: 10.1016/j.bbrc.2006.04.003] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2006] [Accepted: 04/01/2006] [Indexed: 11/16/2022]
Abstract
FAD synthetase (FADS) (EC 2.7.7.2) is a key enzyme in the metabolic pathway that converts riboflavin into the redox cofactor FAD. Two hypothetical human FADSs, which are the products of FLAD1 gene, were over-expressed in Escherichia coli and identified by ESI-MS/MS. Isoform 1 was over-expressed as a T7-tagged protein which had a molecular mass of 63kDa on SDS-PAGE. Isoform 2 was over-expressed as a 6-His-tagged fusion protein, carrying an extra 84 amino acids at the N-terminal with an apparent molecular mass of 60kDa on SDS-PAGE. It was purified near to homogeneity from the soluble cell fraction by one-step affinity chromatography. Both isoforms possessed FADS activity and had a strict requirement for MgCl(2), as demonstrated using both spectrophotometric and chromatographic methods. The purified recombinant isoform 2 showed a specific activity of 6.8+/-1.3nmol of FAD synthesized/min/mg protein and exhibited a K(M) value for FMN of 1.5+/-0.3microM. This is the first report on characterization of human FADS, and the first cloning and over-expression of FADS from an organism higher than yeast.
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Affiliation(s)
- Carmen Brizio
- Dipartimento di Biochimica e Biologia Molecolare Ernesto Quagliariello, Università degli Studi di Bari, Via Orabona 4, I-70126 Bari, Italy
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40
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Abstract
Riboflavin kinases catalyze synthesis of FMN from riboflavin and ATP. These enzymes have to date been cloned from bacteria, yeast, and mammals, but not from plants. Bioinformatic approaches suggested that diverse plant species, including many angiosperms, two gymnosperms, a moss (Physcomitrella patens), and a unicellular green alga (Chlamydomonas reinhardtii), encode proteins that are homologous to riboflavin kinases of yeast and mammals, but contain an N-terminal domain that belongs to the haloacid dehalogenase superfamily of enzymes. The Arabidopsis homolog of these proteins was cloned by RT-PCR, and was shown to have riboflavin kinase and FMN hydrolase activities by characterizing the recombinant enzyme produced in Escherichia coli. Both activities of the purified recombinant Arabidopsis enzyme (AtFMN/FHy) increased when the enzyme assays contained 0.02% Tween 20. The FMN hydrolase activity of AtFMN/FHy greatly decreased when EDTA replaced Mg(2+) in the assays, as expected for a member of the Mg(2+)-dependent haloacid dehalogenase family. The functional overexpression of the individual domains in E. coli establishes that the riboflavin kinase and FMN hydrolase activities reside, respectively, in the C-terminal (AtFMN) and N-terminal (AtFHy) domains of AtFMN/FHy. Biochemical characterization of AtFMN/FHy, AtFMN, and AtFHy shows that the riboflavin kinase and FMN hydrolase domains of AtFMN/FHy can be physically separated, with little change in their kinetic properties.
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Affiliation(s)
- Francisco J Sandoval
- Institute of Biological Chemistry, Washington State University, Pullman, Washington 99164, USA
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41
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Bafunno V, Giancaspero TA, Brizio C, Bufano D, Passarella S, Boles E, Barile M. Riboflavin uptake and FAD synthesis in Saccharomyces cerevisiae mitochondria: involvement of the Flx1p carrier in FAD export. J Biol Chem 2003; 279:95-102. [PMID: 14555654 DOI: 10.1074/jbc.m308230200] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have studied the functional steps by which Saccharomyces cerevisiae mitochondria can synthesize FAD from cytosolic riboflavin (Rf). Riboflavin uptake into mitochondria took place via a mechanism that is consistent with the existence of (at least two) carrier systems. FAD was synthesized inside mitochondria by a mitochondrial FAD synthetase (EC 2.7.7.2), and it was exported into the cytosol via an export system that was inhibited by lumiflavin, and which was different from the riboflavin uptake system. To understand the role of the putative mitochondrial FAD carrier, Flx1p, in this pathway, an flx1Delta mutant strain was constructed. Coupled mitochondria isolated from flx1Delta mutant cells were compared with wild-type mitochondria with respect to the capability to take up Rf, to synthesize FAD from it, and to export FAD into the extramitochondrial phase. Mitochondria isolated from flx1Delta mutant cells specifically lost the ability to export FAD, but did not lose the ability to take up Rf, FAD, or FMN and to synthesize FAD from Rf. Hence, Flx1p is proposed to be the mitochondrial FAD export carrier. Moreover, deletion of the FLX1 gene resulted in a specific reduction of the activities of mitochondrial lipoamide dehydrogenase and succinate dehydrogenase, which are FAD-binding enzymes. For the flavoprotein subunit of succinate dehydrogenase we could demonstrate that this was not due to a changed level of mitochondrial FAD or to a change in the degree of flavinylation of the protein. Instead, the amount of the flavoprotein subunit of succinate dehydrogenase was strongly reduced, indicating an additional regulatory role for Flx1p in protein synthesis or degradation.
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Affiliation(s)
- Valeria Bafunno
- Dipartimento di Biochimica e Biologia Molecolare, Università di Bari, Via Orabona 4, Bari, Italy
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42
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Roberti M, Polosa PL, Bruni F, Musicco C, Gadaleta MN, Cantatore P. DmTTF, a novel mitochondrial transcription termination factor that recognises two sequences of Drosophila melanogaster mitochondrial DNA. Nucleic Acids Res 2003; 31:1597-604. [PMID: 12626700 PMCID: PMC152874 DOI: 10.1093/nar/gkg272] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Using a combination of bioinformatic and molecular biology approaches a Drosophila melanogaster protein, DmTTF, has been identified, which exhibits sequence and structural similarity with two mitochondrial transcription termination factors, mTERF (human) and mtDBP (sea urchin). Import/processing assays indicate that DmTTF is synthesised as a precursor of 410 amino acids and is imported into mitochondria, giving rise to a mature product of 366 residues. Band-shift and DNase I protection experiments show that DmTTF binds two homologous, short, non-coding sequences of Drosophila mitochondrial DNA, located at the 3' end of blocks of genes transcribed on opposite strands. The location of the target sequences coincides with that of two of the putative transcription termination sites previously hypothesised. These results indicate that DmTTF is the termination factor of mitochondrial transcription in Drosophila. The existence of two DmTTF binding sites might serve not only to stop transcription but also to control the overlapping of a large number of transcripts generated by the peculiar transcription mechanism operating in this organism.
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Affiliation(s)
- Marina Roberti
- Dipartimento di Biochimica e Biologia Molecolare, Università di Bari, CNR, Via Orabona 4, 70125 Bari, Italy
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43
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Abstract
The flavinylation and the presequence processing of the mitochondrial matrix enzyme dimethylglycine dehydrogenase (Me(2)GlyDH) were investigated with the reticulocyte lysate translated precursor (pMe(2)GlyDH) added to solubilised mitoplasts of rat liver mitochondria. The flavinylation of pMe(2)GlyDH was strictly dependent on the addition of mitochondrial protein(s), among which the mitochondrial flavinylation stimulating factor [Brizio C., et al. (2000) Eur. J. Biochem 267, 4346-4354], that actively promotes holo-Me(2)GlyDH formation. The precursor processing, that accompanies the biogenesis of the enzyme, was not required to allow the flavinylation to proceed. The comparison of the time course of the flavinylation and the processing of pMe(2)GlyDH demonstrated that the covalent attachment of the flavin moiety preceded the presequence processing by mitochondrial processing peptidase.
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Affiliation(s)
- Carmen Brizio
- Dipartimento di Biochimica e Biologia Molecolare, Università di Bari, C.N.R., Via Orabona 4, Italy
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44
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Di Lisa F, Menabò R, Canton M, Barile M, Bernardi P. Opening of the mitochondrial permeability transition pore causes depletion of mitochondrial and cytosolic NAD+ and is a causative event in the death of myocytes in postischemic reperfusion of the heart. J Biol Chem 2001; 276:2571-5. [PMID: 11073947 DOI: 10.1074/jbc.m006825200] [Citation(s) in RCA: 497] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The opening of the mitochondrial permeability transition pore (PTP) has been suggested to play a key role in various forms of cell death, but direct evidence in intact tissues is still lacking. We found that in the rat heart, 92% of NAD(+) glycohydrolase activity is associated with mitochondria. This activity was not modified by the addition of Triton X-100, although it was abolished by mild treatment with the protease Nagarse, a condition that did not affect the energy-linked properties of mitochondria. The addition of Ca(2+) to isolated rat heart mitochondria resulted in a profound decrease in their NAD(+) content, which followed mitochondrial swelling. Cyclosporin A(CsA), a PTP inhibitor, completely prevented NAD(+) depletion but had no effect on the glycohydrolase activity. Thus, in isolated mitochondria PTP opening makes NAD(+) available for its enzymatic hydrolysis. Perfused rat hearts subjected to global ischemia for 30 min displayed a 30% decrease in tissue NAD(+) content, which was not modified by extending the duration of ischemia. Reperfusion resulted in a more severe reduction of both total and mitochondrial contents of NAD(+), which could be measured in the coronary effluent together with lactate dehydrogenase. The addition of 0.2 microm CsA or of its analogue MeVal-4-Cs (which does not inhibit calcineurin) maintained higher NAD(+) contents, especially in mitochondria, and significantly protected the heart from reperfusion damage, as shown by the reduction in lactate dehydrogenase release. Thus, upon reperfusion after prolonged ischemia, PTP opening in the heart can be documented as a CsA-sensitive release of NAD(+), which is then partly degraded by glycohydrolase and partly released when sarcolemmal integrity is compromised. These results demonstrate that PTP opening is a causative event in reperfusion damage of the heart.
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Affiliation(s)
- F Di Lisa
- Consiglio Nazionale delle Ricerche Unit for the Study of Biomembranes, and the Department of Biological Chemistry, University of Padova, Italy.
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45
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Abstract
Here we provide evidence that mitochondria isolated from rat liver can synthesize FAD from riboflavin that has been taken up and from endogenous ATP. Riboflavin uptake takes place via a carrier-mediated process, as shown by the inverse relationship between fold accumulation and riboflavin concentration, the saturation kinetics [riboflavin Km and Vmax values were 4.4+/-1.3 microM and 35+/-5 pmol x min(-1) (mg protein)(-1), respectively] and the inhibition shown by the thiol reagent mersalyl, which cannot enter the mitochondria. FAD synthesis is due to the existence of FAD synthetase (EC 2.7.7.2), localized in the matrix, which has as a substrate pair mitochondrial ATP and FMN synthesized from taken up riboflavin via the putative mitochondrial riboflavin kinase. In the light of certain features, including the protein thermal stability and molecular mass, mitochondrial FAD synthetase differs from the cytosolic isoenzyme. Apparent Km and apparent Vmax values for FMN were 5.4+/-0.9 microM and 22.9+/-1.4 pmol x min(-1) x (mg matrix protein)(-1), respectively. Newly synthesized FAD inside the mitochondria can be exported from the mitochondria in a manner sensitive to atractyloside but insensitive to mersalyl. The occurrence of the riboflavin/FAD cycle is proposed to account for riboflavin uptake in mitochondria biogenesis and riboflavin recovery in mitochondrial flavoprotein degradation; both are prerequisites for the synthesis of mitochondrial flavin cofactors.
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Affiliation(s)
- M Barile
- Dipartimento di Biochimica e Biologia Molecolare, Università di Bari, and Centro di Studio sui Mitocondri e Metabolismo Energetico, Bari, C.N.R., Italy.
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46
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Brizio C, Otto A, Brandsch R, Passarella S, Barile M. A protein factor of rat liver mitochondrial matrix involved in flavinylation of dimethylglycine dehydrogenase. Eur J Biochem 2000; 267:4346-54. [PMID: 10880957 DOI: 10.1046/j.1432-1327.2000.01464.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The involvement of rat liver mitochondria in the flavinylation of the mitochondrial matrix flavoenzyme dimethylglycine dehydrogenase (Me2GlyDH) has been investigated. Me2GlyDH was synthesized as an apoenzyme in the rabbit reticulocyte lysate (RL) transcription/translation system and its flavinylation was monitored by virtue of the trypsin resistance of the holoenzyme. The rate of holoenzyme formation in the presence of FAD was stimulated with increasing efficiency by the addition of solubilized mitoplasts, mitochondrial matrix and DEAE-purified matrix fraction. Apo-Me2GlyDH was also converted into holoenzyme when the solubilized mitoplasts were supplemented with FMN and ATP. This observation is consistent with the existence of a mitochondrial FAD synthetase generating the FAD needed for holoenzyme formation from its precursors. Holoenzyme formation in the presence of FAD increased linearly with the concentration of matrix protein in the assay, and depended on the amount of externally added Me2GlyDH with saturation characteristics. These findings suggest the presence of a protein factor in the mitochondrial matrix which stimulates Me2GlyDH flavinylation. This factor was different from both mitochondrial heat shock protein (Hsp)70, as shown by immunodepletion experiments, and mitochondrial Hsp60, as demonstrated by the capability of a DEAE-purified matrix fraction devoid of Hsp60 to accelerate flavinylation of both RL translated and purified Me2GlyDH.
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Affiliation(s)
- C Brizio
- Dipartimento di Biochimica e Biologia Molecolare, Università di Bari, Italy
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47
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Vergani L, Barile M, Angelini C, Burlina AB, Nijtmans L, Freda MP, Brizio C, Zerbetto E, Dabbeni-Sala F. Riboflavin therapy. Biochemical heterogeneity in two adult lipid storage myopathies. Brain 1999; 122 ( Pt 12):2401-11. [PMID: 10581232 DOI: 10.1093/brain/122.12.2401] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Two unrelated adult males, aged 36 (patient 1) and 25 (patient 2) years, presented with subacute carnitine-deficient lipid storage myopathy that was totally and partly responsive to riboflavin supplementation in the two patients, respectively. Plasma acyl-carnitine and urinary organic acid profiles indicated multiple acyl coenzyme A dehydrogenase deficiency, which was mild in patient 1 and severe in patient 2. The activities of short-chain and medium-chain acyl coenzyme A dehydrogenases in mitochondrial fractions were decreased, especially in patient 2. This was in agreement with Western blotting results. Flavin-dependent complexes I and II were studied by immunoblotting and densitometric quantification of two-dimensional electrophoresis with comparable results. Complex I was present in normal amounts in both patients, whereas complex II was decreased only in the pretherapy muscle of patient 2. Flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN) concentrations in muscle and isolated mitochondria, and the activity of mitochondrial FAD pyrophosphatase, showed that patient 1 had low levels of FAD (46%) and FMN (49%) in mitochondria, with a significant increase (P < 0.01) in mitochondrial FAD pyrophosphatase (273%) compared with controls. Patient 2 had similar low levels of FAD and FMN in both total muscle (FAD and FMN 22% of controls) and mitochondria (FAD 26%; FMN 16%) and normal activity of mitochondrial FAD pyrophosphatase. All of these biochemical parameters were either totally or partly corrected after riboflavin therapy.
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Affiliation(s)
- L Vergani
- Neuromuscular Center, Department of Neurological Science, University of Padova, Padova, Italy.
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48
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Abstract
In this study, evidence is given that a number of isolated coupled plant mitochondria (from durum wheat, bread wheat, spelt, rye, barley, potato, and spinach) can take up externally added K(+) ions. This was observed by following mitochondrial swelling in isotonic KCl solutions and was confirmed by a novel method in which the membrane potential decrease due to externally added K(+) is measured fluorimetrically by using safranine. A detailed investigation of K(+) uptake by durum wheat mitochondria shows hyperbolic dependence on the ion concentration and specificity. K(+) uptake electrogenicity and the non-competitive inhibition due to either ATP or NADH are also shown. In the whole, the experimental findings reported in this paper demonstrate the existence of the mitochondrial K(+)(ATP) channel in plants (PmitoK(ATP)). Interestingly, Mg(2+) and glyburide, which can inhibit mammalian K(+) channel, have no effect on PmitoK(ATP). In the presence of the superoxide anion producing system (xanthine plus xanthine oxidase), PmitoK(ATP) activation was found. Moreover, an inverse relationship was found between channel activity and mitochondrial superoxide anion formation, as measured via epinephrine photometric assay. These findings strongly suggest that mitochondrial K(+) uptake could be involved in plant defense mechanism against oxidative stress due to reactive oxygen species generation.
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Affiliation(s)
- D Pastore
- Dipartimento di Scienze Animali, Vegetali e dell'Ambiente, Università del Molise, Via De Sanctis, 86100 Campobasso, Italy
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49
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Barile M, Valenti D, Brizio C, Quagliariello E, Passarella S. Rat liver mitochondria can hydrolyse thiamine pyrophosphate to thiamine monophosphate which can cross the mitochondrial membrane in a carrier-mediated process. FEBS Lett 1998; 435:6-10. [PMID: 9755848 DOI: 10.1016/s0014-5793(98)01007-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
We show here that TPP --> TMP conversion can take place in rat liver mitochondria. This occurs via the novel, putative TPP pyrophosphatase localised in the mitochondrial matrix, as shown both by digitonin titration and by an HPLC enzyme assay carried out on the mitochondrial matrix fraction. Certain features of the reaction, including the substrate and pH dependence, are reported. Additional evidence is given that externally added TMP can cross the mitochondrial membrane in a manner consistent with the occurrence of a carrier-mediated process. This can occur both via the TPP translocator and via a novel translocator, inhibited by CAT but different from the ADP/ATP carrier.
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Affiliation(s)
- M Barile
- Dipartimento di Biochimica e Biologia Molecolare, Università di Bari, Italy.
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50
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Pallotta ML, Brizio C, Fratianni A, De Virgilio C, Barile M, Passarella S. Saccharomyces cerevisiae mitochondria can synthesise FMN and FAD from externally added riboflavin and export them to the extramitochondrial phase. FEBS Lett 1998; 428:245-9. [PMID: 9654142 DOI: 10.1016/s0014-5793(98)00544-4] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Evidence is given that mitochondria isolated from Saccharomyces cerevisiae can take up externally added riboflavin and synthesise from it both flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) probably due to the existence of the mitochondrial riboflavin kinase already reported and the novel mitochondria FAD synthetase. Moreover Saccharomyces cerevisiae mitochondria can export the newly synthesised flavin derivatives to the extramitochondrial phase. This has been proven to take place with 1:1 stoichiometry with riboflavin decrease outside mitochondria, thus showing that flavin traffic occurs across the mitochondrial membranes.
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Affiliation(s)
- M L Pallotta
- Dipartimento di Scienze Animali, Vegetali e dell' Ambiente, Università del Molise, Campobasso, Italy
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