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Qi J, Wang Y, Li H, Shang Y, Gao S, Ding C, Liu X, Wang S, Li T, Tian M, Yu S. Mycoplasma synoviae dihydrolipoamide dehydrogenase is an immunogenic fibronectin/plasminogen binding protein and a putative adhesin. Vet Microbiol 2021; 265:109328. [PMID: 35032790 DOI: 10.1016/j.vetmic.2021.109328] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [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: 06/03/2020] [Revised: 11/23/2020] [Accepted: 12/29/2021] [Indexed: 10/19/2022]
Abstract
Mycoplasma synoviae (M. synoviae) is an important avian pathogen that causes arthritis and airsacculitis in young chickens and turkeys. Infection by M. synoviae results in considerable economic losses to the poultry industry worldwide. Cytoadherence is a crucial stage during mycoplasma infection. Dihydrolipoamide dehydrogenase (PdhD) is a flavin-dependent enzyme that is critical for energy metabolism and redox balance. To date, its role in cytoadherence is poorly understood. In this study, recombinant PdhD from M. synoviae (rMSPdhD) was expressed in the supernatant component of E. coli BL21 and rabbit anti-rMSPdhD serum was prepared. rMSPdhD was shown to be an immunogenic protein by immunoblot assays, while the mycoplasmacidal assay revealed that the rabbit anti-rMSPdhD serum had a high complement-dependent mycoplasmacidal rate (88.5 %). Using a suspension immunofluorescence assay and subcellular localization analysis, MSPdhD was shown to be a surface-localized protein distributed in both the cytoplasm and cell membrane of M. synoviae. The enzymatic activity of rMSPdhD was determined by measuring its ability to reduce lipoamide to dihydrolipoamide and convert NADH to NAD+. Using an indirect immunofluorescence assay, rMSPdhD was shown to adhere to DF-1 chicken embryo fibroblast cells. Furthermore, the attachment of M. synoviae to DF-1 cells was significantly inhibited by rabbit anti-rMSPdhD serum. Western blot and ELISA binding assays confirmed that rMSPdhD also bound to fibronectin (Fn) and plasminogen (Plg) in a dose-dependent manner. In conclusion, our data show that MSPdhD is not only a biological enzyme, but also an immunogenic surface-exposed protein that can bind to Fn and Plg as well as adhere to host cells. In addition, we show that rabbit anti-rMSPdhD serum can inhibit the adhesion of M. synoviae to DF-1 cells and has a significant complement-dependent bactericidal activity. Our findings suggest that MSPdhD may be involved in the pathogenesis of M. synoviae.
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Affiliation(s)
- Jingjing Qi
- Shanghai Veterinary Research Institute, the Chinese Academy of Agricultural Sciences (CAAS), 518 Ziyue Road, Shanghai, 200241, PR China
| | - Yu Wang
- Shanghai Veterinary Research Institute, the Chinese Academy of Agricultural Sciences (CAAS), 518 Ziyue Road, Shanghai, 200241, PR China; College of Veterinary Medicine, Yangzhou University, No. 88 University South Road, Yangzhou, Jiangsu 225009, PR China
| | - Haoran Li
- Shanghai Veterinary Research Institute, the Chinese Academy of Agricultural Sciences (CAAS), 518 Ziyue Road, Shanghai, 200241, PR China; College of Animal Science and Technology, Anhui Agricultural University, No. 130 Changjiangxilu, Hefei, Anhui, PR China
| | - Yuanbing Shang
- Shanghai Veterinary Research Institute, the Chinese Academy of Agricultural Sciences (CAAS), 518 Ziyue Road, Shanghai, 200241, PR China; College of Animal Husbandry and Veterinary Medicine, Jin Zhou Medical University, No. 40 Section 3 Songpo Road, Linghe District, Jinzhou City, Liaoning 121001, PR China
| | - Song Gao
- College of Veterinary Medicine, Yangzhou University, No. 88 University South Road, Yangzhou, Jiangsu 225009, PR China
| | - Chan Ding
- Shanghai Veterinary Research Institute, the Chinese Academy of Agricultural Sciences (CAAS), 518 Ziyue Road, Shanghai, 200241, PR China
| | - Xiaohan Liu
- Shanghai Veterinary Research Institute, the Chinese Academy of Agricultural Sciences (CAAS), 518 Ziyue Road, Shanghai, 200241, PR China
| | - Shaohui Wang
- Shanghai Veterinary Research Institute, the Chinese Academy of Agricultural Sciences (CAAS), 518 Ziyue Road, Shanghai, 200241, PR China
| | - Tao Li
- Shanghai Veterinary Research Institute, the Chinese Academy of Agricultural Sciences (CAAS), 518 Ziyue Road, Shanghai, 200241, PR China
| | - Mingxing Tian
- Shanghai Veterinary Research Institute, the Chinese Academy of Agricultural Sciences (CAAS), 518 Ziyue Road, Shanghai, 200241, PR China
| | - Shengqing Yu
- Shanghai Veterinary Research Institute, the Chinese Academy of Agricultural Sciences (CAAS), 518 Ziyue Road, Shanghai, 200241, PR China.
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Duarte IF, Caio J, Moedas MF, Rodrigues LA, Leandro AP, Rivera IA, Silva MFB. Dihydrolipoamide dehydrogenase, pyruvate oxidation, and acetylation-dependent mechanisms intersecting drug iatrogenesis. Cell Mol Life Sci 2021; 78:7451-68. [PMID: 34718827 DOI: 10.1007/s00018-021-03996-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Revised: 09/27/2021] [Accepted: 10/15/2021] [Indexed: 10/19/2022]
Abstract
In human metabolism, pyruvate dehydrogenase complex (PDC) is one of the most intricate and large multimeric protein systems representing a central hub for cellular homeostasis. The worldwide used antiepileptic drug valproic acid (VPA) may potentially induce teratogenicity or a mild to severe hepatic toxicity, where the underlying mechanisms are not completely understood. This work aims to clarify the mechanisms that intersect VPA-related iatrogenic effects to PDC-associated dihydrolipoamide dehydrogenase (DLD; E3) activity. DLD is also a key enzyme of α-ketoglutarate dehydrogenase, branched-chain α-keto acid dehydrogenase, α-ketoadipate dehydrogenase, and the glycine decarboxylase complexes. The molecular effects of VPA will be reviewed underlining the data that sustain a potential interaction with DLD. The drug-associated effects on lipoic acid-related complexes activity may induce alterations on the flux of metabolites through tricarboxylic acid cycle, branched-chain amino acid oxidation, glycine metabolism and other cellular acetyl-CoA-connected reactions. The biotransformation of VPA involves its complete β-oxidation in mitochondria causing an imbalance on energy homeostasis. The drug consequences as histone deacetylase inhibitor and thus gene expression modulator have also been recognized. The mitochondrial localization of PDC is unequivocal, but its presence and function in the nucleus were also demonstrated, generating acetyl-CoA, crucial for histone acetylation. Bridging metabolism and epigenetics, this review gathers the evidence of VPA-induced interference with DLD or PDC functions, mainly in animal and cellular models, and highlights the uncharted in human. The consequences of this interaction may have significant impact either in mitochondrial or in nuclear acetyl-CoA-dependent processes.
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Chiranjivi AK, Prakash J, Saha G, Chandra P, Dubey VK. Mutational studies on Leishmania donovani dihydrolipoamide dehydrogenase (LdBPK291950.1) indicates that the enzyme may not be classical class-I pyridine nucleotide-disulfide oxidoreductase. Int J Biol Macromol 2020; 164:2141-2150. [PMID: 32750477 DOI: 10.1016/j.ijbiomac.2020.07.236] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 07/10/2020] [Accepted: 07/22/2020] [Indexed: 11/17/2022]
Abstract
We report biochemical studies on two Cys residues mutation (Cys15Thr, Cys38Gly) nearest to the active site and three other amino acid substitution mutations expected to be the part of active site of LdDLDH_Variant1. Our biochemical studies show that the replacement of Cys15 increases the Km for dihydrolipoamide (DLD) substrate by five folds and NAD+ by three fold indicating that this mutation affects the binding of DLD and NAD+ significantly. Cys38 was also mutated to 'Gly' which resulted in nine fold greater Km for NAD+ without affecting Km for DLD. However, even after these mutations (Cys15Thr and Cys38Gly), reduced enzyme activity suggests that both the 'Cys' residues are not involved in disulfide bond formation but affect the binding of substrates. The data hints towards the possibility of a different catalytic mechanism from the classical class I - pyridine nucleotide-disulfide oxidoreductase. Remaining other mutated residues Ala48Ile, Asp49Gly, and Ala54Ile showed an increase in two to three-folds Km value for NAD+, which means these residues are important for the binding of NAD+ to the enzyme. However, Ala48Ile and Asp49Gly mutations showed a decrease of Km for DLD. Apart from the mutational studies, localization of LdDLDH_Variant2 of LdDLDH was also analyzed.
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Affiliation(s)
- Adarsh Kumar Chiranjivi
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Assam 781039, India
| | - Jay Prakash
- School of Biochemical Engineering, Indian Institute of Technology BHU, Varanasi, UP 221005, India
| | - Gundappa Saha
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Assam 781039, India
| | - Pranjal Chandra
- School of Biochemical Engineering, Indian Institute of Technology BHU, Varanasi, UP 221005, India
| | - Vikash Kumar Dubey
- School of Biochemical Engineering, Indian Institute of Technology BHU, Varanasi, UP 221005, India.
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Affiliation(s)
- Julien Neveu
- Department of Pediatrics, Hôpitaux Pédiatriques de Nice CHU-Lenval, Nice, France
| | - Célia Hoebeke
- Inborn Error of Metabolism Reference Centre, La Timone Teaching Hospital, Marseille, France
| | - Elise Lebigot
- Biochemistry Department, Hôpital Bicêtre, APHP. Université Paris-Saclay, Le Kremlin Bicêtre, France
| | - Mourad Naïmi
- Laboratoire de Biochimie, Hôpital Pasteur, CHU de Nice, Nice, France
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Li CY, Ma WX, Yan LJ. 5-Methoxyindole-2-Carboylic Acid (MICA) Fails to Retard Development and Progression of Type II Diabetes in ZSF1 Diabetic Rats. React Oxyg Species (Apex) 2020; 9:144-147. [PMID: 32551363 PMCID: PMC7301685 DOI: pmid/32551363] [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] [Grants] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
5-Methoxyindole-2-carboxylic acid (MICA) is a well-established reversible inhibitor of mitochondrial dihydrolipoamide dehydrogenase (DLDH). This chemical, as an indole derivative, has been shown to be neuroprotective against ischemic stroke injury when administered either before or after ischemic stroke in animal models. MICA has also been studied as a potential antidiabetic agent by numerous investigators, though the underlying mechanisms remain sketchy. To attempt to elucidate the mechanisms of its antidiabetic action, we tested the effect of MICA on ZSF1 rat, a widely used rodent model of type 2 diabetes. ZSF1 rats as well as its healthy controls were fed with control diet or MICA-containing diet (200 mg/kg/day) for 9 weeks. Unexpectedly, comparison of body weight changes and blood glucose levels at the end of the 9-week's feeding period indicated that MICA failed to show any anti-diabetic effect in the ZSF1 diabetic rats. The reasons for this failure were discussed.
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Affiliation(s)
- Chun-Yan Li
- Department of Pharmaceutical Sciences, UNT System College of Pharmacy, University of North Texas Health Science Center, Fort Worth, Texas 76107, USA
- Shantou University Medical College, Shantou 515041, Guangdong, China
| | - Wei-Xing Ma
- Department of Pharmaceutical Sciences, UNT System College of Pharmacy, University of North Texas Health Science Center, Fort Worth, Texas 76107, USA
- Qingdao University of Science and Technology, Qingdao 266042, Shandong, China
- Technical Center of Qingdao Customs, Qingdao 266002, Shandong, China
| | - Liang-Jun Yan
- Department of Pharmaceutical Sciences, UNT System College of Pharmacy, University of North Texas Health Science Center, Fort Worth, Texas 76107, USA
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Shin D, Lee J, You JH, Kim D, Roh JL. Dihydrolipoamide dehydrogenase regulates cystine deprivation-induced ferroptosis in head and neck cancer. Redox Biol 2020; 30:101418. [PMID: 31931284 PMCID: PMC6957841 DOI: 10.1016/j.redox.2019.101418] [Citation(s) in RCA: 83] [Impact Index Per Article: 20.8] [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: 11/19/2019] [Revised: 12/16/2019] [Accepted: 12/29/2019] [Indexed: 12/19/2022] Open
Abstract
Ferroptosis is a new form of regulated cell death driven by iron-dependent lipid peroxidation. Glutaminolysis and tricarboxylic acid cycle are involved in ferroptosis, but the underlying metabolic process remains unclear. We examined the role of dihydrolipoamide dehydrogenase (DLD) in ferroptosis induction in head and neck cancer (HNC). The effects of cystine deprivation or sulfasalazine treatment and of DLD gene silencing/overexpression were tested on HNC cell lines and mouse tumor xenograft models. These effects were analyzed with regard to cell death, lipid reactive oxygen species (ROS) and mitochondrial iron production, mitochondrial membrane potential, mRNA/protein expression, and α-ketoglutarate dehydrogenase (KGDH)/succinate/aconitase activities. Cystine deprivation induced ferroptosis via glutaminolysis. Cystine deprivation or import inhibition using sulfasalazine induced cancer cell death and increased lipid ROS and mitochondrial iron levels, which had been significantly decreased by short-interfering RNA (siRNA) or short hairpin RNA (shRNA) targeting DLD (P < 0.01) but not by dihydrolipoyl succinyltransferase. The same results were noted in an in vivo mouse model transplanted with vector or shDLD-transduced HN9 cells. After cystine deprivation or sulfasalazine treatment, mitochondrial membrane potential, mitochondrial free iron level, KGDH activity, and succinate content significantly increased (P < 0.001), which had been blocked by DLD siRNA or shRNA and were consequently rescued by resistant DLD cDNA. Cystine deprivation caused iron starvation response and mitochondrial iron accumulation for Fenton reaction and ferroptosis. Our data suggest a close association of DLD with cystine deprivation- or import inhibition-induced ferroptosis.
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Affiliation(s)
- Daiha Shin
- Department of Otorhinolaryngology-Head and Neck Surgery, CHA Bundang Medical Center, CHA University School of Medicine, Seongnam, Republic of Korea; Western Seoul Center, Korea Basic Science Institute, Seoul, Republic of Korea
| | - Jaewang Lee
- Department of Otorhinolaryngology-Head and Neck Surgery, CHA Bundang Medical Center, CHA University School of Medicine, Seongnam, Republic of Korea
| | - Ji Hyeon You
- Department of Otorhinolaryngology-Head and Neck Surgery, CHA Bundang Medical Center, CHA University School of Medicine, Seongnam, Republic of Korea
| | - Doyeon Kim
- Department of Otorhinolaryngology-Head and Neck Surgery, CHA Bundang Medical Center, CHA University School of Medicine, Seongnam, Republic of Korea
| | - Jong-Lyel Roh
- Department of Otorhinolaryngology-Head and Neck Surgery, CHA Bundang Medical Center, CHA University School of Medicine, Seongnam, Republic of Korea.
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Ambrus A. An Updated View on the Molecular Pathomechanisms of Human Dihydrolipoamide Dehydrogenase Deficiency in Light of Novel Crystallographic Evidence. Neurochem Res 2019; 44:2307-2313. [PMID: 30847858 PMCID: PMC6776566 DOI: 10.1007/s11064-019-02766-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [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: 12/02/2018] [Revised: 02/25/2019] [Accepted: 02/26/2019] [Indexed: 12/22/2022]
Abstract
Dihydrolipoamide dehydrogenase (LADH, E3) deficiency is a rare (autosomal, recessive) genetic disorder generally presenting with an onset in the neonatal age and early death; the highest carrier rate has been found among Ashkenazi Jews. Acute clinical episodes usually involve severe metabolic decompensation and lactate acidosis that result in neurological, cardiological, and/or hepatological manifestations. Clinical severity is due to the fact that LADH is a common E3 subunit to the alpha-ketoglutarate, pyruvate, alpha-ketoadipate, and branched-chain alpha-keto acid dehydrogenase complexes, and is also a constituent in the glycine cleavage system, thus a loss in LADH function adversely affects multiple key metabolic routes. However, the severe clinical pictures frequently still do not parallel the LADH activity loss, which implies the involvement of auxiliary biochemical mechanisms; enhanced reactive oxygen species generation as well as affinity loss for multienzyme complexes proved to be key auxiliary exacerbating pathomechanisms. This review provides an overview and an up-to-date molecular insight into the pathomechanisms of this disease in light of the structural conclusions drawn from the first crystal structure of a disease-causing hE3 variant determined recently in our laboratory.
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Affiliation(s)
- Attila Ambrus
- Department of Medical Biochemistry, MTA-SE Laboratory for Neurobiochemistry, Semmelweis University, 37-47 Tuzolto Street, Budapest, 1094, Hungary.
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Oinuma KI, Yamaguchi I, Shindo D, Fujimoto M, Nishiyama T, Takano H, Takaya N, Ueda K. Extracytoplasmic diaphorase activity of Streptomyces coelicolor A3(2). Biochem Biophys Res Commun 2018; 503:1581-1586. [PMID: 30054046 DOI: 10.1016/j.bbrc.2018.07.083] [Citation(s) in RCA: 1] [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: 07/10/2018] [Accepted: 07/17/2018] [Indexed: 11/18/2022]
Abstract
Metabolism and utilization of plant-derived aromatic substances are fundamental to the saprophytic growth of Streptomyces. Here, we studied an enzyme activity reducing 2,6-dichlorophenolindophenol and nitroblue tetrazolium in the culture supernatant of Streptomyces coelicolor A3(2). N-terminal amino acid sequencing of a nitroblue tetrazolium-reducing enzyme revealed that the enzyme corresponds to the SCO2180 product. The protein exhibited a marked similarity with dihydrolipoamide dehydrogenase, the E3 subunit of 2-oxo-acid dehydrogenase complex. A recombinant SCO2180 protein formed a homodimer and exhibited a diaphorase activity catalyzing NADH-dependent reduction of various quinonic substrates. Similar nitroblue tetrazolium-reducing activities were observed for other Streptomyces strains isolated from soil, implying that the diaphorase-catalyzed reduction of quinonic substances widely occurs in the extracytoplasmic space of Streptomyces.
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Affiliation(s)
- Ken-Ichi Oinuma
- Life Science Research Center, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa, Kanagawa, 252-0880, Japan.
| | - Itaru Yamaguchi
- Life Science Research Center, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa, Kanagawa, 252-0880, Japan
| | - Daiki Shindo
- Life Science Research Center, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa, Kanagawa, 252-0880, Japan
| | - Masahiro Fujimoto
- Life Science Research Center, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa, Kanagawa, 252-0880, Japan
| | - Tatsuya Nishiyama
- Life Science Research Center, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa, Kanagawa, 252-0880, Japan
| | - Hideaki Takano
- Life Science Research Center, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa, Kanagawa, 252-0880, Japan
| | - Naoki Takaya
- Faculty of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8572, Japan
| | - Kenji Ueda
- Life Science Research Center, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa, Kanagawa, 252-0880, Japan.
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Wang X, Wang A, Zhu L, Hua D, Qin J. Altering the sensitivity of Escherichia coli pyruvate dehydrogenase complex to NADH inhibition by structure-guided design. Enzyme Microb Technol 2018; 119:52-7. [PMID: 30243387 DOI: 10.1016/j.enzmictec.2018.09.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2018] [Revised: 08/20/2018] [Accepted: 09/03/2018] [Indexed: 11/22/2022]
Abstract
A sufficient supply of reducing equivalents is essential for obtaining the maximum yield of target products in anaerobic fermentation. The pyruvate dehydrogenase (PDH) complex controls the critical step in pyruvate conversion to acetyl-CoA and NADH. However, in anaerobic Escherichia coli, PDH residing in the dihydrolipoamide dehydrogenase (LPD) component is normally inactive due to inhibition by NADH. In this study, the protein engineering of LPD by structural analysis was explored to eliminate this inhibition. A novel IAA350/351/358VVV triple mutant was successfully verified to be more effective than other LPD mutants reported till date. Notably, PDH activity with the triple mutant at an [NADH]/[NAD+] ratio of 0.15 was still higher than that of the wild-type without NADH addition. The altered enzyme of the PDH complex was also active in the presence of such high NADH levels. This is the first study concerning protein engineering of PDH by structure-guided design. The presence and functional activity of such an NADH-insensitive PDH complex provides a useful metabolic element for fermentation products and has potential for biotechnological application.
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Ahmad W. Dihydrolipoamide dehydrogenase suppression induces human tau phosphorylation by increasing whole body glucose levels in a C. elegans model of Alzheimer's Disease. Exp Brain Res 2018; 236:2857-2866. [PMID: 30056470 DOI: 10.1007/s00221-018-5341-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [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: 12/06/2017] [Accepted: 07/21/2018] [Indexed: 12/01/2022]
Abstract
The microtubule associated tau protein becomes hyperphosphorylated in Alzheimer's disease (AD). While hyperphosphorylation promotes neurodegeneration, the cause and consequences of this abnormal modification are poorly understood. As impaired energy metabolism is an important hallmark of AD progression, we tested whether it could trigger phosphorylation of human tau protein in a transgenic Caenorhabditis elegans model of AD. We found that inhibition of a mitochondrial enzyme of energy metabolism, dihydrolipoamide dehydrogenase (DLD) results in elevated whole-body glucose levels as well as increased phosphorylation of tau. Hyperglycemia and tau phosphorylation were induced by either RNAi suppression of the dld-1 gene or by inhibition of the DLD enzyme by the inhibitor, 2-methoxyindole-2-carboxylic acid (MICA). Although the calcium ionophore A23187 could reduce tau phosphorylation induced by either chemical or genetic suppression of DLD, it was unable to reduce tau phosphorylation induced by hyperglycemia. While inhibition of the dld-1 gene or treatment with MICA partially reversed the inhibition of acetylcholine neurotransmission by tau, neither treatment affected tau inhibited mobility. Conclusively, any abnormalities in energy metabolism were found to significantly affect the AD disease pathology.
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Affiliation(s)
- Waqar Ahmad
- School of Biological Sciences, The University of Queensland, Brisbane, 4072, Australia.
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Chiranjivi AK, Dubey VK. Dihydrolipoamide dehydrogenase from Leishmania donovani: New insights through biochemical characterization. Int J Biol Macromol 2018; 112:1241-1247. [PMID: 29466712 DOI: 10.1016/j.ijbiomac.2018.02.112] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Revised: 02/13/2018] [Accepted: 02/16/2018] [Indexed: 02/06/2023]
Abstract
Dihydrolipoamide dehydrogenase (DLDH) regulates many crucial metabolic pathways as a multi-enzyme complex. Leishmania donovani dihydrolipoamide dehydrogenase (LdDLDH) has two variants present on two different chromosomes with very less sequence similarities. In the current study, we cloned both the variants in pET28a (+) vector and expressed in Rosetta-gami (DE3) E. coli strain. Expressed proteins were finally purified from pellets using Ni-NTA affinity chromatography. Purified enzymes were biochemically characterized and different kinetic parameters were studied. Both the variants showed maximum activity in pH range of 7.0-8.0 and temperature 50±5°C in the physiological direction. The estimated Km for dihydrolipoamide (DLA) and NAD+ were 2.7±0.48mM and 171.23±11.59μM respectively for variant 1 (LdBPK291950.1). In the case of variant 2 (LdBPK323510.1), Km values for DLA and NAD+ were found to be 829.85±37μM and 226±1.56μM respectively. The variant 2 was more efficient in terms of activity. While both the forms of the enzymes showed diaphorase activity, variant 1 was found to be better. Sequence dissimilarities of both forms were analyzed for biological insights.
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Affiliation(s)
- Adarsh Kumar Chiranjivi
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Assam 781039, India
| | - Vikash Kumar Dubey
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Assam 781039, India.
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Wu J, Li R, Li W, Ren M, Thangthaeng N, Sumien N, Liu R, Yang S, Simpkins JW, Forster MJ, Yan LJ. Administration of 5-methoxyindole-2-carboxylic acid that potentially targets mitochondrial dihydrolipoamide dehydrogenase confers cerebral preconditioning against ischemic stroke injury. Free Radic Biol Med 2017; 113:244-254. [PMID: 29017857 PMCID: PMC5699942 DOI: 10.1016/j.freeradbiomed.2017.10.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 09/09/2017] [Accepted: 10/06/2017] [Indexed: 02/06/2023]
Abstract
The objective of this study was to investigate a possible role of mitochondrial dihydrolipoamide dehydrogenase (DLDH) as a chemical preconditioning target for neuroprotection against ischemic injury. We used 5-methoxyindole-2-carboxylic acid (MICA), a reportedly reversible DLDH inhibitor, as the preconditioning agent and administered MICA to rats mainly via dietary intake. Upon completion of 4 week's MICA treatment, rats underwent 1h transient ischemia and 24h reperfusion followed by tissue collection. Our results show that MICA protected the brain against ischemic stroke injury as the infarction volume of the brain from the MICA-treated group was significantly smaller than that from the control group. Data were then collected without or with stroke surgery following MICA feeding. It was found that in the absence of stroke following MICA feeding, DLDH activity was lower in the MICA treated group than in the control group, and this decreased activity could be partly due to DLDH protein sulfenation. Moreover, DLDH inhibition by MICA was also found to upregulate the expression of NAD(P)H-ubiquinone oxidoreductase 1(NQO1) via the Nrf2 signaling pathway. In the presence of stroke following MICA feeding, decreased DLDH activity and increased Nrf2 signaling were also observed along with increased NQO1 activity, decreased oxidative stress, decreased cell death, and increased mitochondrial ATP output. We also found that MICA had a delayed preconditioning effect four weeks post MICA treatment. Our study indicates that administration of MICA confers chemical preconditioning and neuroprotection against ischemic stroke injury.
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Affiliation(s)
- Jinzi Wu
- Department of Pharmaceutical Sciences, UNT System College of Pharmacy, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | - Rongrong Li
- Department of Pharmaceutical Sciences, UNT System College of Pharmacy, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | - Wenjun Li
- Center for Neuroscience Discovery, Institute for Healthy Aging, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | - Ming Ren
- Center for Neuroscience Discovery, Institute for Healthy Aging, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | - Nopporn Thangthaeng
- Center for Neuroscience Discovery, Institute for Healthy Aging, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | - Nathalie Sumien
- Center for Neuroscience Discovery, Institute for Healthy Aging, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | - Ran Liu
- Center for Neuroscience Discovery, Institute for Healthy Aging, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | - Shaohua Yang
- Center for Neuroscience Discovery, Institute for Healthy Aging, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | - James W Simpkins
- Department of Physiology and Pharmacology, Center for Basic and Translational Stroke Research, West Virginia University, 1 Medical Center Drive, Morgantown, WV 26506, USA
| | - Michael J Forster
- Center for Neuroscience Discovery, Institute for Healthy Aging, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | - Liang-Jun Yan
- Department of Pharmaceutical Sciences, UNT System College of Pharmacy, University of North Texas Health Science Center, Fort Worth, TX 76107, USA.
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Wang L, Li P, Wen Y, Yang Q, Zhen L, Fu J, Li Y, Li S, Han C, Li X. Vitamin C exerts novel protective effects against cadmium toxicity in mouse spermatozoa by inducing the dephosphorylation of dihydrolipoamide dehydrogenase. Reprod Toxicol 2017; 75:23-32. [PMID: 29158198 DOI: 10.1016/j.reprotox.2017.11.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [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: 06/28/2017] [Revised: 09/07/2017] [Accepted: 11/16/2017] [Indexed: 11/16/2022]
Abstract
Cadmium (Cd) has been reported to inhibit mouse sperm motility by inducing the tyrosine phosphorylation of dihydrolipoamide dehydrogenase (DLD). This study aimed to assess the potential effects of vitamin C (Vc) on ameliorating Cd-induced tyrosine phosphorylation of DLD and the specific underlying mechanism. Vc induced the dephosphorylation of DLD or inhibited the tyrosine phosphorylation of DLD. Accordingly, DLD activity, nicotinamide adenine dinucleotide hydrogen (NADH) levels, ATP levels and motility parameters were all restored to normal levels by Vc. Moreover, the effects of Vc on ameliorating these indicators had striking similarities to the effects of ethylenediaminetetraacetic acid (EDTA). In addition, neither the antioxidant melatonin nor the universal oxidant H2O2 influenced the tyrosine phosphorylation of DLD. Hence, the protective effects of Vc on the tyrosine phosphorylation of DLD might be attributed to its binding to Cd ions outside or inside sperm, and were not due to its antioxidant properties.
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Affiliation(s)
- Lirui Wang
- Shanghai Key Lab of Veterinary Biotechnology, School of Agriculture and Biology, Shanghai Jiaotong University, Shanghai, 200240, China
| | - Peifei Li
- Shanghai Key Lab of Veterinary Biotechnology, School of Agriculture and Biology, Shanghai Jiaotong University, Shanghai, 200240, China
| | - Yi Wen
- Shanghai Key Lab of Veterinary Biotechnology, School of Agriculture and Biology, Shanghai Jiaotong University, Shanghai, 200240, China
| | - Qiangzhen Yang
- Shanghai Key Lab of Veterinary Biotechnology, School of Agriculture and Biology, Shanghai Jiaotong University, Shanghai, 200240, China
| | - Linqing Zhen
- Shanghai Key Lab of Veterinary Biotechnology, School of Agriculture and Biology, Shanghai Jiaotong University, Shanghai, 200240, China
| | - Jieli Fu
- Shanghai Key Lab of Veterinary Biotechnology, School of Agriculture and Biology, Shanghai Jiaotong University, Shanghai, 200240, China
| | - Yuhua Li
- Shanghai Key Lab of Veterinary Biotechnology, School of Agriculture and Biology, Shanghai Jiaotong University, Shanghai, 200240, China
| | - Sisi Li
- Shanghai Key Lab of Veterinary Biotechnology, School of Agriculture and Biology, Shanghai Jiaotong University, Shanghai, 200240, China
| | - Chengxiao Han
- Shanghai Key Lab of Veterinary Biotechnology, School of Agriculture and Biology, Shanghai Jiaotong University, Shanghai, 200240, China
| | - Xinhong Li
- Shanghai Key Lab of Veterinary Biotechnology, School of Agriculture and Biology, Shanghai Jiaotong University, Shanghai, 200240, China.
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Ambrus A, Adam-Vizi V. Human dihydrolipoamide dehydrogenase (E3) deficiency: Novel insights into the structural basis and molecular pathomechanism. Neurochem Int 2017; 117:5-14. [PMID: 28579060 DOI: 10.1016/j.neuint.2017.05.018] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [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: 02/20/2017] [Revised: 05/22/2017] [Accepted: 05/30/2017] [Indexed: 11/18/2022]
Abstract
This review summarizes our present view on the molecular pathogenesis of human (h) E3-deficiency caused by a variety of genetic alterations with a special emphasis on the moonlighting biochemical phenomena related to the affected (dihydro)lipoamide dehydrogenase (LADH, E3, gene: dld), in particular the generation of reactive oxygen species (ROS). E3-deficiency is a rare autosomal recessive genetic disorder frequently presenting with a neonatal onset and premature death; the highest carrier rate of a single pathogenic dld mutation (1:94-1:110) was found among Ashkenazi Jews. Patients usually die during acute episodes that generally involve severe metabolic decompensation and lactic acidosis leading to neurological, cardiological, and/or hepatological manifestations. The disease owes its severity to the fact that LADH is the common E3 subunit of the alpha-ketoglutarate (KGDHc), pyruvate (PDHc), and branched-chain α-keto acid dehydrogenase complexes and is also part of the glycine cleavage system, hence the malfunctioning of LADH simultaneously incapacitates several central metabolic pathways. Nevertheless, the clinical pictures are usually not unequivocally portrayed through the loss of LADH activities and imply auxiliary mechanisms that exacerbate the symptoms and outcomes of this disorder. Enhanced ROS generation by disease-causing hE3 variants as well as by the E1-E2 subcomplex of the hKGDHc likely contributes to selected pathogeneses of E3-deficiency, which could be targeted by specific drugs or antioxidants; lipoic acid was demonstrated to be a potent inhibitor of ROS generation by hE3 in vitro. Flavin supplementation might prove to be beneficial for those mutations triggering FAD loss in the hE3 component. Selected pathogenic hE3 variants lose their affinity for the E2 component of the hPDHc, a mechanism which warrants scrutiny also for other E3-haboring complexes.
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Affiliation(s)
- Attila Ambrus
- Department of Medical Biochemistry, MTA-SE Laboratory for Neurobiochemistry, Semmelweis University, Budapest, Hungary.
| | - Vera Adam-Vizi
- Department of Medical Biochemistry, MTA-SE Laboratory for Neurobiochemistry, Semmelweis University, Budapest, Hungary.
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15
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Ambrus A, Wang J, Mizsei R, Zambo Z, Torocsik B, Jordan F, Adam-Vizi V. Structural alterations induced by ten disease-causing mutations of human dihydrolipoamide dehydrogenase analyzed by hydrogen/deuterium-exchange mass spectrometry: Implications for the structural basis of E3 deficiency. Biochim Biophys Acta Mol Basis Dis 2016; 1862:2098-2109. [PMID: 27544700 DOI: 10.1016/j.bbadis.2016.08.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Revised: 08/11/2016] [Accepted: 08/16/2016] [Indexed: 01/06/2023]
Abstract
Pathogenic amino acid substitutions of the common E3 component (hE3) of the human alpha-ketoglutarate dehydrogenase and the pyruvate dehydrogenase complexes lead to severe metabolic diseases (E3 deficiency), which usually manifest themselves in cardiological and/or neurological symptoms and often cause premature death. To date, 14 disease-causing amino acid substitutions of the hE3 component have been reported in the clinical literature. None of the pathogenic protein variants has lent itself to high-resolution structure elucidation by X-ray or NMR. Hence, the structural alterations of the hE3 protein caused by the disease-causing mutations and leading to dysfunction, including the enhanced generation of reactive oxygen species by selected disease-causing variants, could only be speculated. Here we report results of an examination of the effects on the protein structure of ten pathogenic mutations of hE3 using hydrogen/deuterium-exchange mass spectrometry (HDX-MS), a new and state-of-the-art approach of solution structure elucidation. On the basis of the results, putative structural and mechanistic conclusions were drawn regarding the molecular pathogenesis of each disease-causing hE3 mutation addressed in this study.
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Affiliation(s)
- Attila Ambrus
- Department of Medical Biochemistry, MTA-SE Laboratory for Neurobiochemistry, Semmelweis University, Budapest, Hungary.
| | - Junjie Wang
- Department of Chemistry, Rutgers University, Newark, NJ, USA
| | - Reka Mizsei
- Department of Medical Biochemistry, MTA-SE Laboratory for Neurobiochemistry, Semmelweis University, Budapest, Hungary
| | - Zsofia Zambo
- Department of Medical Biochemistry, MTA-SE Laboratory for Neurobiochemistry, Semmelweis University, Budapest, Hungary
| | - Beata Torocsik
- Department of Medical Biochemistry, MTA-SE Laboratory for Neurobiochemistry, Semmelweis University, Budapest, Hungary
| | - Frank Jordan
- Department of Chemistry, Rutgers University, Newark, NJ, USA.
| | - Vera Adam-Vizi
- Department of Medical Biochemistry, MTA-SE Laboratory for Neurobiochemistry, Semmelweis University, Budapest, Hungary.
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Ji X, Li Z, Chen H, Li J, Tian H, Li Z, Gao X, Xiang Q, Su Z, Huang Y, Zhang Q. Cytotoxic mechanism related to dihydrolipoamide dehydrogenase in Leydig cells exposed to heavy metals. Toxicology 2015; 334:22-32. [PMID: 25981801 DOI: 10.1016/j.tox.2015.05.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Revised: 04/29/2015] [Accepted: 05/11/2015] [Indexed: 10/23/2022]
Abstract
Heavy metals are common environmental toxicants with adverse effects on steroid biosynthesis. The importance of mitochondria has been recognized in cytotoxic mechanism of heavy metals on Leydig cells these years. But it is still poorly known. Our previous study reported that dihydrolipoamide dehydrogenase (DLD) located on the mitochondria was significantly decreased in Leydig cells exposed to cadmium, which suggested that DLD might be involved in the cytotoxic effects. Therefore, the altered expression of DLD was validated in rats and R2C cells exposed to cadmium, manganese and lead, and the role of DLD in the steroid synthesis pathway cAMP/PKA-ERK1/2 was investigated in this study. With a low expression of DLD, heavy metals dramatically reduced the levels of steroid hormone by inhibiting the activation of cAMP/PKA, PKC signaling pathway and the steroidogenic enzymes StAR, CYP11A1 and 3β-HSD. After knockdown of DLD in R2C cells, progesterone synthesis was reduced by 40%, and the intracellular concentration of cAMP, protein expression of StAR, 3β-HSD, PKA, and the phosphorylation of ERK1/2 were also decreased. These results highlight that DLD is down-regulation and related to steroid biosynthesis in Leyig cells exposed to heavy metals; cAMP/PKA act as downstream effector molecules of DLD, which activate phosphorylation of ERK1/2 to initiate the steroidogenesis.
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Affiliation(s)
- Xunmin Ji
- Institute of Biomedicine, and National Engineering Research Center of Genetic Medicine, Jinan University, Guangzhou 510632, China
| | - Zhiliang Li
- Institute of Biomedicine, and National Engineering Research Center of Genetic Medicine, Jinan University, Guangzhou 510632, China
| | - Hongxia Chen
- Institute of Biomedicine, and National Engineering Research Center of Genetic Medicine, Jinan University, Guangzhou 510632, China
| | - Junqi Li
- Department of Cell Biology & Institute of Biomedicine, College of Life Science and Technology, Jinan University, National Engineering Research Center of Genetic Medicine, Guangdong Provincial Key Laboratory of Bioengineering Medicine, 510632, China
| | - Huajian Tian
- Institute of Biomedicine, and National Engineering Research Center of Genetic Medicine, Jinan University, Guangzhou 510632, China
| | - Zengli Li
- Institute of Biomedicine, and National Engineering Research Center of Genetic Medicine, Jinan University, Guangzhou 510632, China
| | - Xuejuan Gao
- Institute of Life and Health Engineering, Jinan University, Guangzhou 510632, China
| | - Qi Xiang
- Institute of Biomedicine, and National Engineering Research Center of Genetic Medicine, Jinan University, Guangzhou 510632, China; Guangdong Provincial Key Laboratory of Bioengineering Medicine, Jinan University, Guangzhou 510632, China
| | - Zhijian Su
- Institute of Biomedicine, and National Engineering Research Center of Genetic Medicine, Jinan University, Guangzhou 510632, China; Guangdong Provincial Key Laboratory of Bioengineering Medicine, Jinan University, Guangzhou 510632, China
| | - Yadong Huang
- Institute of Biomedicine, and National Engineering Research Center of Genetic Medicine, Jinan University, Guangzhou 510632, China; Guangdong Provincial Key Laboratory of Bioengineering Medicine, Jinan University, Guangzhou 510632, China.
| | - Qihao Zhang
- Institute of Biomedicine, and National Engineering Research Center of Genetic Medicine, Jinan University, Guangzhou 510632, China; Guangdong Provincial Key Laboratory of Bioengineering Medicine, Jinan University, Guangzhou 510632, China.
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Arenas FA, Leal CA, Pinto CA, Arenas-Salinas MA, Morales WA, Cornejo FA, Díaz-Vásquez WA, Vásquez CC. On the mechanism underlying tellurite reduction by Aeromonas caviae ST dihydrolipoamide dehydrogenase. Biochimie 2014; 102:174-82. [PMID: 24680738 DOI: 10.1016/j.biochi.2014.03.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [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: 01/10/2014] [Accepted: 03/17/2014] [Indexed: 10/25/2022]
Abstract
The dihydrolipoamide dehydrogenase (LpdA) from the tellurite-resistant bacterium Aeromonas caviae ST reduces tellurite to elemental tellurium. To characterize this NADH-dependent activity, the A. caviae lpdA gene was subjected to site-directed mutagenesis and genes containing C45A, H322Y and E354K substitutions were individually transformed into Escherichia coli Δlpd. Cells expressing the modified genes exhibited decreased pyruvate dehydrogenase, dihydrolipoamide dehydrogenase and TR activity regarding that observed with the wild type A. caviae lpdA gene. In addition, cells expressing the altered lpdA genes showed increased oxidative stress levels and tellurite sensitivity than those carrying the wild type counterpart. The involvement of Cys residues in LpdA's TR activity was analyzed using specific inhibitors that interact with catalytic cysteines and/or disulfide bridges such as aurothiomalate, zinc or nickel. TR activity of purified LpdA was drastically affected by these compounds. Since LpdA belongs to the flavoprotein family, the involvement of the FAD/NAD(P)(+)-binding domain in TR activity was determined. FAD removal from purified LpdA results in loss of TR activity, which was restored with exogenously added FAD. Substitutions in E354, involved in FAD/NADH binding, resulted in low TR activity because of flavin loss. Finally, changing H322 (involved in NAD(+)/NADH binding) by tyrosine also resulted in altered TR activity.
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Affiliation(s)
- F A Arenas
- Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile
| | - C A Leal
- Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile
| | - C A Pinto
- Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile
| | - M A Arenas-Salinas
- Centro de Bioinformática y Simulación Molecular, Universidad de Talca, Talca, Chile
| | - W A Morales
- Centro de Bioinformática y Simulación Molecular, Universidad de Talca, Talca, Chile
| | - F A Cornejo
- Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile
| | - W A Díaz-Vásquez
- Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile; Facultad de Ciencia, Universidad San Sebastián, Santiago, Chile
| | - C C Vásquez
- Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile.
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Al-Jasmi F, Pramathan T, Swid A, Sahari B, Penefsky HS, Souid AK. Mitochondrial Oxygen Consumption by the Foreskin and its Fibroblast-rich Culture. Sultan Qaboos Univ Med J 2013; 13:411-6. [PMID: 23984027 DOI: 10.12816/0003264] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [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: 09/11/2012] [Revised: 01/02/2013] [Accepted: 03/17/2013] [Indexed: 11/27/2022] Open
Abstract
OBJECTIVES This study investigated the feasibility of using a phosphorescence oxygen analyser to measure cellular respiration (mitochondrial O2 consumption) in foreskin samples and their fibroblast-rich cultures. METHODS Foreskin specimens from normal infants were collected immediately after circumcision and processed for measuring cellular respiration and for culture. Cellular mitochondrial O2 consumption was determined as a function of time from the phosphorescence decay of the Pd (II) meso-tetra-(4-sulfonatophenyl)-tetrabenzoporphyrin. RESULTS In sealed vials containing a foreskin specimen and glucose, O2 concentration decreased linearly with time, confirming the zero-order kinetics of O2 consumption by cytochrome oxidase. Cyanide inhibited O2 consumption, confirming that the oxidation occurred mainly in the mitochondrial respiratory chain. The rate of foreskin respiration (mean ± SD) was 0.074 ± 0.02 μM O2 min(-1) mg(-1) (n = 23). The corresponding rate for fibroblast-rich cultures was 9.84 ± 2.43 μM O2 min(-1) per 10(7) cells (n = 15). Fibroblast respiration was significantly lower in a male infant with dihydrolipoamide dehydrogenase gene mutations, but normalised with the addition of thiamine or carnitine. CONCLUSION The foreskin and its fibroblast-rich culture are suitable for assessment of cellular respiration. However, the clinical utility of foreskin specimens to detect disorders of impaired cellular bioenergetics requires further investigation.
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Affiliation(s)
- Fatma Al-Jasmi
- Department of Paediatrics, College of Medicine & Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
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