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Knauer JF, Schulz C, Zemella A, Wüstenhagen DA, Walter RM, Küpper JH, Kubick S. Synthesis of mono Cytochrome P450 in a modified CHO-CPR cell-free protein production platform. Sci Rep 2024; 14:1271. [PMID: 38218994 PMCID: PMC10787779 DOI: 10.1038/s41598-024-51781-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Accepted: 01/09/2024] [Indexed: 01/15/2024] Open
Abstract
Cytochromes P450 (CYPs) are a group of monooxygenases that can be found in almost all kinds of organisms. For CYPs to receive electrons from co-substrate NADPH, the activity of NADPH-Cytochrome-P450-oxidoreductase (CPR) is required as well. In humans, CYPs are an integral part of liver-based phase-1 biotransformation, which is essential for the metabolization of multiple xenobiotics and drugs. Consequently, CYPs are important players during drug development and therefore these enzymes are implemented in diverse screening applications. For these applications it is usually advantageous to use mono CYP microsomes containing only the CYP of interest. The generation of mono-CYP containing mammalian cells and vesicles is difficult since endogenous CYPs are present in many cell types that contain the necessary co-factors. By obtaining translationally active lysates from a modified CHO-CPR cell line, it is now possible to generate mono CYPs in a cell-free protein synthesis process in a straightforward manner. As a proof of principle, the synthesis of active human CYPs from three different CYP450 gene families (CYP1A2, CYP2B6 and CYP3A4), which are of outstanding interest in industry and academia was demonstrated. Luciferase based activity assays confirm the activity of the produced CYPs and enable the individual adaptation of the synthesis process for efficient cell-free enzyme production. Furthermore, they allow for substrate and inhibitor screenings not only for wild-type CYPs but also for mutants and further CYP isoforms and variants. As an example, the turnover of selected CYP substrates by cell-free synthesized CYPs was demonstrated via an indirect luciferase assay-based screening setup.
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Affiliation(s)
- Jan Felix Knauer
- Fraunhofer Project Group PZ-Syn of the Fraunhofer Institute for Cell Therapy and Immunology, Branch Bioanalytics and Bioprocesses (IZI-BB), Potsdam, Germany
- Fraunhofer Institute for Cell Therapy and Immunology (IZI), Branch Bioanalytics and Bioprocesses (IZI-BB), Potsdam, Germany
- Freie Universität Berlin, Institute of Chemistry and Biochemistry - Biochemistry, Berlin, Germany
| | - Christian Schulz
- Fraunhofer Project Group PZ-Syn of the Fraunhofer Institute for Cell Therapy and Immunology, Branch Bioanalytics and Bioprocesses (IZI-BB), Potsdam, Germany
- Institute of Biotechnology, Brandenburg University of Technology Cottbus-Senftenberg, Senftenberg, Germany
| | - Anne Zemella
- Fraunhofer Institute for Cell Therapy and Immunology (IZI), Branch Bioanalytics and Bioprocesses (IZI-BB), Potsdam, Germany.
| | - Doreen A Wüstenhagen
- Fraunhofer Institute for Cell Therapy and Immunology (IZI), Branch Bioanalytics and Bioprocesses (IZI-BB), Potsdam, Germany
| | - Ruben Magnus Walter
- Fraunhofer Institute for Cell Therapy and Immunology (IZI), Branch Bioanalytics and Bioprocesses (IZI-BB), Potsdam, Germany
- Institute of Biotechnology, Technische Universität Berlin, Gustav-Meyer-Allee 25, 13355, Berlin, Germany
| | - Jan-Heiner Küpper
- Institute of Biotechnology, Brandenburg University of Technology Cottbus-Senftenberg, Senftenberg, Germany
| | - Stefan Kubick
- Fraunhofer Institute for Cell Therapy and Immunology (IZI), Branch Bioanalytics and Bioprocesses (IZI-BB), Potsdam, Germany
- Freie Universität Berlin, Institute of Chemistry and Biochemistry - Biochemistry, Berlin, Germany
- Faculty of Health Sciences, Joint Faculty of the Brandenburg University of Technology Cottbus -Senftenberg, the Brandenburg Medical School Theodor Fontane and the University of Potsdam, Potsdam, Germany
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2
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Bryant P, Walton Bernstedt S, Thutkawkorapin J, Backman AS, Lindblom A, Lagerstedt-Robinson K. Exome sequencing in a Swedish family with PMS2 mutation with varying penetrance of colorectal cancer: investigating the presence of genetic risk modifiers in colorectal cancer risk. Eur J Cancer Prev 2023; 32:113-118. [PMID: 36134613 DOI: 10.1097/cej.0000000000000769] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE Lynch syndrome is caused by germline mutations in the mismatch repair (MMR) genes, such as the PMS2 gene, and is characterised by a familial accumulation of colorectal cancer. The penetrance of cancer in PMS2 carriers is still not fully elucidated as a colorectal cancer risk has been shown to vary between PMS2 carriers, suggesting the presence of risk modifiers. METHODS Whole exome sequencing was performed in a Swedish family carrying a PMS2 missense mutation [c.2113G>A, p.(Glu705Lys)]. Thirteen genetic sequence variants were further selected and analysed in a case-control study (724 cases and 711 controls). RESULTS The most interesting variant was an 18 bp deletion in gene BAG1. BAG1 has been linked to colorectal tumour progression with poor prognosis and is thought to promote colorectal tumour cell survival through increased NF-κB activity. CONCLUSIONS We conclude the genetic architecture behind the incomplete penetrance of PMS2 is complicated and must be assessed in a genome wide manner using large families and multifactorial analysis.
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Affiliation(s)
- Patrick Bryant
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm
- Science for Life Laboratory Department of Biochemistry and Biophysics, Stockholm University
| | - Sophie Walton Bernstedt
- Department of Medicine, Solna, Karolinska Institutet, Stockholm
- Karolinska University Hospital, Division of Gastroenterology, Medical Unit Gastroenterology, Dermatovenereology and Rheumatology, Stockholm, Sweden
| | - Jessada Thutkawkorapin
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm
- Department of Computer Engineering, Faculty of Engineering, Chulalongkorn 20 University, Bangkok, Thailand
| | - Ann-Sofie Backman
- Department of Medicine, Solna, Karolinska Institutet, Stockholm
- Hereditary Cancer, Medical Unit Breast Endocrine and Sarcoma tumour, Karolinska University Hospital
| | - Annika Lindblom
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm
| | - Kristina Lagerstedt-Robinson
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm
- Clinical Genetics, Karolinska University Laboratory, Karolinska University Hospital, Stockholm, Sweden
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3
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Iyanagi T. Roles of Ferredoxin-NADP + Oxidoreductase and Flavodoxin in NAD(P)H-Dependent Electron Transfer Systems. Antioxidants (Basel) 2022; 11:2143. [PMID: 36358515 PMCID: PMC9687028 DOI: 10.3390/antiox11112143] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Revised: 10/19/2022] [Accepted: 10/20/2022] [Indexed: 07/21/2023] Open
Abstract
Distinct isoforms of FAD-containing ferredoxin-NADP+ oxidoreductase (FNR) and ferredoxin (Fd) are involved in photosynthetic and non-photosynthetic electron transfer systems. The FNR (FAD)-Fd [2Fe-2S] redox pair complex switches between one- and two-electron transfer reactions in steps involving FAD semiquinone intermediates. In cyanobacteria and some algae, one-electron carrier Fd serves as a substitute for low-potential FMN-containing flavodoxin (Fld) during growth under low-iron conditions. This complex evolves into the covalent FNR (FAD)-Fld (FMN) pair, which participates in a wide variety of NAD(P)H-dependent metabolic pathways as an electron donor, including bacterial sulfite reductase, cytochrome P450 BM3, plant or mammalian cytochrome P450 reductase and nitric oxide synthase isoforms. These electron transfer systems share the conserved Ser-Glu/Asp pair in the active site of the FAD module. In addition to physiological electron acceptors, the NAD(P)H-dependent diflavin reductase family catalyzes a one-electron reduction of artificial electron acceptors such as quinone-containing anticancer drugs. Conversely, NAD(P)H: quinone oxidoreductase (NQO1), which shares a Fld-like active site, functions as a typical two-electron transfer antioxidant enzyme, and the NQO1 and UDP-glucuronosyltransfease/sulfotransferase pairs function as an antioxidant detoxification system. In this review, the roles of the plant FNR-Fd and FNR-Fld complex pairs were compared to those of the diflavin reductase (FAD-FMN) family. In the final section, evolutionary aspects of NAD(P)H-dependent multi-domain electron transfer systems are discussed.
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Affiliation(s)
- Takashi Iyanagi
- Graduate School of Life Science, University of Hyogo, 3-2-1 Koto, Akoh 678-1297, Hyogo, Japan
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4
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Morihiro K, Ishinabe T, Takatsu M, Osumi H, Osawa T, Okamoto A. Floxuridine Oligomers Activated under Hypoxic Environment. J Am Chem Soc 2021; 143:3340-3347. [PMID: 33648338 DOI: 10.1021/jacs.0c10732] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Floxuridine oligomers are anticancer oligonucleotide drugs composed of a number of floxuridine residues. They show enhanced cytotoxicity per floxuridine monomer because the nuclease degradation of floxuridine oligomers directly releases highly active floxuridine monophosphate in cells. However, their clinical use is limited by the low selectivity against cancer cells. To address this limitation, we herein report floxuridine oligomer prodrugs that are active under hypoxia conditions, which is one of the distinguishing features of the microenvironment of all solid tumors. We designed and synthesized two types of floxuridine oligomer prodrugs that possess hypoxia-responsive moieties on nucleobases. The floxuridine oligomer prodrugs showed lower cytotoxicity under normoxia conditions (O2 = 20%), while the parent floxuridine oligomer showed similar anticancer effects under hypoxia conditions (O2 = 1%). The floxuridine oligomer prodrug enabled tumor growth suppression in live mice. This would be the first example demonstrating the conditional control of the medicinal efficacy of oligomerized nucleoside anticancer drugs.
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Affiliation(s)
- Kunihiko Morihiro
- Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Takuro Ishinabe
- Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Masako Takatsu
- Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan
| | - Hiraki Osumi
- Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Tsuyoshi Osawa
- Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
- Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan
| | - Akimitsu Okamoto
- Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
- Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan
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5
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Guerra-Castellano A, Márquez I, Pérez-Mejías G, Díaz-Quintana A, De la Rosa MA, Díaz-Moreno I. Post-Translational Modifications of Cytochrome c in Cell Life and Disease. Int J Mol Sci 2020; 21:E8483. [PMID: 33187249 PMCID: PMC7697256 DOI: 10.3390/ijms21228483] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 11/05/2020] [Accepted: 11/07/2020] [Indexed: 02/07/2023] Open
Abstract
Mitochondria are the powerhouses of the cell, whilst their malfunction is related to several human pathologies, including neurodegenerative diseases, cardiovascular diseases, and various types of cancer. In mitochondrial metabolism, cytochrome c is a small soluble heme protein that acts as an essential redox carrier in the respiratory electron transport chain. However, cytochrome c is likewise an essential protein in the cytoplasm acting as an activator of programmed cell death. Such a dual role of cytochrome c in cell life and death is indeed fine-regulated by a wide variety of protein post-translational modifications. In this work, we show how these modifications can alter cytochrome c structure and functionality, thus emerging as a control mechanism of cell metabolism but also as a key element in development and prevention of pathologies.
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Affiliation(s)
| | | | | | | | | | - Irene Díaz-Moreno
- Instituto de Investigaciones Químicas (IIQ), Centro de Investigaciones Científicas Isla de la Cartuja (cicCartuja), Universidad de Sevilla, Consejo Superior de Investigaciones Científicas (CSIC), Avda. Américo Vespucio 49, 41092 Sevilla, Spain; (A.G.-C.); (I.M.); (G.P.-M.); (A.D.-Q.); (M.A.D.l.R.)
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6
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Kanazawa H, Ozaki S, Doi Y, Masuo S, Takaya N. Symbiotic riboflavin degradation by Microbacterium and Nocardioides bacteria. Biosci Biotechnol Biochem 2020; 84:1056-1061. [PMID: 31959067 DOI: 10.1080/09168451.2020.1715783] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Unlike its biosynthetic mechanisms and physiological function, current understanding of riboflavin degradation in soil is limited to a few bacteria that decompose it to lumichrome. Here, we isolated six Microbacterium and three Nocardioides strains. These strains utilized riboflavin and lumichrome, respectively, as carbon sources. Among these strains, we identified Microbacterium paraoxydans R16 (R16) and Nocardioides nitrophenolicus L16 (L16), which were isolated form the same enrichment culture. Co-cultured R16 and L16 reconstituted a riboflavin-degrading interspecies consortium, in which the R16 strain degraded riboflavin to lumichrome and ᴅ-ribose. The L16 strain utilized the lumichrome as a carbon source, indicating that R16 is required for L16 to grow in the consortium. Notably, rates of riboflavin degradation and growth were increased in co-cultured, compared with monocultured R16 cells. These results indicated that a beneficial symbiotic interaction between M. paraoxydans R16 and N. nitrophenolicus L16 results in the ability to degrade riboflavin.
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Affiliation(s)
- Hiroshi Kanazawa
- Faculty of Life and Environmental Sciences, Microbiology Research Center for Sustainability, University of Tsukuba, Tsukuba, Japan
| | - Sayoko Ozaki
- Faculty of Life and Environmental Sciences, Microbiology Research Center for Sustainability, University of Tsukuba, Tsukuba, Japan
| | - Yuki Doi
- Faculty of Life and Environmental Sciences, Microbiology Research Center for Sustainability, University of Tsukuba, Tsukuba, Japan
| | - Shunsuke Masuo
- Faculty of Life and Environmental Sciences, Microbiology Research Center for Sustainability, University of Tsukuba, Tsukuba, Japan
| | - Naoki Takaya
- Faculty of Life and Environmental Sciences, Microbiology Research Center for Sustainability, University of Tsukuba, Tsukuba, Japan
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7
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Mistry RK, Brewer AC. Redox-Dependent Regulation of Sulfur Metabolism in Biomolecules: Implications for Cardiovascular Health. Antioxid Redox Signal 2019; 30:972-991. [PMID: 28661184 DOI: 10.1089/ars.2017.7224] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
SIGNIFICANCE Sulfur-containing amino acids are integral to the molecular mechanisms that underlie many aspects of cellular function and homeostasis, facilitated by reversible changes in the oxidation states of sulfur atoms. Sulfur-containing amino acids are metabolically linked by interacting pathways that impact the one-carbon metabolic cycle and generation of methyl groups, the folate cycle, and maintenance of the major cellular redox buffer; glutathione. Dysregulation of these pathways is associated with diverse pathologies, notably of the cardiovascular (CV) system, which are typically characterized by inappropriate plasma levels of sulfur-containing amino acids. Recent Advances: Perhaps not surprisingly, the cellular redox state has emerged as a major regulator of many enzymatic processes within these metabolic cycles. The metabolism of cysteine can also result in the production of hydrogen sulfide (H2S), a signaling molecule whose activity is potentially linked to intracellular levels of both reactive oxygen species (ROS) and molecular oxygen. CRITICAL ISSUES In most cases, the endogenous physiological sources of ROS that might mediate the interlinked metabolic pathways of sulfur-containing biomolecules remain unknown. However, the family of NADPH oxidases, and Nox4 in particular, is emerging as a likely candidate. FUTURE DIRECTIONS This review focuses on the current knowledge of key aspects of sulfur metabolism, which are regulated by redox-based chemical reactions, and the likely intracellular oxidant sources that might mediate this regulation. This knowledge will be important to guide future targeted therapeutic interventions in diverse CV disorders.
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Affiliation(s)
- Rajesh K Mistry
- Department of Cardiology, BHF Centre of Research Excellence, King's College London, London, United Kingdom
| | - Alison C Brewer
- Department of Cardiology, BHF Centre of Research Excellence, King's College London, London, United Kingdom
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8
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Liang D, Wu X, Hasinoff BB, Herbert DE, Tranmer GK. Evaluation of Nitrobenzyl Derivatives of Camptothecin as Anti-Cancer Agents and Potential Hypoxia Targeting Prodrugs. Molecules 2018; 23:molecules23082041. [PMID: 30111719 PMCID: PMC6222813 DOI: 10.3390/molecules23082041] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2018] [Revised: 08/14/2018] [Accepted: 08/14/2018] [Indexed: 12/12/2022] Open
Abstract
As part of our initial efforts into developing a tumor-targeting therapy, C-10 substituted derivatives of a camptothecin analog (SN-38) have been synthesized (2-, 3- and 4-nitrobenzyl) for use as potential hypoxia-activated prodrugs and evaluated for their cytotoxicity, topoisomerase I inhibition and electrochemical (reductive) properties. All three derivatives were found to possess reduced toxicity towards human leukemia K562 cells compared to SN-38, validating a condition for prodrug action. Using an MTS assay, IC50's were found to be 3.0, 25.9, 12.2 and 58.0 nM for SN-38, 2-nitro-, 3-nitro- and 4-nitrobenzyl-C10-substituted-SN-38, respectively, representing an 8-, 4- and 19-fold decrease in cytotoxicity. Using a topoisomerase I assay, one of the analogs (4-nitrobenzyl) was shown to inhibit the ability of this enzyme to relax supercoiled pBR322 DNA, at a similar concentration to the clinically-approved active metabolite SN-38. Cyclic voltammetry detailed the reductive nature of the analogs, and was used to infer the potential of these compounds to serve as hypoxia-targeting prodrugs. The electrochemical results also validated the quasi-reversible nature of the first reduction step, and served as a proof-of-principle that hypoxia-targeting prodrugs of SN-38 can participate in a redox-futile cycle, the proposed mechanism of activation and targeting. Chemical reduction of the 4-nitrobenzyl analog led to the formation/release of SN-38 and validated the prodrug ability of the C-10 substituted derivative.
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Affiliation(s)
- Dinghua Liang
- College of Pharmacy, Faculty of Health Science, University of Manitoba, Winnipeg, MB R3E 0T5, Canada.
| | - Xing Wu
- College of Pharmacy, Faculty of Health Science, University of Manitoba, Winnipeg, MB R3E 0T5, Canada.
| | - Brian B Hasinoff
- College of Pharmacy, Faculty of Health Science, University of Manitoba, Winnipeg, MB R3E 0T5, Canada.
| | - David E Herbert
- Department of Chemistry, Faculty of Science, University of Manitoba, Winnipeg, MB R3T 2N2, Canada.
| | - Geoffrey K Tranmer
- College of Pharmacy, Faculty of Health Science, University of Manitoba, Winnipeg, MB R3E 0T5, Canada.
- Department of Chemistry, Faculty of Science, University of Manitoba, Winnipeg, MB R3T 2N2, Canada.
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9
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Orchestrated Domain Movement in Catalysis by Cytochrome P450 Reductase. Sci Rep 2017; 7:9741. [PMID: 28852004 PMCID: PMC5575293 DOI: 10.1038/s41598-017-09840-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Accepted: 07/31/2017] [Indexed: 12/16/2022] Open
Abstract
NADPH-cytochrome P450 reductase is a multi-domain redox enzyme which is a key component of the P450 mono-oxygenase drug-metabolizing system. We report studies of the conformational equilibrium of this enzyme using small-angle neutron scattering, under conditions where we are able to control the redox state of the enzyme precisely. Different redox states have a profound effect on domain orientation in the enzyme and we analyse the data in terms of a two-state equilibrium between compact and extended conformations. The effects of ionic strength show that the presence of a greater proportion of the extended form leads to an enhanced ability to transfer electrons to cytochrome c. Domain motion is intrinsically linked to the functionality of the enzyme, and we can define the position of the conformational equilibrium for individual steps in the catalytic cycle.
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10
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Niu G, Zhao S, Wang L, Dong W, Liu L, He Y. Structure of the
Arabidopsis thaliana
NADPH
‐cytochrome P450 reductase 2 (ATR2) provides insight into its function. FEBS J 2017; 284:754-765. [DOI: 10.1111/febs.14017] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Revised: 01/10/2017] [Accepted: 01/16/2017] [Indexed: 11/30/2022]
Affiliation(s)
- Guoqi Niu
- College of Life Sciences Capital Normal University Beijing China
| | - Shun Zhao
- Key Laboratory of Photobiology CAS Center for Excellence in Molecular Plant Sciences Institute of Botany Chinese Academy of Sciences Beijing China
- University of Chinese Academy of Sciences Beijing China
| | - Lei Wang
- College of Life Sciences Capital Normal University Beijing China
| | - Wei Dong
- Key Laboratory of Photobiology CAS Center for Excellence in Molecular Plant Sciences Institute of Botany Chinese Academy of Sciences Beijing China
- University of Chinese Academy of Sciences Beijing China
| | - Lin Liu
- Key Laboratory of Photobiology CAS Center for Excellence in Molecular Plant Sciences Institute of Botany Chinese Academy of Sciences Beijing China
| | - Yikun He
- College of Life Sciences Capital Normal University Beijing China
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11
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Milhim M, Gerber A, Neunzig J, Hannemann F, Bernhardt R. A Novel NADPH-dependent flavoprotein reductase from Bacillus megaterium acts as an efficient cytochrome P450 reductase. J Biotechnol 2016; 231:83-94. [DOI: 10.1016/j.jbiotec.2016.05.035] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Revised: 05/20/2016] [Accepted: 05/25/2016] [Indexed: 02/02/2023]
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12
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Aicart-Ramos C, Rodríguez-Crespo I. Binding of PDZ domains to the carboxy terminus of inducible nitric oxide synthase boosts electron transfer and NO synthesis. FEBS Lett 2015; 589:2207-12. [PMID: 26183564 DOI: 10.1016/j.febslet.2015.07.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Revised: 06/29/2015] [Accepted: 07/02/2015] [Indexed: 10/23/2022]
Abstract
iNOS lacks any phosphorylatable residue at its C-terminus despite displaying a 25-residue extension known to block electron transfer and activity. We report that C-terminal deletions of iNOS increased the cytochrome c reduction rate. Moreover, the interaction of the iNOS C-terminus with the PDZ domains of EBP50 or CAP70 resulted not only in augmented reductase activity and greater NO synthesis but also anticipated the formation of the air-stable semiquinone generated after NADPH addition. Hence, the C-terminus of iNOS regulates the activity of the enzyme, albeit, unlike nNOS and eNOS, displacement of the autoinhibitory element occurs upon binding to proteins with PDZ domains.
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Affiliation(s)
- Clara Aicart-Ramos
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040, Spain
| | - Ignacio Rodríguez-Crespo
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040, Spain.
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13
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Haque MM, Bayachou M, Tejero J, Kenney CT, Pearl NM, Im SC, Waskell L, Stuehr DJ. Distinct conformational behaviors of four mammalian dual-flavin reductases (cytochrome P450 reductase, methionine synthase reductase, neuronal nitric oxide synthase, endothelial nitric oxide synthase) determine their unique catalytic profiles. FEBS J 2014; 281:5325-40. [PMID: 25265015 DOI: 10.1111/febs.13073] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Revised: 08/27/2014] [Accepted: 09/25/2014] [Indexed: 12/14/2022]
Abstract
Multidomain enzymes often rely on large conformational motions to function. However, the conformational setpoints, rates of domain motions and relationships between these parameters and catalytic activity are not well understood. To address this, we determined and compared the conformational setpoints and the rates of conformational switching between closed unreactive and open reactive states in four mammalian diflavin NADPH oxidoreductases that catalyze important biological electron transfer reactions: cytochrome P450 reductase, methionine synthase reductase and endothelial and neuronal nitric oxide synthase. We used stopped-flow spectroscopy, single turnover methods and a kinetic model that relates electron flux through each enzyme to its conformational setpoint and its rates of conformational switching. The results show that the four flavoproteins, when fully-reduced, have a broad range of conformational setpoints (from 12% to 72% open state) and also vary 100-fold with respect to their rates of conformational switching between unreactive closed and reactive open states (cytochrome P450 reductase > neuronal nitric oxide synthase > methionine synthase reductase > endothelial nitric oxide synthase). Furthermore, simulations of the kinetic model could explain how each flavoprotein can support its given rate of electron flux (cytochrome c reductase activity) based on its unique conformational setpoint and switching rates. The present study is the first to quantify these conformational parameters among the diflavin enzymes and suggests how the parameters might be manipulated to speed or slow biological electron flux.
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Affiliation(s)
- Mohammad M Haque
- Department of Pathobiology, Lerner Research Institute, The Cleveland Clinic, Cleveland, OH, USA
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14
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Milac AL, Bojarska E, Wypijewska del Nogal A. Decapping Scavenger (DcpS) enzyme: advances in its structure, activity and roles in the cap-dependent mRNA metabolism. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2014; 1839:452-62. [PMID: 24742626 DOI: 10.1016/j.bbagrm.2014.04.007] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 04/07/2014] [Accepted: 04/08/2014] [Indexed: 01/27/2023]
Abstract
Decapping Scavenger (DcpS) enzyme rids eukaryotic cells of short mRNA fragments containing the 5' mRNA cap structure, which appear in the 3'→5' mRNA decay pathway, following deadenylation and exosome-mediated turnover. The unique structural properties of the cap, which consists of 7-methylguanosine attached to the first transcribed nucleoside by a triphosphate chain (m(7)GpppN), guarantee its resistance to non-specific exonucleases. DcpS enzymes are dimers belonging to the Histidine Triad (HIT) superfamily of pyrophosphatases. The specific hydrolysis of m(7)GpppN by DcpS yields m(7)GMP and NDP. By precluding inhibition of other cap-binding proteins by short m(7)GpppN-containing mRNA fragments, DcpS plays an important role in the cap-dependent mRNA metabolism. Over the past decade, lots of new structural, biochemical and biophysical data on DcpS has accumulated. We attempt to integrate these results, referring to DcpS enzymes from different species. Such a synergistic characteristic of the DcpS structure and activity might be useful for better understanding of the DcpS catalytic mechanism, its regulatory role in gene expression, as well as for designing DcpS inhibitors of potential therapeutic application, e.g. in spinal muscular atrophy.
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Affiliation(s)
- Adina L Milac
- Department of Bioinformatics and Structural Biochemistry, Institute of Biochemistry of the Romanian Academy (IBAR), Splaiul Independentei 296, 060031, Bucharest 17, Romania
| | - Elzbieta Bojarska
- Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Zwirki & Wigury 93, 02-089 Warsaw, Poland.
| | - Anna Wypijewska del Nogal
- Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Zwirki & Wigury 93, 02-089 Warsaw, Poland.
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15
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Su J, Gu Y, Pruijn FB, Smaill JB, Patterson AV, Guise CP, Wilson WR. Zinc finger nuclease knock-out of NADPH:cytochrome P450 oxidoreductase (POR) in human tumor cell lines demonstrates that hypoxia-activated prodrugs differ in POR dependence. J Biol Chem 2013; 288:37138-53. [PMID: 24196959 DOI: 10.1074/jbc.m113.505222] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Hypoxia, a ubiquitous feature of tumors, can be exploited by hypoxia-activated prodrugs (HAP) that are substrates for one-electron reduction in the absence of oxygen. NADPH:cytochrome P450 oxidoreductase (POR) is considered one of the major enzymes responsible, based on studies using purified enzyme or forced overexpression in cell lines. To examine the role of POR in HAP activation at endogenous levels of expression, POR knock-outs were generated in HCT116 and SiHa cells by targeted mutation of exon 8 using zinc finger nucleases. Absolute quantitation by proteotypic peptide mass spectrometry of DNA sequence-confirmed multiallelic mutants demonstrated expression of proteins with residual one-electron reductase activity in some clones and identified two (Hko2 from HCT116 and S2ko1 from SiHa) that were functionally null by multiple criteria. Sensitivities of the clones to 11 HAP (six nitroaromatics, three benzotriazine N-oxides, and two quinones) were compared with wild-type and POR-overexpressing cells. All except the quinones were potentiated by POR overexpression. Knocking out POR had a marked effect on antiproliferative activity of the 5-nitroquinoline SN24349 in both genetic backgrounds after anoxic exposure but little or no effect on activity of most other HAP, including the clinical stage 2-nitroimidazole mustard TH-302, dinitrobenzamide mustard PR-104A, and benzotriazine N-oxide SN30000. Clonogenic cell killing and reductive metabolism of PR-104A and SN30000 under anoxia also showed little change in the POR knock-outs. Thus, although POR expression is a potential biomarker of sensitivity to some HAP, identification of other one-electron reductases responsible for HAP activation is needed for their rational clinical development.
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Affiliation(s)
- Jiechuang Su
- From the Auckland Cancer Society Research Centre, Faculty of Medical and Health Sciences, University of Auckland, Private Bag 92019, Auckland, New Zealand
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16
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Flavodoxin cofactor binding induces structural changes that are required for protein-protein interactions with NADP(+) oxidoreductase and pyruvate formate-lyase activating enzyme. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2013; 1834:2512-9. [PMID: 24016774 DOI: 10.1016/j.bbapap.2013.08.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Revised: 08/27/2013] [Accepted: 08/30/2013] [Indexed: 11/23/2022]
Abstract
Flavodoxin (Fld) conformational changes, thermal stability, and cofactor binding were studied using circular dichroism (CD), isothermal titration calorimetry (ITC), and limited proteolysis. Thermodynamics of apo and holo-Fld folding were examined to discern the features of this important electron transfer protein and to provide data on apo-Fld. With the exception of fluorescence and UV-vis binding experiments with its cofactor flavin mononucleotide (FMN), apo-Fld is almost completely uncharacterized in Escherichia coli. Fld is more structured when the FMN cofactor is bound; the association is tight and driven by enthalpy of binding. Surface plasmon resonance binding experiments were carried out under anaerobic conditions for both apo- and holo-Fld and demonstrate the importance of structure and conformation for the interaction with binding partners. Holo-Fld is capable of associating with NADP(+)-dependent flavodoxin oxidoreductase (FNR) and pyruvate formate-lyase activating enzyme (PFL-AE) whereas there is no detectable interaction between apo-Fld and either protein. Limited proteolysis experiments were analyzed by LC-MS to identify the regions in Fld that are involved in conformation changes upon cofactor binding. Docking software was used to model the Fld/PFL-AE complex to understand the interactions between these two proteins and gain insight into electron transfer reactions from Fld to PFL-AE.
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17
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Bernard DG, Netz DJA, Lagny TJ, Pierik AJ, Balk J. Requirements of the cytosolic iron-sulfur cluster assembly pathway in Arabidopsis. Philos Trans R Soc Lond B Biol Sci 2013; 368:20120259. [PMID: 23754812 DOI: 10.1098/rstb.2012.0259] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The assembly of iron-sulfur (Fe-S) clusters requires dedicated protein factors inside the living cell. Striking similarities between prokaryotic and eukaryotic assembly proteins suggest that plant cells inherited two different pathways through endosymbiosis: the ISC pathway in mitochondria and the SUF pathway in plastids. Fe-S proteins are also found in the cytosol and nucleus, but little is known about how they are assembled in plant cells. Here, we show that neither plastid assembly proteins nor the cytosolic cysteine desulfurase ABA3 are required for the activity of cytosolic aconitase, which depends on a [4Fe-4S] cluster. In contrast, cytosolic aconitase activity depended on the mitochondrial cysteine desulfurase NFS1 and the mitochondrial transporter ATM3. In addition, we were able to complement a yeast mutant in the cytosolic Fe-S cluster assembly pathway, dre2, with the Arabidopsis homologue AtDRE2, but only when expressed together with the diflavin reductase AtTAH18. Spectroscopic characterization showed that purified AtDRE2 could bind up to two Fe-S clusters. Purified AtTAH18 bound one flavin per molecule and was able to accept electrons from NAD(P)H. These results suggest that the proteins involved in cytosolic Fe-S cluster assembly are highly conserved, and that dependence on the mitochondria arose before the second endosymbiosis event leading to plastids.
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Affiliation(s)
- Delphine G Bernard
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK
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18
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Iyanagi T, Xia C, Kim JJP. NADPH-cytochrome P450 oxidoreductase: prototypic member of the diflavin reductase family. Arch Biochem Biophys 2012; 528:72-89. [PMID: 22982532 PMCID: PMC3606592 DOI: 10.1016/j.abb.2012.09.002] [Citation(s) in RCA: 88] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2012] [Revised: 09/01/2012] [Accepted: 09/03/2012] [Indexed: 12/31/2022]
Abstract
NADPH-cytochrome P450 oxidoreductase (CYPOR) and nitric oxide synthase (NOS), two members of the diflavin oxidoreductase family, are multi-domain enzymes containing distinct FAD and FMN domains connected by a flexible hinge. FAD accepts a hydride ion from NADPH, and reduced FAD donates electrons to FMN, which in turn transfers electrons to the heme center of cytochrome P450 or NOS oxygenase domain. Structural analysis of CYPOR, the prototype of this enzyme family, has revealed the exact nature of the domain arrangement and the role of residues involved in cofactor binding. Recent structural and biophysical studies of CYPOR have shown that the two flavin domains undergo large domain movements during catalysis. NOS isoforms contain additional regulatory elements within the reductase domain that control electron transfer through Ca(2+)-dependent calmodulin (CaM) binding. The recent crystal structure of an iNOS Ca(2+)/CaM-FMN construct, containing the FMN domain in complex with Ca(2+)/CaM, provided structural information on the linkage between the reductase and oxgenase domains of NOS, making it possible to model the holo iNOS structure. This review summarizes recent advances in our understanding of the dynamics of domain movements during CYPOR catalysis and the role of the NOS diflavin reductase domain in the regulation of NOS isozyme activities.
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Affiliation(s)
- Takashi Iyanagi
- Department of Biochemistry, Medical College of Wisconsin, USA
- Department of Life Science, The Himeji Institute of Technology, University of Hyogo, Japan
| | - Chuanwu Xia
- Department of Biochemistry, Medical College of Wisconsin, USA
| | - Jung-Ja P. Kim
- Department of Biochemistry, Medical College of Wisconsin, USA
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19
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Abstract
Diflavin reductases are essential proteins capable of splitting the two-electron flux from reduced pyridine nucleotides to a variety of one electron acceptors. The primary sequence of diflavin reductases shows a conserved domain organization harboring two catalytic domains bound to the FAD and FMN flavins sandwiched by one or several non-catalytic domains. The catalytic domains are analogous to existing globular proteins: the FMN domain is analogous to flavodoxins while the FAD domain resembles ferredoxin reductases. The first structural determination of one member of the diflavin reductases family raised some questions about the architecture of the enzyme during catalysis: both FMN and FAD were in perfect position for interflavin transfers but the steric hindrance of the FAD domain rapidly prompted more complex hypotheses on the possible mechanisms for the electron transfer from FMN to external acceptors. Hypotheses of domain reorganization during catalysis in the context of the different members of this family were given by many groups during the past twenty years. This review will address the recent advances in various structural approaches that have highlighted specific dynamic features of diflavin reductases.
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Affiliation(s)
- Louise Aigrain
- Gene Machines Group, Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU, UK; E-Mail:
| | - Fataneh Fatemi
- Institut de Chimie des Substances Naturelles, CNRS, UPR 2301, Centre de Recherche de Gif, 1 Av. de la Terrasse, 91198 Gif-sur-Yvette Cedex, France; E-Mails: (F.F.); (O.F.); (E.L.)
| | - Oriane Frances
- Institut de Chimie des Substances Naturelles, CNRS, UPR 2301, Centre de Recherche de Gif, 1 Av. de la Terrasse, 91198 Gif-sur-Yvette Cedex, France; E-Mails: (F.F.); (O.F.); (E.L.)
| | - Ewen Lescop
- Institut de Chimie des Substances Naturelles, CNRS, UPR 2301, Centre de Recherche de Gif, 1 Av. de la Terrasse, 91198 Gif-sur-Yvette Cedex, France; E-Mails: (F.F.); (O.F.); (E.L.)
| | - Gilles Truan
- Université de Toulouse; INSA, UPS, INP; LISBP, 135 Avenue de Rangueil, F-31077 Toulouse, France
- INRA, UMR792 Ingénierie des Systèmes Biologiques et des Procédés, F-31400 Toulouse, France
- CNRS, UMR5504, F-31400 Toulouse, France
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +33-567048813; Fax: +33-567048814
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20
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Haque MM, Fadlalla MA, Aulak KS, Ghosh A, Durra D, Stuehr DJ. Control of electron transfer and catalysis in neuronal nitric-oxide synthase (nNOS) by a hinge connecting its FMN and FAD-NADPH domains. J Biol Chem 2012; 287:30105-16. [PMID: 22722929 PMCID: PMC3436266 DOI: 10.1074/jbc.m112.339697] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2012] [Revised: 06/13/2012] [Indexed: 01/19/2023] Open
Abstract
In nitric-oxide synthases (NOSs), two flexible hinges connect the FMN domain to the rest of the enzyme and may guide its interactions with partner domains for electron transfer and catalysis. We investigated the role of the FMN-FAD/NADPH hinge in rat neuronal NOS (nNOS) by constructing mutants that either shortened or lengthened this hinge by 2, 4, and 6 residues. Shortening the hinge progressively inhibited electron flux through the calmodulin (CaM)-free and CaM-bound nNOS to cytochrome c, whereas hinge lengthening relieved repression of electron flux in CaM-free nNOS and had no impact or slowed electron flux through CaM-bound nNOS to cytochrome c. How hinge length influenced heme reduction depended on whether enzyme flavins were pre-reduced with NADPH prior to triggering heme reduction. Without pre-reduction, changing the hinge length was deleterious; with pre-reduction, the hinge shortening was deleterious, and hinge lengthening increased heme reduction rates beyond wild type. Flavin fluorescence and stopped-flow kinetic studies on CaM-bound enzymes suggested hinge lengthening slowed the domain-domain interaction needed for FMN reduction. All hinge length changes lowered NO synthesis activity and increased uncoupled NADPH consumption. We conclude that several aspects of catalysis are sensitive to FMN-FAD/NADPH hinge length and that the native hinge allows a best compromise among the FMN domain interactions and associated electron transfer events to maximize NO synthesis and minimize uncoupled NADPH consumption.
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Affiliation(s)
- Mohammad Mahfuzul Haque
- From the Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195
| | - Mohammed A. Fadlalla
- From the Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195
| | - Kulwant S. Aulak
- From the Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195
| | - Arnab Ghosh
- From the Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195
| | - Deborah Durra
- From the Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195
| | - Dennis J. Stuehr
- From the Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195
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21
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Sasaki-Haraguchi N, Shimada MK, Taniguchi I, Ohno M, Mayeda A. Mechanistic insights into human pre-mRNA splicing of human ultra-short introns: potential unusual mechanism identifies G-rich introns. Biochem Biophys Res Commun 2012; 423:289-94. [PMID: 22640740 DOI: 10.1016/j.bbrc.2012.05.112] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2012] [Accepted: 05/18/2012] [Indexed: 10/28/2022]
Abstract
It is unknown how very short introns (<65 nt; termed 'ultra-short' introns) could be spliced in a massive spliceosome (>2.7 MDa) without steric hindrance. By screening an annotated human transcriptome database (H-InvDB), we identified three model ultra-short introns: the 56-nt intron in the HNRNPH1 (hnRNP H1) gene, the 49-nt intron in the NDOR1 (NADPH dependent diflavin oxidoreductase 1) gene, and the 43-nt intron in the ESRP2 (epithelial splicing regulatory protein 2) gene. We verified that these endogenous ultra-short introns are spliced, and also recapitulated this in cultured cells transfected with the corresponding mini-genes. The splicing of these ultra-short introns was repressed by a splicing inhibitor, spliceostatin A, suggesting that SF3b (a U2 snRNP component) is involved in their splicing processes. The 56-nt intron containing a pyrimidine-rich tract was spliced out in a lariat form, and this splicing was inhibited by the disruption of U1, U2, or U4 snRNA. In contrast, the 49- and 43-nt introns were purine-rich overall without any pyrimidine-rich tract, and these lariat RNAs were not detectable. Remarkably, shared G-rich intronic sequences in the 49- and 43-nt introns were required for their splicing, suggesting that these ultra-short introns may recruit a novel auxiliary splicing mechanism linked to G-rich intronic splicing enhancers.
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Affiliation(s)
- Noriko Sasaki-Haraguchi
- Division of Gene Expression Mechanism, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake, Aichi 470-1192, Japan
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22
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Meints CE, Gustafsson FS, Scrutton NS, Wolthers KR. Tryptophan 697 modulates hydride and interflavin electron transfer in human methionine synthase reductase. Biochemistry 2011; 50:11131-42. [PMID: 22097960 DOI: 10.1021/bi2012228] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Human methionine synthase reductase (MSR), a diflavin oxidoreductase, plays a vital role in methionine and folate metabolism by sustaining methionine synthase (MS) activity. MSR catalyzes the oxidation of NADPH and shuttles electrons via its FAD and FMN cofactors to inactive MS-cob(II)alamin. A conserved aromatic residue (Trp697) positioned next to the FAD isoalloxazine ring controls nicotinamide binding and catalysis in related flavoproteins. We created four MSR mutants (W697S, W697H, S698Δ, and S698A) and studied their associated kinetic behavior. Multiwavelength stopped-flow analysis reveals that NADPH reduction of the C-terminal Ser698 mutants occurs in three resolvable kinetic steps encompassing transfer of a hydride ion to FAD, semiquinone formation (indicating FAD to FMN electron transfer), and slow flavin reduction by a second molecule of NADPH. Corresponding experiments with the W697 mutants show a two-step flavin reduction without an observable semiquinone intermediate, indicating that W697 supports FAD to FMN electron transfer. Accelerated rates of FAD reduction, steady-state cytochrome c(3+) turnover, and uncoupled NADPH oxidation in the S698Δ and W697H mutants may be attributed to a decrease in the energy barrier for displacement of W697 by NADPH. Binding of NADP(+), but not 2',5'-ADP, is tighter for all mutants than for native MSR. The combined studies demonstrate that while W697 attenuates hydride transfer, it ensures coenzyme selectivity and accelerates FAD to FMN electron transfer. Moreover, analysis of analogous cytochrome P450 reductase (CPR) variants points to key differences in the driving force for flavin reduction and suggests that the conserved FAD stacking tryptophan residue in CPR also promotes interflavin electron transfer.
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Affiliation(s)
- Carla E Meints
- Department of Chemistry, University of British Columbia, Kelowna, BC, Canada V1V 1V7
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23
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Kabil O, Weeks CL, Carballal S, Gherasim C, Alvarez B, Spiro TG, Banerjee R. Reversible heme-dependent regulation of human cystathionine β-synthase by a flavoprotein oxidoreductase. Biochemistry 2011; 50:8261-3. [PMID: 21875066 DOI: 10.1021/bi201270q] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Human CBS is a PLP-dependent enzyme that clears homocysteine, gates the flow of sulfur into glutathione, and contributes to the biogenesis of H(2)S. The presence of a heme cofactor in CBS is enigmatic, and its conversion from the ferric- to ferrous-CO state inhibits enzyme activity. The low heme redox potential (-350 mV) has raised questions about the feasibility of the ferrous-CO state forming under physiological conditions. Herein, we provide the first evidence of reversible inhibition of CBS by CO in the presence of a human flavoprotein and NADPH. These data provide a mechanism for cross talk between two gas-signaling systems, CO and H(2)S, via heme-mediated allosteric regulation of CBS.
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Affiliation(s)
- Omer Kabil
- Department of Biological Chemistry, University of Michigan Medical Center, Ann Arbor, Michigan 48109-0600, United States
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24
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Dumit VI, Cortez N, Matthias Ullmann G. Distinguishing two groups of flavin reductases by analyzing the protonation state of an active site carboxylic acid. Proteins 2011; 79:2076-85. [PMID: 21538544 DOI: 10.1002/prot.23027] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2010] [Revised: 02/08/2011] [Accepted: 02/25/2011] [Indexed: 11/12/2022]
Abstract
Flavin-containing reductases are involved in a wide variety of physiological reactions such as photosynthesis, nitric oxide synthesis, and detoxification of foreign compounds, including therapeutic drugs. Ferredoxin-NADP(H)-reductase (FNR) is the prototypical enzyme of this family. The fold of this protein is highly conserved and occurs as one domain of several multidomain enzymes such as the members of the diflavin reductase family. The enzymes of this family have emerged as fusion of a FNR and a flavodoxin. Although the active sites of these enzymes are very similar, different enzymes function in opposite directions, that is, some reduce oxidized nicotinamide adenine dinucleotide phosphate (NADP(+)) and some oxidize reduced nicotinamide adenine dinucleotide phosphate (NADPH). In this work, we analyze the protonation behavior of titratable residues of these enzymes through electrostatic calculations. We find that a highly conserved carboxylic acid in the active site shows a different titration behavior in different flavin reductases. This residue is deprotonated in flavin reductases present in plastids, but protonated in bacterial counterparts and in diflavin reductases. The protonation state of the carboxylic acid may also influence substrate binding. The physiological substrate for plastidic enzymes is NADP(+), but it is NADPH for the other mentioned reductases. In this article, we discuss the relevance of the environment of this residue for its protonation and its importance in catalysis. Our results allow to reinterpret and explain experimental data.
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Affiliation(s)
- Verónica I Dumit
- Structural Biology/Bioinformatics, University of Bayreuth, 95447 Bayreuth, Germany
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25
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L-carnitine reduces doxorubicin-induced apoptosis through a prostacyclin-mediated pathway in neonatal rat cardiomyocytes. Int J Cardiol 2011; 146:145-52. [DOI: 10.1016/j.ijcard.2009.06.010] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2008] [Revised: 05/12/2009] [Accepted: 06/06/2009] [Indexed: 11/18/2022]
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26
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Tah18 transfers electrons to Dre2 in cytosolic iron-sulfur protein biogenesis. Nat Chem Biol 2010; 6:758-65. [PMID: 20802492 DOI: 10.1038/nchembio.432] [Citation(s) in RCA: 153] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2010] [Accepted: 08/03/2010] [Indexed: 11/09/2022]
Abstract
Cytosolic and nuclear iron-sulfur (Fe-S) proteins play key roles in processes such as ribosome maturation, transcription and DNA repair-replication. For biosynthesis of their Fe-S clusters, a dedicated cytosolic Fe-S protein assembly (CIA) machinery is required. Here, we identify the essential flavoprotein Tah18 as a previously unrecognized CIA component and show by cell biological, biochemical and spectroscopic approaches that the complex of Tah18 and the CIA protein Dre2 is part of an electron transfer chain functioning in an early step of cytosolic Fe-S protein biogenesis. Electrons are transferred from NADPH via the FAD- and FMN-containing Tah18 to the Fe-S clusters of Dre2. This electron transfer chain is required for assembly of target but not scaffold Fe-S proteins, suggesting a need for reduction in the generation of stably inserted Fe-S clusters. The pathway is conserved in eukaryotes, as human Ndor1-Ciapin1 proteins can functionally replace yeast Tah18-Dre2.
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27
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Ivanov AS, Gnedenko OV, Molnar AA, Archakov AI, Podust LM. FMN binding site of yeast NADPH-cytochrome P450 reductase exposed at the surface is highly specific. ACS Chem Biol 2010; 5:767-76. [PMID: 20557022 DOI: 10.1021/cb100055v] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
NADPH-cytochrome P450 reductase (CPR) transfers two reducing equivalents derived from NADPH via FAD and FMN to microsomal P450 monooxygenases in one-electron transfer steps. The crystal structure of yeast CPR (yCPR) contains a surface-exposed FMN binding site (FMN2 site) at the interface of the FMN binding and connecting domains, in addition to the single buried site that has been observed in rat CPR. This finding provides a testable hypothesis of how intramolecular (between FAD and FMN) and intermolecular (between FMN and P450) electron transfer may occur in CPR. To verify that occupancy of the FMN2 site is not an artifact of crystallization, a surface plasmon resonance (SPR) biosensor technique has been applied to probe the selectivity of this site under functional conditions. A series of kinetic and equilibrium binding experiments involving yCPR immobilized on different sensor chip surfaces was performed using FMN and FAD, as well as FMN-derived compounds, including riboflavin, dimethylalloxazine, and alloxazine, and other molecules that resemble the planar isoalloxazine ring structure. Only FMN and FAD showed stoichiometric binding responses. Binding affinity for FMN was in the submicromolar range, 30 times higher than that for FAD. Association kinetic rates for the yCPR/FMN complex were up to 60-fold higher than for the yCPR/FAD complex. Taken together, these data indicate that (i) the surface-exposed site in yCPR is highly selective toward binding flavins, (ii) binding of FMN in this site is notably favored, and finally, (iii) both the phosphate group and the isoalloxazine ring of FMN are essential for binding.
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Affiliation(s)
- Alexis S. Ivanov
- Institute of Biomedical Chemistry, Russian Academy of Medical Sciences, Moscow 119121, Russia
| | - Oksana V. Gnedenko
- Institute of Biomedical Chemistry, Russian Academy of Medical Sciences, Moscow 119121, Russia
| | - Andrey A. Molnar
- Institute of Biomedical Chemistry, Russian Academy of Medical Sciences, Moscow 119121, Russia
| | - Alexander I. Archakov
- Institute of Biomedical Chemistry, Russian Academy of Medical Sciences, Moscow 119121, Russia
| | - Larissa M. Podust
- Department of Pharmaceutical Chemistry, University of California, San Francisco, California 94143
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28
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Varadarajan J, Guilleminot J, Saint-Jore-Dupas C, Piégu B, Chabouté ME, Gomord V, Coolbaugh RC, Devic M, Delorme V. ATR3 encodes a diflavin reductase essential for Arabidopsis embryo development. THE NEW PHYTOLOGIST 2010; 187:67-82. [PMID: 20406405 DOI: 10.1111/j.1469-8137.2010.03254.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
*The Arabidopsis genome possesses two confirmed Cytochrome P450 Reductase (CPR) genes, ATR1 and ATR2, together with a third putative homologue, ATR3, which annotation is questionable. *Phylogenetic analysis classified ATR3 as a CPR-like protein sharing homologies with the animal cytosolic dual flavin reductases, NR1 and Fre-1, distinct from the microsomal CPRs, ATR1 and ATR2. Like NR1 and Fre-1, ATR3 lacks the N-terminal endoplasmic reticulum (ER) anchor domain of CPRs and is localized in the cytoplasm. Recombinant ATR3 in plant soluble extracts was able to reduce cytochrome c but failed to reduce the human P450 CYP1A2. *Loss of ATR3 function resulted in early embryo lethality indicating that this reductase activity is essential. A yeast 2-hybrid screen identified a unique interaction of ATR3 with the homologue of the human anti-apoptotic CIAPIN1 and the yeast Dre2 protein. *This interaction suggests two possible roles for ATR3 in the control of cell death and in chromosome segregation at mitosis. Consistent with these results, the promoter of ATR3 is activated during cell cycle progression. Together these results demonstrated that ATR3 belongs to the NR1 subfamily of diflavin reductases whose characterized members are involved in essential cellular functions.
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Affiliation(s)
- Janani Varadarajan
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907-1155, USA
| | - Jocelyne Guilleminot
- Laboratoire Génome et Développement des Plantes, UMR-CNRS-IRD 5096, Université de Perpignan Via Domitia 58 Avenue Paul Alduy, 66860 Perpignan-Cedex, France
| | - Claude Saint-Jore-Dupas
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 6037, IFRMP 23, UFR des Sciences, Université de Rouen, 76821 Mont-Saint-Aignan Cedex, France
| | - Benoît Piégu
- Laboratoire Génome et Développement des Plantes, UMR-CNRS-IRD 5096, Université de Perpignan Via Domitia 58 Avenue Paul Alduy, 66860 Perpignan-Cedex, France
| | - Marie-Edith Chabouté
- Institut de Biologie Moléculaire des Plantes du CNRS, 12 rue du Général Zimmer, 67084 Strasbourg-Cedex, France
| | - Véronique Gomord
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 6037, IFRMP 23, UFR des Sciences, Université de Rouen, 76821 Mont-Saint-Aignan Cedex, France
| | - Ronald C Coolbaugh
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907-1155, USA
| | - Martine Devic
- Laboratoire Génome et Développement des Plantes, UMR-CNRS-IRD 5096, Université de Perpignan Via Domitia 58 Avenue Paul Alduy, 66860 Perpignan-Cedex, France
| | - Valérie Delorme
- Laboratoire Génome et Développement des Plantes, UMR-CNRS-IRD 5096, Université de Perpignan Via Domitia 58 Avenue Paul Alduy, 66860 Perpignan-Cedex, France
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Jensen K, Møller BL. Plant NADPH-cytochrome P450 oxidoreductases. PHYTOCHEMISTRY 2010; 71:132-41. [PMID: 19931102 DOI: 10.1016/j.phytochem.2009.10.017] [Citation(s) in RCA: 117] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2009] [Accepted: 10/21/2009] [Indexed: 05/23/2023]
Abstract
NADPH-cytochrome P450 oxidoreductase (CPR) serves as the electron donor to almost all eukaryotic cytochromes P450. It belongs to a small family of diflavin proteins and is built of cofactor binding domains with high structural homology to those of bacterial flavodoxins and to ferredoxin-NADP(+) oxidoreductases. CPR shuttles electrons from NADPH through the FAD and FMN-cofactors into the central heme-group of the P450s. Mobile domains in CPR are essential for electron transfer between FAD and FMN and for P450 interaction. Blast searches identified 54 full-length gene sequences encoding CPR derived from a total of 35 different plant species. CPRs from vascular plants cluster into two major phylogenetic groups. Depending on the species, plants contain one, two or three paralogs of which one is inducible. The nature of the CPR-P450 interacting domains is well conserved as demonstrated by the ability of CPRs from different species or even from different kingdoms to at least partially complement each other functionally. This makes CPR an ideal bio-brick in synthetic biology approaches to re-design or develop entirely different combinations of existing biological systems to gain improved or completely altered functionalities based on the "share your parts" principle.
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Affiliation(s)
- Kenneth Jensen
- Plant Biochemistry Laboratory, Department of Plant Biology and Biotechnology, University of Copenhagen, 40 Thorvaldsensvej, DK-1871 Frederiksberg C, Copenhagen, Denmark
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30
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Das A, Sligar SG. Modulation of the cytochrome P450 reductase redox potential by the phospholipid bilayer. Biochemistry 2010; 48:12104-12. [PMID: 19908820 DOI: 10.1021/bi9011435] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Cytochrome P450 reductase (CPR) is a tethered membrane protein which transfers electrons from NADPH to microsomal P450s. We show that the lipid bilayer has a role in defining the redox potential of the CPR flavin domains. In order to quantitate the electrochemical behavior of this central redox protein, full-length CPR was incorporated into soluble nanometer scale discoidal membrane bilayers (nanodiscs), and potentials were measured using spectropotentiometry. The redox potentials of both FMN and FAD were found to shift to more positive values when in a membrane bilayer as compared to a solubilized version of the reductase. The potentials of the semiquinone/hydroquinone couple of both FMN and FAD are altered to a larger extent than the oxidized/semiquinone couple which is understood by a simple electrostatic model. When anionic lipids were used to change the membrane composition of the CPR-nanodisc, the redox potential of both flavins became more negative, favoring electron transfer from CPR to cytochrome P450.
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Affiliation(s)
- Aditi Das
- Department of Biochemistry, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, USA
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31
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Ellis J, Gutierrez A, Barsukov IL, Huang WC, Grossmann JG, Roberts GCK. Domain motion in cytochrome P450 reductase: conformational equilibria revealed by NMR and small-angle x-ray scattering. J Biol Chem 2009; 284:36628-36637. [PMID: 19858215 PMCID: PMC2794777 DOI: 10.1074/jbc.m109.054304] [Citation(s) in RCA: 115] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2009] [Revised: 10/21/2009] [Indexed: 11/06/2022] Open
Abstract
NADPH-cytochrome P450 reductase (CPR), a diflavin reductase, plays a key role in the mammalian P450 mono-oxygenase system. In its crystal structure, the two flavins are close together, positioned for interflavin electron transfer but not for electron transfer to cytochrome P450. A number of lines of evidence suggest that domain motion is important in the action of the enzyme. We report NMR and small-angle x-ray scattering experiments addressing directly the question of domain organization in human CPR. Comparison of the (1)H-(15)N heteronuclear single quantum correlation spectrum of CPR with that of the isolated FMN domain permitted identification of residues in the FMN domain whose environment differs in the two situations. These include several residues that are solvent-exposed in the CPR crystal structure, indicating the existence of a second conformation in which the FMN domain is involved in a different interdomain interface. Small-angle x-ray scattering experiments showed that oxidized and NADPH-reduced CPRs have different overall shapes. The scattering curve of the reduced enzyme can be adequately explained by the crystal structure, whereas analysis of the data for the oxidized enzyme indicates that it exists as a mixture of approximately equal amounts of two conformations, one consistent with the crystal structure and one a more extended structure consistent with that inferred from the NMR data. The correlation between the effects of adenosine 2',5'-bisphosphate and NADPH on the scattering curve and their effects on the rate of interflavin electron transfer suggests that this conformational equilibrium is physiologically relevant.
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Affiliation(s)
- Jacqueline Ellis
- Henry Wellcome Laboratories for Structural Biology, Department of Biochemistry, University of Leicester, Leicester LE1 9HN, United Kingdom
| | - Aldo Gutierrez
- Henry Wellcome Laboratories for Structural Biology, Department of Biochemistry, University of Leicester, Leicester LE1 9HN, United Kingdom
| | - Igor L Barsukov
- Henry Wellcome Laboratories for Structural Biology, Department of Biochemistry, University of Leicester, Leicester LE1 9HN, United Kingdom
| | - Wei-Cheng Huang
- Henry Wellcome Laboratories for Structural Biology, Department of Biochemistry, University of Leicester, Leicester LE1 9HN, United Kingdom
| | - J Günter Grossmann
- Molecular Biophysics Group, Science and Technology Facilities Council Daresbury Laboratory, Warrington, Cheshire WA4 4AD, United Kingdom
| | - Gordon C K Roberts
- Henry Wellcome Laboratories for Structural Biology, Department of Biochemistry, University of Leicester, Leicester LE1 9HN, United Kingdom.
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Kim J, Hannibal L, Gherasim C, Jacobsen DW, Banerjee R. A human vitamin B12 trafficking protein uses glutathione transferase activity for processing alkylcobalamins. J Biol Chem 2009; 284:33418-24. [PMID: 19801555 DOI: 10.1074/jbc.m109.057877] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Pathways for tailoring and processing vitamins into active cofactor forms exist in mammals that are unable to synthesize these cofactors de novo. A prerequisite for intracellular tailoring of alkylcobalamins entering from the circulation is removal of the alkyl group to generate an intermediate that can subsequently be converted into the active cofactor forms. MMACHC, a cytosolic cobalamin trafficking chaperone, has been shown recently to catalyze a reductive decyanation reaction when it encounters cyanocobalamin. In this study, we demonstrate that this versatile protein catalyzes an entirely different chemical reaction with alkylcobalamins using the thiolate of glutathione for nucleophilic displacement to generate cob(I)alamin and the corresponding glutathione thioether. Biologically relevant thiols, e.g. cysteine and homocysteine, cannot substitute for glutathione. The catalytic turnover numbers for the dealkylation of methylcobalamin and 5'-deoxyadenosylcobalamin by MMACHC are 11.7 +/- 0.2 and 0.174 +/- 0.006 h(-1) at 20 degrees C, respectively. This glutathione transferase activity of MMACHC is reminiscent of the methyltransferase chemistry catalyzed by the vitamin B(12)-dependent methionine synthase and is impaired in the cblC group of inborn errors of cobalamin disorders.
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Affiliation(s)
- Jihoe Kim
- Department of Biological Chemistry, University of Michigan Medical Center, Ann Arbor, Michigan 48109-5066, USA
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Kochhann D, Pavanato MA, Llesuy SF, Correa LM, Konzen Riffel AP, Loro VL, Mesko MF, Flores EMM, Dressler VL, Baldisserotto B. Bioaccumulation and oxidative stress parameters in silver catfish (Rhamdia quelen) exposed to different thorium concentrations. CHEMOSPHERE 2009; 77:384-391. [PMID: 19665757 DOI: 10.1016/j.chemosphere.2009.07.022] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2009] [Revised: 06/24/2009] [Accepted: 07/13/2009] [Indexed: 05/28/2023]
Abstract
The objective of this study was to evaluate the effect of chronic thorium (Th) exposure on bioaccumulation, metabolism (through biochemical parameters of the muscle) and oxidative parameters (lipidic peroxidation levels and antioxidant enzymes in the gills and in the hepatic and muscular tissues) of silver catfish (Rhamdia quelen). Silver catfish juveniles were exposed to different waterborne Th levels (in microg L(-1)): 0 (control), 25.3+/-3.2, 80.6+/-12.0, 242.4+/-35.6, and 747.2+/-59.1 for 30 d. The gills and skin were the organs that accumulated the highest Th levels. The increase in the waterborne Th concentration corresponded to a progressive increase in the Th levels in the gills and kidney. Chronic Th exposure causes alterations in the oxidative parameters of silver catfish gills, which are correlated with the Th accumulation in this organ. The levels of GST decreased in the gills of fish exposed to 747.2 microg L(-1) Th and SOD activity decreased in silver catfish exposed to 242.4 and 747.2 microg L(-1) Th. In addition, the increase in the LPO in the gills exposed to 242.4 and 747.2 microg L(-1) Th suggests that higher oxidative damage occurred in the gills. However, in the liver and muscle, these alterations occurred mainly in the lowest waterborne Th level. Metabolic intermediates in the muscle were altered by Th exposure, but no clear relationship was found.
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Affiliation(s)
- Daiani Kochhann
- Departamento de Fisiologia e Farmacologia, Universidade Federal de Santa Maria, 97105-900 Santa Maria, RS, Brazil
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Hamdane D, Xia C, Im SC, Zhang H, Kim JJP, Waskell L. Structure and function of an NADPH-cytochrome P450 oxidoreductase in an open conformation capable of reducing cytochrome P450. J Biol Chem 2009; 284:11374-84. [PMID: 19171935 PMCID: PMC2670143 DOI: 10.1074/jbc.m807868200] [Citation(s) in RCA: 166] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2008] [Revised: 01/12/2009] [Indexed: 11/06/2022] Open
Abstract
NADPH-cytochrome P450 oxidoreductase (CYPOR) catalyzes the transfer of electrons to all known microsomal cytochromes P450. A CYPOR variant, with a 4-amino acid deletion in the hinge connecting the FMN domain to the rest of the protein, has been crystallized in three remarkably extended conformations. The variant donates an electron to cytochrome P450 at the same rate as the wild-type, when provided with sufficient electrons. Nevertheless, it is defective in its ability to transfer electrons intramolecularly from FAD to FMN. The three extended CYPOR structures demonstrate that, by pivoting on the C terminus of the hinge, the FMN domain of the enzyme undergoes a structural rearrangement that separates it from FAD and exposes the FMN, allowing it to interact with its redox partners. A similar movement most likely occurs in the wild-type enzyme in the course of transferring electrons from FAD to its physiological partner, cytochrome P450. A model of the complex between an open conformation of CYPOR and cytochrome P450 is presented that satisfies mutagenesis constraints. Neither lengthening the linker nor mutating its sequence influenced the activity of CYPOR. It is likely that the analogous linker in other members of the diflavin family functions in a similar manner.
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Affiliation(s)
- Djemel Hamdane
- University of Michigan Medical School and Veterans Affairs Medical Research Center, Ann Arbor, Michigan 48105, USA
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35
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Wolthers KR, Scrutton NS. Cobalamin uptake and reactivation occurs through specific protein interactions in the methionine synthase-methionine synthase reductase complex. FEBS J 2009; 276:1942-51. [PMID: 19243433 DOI: 10.1111/j.1742-4658.2009.06919.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Human methionine synthase reductase (MSR), a diflavin enzyme, restores the activity of human methionine synthase through reductive methylation of methionine synthase (MS)-bound cob(II)alamin. Recently, it was also reported that MSR enhances uptake of cobalamin by apo-MS, a role associated with the MSR-catalysed reduction of exogenous aquacob(III)alamin to cob(II)alamin [Yamada K, Gravel RA, TorayaT & Matthews RG (2006) Proc Natl Acad Sci USA103, 9476-9481]. Here, we report the expression and purification of human methionine synthase from Pichia pastoris. This has enabled us to assess the ability of human MSR and two other structurally related diflavin reductase enzymes (cytochrome P450 reductase and the reductase domain of neuronal nitric oxide synthase) to: (a) stimulate formation of holo-MS from aquacob(III)alamin and the apo-form of MS; and (b) reactivate the inert cob(II)alamin form of MS that accumulates during enzyme catalysis. Of the three diflavin reductases studied, cytochrome P450 reductase had the highest turnover rate (55.5 s(-1)) for aquacob(III)alamin reduction, and the reductase domain of neuronal nitric oxide synthase elicited the highest specificity (k(cat)/K(m) of 1.5 x 10(5) m(-1) s(-1)) and MSR had the lowest K(m) (6.6 microm) for the cofactor. Despite the ability of all three enzymes to reduce aquacob(III)alamin, only MSR (the full-length form or the isolated FMN domain) enhanced the uptake of cobalamin by apo-MS. MSR was also the only diflavin reductase to reactivate the inert cob(II)alamin form of purified human MS (K(act) of 107 nm) isolated from Pichia pastoris. Our work shows that reactivation of cob(II)alamin MS and incorporation of cobalamin into apo-MS is enhanced through specific protein-protein interactions between the MSR FMN domain and MS.
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Affiliation(s)
- Kirsten R Wolthers
- Manchester Interdisciplinary Biocentre, University of Manchester, Manchester, UK
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36
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Chen HC, Swenson RP. Effect of the Insertion of a Glycine Residue into the Loop Spanning Residues 536-541 on the Semiquinone State and Redox Properties of the Flavin Mononucleotide-Binding Domain of Flavocytochrome P450BM-3 from Bacillus megaterium. Biochemistry 2009; 47:13788-99. [PMID: 19055322 DOI: 10.1021/bi800954h] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Despite sharing sequence and structural similarities with other diflavin reductases such as NADPH-cytochrome P450 reductase (CPR) and nitric oxide synthase, flavocytochrome P450BM-3 displays some unique redox and electron transferring properties, including the inability to thermodynamically stabilize the neutral semiquinone (SQ) state of the flavin mononucleotide (FMN) cofactor. Rather, the anionic SQ species is only transiently formed during rapid reduction. Why is this? The absence of a conserved glycine residue and, as a consequence, the shorter and less flexible cofactor-binding loop in P450BM-3 represents a notable difference from other diflavin reductases and the structurally related flavodoxin. This difference may facilitate the formation of a strong hydrogen bond between backbone amide NH group of Asn537 and N5 of the oxidized FMN, an interaction not found in the other proteins. In the flavodoxin, the conserved glycine residue plays a crucial role in a redox-linked conformational change that contributes to the thermodynamic stabilization of the neutral SQ species of the FMN through the formation of a hydrogen bond with the N5H group of the flavin. In this study, a glycine residue was inserted after Tyr536 in the loop within the isolated FMN-binding domain as well as the diflavin reductase domain of P450BM-3, a position equivalent to Gly141 in human CPR. As a result, the insertion variant was observed to accumulate the neutral form of the FMN SQ species much like CPR. The midpoint potential for the SQ/HQ couple decreased by 68 mV, while that for the OX/SQ couple remained unchanged. (15)N NMR data provide evidence of the disruption of the hydrogen bond between the backbone amide group of Asn537 and the N5 atom in the oxidized state of the FMN. Molecular models suggest that the neutral FMN SQ could be stabilized through hydrogen bonding with the backbone carbonyl group of the inserted glycine residue in a manner similar to that of CPR and the flavodoxin. The insertion of the glycine at the same location within the diflavin domain resulted in a purified protein that retained nearly stoichiometric levels of bound FAD but tended to lose the FMN cofactor. This preparation retained one-third of the ferricyanide reductase activity but <1% of the cytochrome c reductase activity of the wild type. However, the insertion variant reconstituted with FMN regained nearly half of the wild-type cytochrome c reductase activity. These results demonstrate the importance of the unique structural characteristics of the shorter loop in P450BM-3 in establishing the unique redox properties of the FMN in this protein but not its general cytochrome reductase activity.
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Affiliation(s)
- Huai-Chun Chen
- Department of Biochemistry and Ohio State Biochemistry Program, The Ohio State University, Columbus, Ohio 43210
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37
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Abstract
The mystery of how the cyanide group in vitamin B(12) or cyanocobalamin, discovered 60 years ago, is removed, has been solved by the demonstration that the trafficking chaperone, MMACHC, catalyzes a reductive decyanation reaction. Electrons transferred from NADPH via cytosolic flavoprotein oxidoreductases are used to cleave the cobalt-carbon bond with reductive elimination of the cyanide ligand. The product, cob(II)alamin, is a known substrate for assimilation into the active cofactor forms, methylcobalamin and 5'-deoxyadenosylcobalamin, and is bound in the "base-off" state that is needed by the two B(12)-dependent target enzymes, methionine synthase and methylmalonyl-CoA mutase. Defects in MMACHC represent the most common cause of inborn errors of B(12) metabolism, and our results explain the observation that fibroblasts from these patients are poorly responsive to vitamin B(12) but show some metabolic correction with aquocobalamin, a cofactor form lacking the cyanide ligand, which is mirrored by patients showing poorer clinical responsiveness to cyano- versus aquocobalamin.
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Multiple NADPH–cytochrome P450 reductases from Trypanosoma cruzi. Mol Biochem Parasitol 2008; 160:42-51. [DOI: 10.1016/j.molbiopara.2008.03.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2007] [Revised: 03/12/2008] [Accepted: 03/13/2008] [Indexed: 11/22/2022]
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Sumimoto H. Structure, regulation and evolution of Nox-family NADPH oxidases that produce reactive oxygen species. FEBS J 2008; 275:3249-77. [PMID: 18513324 DOI: 10.1111/j.1742-4658.2008.06488.x] [Citation(s) in RCA: 511] [Impact Index Per Article: 31.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
NADPH oxidases of the Nox family exist in various supergroups of eukaryotes but not in prokaryotes, and play crucial roles in a variety of biological processes, such as host defense, signal transduction, and hormone synthesis. In conjunction with NADPH oxidation, Nox enzymes reduce molecular oxygen to superoxide as a primary product, and this is further converted to various reactive oxygen species. The electron-transferring system in Nox is composed of the C-terminal cytoplasmic region homologous to the prokaryotic (and organelle) enzyme ferredoxin reductase and the N-terminal six transmembrane segments containing two hemes, a structure similar to that of cytochrome b of the mitochondrial bc(1) complex. During the course of eukaryote evolution, Nox enzymes have developed regulatory mechanisms, depending on their functions, by inserting a regulatory domain (or motif) into their own sequences or by obtaining a tightly associated protein as a regulatory subunit. For example, one to four Ca(2+)-binding EF-hand motifs are present at the N-termini in several subfamilies, such as the respiratory burst oxidase homolog (Rboh) subfamily in land plants (the supergroup Plantae), the NoxC subfamily in social amoebae (the Amoebozoa), and the Nox5 and dual oxidase (Duox) subfamilies in animals (the Opisthokonta), whereas an SH3 domain is inserted into the ferredoxin-NADP(+) reductase region of two Nox enzymes in Naegleria gruberi, a unicellular organism that belongs to the supergroup Excavata. Members of the Nox1-4 subfamily in animals form a stable heterodimer with the membrane protein p22(phox), which functions as a docking site for the SH3 domain-containing regulatory proteins p47(phox), p67(phox), and p40(phox); the small GTPase Rac binds to p67(phox) (or its homologous protein), which serves as a switch for Nox activation. Similarly, Rac activates the fungal NoxA via binding to the p67(phox)-like protein Nox regulator (NoxR). In plants, on the other hand, this GTPase directly interacts with the N-terminus of Rboh, leading to superoxide production. Here I describe the regulation of Nox-family oxidases on the basis of three-dimensional structures and evolutionary conservation.
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Affiliation(s)
- Hideki Sumimoto
- Medical Institute of Bioregulation, Kyushu University, Fukuoka CREST, Japan Science and Technology Agency, Tokyo, Japan.
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Froese DS, Wu X, Zhang J, Dumas R, Schoel WM, Amrein M, Gravel RA. Restricted role for methionine synthase reductase defined by subcellular localization. Mol Genet Metab 2008; 94:68-77. [PMID: 18221906 PMCID: PMC2765244 DOI: 10.1016/j.ymgme.2007.11.019] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2007] [Revised: 11/23/2007] [Accepted: 11/23/2007] [Indexed: 11/19/2022]
Abstract
Methionine synthase reductase (MSR; gene name MTRR) is responsible for the reductive activation of methionine synthase. Cloning of the MTRR gene had revealed two major transcription start sites which, by alternative splicing, allows for two potential translation products of 698 and 725 amino acids. While the shorter protein was expected to target the cytosol where methionine synthase is located, the additional sequence in the longer protein was consistent with a role as a mitochondrial leader sequence. The possibility that MSR might target mitochondria was also suggested by the work of Leal et al. [N.A. Leal, H. Olteanu, R. Banerjee, T.A. Bobik, Human ATP:Cob(I)alamin adenosyltransferase and its interaction with methionine synthase reductase, J. Biol. Chem. 279 (2004) 47536-47542.] who showed that it can act as the reducing enzyme in combination with MMAB (ATP:Cob(I)alamin adenosyltransferase) to generate adenosylcobalamin from cob(II)alamin in vitro. Here we examined directly whether MSR protein is found in mitochondria. We show that, while two transcripts are produced by alternative splicing, the N-terminal segment of the putative mitochondrial form of MSR fused to GFP does not contain a sufficiently strong mitochondrial leader sequence to direct the fusion protein to the mitochondria of human fibroblasts. Further, antibodies to MSR protein localized MSR to the cytosol, but not to the mitochondria of human fibroblasts or the human hepatoma line Huh-1, as determined by Western blot analysis and immunofluorescence of cells in situ. These data confirm that MSR protein is restricted to the cytosol but, based on the Leal study, suggest that a similar protein may interact with MMAB to reduce the mitochondrial cobalamin substrate in the generation of adenosylcobalamin.
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Affiliation(s)
- D S Froese
- Department of Biochemistry and Molecular Biology, University of Calgary, 3330 Hospital Drive NW, Calgary, Alta., Canada T2N 4N1
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Gonzalez-Kristeller DC, Farage L, Fiorini LC, Loomis WF, da Silva AM. The P450 oxidoreductase, RedA, controls development beyond the mound stage in Dictyostelium discoideum. BMC DEVELOPMENTAL BIOLOGY 2008; 8:8. [PMID: 18218133 PMCID: PMC2257935 DOI: 10.1186/1471-213x-8-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/28/2007] [Accepted: 01/24/2008] [Indexed: 01/19/2023]
Abstract
BACKGROUND NADPH-cytochrome-P450 oxidoreductase (CPR) is a ubiquitous enzyme that belongs to a family of diflavin oxidoreductases and is required for activity of the microsomal cytochrome-P450 monooxygenase system. CPR gene-disruption experiments have demonstrated that absence of this enzyme causes developmental defects both in mouse and insect. RESULTS Annotation of the sequenced genome of D. discoideum revealed the presence of three genes (redA, redB and redC) that encode putative members of the diflavin oxidoreductase protein family. redA transcripts are present during growth and early development but then decline, reaching undetectable levels after the mound stage. redB transcripts are present in the same levels during growth and development while redC expression was detected only in vegetative growing cells. We isolated a mutant strain of Dictyostelium discoideum following restriction enzyme-mediated integration (REMI) mutagenesis in which redA was disrupted. This mutant develops only to the mound stage and accumulates a bright yellow pigment. The mound-arrest phenotype is cell-autonomous suggesting that the defect occurs within the cells rather than in intercellular signaling. CONCLUSION The developmental arrest due to disruption of redA implicates CPR in the metabolism of compounds that control cell differentiation.
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Affiliation(s)
- Daniela C Gonzalez-Kristeller
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Av, Prof, Lineu Prestes 748, 05508-000, São Paulo, Brasil.
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Ruiz-Vela A, Korsmeyer SJ. Proapoptotic histone H1.2 induces CASP-3 and -7 activation by forming a protein complex with CYT c, APAF-1 and CASP-9. FEBS Lett 2007; 581:3422-8. [PMID: 17618626 DOI: 10.1016/j.febslet.2007.06.049] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2007] [Revised: 06/05/2007] [Accepted: 06/18/2007] [Indexed: 11/28/2022]
Abstract
Cytochrome c (CYT c) is a protein that employs the caspase recruitment domain (CARD)-containing proteins APAF-1 and CASP-9 to activate effectors CASP-3 and -7. By using affinity labeling techniques and mass spectrometry analysis, we show that histone H1.2 is a regulator of caspases upon UV irradiation. We demonstrated that histone H1.2 forms a protein complex with APAF-1, CASP-9 and CYT c upon UV irradiation. In cell-free systems, we show that histone H1.2 triggers activation of CASP-3 and -7 via APAF-1 and CASP-9. We therefore conclude that upon DNA damage histone H1.2 acts as a positive regulator of apoptosome formation.
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Affiliation(s)
- Antonio Ruiz-Vela
- Howard Hughes Medical Institute, Department of Pathology and Medicine, Harvard Medical School, Boston, MA 02115, USA.
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43
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Girvan HM, Waltham TN, Neeli R, Collins HF, McLean KJ, Scrutton NS, Leys D, Munro AW. Flavocytochrome P450 BM3 and the origin of CYP102 fusion species. Biochem Soc Trans 2006; 34:1173-7. [PMID: 17073779 DOI: 10.1042/bst0341173] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Flavocytochrome P450 (cytochrome P450) BM3 is an intensively studied model system within the P450 enzyme superfamily, and is a natural fusion of a P450 to its P450 reductase redox partner. The fusion arrangement enables efficient electron transfer within the enzyme and a catalytic efficiency that cannot be matched in P450 systems from higher organisms. P450 BM3's potential for industrially relevant chemical transformations is now recognized, and variants with biotechnological applications have been constructed. Simultaneously, structural and mechanistic studies continue to reveal the intricate mechanistic details of this enzyme, including its dimeric organization and the relevance of this quaternary structure to catalysis. Homologues of BM3 have been found in several bacteria and fungi, indicating important physiological functions in these microbes and enabling first insights into evolution of the enzyme family. This short paper deals with recent developments in our understanding of structure, function, evolution and biotechnological applications of this important P450 system.
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Affiliation(s)
- H M Girvan
- Manchester Interdisciplinary Biocentre, School of Chemical Engineering and Analytical Science, University of Manchester, 131 Princess Street, Manchester M1 7ND, UK
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Munro AW, Girvan HM, McLean KJ. Cytochrome P450--redox partner fusion enzymes. Biochim Biophys Acta Gen Subj 2006; 1770:345-59. [PMID: 17023115 DOI: 10.1016/j.bbagen.2006.08.018] [Citation(s) in RCA: 164] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2006] [Revised: 08/23/2006] [Accepted: 08/25/2006] [Indexed: 12/23/2022]
Abstract
The cytochromes P450 (P450s) are a broad class of heme b-containing mono-oxygenase enzymes. The vast majority of P450s catalyse reductive scission of molecular oxygen using electrons usually derived from coenzymes (NADH and NADPH) and delivered from redox partner proteins. Evolutionary advantages may be gained by fusion of one or more redox partners to the P450 enzyme in terms of e.g. catalytic efficiency. This route was taken by the well characterized flavocytochrome P450(BM3) system (CYP102A1) from Bacillus megaterium, in which soluble P450 and cytochrome P450 reductase enzymes are covalently linked to produce a highly efficient electron transport system for oxygenation of fatty acids and related molecules. However, genome analysis and ongoing enzyme characterization has revealed that there are a number of other novel classes of P450-redox partner fusion enzymes distributed widely in prokaryotes and eukaryotes. This review examines our current state of knowledge of the diversity of these fusion proteins and explores their structural composition and evolutionary origins.
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Affiliation(s)
- Andrew W Munro
- Manchester Interdisciplinary Biocentre, School of Chemical Engineering and Analytical Science, University of Manchester, 131 Princess Street, Manchester, M1 7ND, UK.
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Lamb DC, Kim Y, Yermalitskaya LV, Yermalitsky VN, Lepesheva GI, Kelly SL, Waterman MR, Podust LM. A second FMN binding site in yeast NADPH-cytochrome P450 reductase suggests a mechanism of electron transfer by diflavin reductases. Structure 2006; 14:51-61. [PMID: 16407065 DOI: 10.1016/j.str.2005.09.015] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2005] [Revised: 09/19/2005] [Accepted: 09/19/2005] [Indexed: 11/22/2022]
Abstract
NADPH-cytochrome P450 reductase transfers two reducing equivalents derived from a hydride ion of NADPH via FAD and FMN to the large family of microsomal cytochrome P450 monooxygenases in one-electron transfer steps. The mechanism of electron transfer by diflavin reductases remains elusive and controversial. Here, we determined the crystal structure of truncated yeast NADPH-cytochrome P450 reductase, which is functionally active toward its physiological substrate cytochrome P450, and discovered a second FMN binding site at the interface of the connecting and FMN binding domains. The two FMN binding sites have different accessibilities to the bulk solvent and different amino acid environments, suggesting stabilization of different electronic structures of the reduced flavin. Since only one FMN cofactor is required for function, a hypothetical mechanism of electron transfer is discussed that proposes shuttling of a single FMN between these two sites coupled with the transition between two semiquinone forms, neutral (blue) and anionic (red).
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Affiliation(s)
- David C Lamb
- Wolfson Laboratory of P450 Biodiversity, Swansea Medical School University of Wales Swansea, Swansea, Wales SA2 8PP, UK
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Dudka J. Decrease in NADPH-Cytochrome P450 Reductase Activity of the Human Heart, Liver and Lungs in the Presence of Alpha-Lipoic Acid. ANNALS OF NUTRITION AND METABOLISM 2006; 50:121-5. [PMID: 16391466 DOI: 10.1159/000090632] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2005] [Accepted: 07/15/2005] [Indexed: 11/19/2022]
Abstract
BACKGROUND NADPH-cytochrome P450 reductase (CPR) is the electron donor protein for several oxygenase enzymes located in the endoplasmic reticulum. These oxygenases include P450 family enzymes involved in the metabolism of endogenous and exogenous substances. The enzyme is involved in adriamycin (anticancer drug) and paraquat (herbicide) toxicity. CPR is a flavoprotein containing both flavine-adenine dinucleotide and flavine mononucleotide. A structural study showed the presence of several sulfhydryl (SH) groups in the CPR molecule. Some of them play a key role in catalytic activity. As alpha-lipoic acid contains a disulfide bond, it may react with the SH group of CPR. The aim of the study was to evaluate the effect of alpha-lipoic acid on human P450 reductase activity. METHODS The activity of the enzyme was determined by measuring the rate of cytochrome c reduction at 550 nm, in vitro, using heart, liver and lung microsomes. RESULTS The activity of CPR was decreased in all organs after addition of alpha-lipoic acid to the reaction mixture at concentrations of 0.01, 0.10 and 1.00 mM. The decreases in CPR activity were concentration-dependent and the sequence of relative inhibition was as follows: heart >lung >liver. However, the statistical significance of CPR activity vs. control was observed in the heart in the presence of 1.00 mM alpha-lipoic acid and in the lung at 0.10 and 1.00 mM alpha-lipoic acid. CONCLUSION alpha-Lipoic acid decreased NADPH-CPR activity in the lung and heart. The present results are promising for future studies to obtain the most effective antidote for adriamycin and paraquat toxicity.
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Affiliation(s)
- Jaroslaw Dudka
- Department of Clinical Pathomorphology, Medical University of Lublin, Lublin, Poland.
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Ask K, Décologne N, Ginies C, Låg M, Boucher JL, Holme JA, Pelczar H, Camus P. Metabolism of nilutamide in rat lung. Biochem Pharmacol 2006; 71:377-85. [PMID: 16313887 DOI: 10.1016/j.bcp.2005.10.034] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2005] [Revised: 10/14/2005] [Accepted: 10/20/2005] [Indexed: 11/29/2022]
Abstract
Nilutamide is a non-steroidal anti-androgen drug proposed in the treatment of metastatic prostatic carcinoma. Its therapeutic effects are overshadowed by the occurrence of adverse reactions, mediated by mechanisms that remain elusive. To elucidate possible mechanisms for nilutamide toxicity, we investigated the metabolism of nilutamide in rat lung homogenates, in subcellular fractions and in freshly isolated cells. In whole lung homogenates, the nitro group of nilutamide was reduced to the amine and hydroxylamine moieties. These conversions occurred exclusively in the absence of dioxygen, were increased by the addition of FMN, FAD, or NADPH. Reductive metabolism of nilutamide to the amine and hydroxylamine was further evidenced in subcellular fractions obtained by differential ultracentrifugation. It was found to take place mainly in the cytosol of rat lung and to be stimulated, strongly, upon co-addition of NADPH and FMN. Addition of inhibitors of enzymes involved in the reductive metabolism of nitroaromatic compounds indicated that reduction of nilutamide involved, mainly, soluble flavoproteins. Incubations with freshly isolated lung cells revealed that macrophages were the main players in nitroreduction of nilutamide whereas the epithelial type II cells and the non-ciliated Clara cells were less efficient in catalyzing this reaction. Our results show that nilutamide is extensively reduced by lung tissues in the absence of oxygen, especially by enzymes found in alveolar macrophages. In accordance with recent findings, subcellular localization, oxygen sensitivity, cofactor requirements and inhibitor studies lead us to suggest the involvement of a soluble nitric oxide synthase in lung cytosolic nitroreduction.
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Affiliation(s)
- Kjetil Ask
- Laboratory of Pulmonary Pharmacology and Toxicology, UMR INRA/Université de Bourgogne 1234, Faculté de Médecine et de Pharmacie, Dijon, France.
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Finn RD, Wilkie M, Smith G, Paine MJI. Identification of a functionally impaired allele of human novel oxidoreductase 1 (NDOR1), NDOR1*1. Pharmacogenet Genomics 2005; 15:381-6. [PMID: 15900210 DOI: 10.1097/01213011-200506000-00002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES Human novel oxidoreductase 1 (NDOR1) is a diflavin reductase closely related to cytochrome P450 reductase (POR) and nitric oxide synthase (NOS), which are involved in the metabolism of antitumour agents. A variant cDNA sequence of NDOR1, NDOR1 p.518-519ins9 or NDOR1_v1, has been deposited in GenBank (accession no. AK026089 and AY077845) that encodes an additional nine amino acids, which led us to investigate NDOR1 polymorphism. METHODS AND RESULTS We analysed genomic DNA from 200 Caucasian and 49 Japanese individuals by PCR--restriction fragment length polymorphism analysis. The nine amino acid residue sequence was found to be present in all individuals, encoded by a 27 nt intronic nucleotide sequence at an intron/exon junction, suggesting that this variant did not represent a common genetic polymorphism, but may have arisen from an alternative mRNA splicing event. However, further analysis of NDOR1 revealed a polymorphic c.1564G>A transition (NDOR1*1), detected in 24/200 Caucasian and 1/49 Japanese individuals, producing a valine to isoleucine substitution at codon 522 in the NADPH binding region. Expression of the flavin adenine dinucleotide/reduced nicotinamide phosphate dehydrogenase (NADPH) domain in Escherichia coli showed a significant 74% reduction in potassium ferricyanide reductase activity, but no effect on NADPH binding. NDOR1_v1 showed a 10-fold decrease in affinity for NADPH, and a 90% reduction in ferricyanide reductase activity. CONCLUSIONS We have discovered a polymorphic variant of NDOR1, NDOR1*1, that produces a functionally impaired enzyme. This will help define the structure and function of NDOR1 and its relationship to cancer and other diseases.
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Affiliation(s)
- Robert D Finn
- Cancer Research UK Molecular Pharmacology Unit, Ninewells Hospital & Medical School, Dundee DD1 9SY, UK
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Yamamoto K, Kimura S, Shiro Y, Iyanagi T. Interflavin one-electron transfer in the inducible nitric oxide synthase reductase domain and NADPH-cytochrome P450 reductase. Arch Biochem Biophys 2005; 440:65-78. [PMID: 16009330 DOI: 10.1016/j.abb.2005.05.027] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2005] [Revised: 05/26/2005] [Accepted: 05/30/2005] [Indexed: 10/25/2022]
Abstract
In this study, we have analyzed interflavin electron transfer reactions from FAD to FMN in both the full-length inducible nitric oxide synthase (iNOS) and its reductase domain. Comparison is made with the interflavin electron transfer in NADPH-cytochrome P450 reductase (CPR). For the analysis of interflavin electron transfer and the flavin intermediates observed during catalysis we have used menadione (MD), which can accept an electron from both the FAD and FMN sites of the enzyme. A characteristic absorption peak at 630 and 520 nm can identify each FAD and FMN semiquinone species, which is derived from CPR and iNOS, respectively. The charge transfer complexes of FAD with NADP+ or NADPH were monitored at 750 nm. In the presence of MD, the air-stable neutral (blue) semiquinone form (FAD-FMNH*) was observed as a major intermediate during the catalytic cycle in both the iNOS reductase domain and full-length enzyme, and its formation occurred without any lag phase indicating rapid interflavin electron transfer following the reduction of FAD by NADPH. These data also strongly suggest that the low level reactivity of a neutral (blue) FMN semiquinone radical with electron acceptors enables one-electron transfer in the catalytic cycle of both the FAD-FMN pairs in CPR and iNOS. On the basis of these data, we propose a common model for the catalytic cycle of both CaM-bound iNOS reductase domain and CPR.
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Affiliation(s)
- Keita Yamamoto
- Graduate School of Life Science, Himeji Institute of Technology, University of Hyogo, 3-2-1 Kouto, Kamigori-cho, Hyogo 678-1297, Japan
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Kwaśnicka-Crawford DA, Vincent SR. Role of a novel dual flavin reductase (NR1) and an associated histidine triad protein (DCS-1) in menadione-induced cytotoxicity. Biochem Biophys Res Commun 2005; 336:565-71. [PMID: 16140270 DOI: 10.1016/j.bbrc.2005.08.129] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2005] [Accepted: 08/11/2005] [Indexed: 10/25/2022]
Abstract
Microsomal cytochrome P450 reductase catalyzes the one-electron transfer from NADPH via FAD and FMN to various electron acceptors, such as cytochrome P450s or to some anti-cancer quinone drugs. This results in generation of free radicals and toxic oxygen metabolites, which can contribute to the cytotoxicity of these compounds. Recently, a cytosolic NADPH-dependent flavin reductase, NR1, has been described which is highly homologous to the microsomal cytochrome P450 reductase. In this study, we show that over-expression of NR1 in human embryonic kidney cells enhances the cytotoxic action of the model quinone, menadione. Furthermore, we show that a novel human histidine triad protein DCS-1, which is expressed together with NR1 in many tissues, can significantly reduce menadione-induced cytotoxicity in these cells. We also show that DCS-1 binds NF1 and directly modulates its activity. These results suggest that NR1 may play a role in carcinogenicity and cell death associated with one-electron reductions.
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Affiliation(s)
- Dorota A Kwaśnicka-Crawford
- Graduate Program in Neuroscience, Department of Psychiatry and the Brain Research Centre, The University of British Columbia, Vancouver, Canada BC V6T 1Z3
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