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Jay N, Duffy SR, Estrada DF. Characterization of a Cleavable Fusion of Human CYP24A1 with Adrenodoxin Reveals the Variable Role of Hydrophobics in Redox Partner Binding. Biochemistry 2022; 61:57-66. [PMID: 34979083 DOI: 10.1021/acs.biochem.1c00770] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The improper maintenance of the bioactivated form of vitamin-D (1α,25(OH)2D) may result in vitamin-D insufficiency and therefore compromise the absorption of dietary calcium. A significant regulator of vitamin-D metabolism is the inactivating function of the mitochondrial enzyme cytochrome P450 24A1 (CYP24A1). In humans, CYP24A1 carries out hydroxylation of carbon-23 (C23) or carbon-24 (C24) of the 1α,25(OH)2D side chain, eventually resulting in production of either an antagonist of the vitamin-D receptor (C23 pathway) or calcitroic acid (C24 pathway). Despite its importance to human health, the human isoform (hCYP24A1) remains largely uncharacterized due in part to the difficulty in producing the enzyme using recombinant means. In this study, we utilize a cleavable fusion with the cognate redox partner, human Adx (hAdx), to stabilize hCYP24A1 during production. The subsequent cleavage and isolation of active hCYP24A1 allowed for an investigation of substrate and analog binding, enzymatic activity, and redox partner recognition. We demonstrate involvement of a nonpolar contact involving Leu-80 of hAdx and a nonconserved proximal surface of hCYP24A1. Interestingly, shortening the length of this residue (L80V) results in enhanced binding between the CYP-Adx complex and 1α,25(OH)2D yet unexpectedly results in decreased catalysis. The same mutation has a negligible effect on rat CYP24A1 (a C24-hydroxylase), indicating the presence of a species-specific requirement that may correlate with differences in regioselectivity of the reaction. Taken together, this work presents an example of production of a challenging human CYP as well as providing details regarding hydrophobic modulation of a CYP-Adx complex that is critical to human vitamin-D metabolism.
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Affiliation(s)
- Natalie Jay
- Department of Biochemistry, University at Buffalo, Buffalo, New York 14203, United States
| | - Sean R Duffy
- Department of Biochemistry, University at Buffalo, Buffalo, New York 14203, United States
| | - D Fernando Estrada
- Department of Biochemistry, University at Buffalo, Buffalo, New York 14203, United States
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2
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Das A, Weigle AT, Arnold WR, Kim JS, Carnevale LN, Huff HC. CYP2J2 Molecular Recognition: A New Axis for Therapeutic Design. Pharmacol Ther 2020; 215:107601. [PMID: 32534953 PMCID: PMC7773148 DOI: 10.1016/j.pharmthera.2020.107601] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Accepted: 05/28/2020] [Indexed: 12/11/2022]
Abstract
Cytochrome P450 (CYP) epoxygenases are a special subset of heme-containing CYP enzymes capable of performing the epoxidation of polyunsaturated fatty acids (PUFA) and the metabolism of xenobiotics. This dual functionality positions epoxygenases along a metabolic crossroad. Therefore, structure-function studies are critical for understanding their role in bioactive oxy-lipid synthesis, drug-PUFA interactions, and for designing therapeutics that directly target the epoxygenases. To better exploit CYP epoxygenases as therapeutic targets, there is a need for improved understanding of epoxygenase structure-function. Of the characterized epoxygenases, human CYP2J2 stands out as a potential target because of its role in cardiovascular physiology. In this review, the early research on the discovery and activity of epoxygenases is contextualized to more recent advances in CYP epoxygenase enzymology with respect to PUFA and drug metabolism. Additionally, this review employs CYP2J2 epoxygenase as a model system to highlight both the seminal works and recent advances in epoxygenase enzymology. Herein we cover CYP2J2's interactions with PUFAs and xenobiotics, its tissue-specific physiological roles in diseased states, and its structural features that enable epoxygenase function. Additionally, the enumeration of research on CYP2J2 identifies the future needs for the molecular characterization of CYP2J2 to enable a new axis of therapeutic design.
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Affiliation(s)
- Aditi Das
- Department of Comparative Biosciences, University of Illinois Urbana-Champaign, Urbana, IL 61801, USA; Department of Biochemistry, University of Illinois Urbana-Champaign, Urbana, IL 61801, USA; Division of Nutritional Sciences, University of Illinois Urbana-Champaign, Urbana, IL 61801, USA; Center for Biophysics and Computational Biology, University of Illinois Urbana-Champaign, Urbana, IL 61801, USA; Department of Bioengineering, Neuroscience Program, Beckman Institute for Advanced Science and Technology, Cancer Center at Illinois, University of Illinois Urbana-Champaign, Urbana, IL 61801, USA.
| | - Austin T Weigle
- Department of Chemistry, University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
| | - William R Arnold
- Department of Biochemistry, University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
| | - Justin S Kim
- Division of Nutritional Sciences, University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
| | - Lauren N Carnevale
- Department of Biochemistry, University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
| | - Hannah C Huff
- Department of Chemistry, University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
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3
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Picard M, McEwen BS, Epel ES, Sandi C. An energetic view of stress: Focus on mitochondria. Front Neuroendocrinol 2018; 49:72-85. [PMID: 29339091 PMCID: PMC5964020 DOI: 10.1016/j.yfrne.2018.01.001] [Citation(s) in RCA: 278] [Impact Index Per Article: 46.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Revised: 01/09/2018] [Accepted: 01/10/2018] [Indexed: 12/19/2022]
Abstract
Energy is required to sustain life and enable stress adaptation. At the cellular level, energy is largely derived from mitochondria - unique multifunctional organelles with their own genome. Four main elements connect mitochondria to stress: (1) Energy is required at the molecular, (epi)genetic, cellular, organellar, and systemic levels to sustain components of stress responses; (2) Glucocorticoids and other steroid hormones are produced and metabolized by mitochondria; (3) Reciprocally, mitochondria respond to neuroendocrine and metabolic stress mediators; and (4) Experimentally manipulating mitochondrial functions alters physiological and behavioral responses to psychological stress. Thus, mitochondria are endocrine organelles that provide both the energy and signals that enable and direct stress adaptation. Neural circuits regulating social behavior - as well as psychopathological processes - are also influenced by mitochondrial energetics. An integrative view of stress as an energy-driven process opens new opportunities to study mechanisms of adaptation and regulation across the lifespan.
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Affiliation(s)
- Martin Picard
- Department of Psychiatry, Division of Behavioral Medicine, Columbia University, Medical Center, New York, NY 10032, USA; Department of Neurology, The H. Houston Merritt Center, Columbia Translational Neuroscience Initiative, Columbia University Medical Center, New York, NY 10032, USA; Columbia Aging Center, Columbia University, New York, NY 10032, USA.
| | - Bruce S McEwen
- Laboratory for Neuroendocrinology, The Rockefeller University, New York, NY 10065, USA
| | - Elissa S Epel
- Department of Psychiatry, University of California, San Francisco, San Francisco, CA, USA
| | - Carmen Sandi
- Brain Mind Institute, Ecole Polytechnique Federale de Lausanne, EPFL, 1015 Lausanne, Switzerland
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4
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Hanukoglu I. Conservation of the Enzyme-Coenzyme Interfaces in FAD and NADP Binding Adrenodoxin Reductase-A Ubiquitous Enzyme. J Mol Evol 2017; 85:205-218. [PMID: 29177972 DOI: 10.1007/s00239-017-9821-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 11/21/2017] [Indexed: 10/18/2022]
Abstract
FAD and NAD(P) together represent an ideal pair for coupled redox reactions in their capacity to accept two electrons and their redox potentials. Enzymes that bind both NAD(P) and FAD represent large superfamilies that fulfill essential roles in numerous metabolic pathways. Adrenodoxin reductase (AdxR) shares Rossmann fold features with some of these superfamilies but remains in a group of its own in the absence of sequence homology. This article documents the phylogenetic distribution of AdxR by examining whole genome databases for Metazoa, Plantae, Fungi, and Protista, and determines the conserved structural features of AdxR. Scanning these databases showed that most organisms have a single gene coding for an AdxR ortholog. The sequence identity between AdxR orthologs is correlated with the phylogenetic distance among metazoan species. The NADP binding site of all AdxR orthologs showed a modified Rossmann fold motif with a GxGxxA consensus instead of the classical GxGxxG at the edge of the first βα-fold. To examine the hypothesis that enzyme-coenzyme interfaces represent the conserved regions of AdxR, the residues interfacing FAD and NADP were identified and compared with multiple-sequence alignment results. Most conserved residues were indeed found at sites that surround the interfacing residues between the enzyme and the two coenzymes. In contrast to protein-protein interaction hot-spots that may appear in isolated patches, in AdxR the conserved regions show strict preservation of the overall structure. This structure maintains the precise positioning of the two coenzymes for optimal electron transfer between NADP and FAD without electron leakage to other acceptors.
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Affiliation(s)
- Israel Hanukoglu
- Laboratory of Cell Biology, Ariel University, 40700, Ariel, Israel.
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5
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Lin Y, Hou X, Shen WJ, Hanssen R, Khor VK, Cortez Y, Roseman AN, Azhar S, Kraemer FB. SNARE-Mediated Cholesterol Movement to Mitochondria Supports Steroidogenesis in Rodent Cells. Mol Endocrinol 2016; 30:234-47. [PMID: 26771535 DOI: 10.1210/me.2015-1281] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Vesicular transport involving soluble N-ethylmaleimide sensitive factor attachment protein receptor (SNARE) proteins is known to be responsible for many major cellular activities. In steroidogenic tissues, chronic hormone stimulation results in increased expression of proteins involved in the steroidogenic pathway, whereas acute hormone stimulation prompts the rapid transfer of cholesterol to the inner mitochondrial membrane to be utilized as substrate for steroid hormone production. Several different pathways are involved in supplying cholesterol to mitochondria, but mobilization of stored cholesteryl esters appears to initially constitute the preferred source; however, the mechanisms mediating this cholesterol transfer are not fully understood. To study the potential contribution of SNARE proteins in steroidogenesis, we examined the expression levels of various SNARE proteins in response to hormone stimulation in steroidogenic tissues and cells and established an in vitro mitochondria reconstitution assay system to assess the contribution of various SNARE proteins on cholesterol delivery for steroidogenesis. Our results from reconstitution experiments along with knockdown studies in rat primary granulosa cells and in a Leydig cell line show that soluble N-ethylmaleimide sensitive factor attachment protein-α, synaptosomal-associated protein of 25 kDa, syntaxin-5, and syntaxin-17 facilitate the transport of cholesterol to mitochondria. Thus, although StAR is required for efficient cholesterol movement into mitochondria for steroidogenesis, specific SNAREs participate and are necessary to mediate cholesterol movement to mitochondria.
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Affiliation(s)
- Ye Lin
- Division of Endocrinology, Gerontology, and Metabolism (Y.L., X.H., W.-J.S., R.H., V.K.K., S.A., F.B.K.), Stanford University, and Veterans Affairs Palo Alto Health Care System (Y.L., X.H., W.-J.S., R.H., V.K.K., Y.C., A.N.R., S.A., F.B.K.), Palo Alto, California 94304
| | - Xiaoming Hou
- Division of Endocrinology, Gerontology, and Metabolism (Y.L., X.H., W.-J.S., R.H., V.K.K., S.A., F.B.K.), Stanford University, and Veterans Affairs Palo Alto Health Care System (Y.L., X.H., W.-J.S., R.H., V.K.K., Y.C., A.N.R., S.A., F.B.K.), Palo Alto, California 94304
| | - Wen-Jun Shen
- Division of Endocrinology, Gerontology, and Metabolism (Y.L., X.H., W.-J.S., R.H., V.K.K., S.A., F.B.K.), Stanford University, and Veterans Affairs Palo Alto Health Care System (Y.L., X.H., W.-J.S., R.H., V.K.K., Y.C., A.N.R., S.A., F.B.K.), Palo Alto, California 94304
| | - Ruth Hanssen
- Division of Endocrinology, Gerontology, and Metabolism (Y.L., X.H., W.-J.S., R.H., V.K.K., S.A., F.B.K.), Stanford University, and Veterans Affairs Palo Alto Health Care System (Y.L., X.H., W.-J.S., R.H., V.K.K., Y.C., A.N.R., S.A., F.B.K.), Palo Alto, California 94304
| | - Victor K Khor
- Division of Endocrinology, Gerontology, and Metabolism (Y.L., X.H., W.-J.S., R.H., V.K.K., S.A., F.B.K.), Stanford University, and Veterans Affairs Palo Alto Health Care System (Y.L., X.H., W.-J.S., R.H., V.K.K., Y.C., A.N.R., S.A., F.B.K.), Palo Alto, California 94304
| | - Yuan Cortez
- Division of Endocrinology, Gerontology, and Metabolism (Y.L., X.H., W.-J.S., R.H., V.K.K., S.A., F.B.K.), Stanford University, and Veterans Affairs Palo Alto Health Care System (Y.L., X.H., W.-J.S., R.H., V.K.K., Y.C., A.N.R., S.A., F.B.K.), Palo Alto, California 94304
| | - Ann N Roseman
- Division of Endocrinology, Gerontology, and Metabolism (Y.L., X.H., W.-J.S., R.H., V.K.K., S.A., F.B.K.), Stanford University, and Veterans Affairs Palo Alto Health Care System (Y.L., X.H., W.-J.S., R.H., V.K.K., Y.C., A.N.R., S.A., F.B.K.), Palo Alto, California 94304
| | - Salman Azhar
- Division of Endocrinology, Gerontology, and Metabolism (Y.L., X.H., W.-J.S., R.H., V.K.K., S.A., F.B.K.), Stanford University, and Veterans Affairs Palo Alto Health Care System (Y.L., X.H., W.-J.S., R.H., V.K.K., Y.C., A.N.R., S.A., F.B.K.), Palo Alto, California 94304
| | - Fredric B Kraemer
- Division of Endocrinology, Gerontology, and Metabolism (Y.L., X.H., W.-J.S., R.H., V.K.K., S.A., F.B.K.), Stanford University, and Veterans Affairs Palo Alto Health Care System (Y.L., X.H., W.-J.S., R.H., V.K.K., Y.C., A.N.R., S.A., F.B.K.), Palo Alto, California 94304
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6
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Ewen KM, Kleser M, Bernhardt R. Adrenodoxin: the archetype of vertebrate-type [2Fe-2S] cluster ferredoxins. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2010; 1814:111-25. [PMID: 20538075 DOI: 10.1016/j.bbapap.2010.06.003] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2010] [Revised: 05/28/2010] [Accepted: 06/01/2010] [Indexed: 11/15/2022]
Abstract
Adrenodoxin is probably the best characterized member of the vertebrate-type [2Fe-2S]-cluster ferredoxins. It has been in the spotlight of scientific interest for many years due to its essential role in mammalian steroid hormone biosynthesis, where it acts as electron mediator between the NADPH-dependent adrenodoxin reductase and several mitochondrial cytochromes P450. In this review we will focus on the present knowledge about protein-protein recognition in the mitochondrial cytochrome P450 system and the modulation of the electron transfer between Adx and its redox partners, AdR and CYP(s). We also intend to point out the potential biotechnological applications of Adx as a versatile electron donor to different cytochromes P450, both in vitro and in vivo. Finally we will address the comparison between the mammalian cytochrome P450-associated adrenodoxin and ferredoxins involved in iron-sulfur-cluster biosynthesis. Despite their different functions, these proteins display an amazing similarity regarding their primary sequence, tertiary structure and biophysical features.
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Affiliation(s)
- Kerstin Maria Ewen
- Department of Biochemistry, Saarland University, D-66041 Saarbrücken, Germany
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7
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Hanukoglu I. Antioxidant Protective Mechanisms against Reactive Oxygen Species (ROS) Generated by Mitochondrial P450 Systems in Steroidogenic Cells. Drug Metab Rev 2008; 38:171-96. [PMID: 16684656 DOI: 10.1080/03602530600570040] [Citation(s) in RCA: 145] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Mitochondrial P450 type enzymes catalyze central steps in steroid biosynthesis, including cholesterol conversion to pregnenolone, 11beta and 18 hydroxylation in glucocorticoid and mineralocorticoid synthesis, C-27 hydroxylation of bile acids, and 1alpha and 24 hydroxylation of 25-OH-vitamin D. These monooxygenase reactions depend on electron transfer from NADPH via FAD adrenodoxin reductase and 2Fe-2S adrenodoxin. These systems can function as a futile NADPH oxidase, oxidizing NADPH in absence of substrate, and leak electrons via adrenodoxin and P450 to O(2), producing superoxide and other reactive oxygen species (ROS). The degree of uncoupling depends on the P450 and steroid substrate. Studies with purified proteins and overexpression in cultured cells show consistently that adrenodoxin, but not reductase, is responsible for ROS production that can lead to apoptosis. In the ovary and corpus luteum, antioxidant enzyme activities superoxide dismutase, catalase, and glutathione peroxidase parallel steroidogenesis. Antioxidant beta-carotene, alpha-tocopherol, and ascorbate can protect against oxidative damages of P450 systems. In testis Leydig cells, steroidogenesis is associated with aging of the steroidogenic capacity.
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Affiliation(s)
- Israel Hanukoglu
- Department of Molecular Biology, College of Judea and Samaria, Ariel, Israel.
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8
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Behlke J, Ristau O, Müller EC, Hannemann F, Bernhardt R. Self-association of adrenodoxin studied by using analytical ultracentrifugation. Biophys Chem 2007; 125:159-65. [PMID: 16916573 DOI: 10.1016/j.bpc.2006.07.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2006] [Revised: 07/19/2006] [Accepted: 07/19/2006] [Indexed: 11/28/2022]
Abstract
The mitochondrial steroid hydroxylase system of vertebrates utilizes adrenodoxin (Adx), a small iron-sulfur cluster protein of about 14 kDa as an electron carrier between a reductase and cytochrome P450. Although the crystal structure of this protein has been elucidated, the solution structure of Adx was discussed contrary in the literature [I.A. Pikuleva, K. Tesh, M.R. Waterman, Y. Kim, The tertiary structure of full-length bovine adrenodoxin suggests functional dimers, Arch. Biochem. Biophys. 373 (2000) 44-55; D. Beilke, R. Weiss, F. Löhr, P. Pristovsek, F. Hannemann, R. Bernhardt, H. Rüterjans, A new electron mechanism in mitochondrial steroid hydroxylase systems based on structural changes upon the reduction of adrenodoxin, Biochemistry 41 (2002) 7969-7978]. Therefore, it was necessary to study the self-association of this protein by using analytical ultracentrifugation over a larger concentration range. As could be demonstrated in sedimentation velocity experiments, as well as sedimentation equilibrium runs with explicit consideration of thermodynamic non-ideality, the full-length protein (residues 1-128) in the oxidized state resulted in a monomer-dimer equilibrium (K(a) approximately 3 x 10(2) M(-1)). For truncated Adx (1-108), as well as the reduced Adx, the association behavior was strongly reduced. The consequences of this behavior are discussed with respect to the physiological meaning for the Adx system.
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Affiliation(s)
- Joachim Behlke
- Max Delbrück Center for Molecular Medicine, 13092 Berlin, FRG.
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9
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Sevrioukova IF, Li H, Poulos TL. Crystal structure of putidaredoxin reductase from Pseudomonas putida, the final structural component of the cytochrome P450cam monooxygenase. J Mol Biol 2004; 336:889-902. [PMID: 15095867 DOI: 10.1016/j.jmb.2003.12.067] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2003] [Revised: 12/22/2003] [Accepted: 12/29/2003] [Indexed: 11/28/2022]
Abstract
The crystal structure of recombinant putidaredoxin reductase (Pdr), an FAD-containing NADH-dependent flavoprotein component of the cytochrome P450cam monooxygenase from Pseudomonas putida, has been determined to 1.90 A resolution. The protein has a fold similar to that of disulfide reductases and consists of the FAD-binding, NAD-binding, and C-terminal domains. Compared to homologous flavoenzymes, the reductase component of biphenyl dioxygenase (BphA4) and apoptosis-inducing factor, Pdr lacks one of the arginine residues that compensates partially for the negative charge on the pyrophosphate of FAD. This uncompensated negative charge is likely to decrease the electron-accepting ability of the flavin. The aromatic side-chain of the "gatekeeper" Tyr159 is in the "out" conformation and leaves the nicotinamide-binding site of Pdr completely open. The presence of electron density in the NAD-binding channel indicates that NAD originating from Escherichia coli is partially bound to Pdr. A structural comparison of Pdr with homologous flavoproteins indicates that an open and accessible nicotinamide-binding site, the presence of an acidic residue in the middle part of the NAD-binding channel that binds the nicotinamide ribose, and multiple positively charged arginine residues surrounding the entrance of the NAD-binding channel are the special structural elements that assist tighter and more specific binding of the oxidized pyridine nucleotide by the BphA4-like flavoproteins. The crystallographic model of Pdr explains differences in the electron transfer mechanism in the Pdr-putidaredoxin redox couple and their mammalian counterparts, adrenodoxin reductase and adrenodoxin.
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Affiliation(s)
- Irina F Sevrioukova
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92612-3900, USA.
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10
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Müller EC, Lapko A, Otto A, Müller JJ, Ruckpaul K, Heinemann U. Covalently crosslinked complexes of bovine adrenodoxin with adrenodoxin reductase and cytochrome P450scc. ACTA ACUST UNITED AC 2003. [DOI: 10.1046/j.1432-1327.2001.02058.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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11
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12
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Ziegler GA, Vonrhein C, Hanukoglu I, Schulz GE. The structure of adrenodoxin reductase of mitochondrial P450 systems: electron transfer for steroid biosynthesis. J Mol Biol 1999; 289:981-90. [PMID: 10369776 DOI: 10.1006/jmbi.1999.2807] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Adrenodoxin reductase is a monomeric 51 kDa flavoenzyme that is involved in the biosynthesis of all steroid hormones. The structure of the native bovine enzyme was determined at 2.8 A resolution, and the structure of the respective recombinant enzyme at 1.7 A resolution. Adrenodoxin reductase receives a two-electron package from NADPH and converts it to two single electrons that are transferred via adrenodoxin to all mitochondrial cytochromes P 450. The structure suggests how the observed flavin semiquinone is stabilized. A striking feature is the asymmetric charge distribution, which most likely controls the approach of the electron carrier adrenodoxin. A model for the interaction is proposed. Adrenodoxin reductase shows clear sequence homology to half a dozen proteins identified in genome analysis projects, but neither sequence nor structural homology to established, functionally related electron transferases. Yet, the structure revealed a relationship to the disulfide oxidoreductases, permitting the assignment of the NADP-binding site.
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Affiliation(s)
- G A Ziegler
- Albert-Ludwigs-Universität, Albertstrasse 21, Freiburg im Breisgau, D-79104, Germany
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13
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Kisselev P, Tuckey RC, Woods ST, Triantopoulos T, Schwarz D. Enzymatic properties of vesicle-reconstituted human cytochrome P450SCC (CYP11A1) differences in functioning of the mitochondrial electron-transfer chain using human and bovine adrenodoxin and activation by cardiolipin. EUROPEAN JOURNAL OF BIOCHEMISTRY 1999; 260:768-73. [PMID: 10103006 DOI: 10.1046/j.1432-1327.1999.00206.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The recently reported heterologous expression and purification of both human cytochrome P450SCC and adrenodoxin [Woods, S.T., Sadleir, J., Downs, T., Triantopoulos, T., Haedlam, M.J. & Tuckey, R.C. (1998) Arch. Biochem. Biophys. 353, 109-115] has enabled us to perform studies with the membrane-reconstituted human enzymes to better understand the side-chain cleavage reaction in humans. Human P450SCC was successfully reconstituted into dioleoylphosphatidylcholine vesicles with and without cardiolipin and its enzymatic properties characterized in the membrane-bound state. Enhancement of the P450SCC activity and significant activation by cardiolipin were observed when human adrenodoxin instead of bovine adrenodoxin was used as electron donor. In the absence of cardiolipin, Km for cholesterol was decreased twice in the case of human adrenodoxin indicating enhanced cholesterol binding. On the other hand, in the presence of cardiolipin in the membrane both Km and V for cholesterol were decreased with human adrenodoxin as electron donor. Kinetic analysis of the interaction between human P450SCC and its redox partners provided evidence for enhanced binding of the human electron donor to human P450SCC indicated by both an increased V and decreased Kd for human adrenodoxin compared with the values with bovine adrenodoxin. Because no similar effects were observed in Tween 20 micelles, these results suggest that the phospholipid membrane may play an important role in the interaction of human adrenodoxin with human P450SCC.
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Affiliation(s)
- P Kisselev
- Institute of Bioorganic Chemistry, Academy of Sciences of Belarus, Minsk, Belarus, Germany
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14
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Kisselev P, Wessel R, Pisch S, Bornscheuer U, Schmid RD, Schwarz D. Branched phosphatidylcholines stimulate activity of cytochrome P450SCC (CYP11A1) in phospholipid vesicles by enhancing cholesterol binding, membrane incorporation, and protein exchange. J Biol Chem 1998; 273:1380-6. [PMID: 9430672 DOI: 10.1074/jbc.273.3.1380] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Phosphatidylcholines (PCs) with branched fatty acyl chains substituted in the two positions of the main chains (branched PCs) have been shown to be potent activators of the side chain cleavage activity of cytochrome P450SCC (CYP11A1) (Schwarz, D., Kisselev, P., Wessel, R., Jueptner, O., and Schmid, R. D. (1996) J. Biol. Chem. 271, 12840-12846). The present study reports on the effect of a series of branched PC on cholesterol binding, membrane integration, and protein exchange in large unilamellar vesicles prepared by an extrusion technique. Enzyme kinetics using vesicles as well as optical titration using a micelle system with the detergent Tween 20 demonstrate that activation is correlated with the fraction of P450SCC in the high spin form. The potency of branched PCs both to activate the enzyme and to induce spin state changes increases with increasing lengths of both the branched and main fatty acyl chains. We found that the extent as well as the rate of integration of P450SCC into vesicle membranes studied by gel chromatography and stopped flow kinetics were increased by branched PC. Finally, it is demonstrated by measurement of the enzymatic activity in primary and secondary vesicles that branched PCs are potent in retaining a very rapid exchange of P450SCC between vesicles, in contrast to cardiolipin, that partially inhibits this exchange process. The data suggest that different properties of P450SCC in membrane systems including cholesterol binding, membrane integration, and protein exchange are affected by branched PCs and probably by other phospholipids, too, and therefore must be considered in an explanation of the observed high stimulation of activity.
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Affiliation(s)
- P Kisselev
- Institute of Clinical Pharmacology, Charite-Humboldt University of Berlin, Berlin/Max Delbrueck Centrum for Molecular Medicine, Berlin-Buch, Germany
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Abstract
Mitochondrial monooxygenase systems are involved in the biosynthesis of glucocorticoids, mineralocorticoids, bile acids, and 1,25-dihydroxyvitamin D. The reactions are catalyzed by specific P450 enzymes that receive reducing equivalents via NADPH-ferredoxin oxidoreductase (adrenodoxin reductase) and ferredoxin (adrenodoxin). Although the three-dimensional structures of the individual components have not yet been solved, methods of expressing recombinant forms of these enzymes in Escherichia coli have allowed the use of site-directed mutagenesis to investigate the roles of specific amino acids in protein binding interactions, electron transfer, and catalysis. These studies have identified key charged residues in NADPH-ferredoxin oxidoreductase, ferredoxin, and P450scc, which are involved in electrostatic interactions critical for recognition, high-affinity binding, and electron transfer. The finding that the binding sites on ferredoxin for NADPH-ferredoxin oxidoreductase and P450 show significant overlap supports the proposed function for ferredoxin as a mobile electron shuttle between the reductase and P450 enzymes and is consistent with ferredoxin's role in serving multiple P450 isoforms.
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Affiliation(s)
- L E Vickery
- Department of Physiology and Biophysics, University of California, Irvine 92697-4560, USA
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16
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Schwarz D, Kisselev P, Wessel R, Jueptner O, Schmid RD. Alpha-branched 1,2-diacyl phosphatidylcholines as effectors of activity of cytochrome P450SCC (CYP11A1). Modeling the structure of the fatty acyl chain region of cardiolipin. J Biol Chem 1996; 271:12840-6. [PMID: 8662703 DOI: 10.1074/jbc.271.22.12840] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Cardiolipin has been shown to be the most effective activator of cholesterol side chain cleavage activity of cytochrome P450SCC, and evidence has been provided for a lipid effector site on the enzyme. Results suggested the headgroup of cardiolipin as major determinant of lipid interaction with P450SCC (Lambeth, J. D. (1981) J. Biol. Chem. 256, 4757-4762). The role of unsaturation is contradictory and open to question (Igarashi, Y. and Kimura, T. (1986) Biochemistry 25, 6461-6466). We synthesized phosphatidylcholines with fully saturated branched fatty acyl chains substituted in the 2-positions of the main chains and studied the influence of these lipids on the activity and other properties of P450SCC in vesicle-reconstituted systems. These saturated branched lipids, with regard to the fatty acyl moiety in molecular shape similar to cardiolipin but with the headgroup of phosphatidylcholines retained, showed a stimulatory efficiency higher than any other phospholipid and at least comparable to cardiolipin. Activation is sensitive to the acyl chain structure and composition. Results suggest that the shape of the molecule at least partially plays an important role in the process of stimulation of the activity of P450SCC. Because binding of cholesterol was increased by the branched lipids monitored optically by the fraction of P450SCC in the high spin form, it was concluded that these lipids, like cardiolipin and other lipids, exert their effects by regulating the binding of cholesterol to P450SCC. These data suggest that polymorphic lipids such as branched phosphatidylcholines and cardiolipin might influence P450SCC function by maintenance of the membrane curvature at a value optimal for activity.
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Affiliation(s)
- D Schwarz
- Max Delbrueck Centrum for Molecular Medicine, 13125 Berlin-Buch, Germany, the Institute of Bioorganic Chemistry, Academy of Sciences of Belarus, 220141 Minsk, Belarus
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17
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Electron Transfer Proteins of Cytochrome P450 Systems. ADVANCES IN MOLECULAR AND CELL BIOLOGY 1996. [DOI: 10.1016/s1569-2558(08)60339-2] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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18
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Uhlmann H, Kraft R, Bernhardt R. C-terminal region of adrenodoxin affects its structural integrity and determines differences in its electron transfer function to cytochrome P-450. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)31682-4] [Citation(s) in RCA: 97] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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19
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Ikushiro S, Kominami S, Takemori S. Adrenal P-450scc modulates activity of P-45011 beta in liposomal and mitochondrial membranes. Implication of P-450scc in zone specificity of aldosterone biosynthesis in bovine adrenal. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)45968-6] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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20
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Iwahashi K, Tsubaki M, Miyatake A, Miura S, Hosokawa K, Ichikawa Y. Catalytic properties of cytochrome P-450scc from bovine and porcine adrenocortical mitochondria: effect of Tween20 concentration. J Steroid Biochem Mol Biol 1991; 38:727-31. [PMID: 2064988 DOI: 10.1016/0960-0760(91)90085-j] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Cholesterol side-chain cleavage activities of cytochrome P-450ssc purified from bovine adrenocortical mitochondria were measured for various substrates, including cholesterol, 20[S]-hydroxycholesterol, 22[R]-hydroxycholesterol and 20[R], 22[R]-dihydroxycholesterol, in the reconstituted enzyme system at various Tween20 concentrations. The side-chain cleavage activity for cholesterol showed more than 10-fold enhancement upon addition of 0.1% Tween20, compared with that without the detergent. Addition of Tween20 did not cause any enhancement of the side-chain cleavage activities for 20[S]-hydroxycholesterol and 22[R]-hydroxycholesterol; rather, it resulted in an inhibition of the activities. The side-chain cleavage activity for 20[R],22[R]-dihydroxycholesterol showed a very high value even without the detergent. As the stimulatory effect of Tween20 was only specific for cholesterol, Tween20 seemed to enhance the rate of access of cholesterol to cytochrome P-450scc. These results are consistent with the suggestion that a transfer of substrate, cholesterol, in mitochondrial inner membrane, to the substrate-binding site of cytochrome P-450scc is the rate-limiting step in the cholesterol side-chain cleavage reaction.
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Affiliation(s)
- K Iwahashi
- Department of Biochemistry, Kagawa Medical School, Japan
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21
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Iwahashi K, Tsubaki M, Miyatake A, Ichikawa Y. Purification and comparative characterization of cytochrome P-450scc from porcine adrenocortical mitochondria. THE INTERNATIONAL JOURNAL OF BIOCHEMISTRY 1991; 23:901-9. [PMID: 1773895 DOI: 10.1016/0020-711x(91)90078-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Cytochrome P-450scc (cholesterol side-chain cleavage enzyme) was purified from porcine adrenocortical mitochondria. 2. The purified cytochrome P-450scc was found to be homogeneous on SDS-polyacrylamide gel electrophoresis. 3. The heme content of the purified enzyme was 20.6 nmol/mg protein. 4. The enzymatic activity of the reconstituted cytochrome P-450scc-linked monooxygenase system amounted to 7.8 nmol of pregnenolone formed per nmole of P-450 per minute, with cholesterol as a substrate. 5. The amino acid sequence of the amino-terminal region of the cytochrome P-450scc and the amino acid residue at the carboxyl terminal were determined and compared with those of other mammalian cytochromes P-450scc.
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Affiliation(s)
- K Iwahashi
- Department of Biochemistry, Kagawa Medical School, Japan
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22
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Orme-Johnson NR. Distinctive properties of adrenal cortex mitochondria. BIOCHIMICA ET BIOPHYSICA ACTA 1990; 1020:213-31. [PMID: 2174262 DOI: 10.1016/0005-2728(90)90151-s] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The mitochondria in cells that synthesize steroid hormones not only have enzymes not present in mitochondria of non-steroidogenic cells but also have unique mechanisms for regulating the steroid substrate availability for certain of these enzymes. We have considered in detail the cytochrome P-450scc system that is located in the inner mitochondrial membrane and that catalyzes the initial and rate-determining step in the steroid hormone biosynthetic pathway. The flux through this pathway is regulated both by the levels of these catalysts themselves and by the availability of the substrate cholesterol for conversion to pregnenolone. These two levels of regulation occur in different time frames but are both controlled externally by the action of tissue-specific peptide hormone. We have used the adrenal cortex fasciculata cells as our paradigmatic cell type. The overall picture seems closely similar for mitochondria in other such steroidogenic cells when analogous data are available. Thus, in adrenal cortex fasciculata cells ACTH triggers several long-term (trophic) and short-term (acute) effects upon and within mitochondria that influence the initial and rate-determining step in the steroid hormone biosynthetic pathway. The only second messenger for both effects characterized thus far is cAMP. An increase in membrane-associated cAMP rapidly activates cAMP-dependent protein kinase, which in turn phosphorylates several cellular proteins, e.g., cholesterol ester hydrolase (vide supra). The trophic action, i.e., that produced by exposure of the cells to increased levels of ACTH or cAMP for a prolonged period (minutes to hours), increases the amounts of the steroid hormone synthesizing proteins in the mitochondria by increasing the transcription of the relevant nuclear genes. This latter process is not needed for the acute increase in the rate of steroid hormone biosynthesis. Whether induction of steroidogenic enzymes requires activation of a kinase has not been determined. However, the postulated SHIP proteins provide a mechanism by which cAMP levels and protein synthesis itself may regulate this induction. Mitochondria in steroidogenic tissues exert control over this process by their ability to recognize, import and process correctly the nuclear encoded precursors of the steroidogenic enzymes. Whether control at this level is ultimately dictated by nuclear or mitochondrial gene products or by an interplay between them is still unknown.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- N R Orme-Johnson
- Department of Biochemistry, Tufts University Health Sciences Campus, Boston, MA 02108
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23
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Abstract
The present studies were performed using primary monolayer cultures of bovine glomerulosa cells to determine whether the elevation in cytosolic calcium concentration produced by angiotensin II was accompanied by an elevation in mitochondrial calcium. Exchangeable mitochondria calcium content was assessed indirectly by measuring the changes in cytosolic calcium concentration and calcium efflux produced by the mitochondrial uncoupler, carbonyl cyanide m-chlorophenylhydrazone (CCCP). Total mitochondrial calcium content was also assessed directly by atomic absorption spectroscopy. CCCP had a direct effect to promote calcium release from an oligomycin/antimycin-sensitive (mitochondrial) calcium pool in permeabilized cells. In intact cells, CCCP caused rapid reductions in cellular ATP content and the ratio of ATP to ADP. Still, its effects on calcium dynamics were exerted primarily at the mitochondrial level as evidenced by inhibition with ruthenium red, but not dantrolene. As expected, angiotensin II produced a rapid increase in calcium efflux and an equally rapid and sustained increase in cytosolic calcium concentration. Nonetheless, CCCP-stimulated elevations in cytosolic calcium concentration and calcium efflux were reduced by angiotensin II in a concentration-dependent manner. Total mitochondrial calcium content was also lower in angiotensin-treated than in control cells. These results indicate that angiotensin II causes a net decrease in mitochondrial calcium stores. On the basis of these data, it is proposed that alterations in calcium metabolism initiated by angiotensin II are exerted not only at the membrane and cytosolic levels but also at the level of the mitochondria. Changes in mitochondrial calcium dynamics may directly contribute to the regulation of mitochondrial steroidogenic enzymes by angiotensin II.
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Affiliation(s)
- R E Kramer
- Department of Pharmacology, University of Tennessee, Memphis 38163
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24
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Hanukoglu I, Suh BS, Himmelhoch S, Amsterdam A. Induction and mitochondrial localization of cytochrome P450scc system enzymes in normal and transformed ovarian granulosa cells. J Biophys Biochem Cytol 1990; 111:1373-81. [PMID: 2170421 PMCID: PMC2116250 DOI: 10.1083/jcb.111.4.1373] [Citation(s) in RCA: 59] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
After ovulation of an oocyte, granulosa cells of the ovarian follicle differentiate into luteal cells and become a major factor dedicated to the synthesis of the steroid hormone progesterone. We recently established granulosa cell lines by cotransfection of granulosa cells with SV-40 and Ha-ras oncogene. In these cells progesterone secretion can be induced by cAMP as in normal rat granulosa cells. The induction of progesterone secretion is observed only after approximately 24 h and closely follows the delayed but quantitatively dramatic induction of the mitochondrial cytochrome P450scc which catalyzes the first step in steroid hormone biosynthesis. The mitochondrial P450 system electron transport proteins, adrenodoxin and adrenodoxin reductase, are also induced but adrenodoxin shows a faster induction. Immunofluorescence studies show that the three enzymes are induced in all cells and incorporated into all mitochondria uniformly. Electron microscopic examination using immunogold technique further confirms this and reveals that adrenodoxin is predominantly located on the matrix side of the inner mitochondrial membrane. Thus, adrenodoxin, which is a small highly charged protein, shows a distribution similar to P450scc which is an integral membrane protein. The uniformity of the response of the cells provides further evidence for the homogeneity of the cell line and makes this new granulosa cell line a highly promising system for the study of the molecular mechanisms involved in changes in gene expression during the process of granulosa cell differentiation.
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Affiliation(s)
- I Hanukoglu
- Department of Hormone Research, Weizmann Institute of Science, Rehovot, Israel
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25
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Dhariwal MS, Jefcoate CR. Cholesterol metabolism by purified cytochrome P-450scc is highly stimulated by octyl glucoside and stearic acid exclusively in large unilamellar phospholipid vesicles. Biochemistry 1989; 28:8397-402. [PMID: 2605191 DOI: 10.1021/bi00447a019] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Cholesterol side-chain cleavage (CSCC) catalyzed by purified bovine adrenal mitochondrial cytochrome P-450scc is highly dependent on the vesicles that supply cholesterol. Six-fold higher rates are achieved with large unilamellar dioleoylphosphatidylcholine vesicles (diameter 150 nm) prepared by octyl glucoside (OG) dialysis (DOPC-LUV) than with small sonicated vesicles (diameter 30 nm) (DOPC-SUV) (Vmax = 25 and 4 min-1, respectively. Extensive dialysis that may remove OG decreased Vmax rates for DOPC-LUV almost to rates seen with DOPC-SUV. These dialyzed DOPC-LUV were, however, very sensitive to addition of OG (EC50 = 2.5 microM, 4.3-fold stimulation) while DOPC-SUV were only weakly affected (EC50 = 100 microM, 1.6-fold stimulation). This enhancement of CSCC in LUV by OG only occurred when the cholesterol:DOPC exceeded 0.1 and was associated with a 15-fold increase in the Km for cholesterol. Structural changes in both SUV and LUV at high cholesterol:DOPC ratios (0.1-1) were indicated by decreases in internal volume that were insensitive to OG and did not affect the external diameters. Stearic acid produced a similar stimulation of CSCC in LUV (EC50 = 50 microM) and had no effect on SUV. The Vmax for CSCC, produced by OG activation of DOPC-LUV, is comparable to the highest attained for cytochrome P-450scc (Tween 20/cholesterol). In LUV, a minor proportion of OG (1-5% of cholesterol) is thus sufficient to generate a domain of reactive cholesterol that maintains a near-optimum turnover. This increased CSCC was paralleled by increased binding of cholesterol to P-450scc, suggesting that this cholesterol is more readily donated by the membrane to the cytochrome.
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Affiliation(s)
- M S Dhariwal
- Department of Pharmacology, University of Wisconsin Medical School, Madison 53706
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26
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Tsubaki M, Iwamoto Y, Hiwatashi A, Ichikawa Y. Inhibition of electron transfer from adrenodoxin to cytochrome P-450scc by chemical modification with pyridoxal 5'-phosphate: identification of adrenodoxin-binding site of cytochrome P-450scc. Biochemistry 1989; 28:6899-907. [PMID: 2819041 DOI: 10.1021/bi00443a019] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Covalent modification of cytochrome P-450scc (purified from bovine adrenocortical mitochondria) with pyridoxal 5'-phosphate (PLP) was found to cause inhibition of the electron-accepting ability of this enzyme from its physiological electron donor, adrenodoxin, without conversion to the "P-420" form. Reaction conditions leading to the modification level of 0.82 and 2.85 PLP-Lys residues per cytochrome P-450scc molecule resulted in 60% and 98% inhibition, respectively, of electron-transfer rate from adrenodoxin to cytochrome P-450scc (with beta-NADPH as an electron donor via NADPH-adrenodoxin reductase and with phenyl isocyanide as the exogenous heme ligand of the cytochrome). It was found that covalent PLP modification caused a drastic decrease of cholesterol side-chain cleavage activity when the cholesterol side-chain cleavage enzyme system was reconstituted with native (or PLP-modified) cytochrome P-450scc, adrenodoxin, and NADPH-adrenodoxin reductase. Approximately 60% of the original enzymatic activity of cytochrome P-450scc was protected against inactivation by covalent PLP modification when 20% mole excess adrenodoxin was included during incubation with PLP. Binding affinity of substrate (cholesterol) to cytochrome P-450scc was found to be increased slightly upon covalent modification with PLP by analyzing a substrate-induced spectral change. The interaction of adrenodoxin with cytochrome P-450scc in the absence of substrate (cholesterol) was analyzed by difference absorption spectroscopy with a four-cuvette assembly, and the apparent dissociation constant (Ks) for adrenodoxin binding was found to be increased from 0.38 microM (native) to 33 microM (covalently PLP modified).(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- M Tsubaki
- Department of Biochemistry, Kagawa Medical School, Japan
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27
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Hanukoglu I, Gutfinger T, Haniu M, Shively JE. Isolation of a cDNA for adrenodoxin reductase (ferredoxin-NADP+ reductase). Implications for mitochondrial cytochrome P-450 systems. EUROPEAN JOURNAL OF BIOCHEMISTRY 1987; 169:449-55. [PMID: 3691502 DOI: 10.1111/j.1432-1033.1987.tb13632.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Using specific antibodies against adrenodoxin reductase (AR), we screened lambda gt11 cDNA expression libraries constructed from bovine adrenal cortex mRNA, and isolated several putative clones coding for this enzyme. Concurrently we determined the amino acid sequences of fragments from it. A deoxyinosine-containing oligonucleotide probe, generated for one of the sequences, reacted specifically with one of the cloned cDNAs of about 1600 base pairs. The codon sequence of this cDNA matched the peptide sequences, further confirming its identity as a copy of AR mRNA. RNA blot analysis indicates that in the adrenal cortex and corpus luteum there is only one major mRNA (approximately 2000 bp) for AR. The levels of this mRNA are at least 40-fold lower in the liver and kidney which are also known to contain in homologue of AR. As compared to adrenodoxin and cytochrome P-450scc mRNAs, AR mRNA levels in the adrenal cortex appear to be about 10-fold lower. Southern blot analysis of bovine and human genomic DNAs reveals that in both of these species there is only one gene for AR. These results indicate that only a single reductase serves the different mitochondrial P-450 systems in steroidogenic tissues.
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Affiliation(s)
- I Hanukoglu
- Department of Biology, Technion-Israel Institute of Technology, Haifa, Israel
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28
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Privalle CT, McNamara BC, Dhariwal MS, Jefcoate CR. ACTH control of cholesterol side-chain cleavage at adrenal mitochondrial cytochrome P-450scc. Regulation of intramitochondrial cholesterol transfer. Mol Cell Endocrinol 1987; 53:87-101. [PMID: 2822509 DOI: 10.1016/0303-7207(87)90195-x] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Rat adrenal mitochondria exhibit a linear 2-fold accumulation of cholesterol for 20 min following either in vivo ether stress or ACTH administration, providing cholesterol metabolism is inhibited by aminoglutethimide (AMG). Additional cycloheximide (CX) pretreatment only slightly decreases this increase, but the location of accumulation shifts from the inner membrane to the outer membrane, implying a decreased cholesterol transfer from outer to inner membrane. Although the capacity of outer mitochondrial membranes was saturated after a 10-min treatment with CX, a 20-min treatment resulted in further retention of cholesterol in intact mitochondria that was not recovered in the isolated membranes. An additional pool of loosely bound cholesterol is proposed for CX mitochondria. These studies provide evidence that the CX-sensitive step of adrenal steroidogenesis attributed to loss of a labile ACTH regulatory protein (Pedersen, R.C. and Brownie, A.C. (1983) Proc. Natl. Acad. Sci. U.S.A. 80, 1882-1886) involves cholesterol transfer from the outer to the inner mitochondrial membrane. ACTH also enhances the PI and PE content of the outer membranes by a CX-sensitive mechanism that may contribute to intramitochondrial cholesterol transport. CX treatment does not affect cholesterol uptake by the inner membrane from phospholipid vesicles. The initial rate of endogenous metabolism in isolated inner membranes is insensitive to pretreatment (2 nmol/nmol P-450/min). The duration of this linear rate was increased 4-fold by AMG treatment while this increase was prevented by CX treatment. The kinetics indicate differences in inner membrane reactive cholesterol levels. Inner membranes also contained a fraction of unreactive cholesterol that is insensitive to pretreatment. Cholesterol-P-450scc complex formation for all pretreatments fits a single hyperbolic function of the reactive cholesterol content of the inner mitochondrial membrane (Kd = 0.025 mol cholesterol/mol phospholipid), and is activated over 5-fold upon mitochondrial disruption. All changes in inner membranes caused by CX can, therefore, be attributed solely to the restricted cholesterol access in vivo.
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Affiliation(s)
- C T Privalle
- Department of Pharmacology, University of Wisconsin Medical School, Madison 53706
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29
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30
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Hanukoglu I, Hanukoglu Z. Stoichiometry of mitochondrial cytochromes P-450, adrenodoxin and adrenodoxin reductase in adrenal cortex and corpus luteum. Implications for membrane organization and gene regulation. EUROPEAN JOURNAL OF BIOCHEMISTRY 1986; 157:27-31. [PMID: 3011431 DOI: 10.1111/j.1432-1033.1986.tb09633.x] [Citation(s) in RCA: 81] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
We have estimated the concentrations of cytochromes P-450scc and P-45011 beta and the electron-transfer proteins adrenodoxin reductase and adrenodoxin in the adrenal cortex and corpus luteum using specific antibodies against these enzymes. While in the adrenal cortex the concentrations of these enzymes are relatively constant in different animals and show no significant sex differences, in corpora lutea they vary considerably and can increase at least up to fifty-fold over the levels found in the ovary. The average relative concentrations of adrenodoxin reductase, adrenodoxin and P-450 are 1:3:8 in the adrenal cortex (which has two cytochromes P-450, P-450scc and P-450(11) beta, in equal concentrations) and 1:2.5:3 in the corpus luteum (which has only P-450scc). We further present evidence that the levels of cytochrome c oxidase also show a degree of correlation with the levels of the mitochondrial steroidogenic enzymes.
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31
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Nisimoto Y, Lambeth JD. NADPH-cytochrome P-450 reductase-cytochrome b5 interactions: crosslinking of the phospholipid vesicle-associated proteins by a water-soluble carbodiimide. Arch Biochem Biophys 1985; 241:386-96. [PMID: 3929686 DOI: 10.1016/0003-9861(85)90561-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Detergent-solubilized and purified rabbit liver microsomal NADPH-cytochrome P-450 reductase and cytochrome b5 were coreconstituted into phospholipid vesicles. When the proteoliposomes were incubated with a water-soluble carbodiimide, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC), a new higher-molecular-weight band was seen by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The band was purified by chromatography on DEAE-Sepharose CL-6B, 2'5'-ADP-Sepharose 4B, and Sephadex G-100. The heme absorption spectrum and fluorophotometric assay of flavin of the purified material demonstrate that this product is a 1:1 crosslinked complex containing one molecule each of the flavoprotein and cytochrome. Proteolysis of the crosslinked form indicates that the hydrophilic catalytic domains participate in the covalent attachment, and that the hydrophobic membrane-attachment peptide is necessary for the protein interaction. The purified crosslinked derivative showed no activities for reduction of either cytochrome c or ferricyanide. About half of the enzyme-associated flavin was reduced rapidly by NADPH, as was 20-30% of the crosslinked cytochrome, indicating that, in at least some of the complexes, the flavin-mediated pathway for reduction of cytochrome by pyridine nucleotide was intact. These data suggest that the output- rather than the input-electron transfer site(s) in the flavoprotein was (were) blocked by the covalently attached cytochrome.
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32
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Hattori MA, Aquilano DR, Dufau ML. An early steroidogenic defect in hormone-induced Leydig cell desensitization. ACTA ACUST UNITED AC 1984; 21:265-77. [PMID: 6548538 DOI: 10.1016/0022-4731(84)90279-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
To define the nature of the lesion of the early steroidogenic pathway (prior to pregnenolone formation) in gonadotropin-induced desensitization of rat testicular Leydig cells, we evaluated cholesterol side-chain cleavage activity in isolated mitochondria by measurement of pregnenolone synthesis and [14C]isocaproic acid formation from [26-14C]cholesterol. The enzyme activity was shown to be reduced after in vivo treatment with 10 micrograms hCG when compared to that of mitochondria from control animals only when measured in the presence of limiting NADPH concentrations (100 microM). Sonication of mitochondria from control and hCG-treated rats caused complete loss of cholesterol side-chain cleavage activity. When acetone-powdered adrenal cell mitochondria were employed as the source of the enzyme, the addition of sonicated Leydig cell mitochondria from control and hCG-treated animals caused the same differences as those observed with intact Leydig cell mitochondria in the presence of low concentration of NADPH. The Km value of the adrenal enzyme for NADPH incubated with Leydig cell mitochondria increased from 0.111 mM in control to 0.37 mM after hCG, with no changes in Vmax. Moreover, cholesterol side-chain cleavage activity of adrenal mitochondria assayed in the presence of 100 microM cholesterol was progressively inhibited by increasing amounts of acetone powder from Leydig cell mitochondria of control and hCG-treated rats, with ID50 of 500 and 280 micrograms protein, respectively. The inhibiting factor was not a lipid or steroid but a heat-labile protein, with an approximate Stokes radius of 4.8 nm and an isoelectric point of 5.05 +/- 0.23 SD (n = 8). The inhibitory effect was confined to the Leydig cell mitochondrial membrane, and was not related to changes in oxidative phosphorylation. NADPH was not directly oxidized or immobilized by the mitochondrial factor, and this inhibiting substance was not adsorbed on 2',5' ADP-Sepharose 4B. These results have demonstrated that a heat-labile inhibiting protein factor is present in mitochondria from normal Leydig cells and is markedly activated or increased by hCG treatment. This substance that competitively modulates cholesterol side-chain cleavage activity could contribute to the early steroidogenic lesion, and also serve as an endogenous modulator of steroid hormone biosynthesis.
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33
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Adrenodoxin interaction with adrenodoxin reductase and cytochrome P-450scc. Cross-linking of protein complexes and effects of adrenodoxin modification by 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide. J Biol Chem 1984. [DOI: 10.1016/s0021-9258(18)90921-x] [Citation(s) in RCA: 82] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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34
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Pasanen M, Pelkonen O. Cholesterol side-chain cleavage activity in human placenta and bovine adrenals: an one-step method for separation of pregnenolone formed in vitro. Steroids 1984; 43:517-27. [PMID: 6549417 DOI: 10.1016/s0039-128x(84)90156-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cholesterol side-chain cleavage (CSCC) activity towards exogenous cholesterol was quantified by an one-step reversed-phase minicolumn method for the separation of pregnenolone formed in the reaction. The assay is rapid and reproducible. The method is linear for up to 2 mg of placental mitochondrial protein and up to 1 mg of bovine adrenal mitochondrial protein in the incubata over 30 min and 5 min reaction times, respectively. Average Km and Vmax values were 14.1 microM and 3.4 pmol/min/mg for the placental preparation and 1.5 microM and 20.7 pmol/min/mg for the bovine adrenal mitochondrial preparation. In human placenta, the mitochondrial fraction contained most of the CSCC activity. Inhibition studies showed that aminoglutethimide (500 microM) inhibited both placental and bovine adrenal activities at the same level (about 80-90% inhibition) but androstenedione (500 microM), metyrapone (500 microM), benzo(a)pyrene (800 microM) and Emulgen 911 (0.05%) were more effective in human placental preparations. Neither of the activities were inhibited to any great extent by alpha-naphthoflavone (500 microM), SKF 525A (500 microM) or 7-ethoxycoumarin (1 mM).
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Farese RV. The phosphatidate-phosphoinositide cycle: an intracellular messenger system in the action of hormones and neurotransmitters. Metabolism 1983; 32:628-41. [PMID: 6133206 DOI: 10.1016/0026-0495(83)90035-5] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Many hormones and neurotransmitters provoke rapid and striking changes in the metabolism of phospholipids in the phosphatidate-inositide cycle. These changes appear to occur before and after the generation of other accepted "second messengers" (e.g., Ca++ and cAMP), and seem to be important intracellular effector substances for the elicitation of biological effects. The two major mechanisms for perturbing the phosphatidate-inositide cycle are phosphatidylinositol hydrolysis and de novo phosphatidate-inositide synthesis. Phosphatidylinositol hydrolysis occurs in the action of all agents which operate via Ca++ and appears to be provoked both by Ca++-dependent and Ca++-independent mechanisms. Ca++-independent phosphatidylinositol hydrolysis may be triggered directly by receptor activation and may control Ca++ release or entry into the cytosol. Ca++-dependent phosphatidylinositol hydrolysis may be important for further changes in cellular Ca++ distribution and membrane fusion during exocytosis. The de novo phosphatidate-inositide synthesis effect has been observed in the action of most steroidogenic agents (ACTH, luteinizing hormone, angiotensin II, K+, serotonin), parathyroid hormone and insulin. The de novo effect is inhibited by cycloheximide, requires Ca++, and appears to serve as a post-second messenger mechanism to alter membrane structure and the function of membrane associated substances. Considerable evidence suggests that the de novo effect is important in the control of steroidogenesis by the above-mentioned agents; it may also be important in the action of insulin in adipose tissue.
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Lambeth JD, Pember SO. Cytochrome P-450scc-adrenodoxin complex. Reduction properties of the substrate-associated cytochrome and relation of the reduction states of heme and iron-sulfur centers to association of the proteins. J Biol Chem 1983. [DOI: 10.1016/s0021-9258(20)81932-2] [Citation(s) in RCA: 34] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Meredith MJ, Reed DJ. Depletion in vitro of mitochondrial glutathione in rat hepatocytes and enhancement of lipid peroxidation by adriamycin and 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU). Biochem Pharmacol 1983; 32:1383-8. [PMID: 6860357 DOI: 10.1016/0006-2952(83)90451-3] [Citation(s) in RCA: 148] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Treatment of isolated rat hepatocytes with 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) and adriamycin (ADR) produced a complete depletion of cellular glutathione accompanied by a significant increase in lactate dehydrogenase (LDH) leakage. Separation of the mitochondrial and cytoplasmic pools of glutathione by digitonin disruption showed that, although BCNU, a specific inhibitor of glutathione, completely depleted the cytoplasmic pool of glutathione, the mitochondrial supply was not entirely expended and LDH leakage was only moderately stimulated. Only after depletion of the mitochondrial supply of glutathione by ADR and BCNU did LDH leakage increase markedly. Measurement of lipid peroxidation, by monitoring malondialdehyde through the thiobarbituric acid procedure, showed that malondialdehyde accumulated more extensively and at a rate mirroring release of LDH from ADR/BCNU treated cells. The time of increase in LDH leakage and malondialdehyde production corresponded to the time of depletion of mitochondrial glutathione to less than 10% of the initial pool size. No such increase in LDH leakage was observed with BCNU or ADU treatment alone or when aminopyrine, an inhibitor of lipid peroxidation, was included. Aminopyrine was found to prevent, in a dose-dependent manner, both LDH leakage and malondialdehyde production stimulated by ADR/BCNU treatment. The protective effect peaked at 5 mM aminopyrine, and higher concentrations produced significant LDH leakage exhibiting LDH release kinetics different than those observed with ADR/BCNU. Although aminopyrine had no effect on the rate or extent of cytoplasmic glutathione depletion by ADR/BCNU treatment, the mitochondrial pool was conserved significantly in those cells protected by aminopyrine. These data suggest that enhanced hepatocyte damage observed after treatment with a combination of ADR and BCNU versus BCNU or ADR alone is due to the extensive depletion of mitochondrial glutathione supported by ADR after glutathione reductase inhibition. Further, enhancement of lipid peroxidation is strongly implicated in the mechanism of adriamycin toxicity.
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19 P-450 Oxygenases in Lipid Transformation. ACTA ACUST UNITED AC 1983. [DOI: 10.1016/s1874-6047(08)60317-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/31/2023]
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Farese RV, Sabir MA, Larson RE. Comparison of changes in inositide and noninositide phospholipids during acute and prolonged adrenocorticotropic hormone treatment in vivo. Biochemistry 1982; 21:3318-21. [PMID: 6288071 DOI: 10.1021/bi00257a011] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Lambeth JD, Seybert DW, Lancaster JR, Salerno JC, Kamin H. Steroidogenic electron transport in adrenal cortex mitochondria. Mol Cell Biochem 1982; 45:13-31. [PMID: 7050653 DOI: 10.1007/bf01283159] [Citation(s) in RCA: 164] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The flavoprotein NADPH-adrenodoxin reductase and the iron sulfur protein adrenodoxin function as a short electron transport chain which donates electrons one-at-a-time to adrenal cortex mitochondrial cytochromes P-450. The soluble adrenodoxin acts as a mobile one-electron shuttle, forming a complex first with NADPH-reduced adrenodoxin reductase from which it accepts an electron, then dissociating, and finally reassociating with and donating an electron to the membrane-bound cytochrome P-450 (Fig. 9). Dissociation and reassociation with flavoprotein then allows a second cycle of electron transfers. A complex set of factors govern the sequential protein-protein interactions which comprise this adrenodoxin shuttle mechanism; among these factors, reduction of the iron sulfur center by the flavin weakens the adrenodoxin-adrenodoxin reductase interaction, thus promoting dissociation of this complex to yield free reduced adrenodoxin. Substrate (cholesterol) binding to cytochrome P-450scc both promotes the binding of the free adrenodoxin to the cytochrome, and alters the oxidation-reduction potential of the heme so as to favor reduction by adrenodoxin. The cholesterol binding site on cytochrome P-450scc appears to be in direct communication with the hydrophobic phospholipid milieu in which this substrate is dissolved. Specific effects of both phospholipid headgroups and fatty acyl side-chains regulate the interaction of cholesterol with its binding side. Cardiolipin is an extremely potent positive effector for cholesterol binding, and evidence supports the existence of a specific effector lipid binding site on cytochrome P.450scc to which this phospholipid binds.
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Koritz SB. The effect of the administration of the adrenocorticotrophic hormone to rats on in vivo steroidogenesis and on the reduction cytochrome P-450 in adrenal mitochondria. BIOCHIMICA ET BIOPHYSICA ACTA 1982; 714:382-5. [PMID: 6275914 DOI: 10.1016/0304-4165(82)90350-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Hanukoglu I, Spitsberg V, Bumpus JA, Dus KM, Jefcoate CR. Adrenal mitochondrial cytochrome P-450scc. Cholesterol and adrenodoxin interactions at equilibrium and during turnover. J Biol Chem 1981; 256:4321-8. [PMID: 7217084 DOI: 10.1016/s0021-9258(19)69436-6] [Citation(s) in RCA: 85] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
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