1
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Knerr L, Prakash TP, Lee R, Drury Iii WJ, Nikan M, Fu W, Pirie E, Maria LD, Valeur E, Hayen A, Ölwegård-Halvarsson M, Broddefalk J, Ämmälä C, Østergaard ME, Meuller J, Sundström L, Andersson P, Janzén D, Jansson-Löfmark R, Seth PP, Andersson S. Glucagon Like Peptide 1 Receptor Agonists for Targeted Delivery of Antisense Oligonucleotides to Pancreatic Beta Cell. J Am Chem Soc 2021; 143:3416-3429. [PMID: 33626278 DOI: 10.1021/jacs.0c12043] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The extra hepatic delivery of antisense oligonucleotides (ASOs) remains a challenge and hampers the widespread application of this powerful class of therapeutic agents. In that regard, pancreatic beta cells are a particularly attractive but challenging cell type because of their pivotal role in diabetes and the fact that they are refractory to uptake of unconjugated ASOs. To circumvent this, we have expanded our understanding of the structure activity relationship of ASOs conjugated to Glucagon Like Peptide 1 Receptor (GLP1R) agonist peptide ligands. We demonstrate the key role of the linker chemistry and its optimization to design maleimide based conjugates with improved in vivo efficacy. In addition, truncation studies and scoping of a diverse set of GLP1R agonists proved fruitful to identify additional targeting ligands efficacious in vivo including native hGLP1(7-36)NH2. Variation of the carrier peptide also shed some light on the dramatic impact of subtle sequence differences on the corresponding ASO conjugate performance in vivo, an area which clearly warrant further investigations. We have confirmed the remarkable potential of GLP1R agonist conjugation for the delivery of ASOs to pancreatic beta cell by effectively knocking down islet amyloid polypeptide (IAPP) mRNA, a potential proapoptotic target, in mice.
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Affiliation(s)
- Laurent Knerr
- Medicinal Chemistry, Research and Early Development Cardiovascular, Renal and Metabolism, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Thazha P Prakash
- Ionis Pharmaceuticals Inc., 2855 Gazelle Court, Carlsbad, California 92010, United States
| | - Richard Lee
- Ionis Pharmaceuticals Inc., 2855 Gazelle Court, Carlsbad, California 92010, United States
| | - William J Drury Iii
- Medicinal Chemistry, Research and Early Development Cardiovascular, Renal and Metabolism, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Mehran Nikan
- Ionis Pharmaceuticals Inc., 2855 Gazelle Court, Carlsbad, California 92010, United States
| | - Wuxia Fu
- Ionis Pharmaceuticals Inc., 2855 Gazelle Court, Carlsbad, California 92010, United States
| | - Elaine Pirie
- Ionis Pharmaceuticals Inc., 2855 Gazelle Court, Carlsbad, California 92010, United States
| | - Leonardo De Maria
- Medicinal Chemistry, Research and Early Development, Respiratory & Immunology, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Eric Valeur
- Medicinal Chemistry, Research and Early Development Cardiovascular, Renal and Metabolism, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Ahlke Hayen
- Medicinal Chemistry, Research and Early Development Cardiovascular, Renal and Metabolism, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Maria Ölwegård-Halvarsson
- Medicinal Chemistry, Research and Early Development Cardiovascular, Renal and Metabolism, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Johan Broddefalk
- Medicinal Chemistry, Research and Early Development Cardiovascular, Renal and Metabolism, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Carina Ämmälä
- Bioscience, Research and Early Development Cardiovascular, Renal and Metabolism, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Michael E Østergaard
- Ionis Pharmaceuticals Inc., 2855 Gazelle Court, Carlsbad, California 92010, United States
| | - Johan Meuller
- Mechanistic Biology & Profiling, Discovery Sciences, R&D, AstraZeneca, Gothenburg, Sweden
| | - Linda Sundström
- Mechanistic Biology & Profiling, Discovery Sciences, R&D, AstraZeneca, Gothenburg, Sweden
| | - Patrik Andersson
- Respiratory and Immunology Safety, Clinical Pharmacology & Safety Sciences, R&D, AstraZeneca, Gothenburg, Sweden
| | - David Janzén
- DMPK, Research and Early Development, Cardiovascular, Renal and Metabolism (CVRM), BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Rasmus Jansson-Löfmark
- DMPK, Research and Early Development, Cardiovascular, Renal and Metabolism (CVRM), BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Punit P Seth
- Ionis Pharmaceuticals Inc., 2855 Gazelle Court, Carlsbad, California 92010, United States
| | - Shalini Andersson
- Research and early Development, Discovery Sciences,, AstraZeneca, Gothenburg, Sweden
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2
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Zhao W, Fan J, Kulic I, Koh C, Clark A, Meuller J, Engkvist O, Barichievy S, Raynoschek C, Hicks R, Maresca M, Wang Q, Brown DG, Lok A, Parro C, Robert J, Chou HY, Zuhl AM, Wood MW, Brandon NJ, Wellington CL. Axl receptor tyrosine kinase is a regulator of apolipoprotein E. Mol Brain 2020; 13:66. [PMID: 32366277 PMCID: PMC7197143 DOI: 10.1186/s13041-020-00609-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2019] [Accepted: 04/24/2020] [Indexed: 12/13/2022] Open
Abstract
Alzheimer's disease (AD), the leading cause of dementia, is a chronic neurodegenerative disease. Apolipoprotein E (apoE), which carries lipids in the brain in the form of lipoproteins, plays an undisputed role in AD pathophysiology. A high-throughput phenotypic screen was conducted using a CCF-STTG1 human astrocytoma cell line to identify small molecules that could upregulate apoE secretion. AZ7235, a previously discovered Axl kinase inhibitor, was identified to have robust apoE activity in brain microglia, astrocytes and pericytes. AZ7235 also increased expression of ATP-binding cassette protein A1 (ABCA1), which is involved in the lipidation and secretion of apoE. Moreover, AZ7235 did not exhibit Liver-X-Receptor (LXR) activity and stimulated apoE and ABCA1 expression in the absence of LXR. Target validation studies using AXL-/- CCF-STTG1 cells showed that Axl is required to mediate AZ7235 upregulation of apoE and ABCA1. Intriguingly, apoE expression and secretion was significantly attenuated in AXL-deficient CCF-STTG1 cells and reconstitution of Axl or kinase-dead Axl significantly restored apoE baseline levels, demonstrating that Axl also plays a role in maintaining apoE homeostasis in astrocytes independent of its kinase activity. Lastly, these effects may require human apoE regulatory sequences, as AZ7235 exhibited little stimulatory activity toward apoE and ABCA1 in primary murine glia derived from neonatal human APOE3 targeted-replacement mice. Collectively, we identified a small molecule that exhibits robust apoE and ABCA1 activity independent of the LXR pathway in human cells and elucidated a novel relationship between Axl and apoE homeostasis in human astrocytes.
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Affiliation(s)
- Wenchen Zhao
- Department of Pathology and Laboratory Medicine, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, 2215 Wesbrook Mall, Vancouver, British Columbia, V6T 1Z3, Canada
| | - Jianjia Fan
- Department of Pathology and Laboratory Medicine, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, 2215 Wesbrook Mall, Vancouver, British Columbia, V6T 1Z3, Canada
| | - Iva Kulic
- Department of Pathology and Laboratory Medicine, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, 2215 Wesbrook Mall, Vancouver, British Columbia, V6T 1Z3, Canada
| | - Cheryl Koh
- Mechanistic Biology & Profiling, Discovery Sciences, R&D, AstraZeneca, Boston, USA
| | - Amanda Clark
- Department of Pathology and Laboratory Medicine, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, 2215 Wesbrook Mall, Vancouver, British Columbia, V6T 1Z3, Canada
| | - Johan Meuller
- Mechanistic Biology & Profiling, Discovery Sciences, R&D, AstraZeneca, Gothenburg, Sweden
| | - Ola Engkvist
- Hit Discovery, Discovery Sciences, R&D, AstraZeneca, Gothenburg, Sweden
| | | | - Carina Raynoschek
- Discovery Biology, Discovery Sciences, R&D, AstraZeneca, Gothenburg, Sweden
| | - Ryan Hicks
- Discovery Biology, Discovery Sciences, R&D, AstraZeneca, Gothenburg, Sweden
| | - Marcello Maresca
- Discovery Biology, Discovery Sciences, R&D, AstraZeneca, Gothenburg, Sweden
| | - Qi Wang
- Neuroscience, BioPharmaceuticals R&D, AstraZeneca, Boston, USA
| | - Dean G Brown
- Hit Discovery, Discovery Sciences, R&D, AstraZeneca, Boston, USA
| | - Alvin Lok
- Department of Pathology and Laboratory Medicine, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, 2215 Wesbrook Mall, Vancouver, British Columbia, V6T 1Z3, Canada
| | - Cameron Parro
- Department of Pathology and Laboratory Medicine, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, 2215 Wesbrook Mall, Vancouver, British Columbia, V6T 1Z3, Canada
| | - Jerome Robert
- Department of Pathology and Laboratory Medicine, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, 2215 Wesbrook Mall, Vancouver, British Columbia, V6T 1Z3, Canada
| | - Hsien-Ya Chou
- Department of Pathology and Laboratory Medicine, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, 2215 Wesbrook Mall, Vancouver, British Columbia, V6T 1Z3, Canada
| | - Andrea M Zuhl
- Discovery Biology, Discovery Sciences, R&D, AstraZeneca, Boston, USA
| | - Michael W Wood
- Neuroscience, BioPharmaceuticals R&D, AstraZeneca, Boston, USA
| | | | - Cheryl L Wellington
- Department of Pathology and Laboratory Medicine, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, 2215 Wesbrook Mall, Vancouver, British Columbia, V6T 1Z3, Canada.
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3
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Lemurell M, Ulander J, Emtenäs H, Winiwarter S, Broddefalk J, Swanson M, Hayes MA, Prieto Garcia L, Westin Eriksson A, Meuller J, Cassel J, Saarinen G, Yuan ZQ, Löfberg C, Karlsson S, Sundqvist M, Whatling C. Novel Chemical Series of 5-Lipoxygenase-Activating Protein Inhibitors for Treatment of Coronary Artery Disease. J Med Chem 2019; 62:4325-4349. [DOI: 10.1021/acs.jmedchem.8b02012] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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4
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Ämmälä C, Drury WJ, Knerr L, Ahlstedt I, Stillemark-Billton P, Wennberg-Huldt C, Andersson EM, Valeur E, Jansson-Löfmark R, Janzén D, Sundström L, Meuller J, Claesson J, Andersson P, Johansson C, Lee RG, Prakash TP, Seth PP, Monia BP, Andersson S. Targeted delivery of antisense oligonucleotides to pancreatic β-cells. Sci Adv 2018; 4:eaat3386. [PMID: 30345352 PMCID: PMC6192685 DOI: 10.1126/sciadv.aat3386] [Citation(s) in RCA: 113] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Accepted: 09/12/2018] [Indexed: 05/03/2023]
Abstract
Antisense oligonucleotide (ASO) silencing of the expression of disease-associated genes is an attractive novel therapeutic approach, but treatments are limited by the ability to deliver ASOs to cells and tissues. Following systemic administration, ASOs preferentially accumulate in liver and kidney. Among the cell types refractory to ASO uptake is the pancreatic insulin-secreting β-cell. Here, we show that conjugation of ASOs to a ligand of the glucagon-like peptide-1 receptor (GLP1R) can productively deliver ASO cargo to pancreatic β-cells both in vitro and in vivo. Ligand-conjugated ASOs silenced target genes in pancreatic islets at doses that did not affect target gene expression in liver or other tissues, indicating enhanced tissue and cell type specificity. This finding has potential to broaden the use of ASO technology, opening up novel therapeutic opportunities, and presents an innovative approach for targeted delivery of ASOs to additional cell types.
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Affiliation(s)
- C. Ämmälä
- Cardiovascular Renal and Metabolic Diseases, IMED Biotech Unit, AstraZeneca, Gothenburg, Sweden
- Corresponding author. (C.Ä.); (P.P.S.)
| | - W. J. Drury
- Cardiovascular Renal and Metabolic Diseases, IMED Biotech Unit, AstraZeneca, Gothenburg, Sweden
| | - L. Knerr
- Cardiovascular Renal and Metabolic Diseases, IMED Biotech Unit, AstraZeneca, Gothenburg, Sweden
| | - I. Ahlstedt
- Cardiovascular Renal and Metabolic Diseases, IMED Biotech Unit, AstraZeneca, Gothenburg, Sweden
| | - P. Stillemark-Billton
- Cardiovascular Renal and Metabolic Diseases, IMED Biotech Unit, AstraZeneca, Gothenburg, Sweden
| | - C. Wennberg-Huldt
- Cardiovascular Renal and Metabolic Diseases, IMED Biotech Unit, AstraZeneca, Gothenburg, Sweden
| | - E.-M. Andersson
- Cardiovascular Renal and Metabolic Diseases, IMED Biotech Unit, AstraZeneca, Gothenburg, Sweden
| | - E. Valeur
- Cardiovascular Renal and Metabolic Diseases, IMED Biotech Unit, AstraZeneca, Gothenburg, Sweden
| | - R. Jansson-Löfmark
- Cardiovascular Renal and Metabolic Diseases, IMED Biotech Unit, AstraZeneca, Gothenburg, Sweden
| | - D. Janzén
- Cardiovascular Renal and Metabolic Diseases, IMED Biotech Unit, AstraZeneca, Gothenburg, Sweden
| | - L. Sundström
- Discovery Sciences, IMED Biotech Unit, AstraZeneca, Gothenburg, Sweden
| | - J. Meuller
- Discovery Sciences, IMED Biotech Unit, AstraZeneca, Gothenburg, Sweden
| | - J. Claesson
- Discovery Sciences, IMED Biotech Unit, AstraZeneca, Gothenburg, Sweden
| | - P. Andersson
- Drug Safety and Metabolism, IMED Biotech Unit, AstraZeneca, Gothenburg, Sweden
| | - C. Johansson
- Drug Safety and Metabolism, IMED Biotech Unit, AstraZeneca, Gothenburg, Sweden
| | - R. G. Lee
- Ionis Pharmaceuticals, 2855 Gazelle Court, Carlsbad, CA 92010, USA
| | - T. P. Prakash
- Ionis Pharmaceuticals, 2855 Gazelle Court, Carlsbad, CA 92010, USA
| | - P. P. Seth
- Ionis Pharmaceuticals, 2855 Gazelle Court, Carlsbad, CA 92010, USA
- Corresponding author. (C.Ä.); (P.P.S.)
| | - B. P. Monia
- Ionis Pharmaceuticals, 2855 Gazelle Court, Carlsbad, CA 92010, USA
| | - S. Andersson
- Cardiovascular Renal and Metabolic Diseases, IMED Biotech Unit, AstraZeneca, Gothenburg, Sweden
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5
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Stulz R, Meuller J, Baždarević D, Wennberg Huldt C, Strömberg R, Andersson S, Dahlén A. A Versatile and Convenient Synthesis of 34 S-Labeled Phosphorothioate Oligonucleotides. Chembiochem 2018; 19:2114-2119. [PMID: 30062829 PMCID: PMC6585993 DOI: 10.1002/cbic.201800417] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Indexed: 12/20/2022]
Abstract
A synthetic protocol for 34 S-labeled phosphorothioate oligonucleotides (PS ONs) was developed to facilitate MS-based assay analysis. This was enabled by a highly efficient, two-step, one-pot synthesis of 34 S-labeled phenylacetyl disulfide (34 S-PADS), starting from 34 S-enriched elemental sulfur (34 S8 ). 34 S-PADS was subsequently used for stable isotope labeling (SIL) of oligonucleotides containing a phosphorothioate backbone. The 34 S-SIL PS ONs are shown to retain the same melting temperature, antisense activity, and secondary structure as those of the corresponding unlabeled 32 S PS ONs.
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Affiliation(s)
- Rouven Stulz
- Cardiovascular, Renal and Metabolism IMED Biotech Unit, AstraZeneca, Pepparedsleden 1, 43150, Mölndal, Sweden.,Department of Biosciences and Nutrition, Karolinska Institutet, NEO, Hälsovägen 9, 14157, Huddinge, Sweden
| | - Johan Meuller
- Discovery Sciences IMED Biotech Unit, AstraZeneca, Pepparedsleden 1, 43150, Mölndal, Sweden
| | - Dženita Baždarević
- Cardiovascular, Renal and Metabolism IMED Biotech Unit, AstraZeneca, Pepparedsleden 1, 43150, Mölndal, Sweden
| | - Charlotte Wennberg Huldt
- Cardiovascular, Renal and Metabolism IMED Biotech Unit, AstraZeneca, Pepparedsleden 1, 43150, Mölndal, Sweden
| | - Roger Strömberg
- Department of Biosciences and Nutrition, Karolinska Institutet, NEO, Hälsovägen 9, 14157, Huddinge, Sweden
| | - Shalini Andersson
- Cardiovascular, Renal and Metabolism IMED Biotech Unit, AstraZeneca, Pepparedsleden 1, 43150, Mölndal, Sweden
| | - Anders Dahlén
- Cardiovascular, Renal and Metabolism IMED Biotech Unit, AstraZeneca, Pepparedsleden 1, 43150, Mölndal, Sweden
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6
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Fan J, Zhao RQ, Parro C, Zhao W, Chou HY, Robert J, Deeb TZ, Raynoschek C, Barichievy S, Engkvist O, Maresca M, Hicks R, Meuller J, Moss SJ, Brandon NJ, Wood MW, Kulic I, Wellington CL. Small molecule inducers of ABCA1 and apoE that act through indirect activation of the LXR pathway. J Lipid Res 2018; 59:830-842. [PMID: 29563219 DOI: 10.1194/jlr.m081851] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Revised: 02/13/2018] [Indexed: 01/01/2023] Open
Abstract
apoE is the primary lipid carrier within the CNS and the strongest genetic risk factor for late onset Alzheimer's disease (AD). apoE is primarily lipidated via ABCA1, and both are under transcriptional regulation by the nuclear liver X receptor (LXR). Considerable evidence from genetic (using ABCA1 overexpression) and pharmacological (using synthetic LXR agonists) studies in AD mouse models suggests that increased levels of lipidated apoE can improve cognitive performance and, in some strains, can reduce amyloid burden. However, direct synthetic LXR ligands have hepatotoxic side effects that limit their clinical use. Here, we describe a set of small molecules, previously annotated as antagonists of the purinergic receptor, P2X7, which enhance ABCA1 expression and activity as well as apoE secretion, and are not direct LXR ligands. Furthermore, P2X7 is not required for these molecules to induce ABCA1 upregulation and apoE secretion, demonstrating that the ABCA1 and apoE effects are mechanistically independent of P2X7 inhibition. Hence, we have identified novel dual activity compounds that upregulate ABCA1 across multiple CNS cell types, including human astrocytes, pericytes, and microglia, through an indirect LXR mechanism and that also independently inhibit P2X7 receptor activity.
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Affiliation(s)
- Jianjia Fan
- Department of Pathology and Laboratory Medicine, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia, Canada
| | - Rui Qi Zhao
- Department of Pathology and Laboratory Medicine, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia, Canada
| | - Cameron Parro
- Department of Pathology and Laboratory Medicine, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia, Canada
| | - Wenchen Zhao
- Department of Pathology and Laboratory Medicine, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia, Canada
| | - Hsien-Ya Chou
- Department of Pathology and Laboratory Medicine, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia, Canada
| | - Jerome Robert
- Department of Pathology and Laboratory Medicine, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia, Canada
| | - Tarek Z Deeb
- Tufts-AstraZeneca Laboratory for Basic and Translational Neuroscience, Boston, MA
| | - Carina Raynoschek
- Discovery Sciences, Innovative Medicines and Early Development (IMED) Biotech Unit, AstraZeneca, Gothenburg, Sweden
| | - Samantha Barichievy
- Discovery Sciences, Innovative Medicines and Early Development (IMED) Biotech Unit, AstraZeneca, Gothenburg, Sweden
| | - Ola Engkvist
- Discovery Sciences, Innovative Medicines and Early Development (IMED) Biotech Unit, AstraZeneca, Gothenburg, Sweden
| | - Marcello Maresca
- Discovery Sciences, Innovative Medicines and Early Development (IMED) Biotech Unit, AstraZeneca, Gothenburg, Sweden
| | - Ryan Hicks
- Discovery Sciences, Innovative Medicines and Early Development (IMED) Biotech Unit, AstraZeneca, Gothenburg, Sweden
| | - Johan Meuller
- Discovery Sciences, Innovative Medicines and Early Development (IMED) Biotech Unit, AstraZeneca, Gothenburg, Sweden
| | - Stephen J Moss
- Tufts-AstraZeneca Laboratory for Basic and Translational Neuroscience, Boston, MA.,Department of Neuroscience, Tufts University School of Medicine, Boston, MA and Department of Neuroscience, Physiology, and Pharmacology, University College London, London, United Kingdom
| | - Nicholas J Brandon
- Neuroscience, Innovative Medicines and Early Development (IMED) Biotech Unit, AstraZeneca, Boston, MA
| | - Michael W Wood
- Neuroscience, Innovative Medicines and Early Development (IMED) Biotech Unit, AstraZeneca, Boston, MA
| | - Iva Kulic
- Department of Pathology and Laboratory Medicine, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia, Canada
| | - Cheryl L Wellington
- Department of Pathology and Laboratory Medicine, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia, Canada
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7
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Roos K, Viklund J, Meuller J, Kaspersson K, Svensson M. Potency prediction of β-secretase (BACE-1) inhibitors using density functional methods. J Chem Inf Model 2014; 54:818-25. [PMID: 24456077 DOI: 10.1021/ci400374z] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Scoring potency is a main challenge for structure based drug design. Inductive effects of subtle variations in the ligand are not possible to accurately predict by classical computational chemistry methods. In this study, the problem of predicting potency of ligands with electronic variations participating in key interactions with the protein was addressed. The potency was predicted for a large set of cyclic amidine and guanidine cores extracted from β-secretase (BACE-1) inhibitors. All cores were of similar size and had equal interaction motifs but were diverse with respect to electronic substitutions. A density functional theory approach, in combination with a representation of the active site of a protein using only key residues, was shown to be predictive. This computational approach was used to guide and support drug design, within the time frame of a normal drug discovery design cycle.
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Affiliation(s)
- Katarina Roos
- Department of Medicinal Chemistry and §Discovery Sciences, AstraZeneca R&D Mölndal , SE-431 83 Mölndal, Sweden
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8
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Wöhri AB, Hillertz P, Eriksson PO, Meuller J, Dekker N, Snijder A. Thermodynamic studies of ligand binding to the human homopentameric glycine receptor using isothermal titration calorimetry. Mol Membr Biol 2012; 30:169-83. [DOI: 10.3109/09687688.2012.696733] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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9
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Kanter-Smoler G, Fritzell K, Rohlin A, Engwall Y, Hallberg B, Bergman A, Meuller J, Grönberg H, Karlsson P, Björk J, Nordling M. Clinical characterization and the mutation spectrum in Swedish adenomatous polyposis families. BMC Med 2008; 6:10. [PMID: 18433509 PMCID: PMC2386495 DOI: 10.1186/1741-7015-6-10] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2008] [Accepted: 04/24/2008] [Indexed: 01/24/2023] Open
Abstract
BACKGROUND The dominantly inherited condition familial adenomatous polyposis (FAP) is caused by germline mutations in the APC gene. Finding the causative mutations has great implications for the families. Correlating the genotypes to the phenotypes could help to improve the diagnosis and follow-up of patients. METHODS Mutation screening of APC and the clinical characterization of 96 unrelated FAP patients from the Swedish Polyposis Registry was performed. In addition to generally used mutation screening methods, analyses of splicing-affecting mutations and investigations of the presence of low-frequency mutation alleles, indicating mosaics, have been performed, as well as quantitative real-time polymerase chain reaction to detect lowered expression of APC. RESULTS Sixty-one different APC mutations in 81 of the 96 families were identified and 27 of those are novel. We have previously shown that 6 of the 96 patients carried biallelic MUTYH mutations. The 9 mutation-negative cases all display an attenuated or atypical phenotype. Probands with a genotype (codon 1250-1464) predicting a severe phenotype had a median age at diagnosis of 21.8 (range, 11-49) years compared with 34.4 (range, 14-57) years among those with mutations outside this region (P < 0.017). Dense polyposis (> 1000) occurred in 75% of the probands with a severe phenotype compared with 30% in those with mutations outside this region. The morbidity in colorectal cancer among probands was 25% at a mean age of 37.5 years and 29% at a mean age of 46.6 years. CONCLUSION Using a variety of mutation-detection techniques, we have achieved a 100% detection frequency in classical FAP. Probands with APC mutations outside codon 1250-1464, although exhibiting a less-severe phenotype, are at high risk of having a colorectal cancer at diagnosis indicating that age at diagnosis is as important as the severity of the disease for colorectal cancer morbidity.
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Affiliation(s)
- Gunilla Kanter-Smoler
- Department of Molecular and Clinical Genetics, Institute of Biomedicine, Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden.
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10
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Saidijam M, Benedetti G, Ren Q, Xu Z, Hoyle CJ, Palmer SL, Ward A, Bettaney KE, Szakonyi G, Meuller J, Morrison S, Pos MK, Butaye P, Walravens K, Langton K, Herbert RB, Skurray RA, Paulsen IT, O'reilly J, Rutherford NG, Brown MH, Bill RM, Henderson PJF. Microbial drug efflux proteins of the major facilitator superfamily. Curr Drug Targets 2006; 7:793-811. [PMID: 16842212 DOI: 10.2174/138945006777709575] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Drug efflux proteins are widespread amongst microorganisms, including pathogens. They can contribute to both natural insensitivity to antibiotics and to emerging antibiotic resistance and so are potential targets for the development of new antibacterial drugs. The design of such drugs would be greatly facilitated by knowledge of the structures of these transport proteins, which are poorly understood, because of the difficulties of obtaining crystals of quality. We describe a structural genomics approach for the amplified expression, purification and characterisation of prokaryotic drug efflux proteins of the 'Major Facilitator Superfamily' (MFS) of transport proteins from Helicobacter pylori, Staphylococcus aureus, Escherichia coli, Enterococcus faecalis, Bacillus subtilis, Brucella melitensis, Campylobacter jejuni, Neisseria meningitides and Streptomyces coelicolor. The H. pylori putative drug resistance protein, HP1092, and the S. aureus QacA proteins are used as detailed examples. This strategy is an important step towards reproducible production of transport proteins for the screening of drug binding and for optimisation of crystallisation conditions to enable subsequent structure determination.
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Affiliation(s)
- Massoud Saidijam
- Astbury Centre for Structural Molecular Biology, School of Biochemistry and Microbiology, University of Leeds, Leeds LS2 9JT, UK
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11
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Saidijam M, Bettaney KE, Szakonyi G, Psakis G, Shibayama K, Suzuki S, Clough JL, Blessie V, Abu-Bakr A, Baumberg S, Meuller J, Hoyle CK, Palmer SL, Butaye P, Walravens K, Patching SG, O'reilly J, Rutherford NG, Bill RM, Roper DI, Phillips-Jones MK, Henderson PJF. Active membrane transport and receptor proteins from bacteria. Biochem Soc Trans 2005; 33:867-72. [PMID: 16042616 DOI: 10.1042/bst0330867] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
A general strategy for the expression of bacterial membrane transport and receptor genes in Escherichia coli is described. Expression is amplified so that the encoded proteins comprise 5-35% of E. coli inner membrane protein. Depending upon their topology, proteins are produced with RGSH6 or a Strep tag at the C-terminus. These enable purification in mg quantities for crystallization and NMR studies. Examples of one nutrient uptake and one multidrug extrusion protein from Helicobacter pylori are described. This strategy is successful for membrane proteins from H. pylori, E. coli, Enterococcus faecalis, Bacillus subtilis, Staphylococcus aureus, Microbacterium liquefaciens, Brucella abortus, Brucella melitensis, Campylobacter jejuni, Neisseria meningitides, Streptomyces coelicolor and Rhodobacter sphaeroides.
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Affiliation(s)
- M Saidijam
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, U.K
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12
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Meuller J, Kanter-Smoler G, Nygren AOH, Errami A, Grönberg H, Holmberg E, Björk J, Wahlström J, Nordling M. Identification of genomic deletions of the APC gene in familial adenomatous polyposis by two independent quantitative techniques. ACTA ACUST UNITED AC 2005; 8:248-56. [PMID: 15727247 DOI: 10.1089/gte.2004.8.248] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Large deletions in the APC (adenomatous polyposis coli) gene, causing familial adenomatous polyposis (FAP), cannot easily be detected by conventional mutation-detection techniques. Therefore, we have developed two independent quantitative methods for the detection of large deletions, encompassing one or more exons, of APC. Multiplex ligation-dependent probe amplification (MLPA) is performed in one reaction for the initial quantification of all APC exon copy numbers. Subsequently, quantitative real-time PCR (QRT-PCR) is used to verify the results obtained in the MLPA reaction. The identification of a deletion of the whole APC gene in a patient with classical FAP is described. The mutation was detected with the two quantitative methods and further verified on chromosomal level by the use of FISH (fluorescence in situ hybridization) on metaphase spreads. Furthermore, a large deletion covering exons 11-13 of the APC gene was detected in two apparently unrelated families. This deletion was further verified and characterized with long-range PCR. The MLPA test ensures a sensitive high-throughput screening for large deletions of the APC gene and can easily be implemented in the diagnostic testing for FAP.
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Affiliation(s)
- Johan Meuller
- Department of Clinical Genetics, Göteborg University, Sahlgrenska University Hospital/Ostra, Göteborg, Sweden
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13
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Saidijam M, Psakis G, Clough JL, Meuller J, Suzuki S, Hoyle CJ, Palmer SL, Morrison SM, Pos MK, Essenberg RC, Maiden MCJ, Abu-bakr A, Baumberg SG, Neyfakh AA, Griffith JK, Stark MJ, Ward A, O'Reilly J, Rutherford NG, Phillips-Jones MK, Henderson PJF. Collection and characterisation of bacterial membrane proteins. FEBS Lett 2003; 555:170-5. [PMID: 14630338 DOI: 10.1016/s0014-5793(03)01148-7] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
A general strategy for the amplified expression in Escherichia coli of membrane transport and receptor proteins from other bacteria is described. As an illustration we report the cloning of the putative alpha-ketoglutarate membrane transport gene from the genome of Helicobacter pylori, overexpression of the protein tagged with RGS(His)6 at the C-terminus, and its purification in mg quantities. The retention of structural and functional integrity was verified by circular dichroism spectroscopy and reconstitution of transport activity. This strategy for overexpression and purification is extended to additional membrane proteins from H. pylori and from other bacteria.
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Affiliation(s)
- Massoud Saidijam
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK
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14
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Fagman H, Larsson F, Arvidsson Y, Meuller J, Nordling M, Martinsson T, Helmbrecht K, Brabant G, Nilsson M. Nuclear accumulation of full-length and truncated adenomatous polyposis coli protein in tumor cells depends on proliferation. Oncogene 2003; 22:6013-22. [PMID: 12955080 DOI: 10.1038/sj.onc.1206731] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The adenomatous polyposis coli (APC) tumor suppressor is a nucleocytoplasmic protein. The nuclear accumulation of APC was recently found to vary depending on cell density, suggesting that putative APC function(s) in the nucleus is controlled by the establishment of cell contacts. We report here that the density-dependent redistribution of APC between nucleus and cytoplasm prevails in 6/6 thyroid and colorectal carcinoma cell lines. Moreover, mutated APC lacking known nuclear localization sequences had the similar distribution pattern as the full-length protein. APC invariably accumulated in the nuclei of Ki-67 expressing cells, but was largely cytoplasmic when cell cycle exit was induced by serum starvation or at high cell density. APC colocalized with beta-catenin in the nucleus only in one cell line (SW480). Also, APC maintained a predominantly nuclear position in early confluent states when cytoplasmic beta-catenin was recruited to newly formed adherens-like junctions. The results indicate that nuclear targeting of APC is driven by cell cycle entry rather than altered cell-cell contact. The ability of C-terminally truncated APC to accumulate in the nucleus suggests that nuclear import signals other than NLS1(APC) and NLS2(APC) are functionally important. Residual function(s) of N-terminal APC fragments in tumor cells carrying APC mutations might be beneficial to tumor growth and survival.
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Affiliation(s)
- Henrik Fagman
- Institute of Anatomy and Cell Biology, Göteborg University, Box 420, SE-40530 Göteborg, Sweden.
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15
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Meuller J, Mjörn K, Karlsson J, Tigerström A, Rydström J, Hou C, Bragg PD. Properties of a proton-translocating nicotinamide nucleotide transhydrogenase from Escherichia coli with alpha and beta subunits linked through fused transmembrane helices. Biochim Biophys Acta 2001; 1506:163-71. [PMID: 11779549 DOI: 10.1016/s0005-2728(01)00191-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Proton-translocating nicotinamide nucleotide transhydrogenase from Escherichia coli is composed of an alpha and a beta subunit, whereas the homologues mitochondrial enzyme contains a single polypeptide. As compared to the latter transhydrogenase, using a 14-helix model for its membrane topology, the point of fusion is between the transmembrane helices 4 and 6 where the fusion linker provides the extra transmembrane helix 5. In order to clarify the potential role of this extra helix/linker, the alpha and the beta subunits were fused using three connecting peptides of different lengths, one (pAX9) involving essentially a direct coupling, a second (pKM) with a linking peptide of 18 residues, and a third (pKMII) with a linking peptide of 32 residues, as compared to the mitochondrial extra peptide of 27 residues. The results demonstrate that the plasma membrane-bound and purified pAX9 enzyme with the short linker was partly misfolded and strongly inhibited with regard to both catalytic activities and proton translocation, whereas the properties of pKM and pKMII with longer linkers were similar to those of wild-type E. coli transhydrogenase but partly different from those of the mitochondrial enzyme although pKMII generally gave higher activities. It is concluded that a mitochondrial-like linking peptide is required for proper folding and activity of the E. coli fused transhydrogenase, and that differences between the catalytic properties of the E. coli and the mitochondrial enzymes are unrelated to the linking peptide. This is the first time that larger subunits of a membrane protein with multiple transmembrane helices have been fused with retained activity.
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Affiliation(s)
- J Meuller
- Depatment of Biochemistry and Biophysics, Göteborg University, Sweden
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16
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Bizouarn T, Meuller J, Axelsson M, Rydström J. The transmembrane domain and the proton channel in proton-pumping transhydrogenases. Biochim Biophys Acta 2000; 1459:284-90. [PMID: 11004441 DOI: 10.1016/s0005-2728(00)00163-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Proton-pumping nicotinamide nucleotide transhydrogenases are composed of three main domains, the NAD(H)-binding and NADP(H)-binding hydrophilic domains I (dI) and III (dIII), respectively, and the hydrophobic domain II (dII) containing the assumed proton channel. dII in the Escherichia coli enzyme has recently been characterised with regard to topology and a packing model of the helix bundle in dII is proposed. Extensive mutagenesis of conserved charged residues of this domain showed that important residues are betaHis91 and betaAsn222. The pH dependence of betaH91D, as well as betaH91C (unpublished), when compared to that of wild type shows that reduction of 3-acetylpyridine-NAD(+) by NADPH, i.e., the reverse reaction, is optimal at a pH essentially coinciding with the pK(a) of the residue in the beta91 position. It is therefore concluded that the wild-type transhydrogenase is regulated by the degree of protonation of betaHis91. The mechanisms of the interactions between dI+dIII and dII are suggested to involve pronounced conformational changes in a 'hinge' region around betaR265.
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Affiliation(s)
- T Bizouarn
- Department of Biochemistry and Biophysics, Göteborg University, Sweden
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17
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Bizouarn T, Fjellström O, Meuller J, Axelsson M, Bergkvist A, Johansson C, Göran Karlsson B, Rydström J. Proton translocating nicotinamide nucleotide transhydrogenase from E. coli. Mechanism of action deduced from its structural and catalytic properties. Biochim Biophys Acta 2000; 1457:211-28. [PMID: 10773166 DOI: 10.1016/s0005-2728(00)00103-1] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Transhydrogenase couples the stereospecific and reversible transfer of hydride equivalents from NADH to NADP(+) to the translocation of proton across the inner membrane in mitochondria and the cytoplasmic membrane in bacteria. Like all transhydrogenases, the Escherichia coli enzyme is composed of three domains. Domains I and III protrude from the membrane and contain the binding site for NAD(H) and NADP(H), respectively. Domain II spans the membrane and constitutes at least partly the proton translocating pathway. Three-dimensional models of the hydrophilic domains I and III deduced from crystallographic and NMR data and a new topology of domain II are presented. The new information obtained from the structures and the numerous mutation studies strengthen the proposition of a binding change mechanism, as a way to couple the reduction of NADP(+) by NADH to proton translocation and occurring mainly at the level of the NADP(H) binding site.
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Affiliation(s)
- T Bizouarn
- Department of Biochemistry and Biophysics, Göteborg University, Göteborg, Sweden
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18
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Abstract
The membrane topology of proton-pumping nicotinamide-nucleotide transhydrogenase from Escherichia coli was determined by site-specific chemical labeling. A His-tagged cysteine-free transhydrogenase was used to introduce unique cysteines in positions corresponding to potential membrane loops. The cysteines were reacted with fluorescent reagents, fluorescein 5-maleimide or 2-[(4'-maleimidyl)anilino]naphthalene-6-sulfonic acid, in both intact cells and inside-out vesicles. Labeled transhydrogenase was purified with a small-scale procedure using a metal affinity resin, and the amount of labeling was measured as fluorescence on UV-illuminated acrylamide gels. The difference in labeling between intact cells and inside-out vesicles was used to discriminate between a periplasmic and a cytosolic location of the residues. The membrane region was found to be composed of 13 helices (four in the alpha-subunit and nine in the beta-subunit), with the C terminus of the alpha-subunit and the N terminus of the beta-subunit facing the cytosolic and periplasmic sides, respectively. These results differ from previous models with regard to both number of helices and the relative location and orientation of certain helices. This study constitutes the first in which all transmembrane segments of transhydrogenase have been experimentally determined and provides an explanation for the different topologies of the mitochondrial and E. coli transhydrogenases.
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Affiliation(s)
- J Meuller
- Department of Chemistry, Division of Biochemistry and Biophysics, Göteborg University and Chalmers University of Technology, Medicinaregatan 9C, P. O. Box 462, 40530 Göteborg, Sweden
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19
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Fjellström O, Axelsson M, Bizouarn T, Hu X, Johansson C, Meuller J, Rydström J. Mapping of residues in the NADP(H)-binding site of proton-translocating nicotinamide nucleotide transhydrogenase from Escherichia coli. A study of structure and function. J Biol Chem 1999; 274:6350-9. [PMID: 10037725 DOI: 10.1074/jbc.274.10.6350] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Conformational changes in proton pumping transhydrogenases have been suggested to be dependent on binding of NADP(H) and the redox state of this substrate. Based on a detailed amino acid sequence analysis, it is argued that a classical betaalphabetaalphabeta dinucleotide binding fold is responsible for binding NADP(H). A model defining betaA, alphaB, betaB, betaD, and betaE of this domain is presented. To test this model, four single cysteine mutants (cfbetaA348C, cfbetaA390C, cfbetaK424C, and cfbetaR425C) were introduced into a functional cysteine-free transhydrogenase. Also, five cysteine mutants were constructed in the isolated domain III of Escherichia coli transhydrogenase (ecIIIH345C, ecIIIA348C, ecIIIR350C, ecIIID392C, and ecIIIK424C). In addition to kinetic characterizations, effects of sulfhydryl-specific labeling with N-ethylmaleimide, 2-(4'-maleimidylanilino)naphthalene-6-sulfonic acid, and diazotized 3-aminopyridine adenine dinucleotide (phosphate) were examined. The results are consistent with the view that, in agreement with the model, beta-Ala348, beta-Arg350, beta-Ala390, beta-Asp392, and beta-Lys424 are located in or close to the NADP(H) site. More specifically, beta-Ala348 succeeds betaB. The remarkable reactivity of betaR350C toward NNADP suggests that this residue is close to the nicotinamide moiety of NADP(H). beta-Ala390 and beta-Asp392 terminate or succeed betaD, and are thus, together with the region following betaA, creating the switch point crevice where NADP(H) binds. beta-Asp392 is particularly important for the substrate affinity, but it could also have a more complex role in the coupling mechanism for transhydrogenase.
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Affiliation(s)
- O Fjellström
- Department of Biochemistry and Biophysics, Göteborg University and Chalmers University of Technology, S-405 30, Göteborg, Sweden
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20
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Rydström J, Hu X, Fjellström O, Meuller J, Zhang J, Johansson C, Bizouarn T. Domains, specific residues and conformational states involved in hydride ion transfer and proton pumping by nicotinamide nucleotide transhydrogenase from Escherichia coli. Biochim Biophys Acta 1998; 1365:10-6. [PMID: 9693716 DOI: 10.1016/s0005-2728(98)00038-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Nicotinamide nucleotide transhydrogenase constitutes a proton pump which links the NAD(H) and NADP(H) pools in the cell by catalyzing a reversible reduction of NADP+ by NADH. The recent cloning and characterization of several proton-pumping transhydrogenases show that they share a number of features. They are composed of three domains, i.e., the hydrophilic domains I and III containing the NAD(H)- and NADP(H)-binding sites, respectively, and domain II containing the transmembrane and proton-conducting region. When expressed separately, the two hydrophilic domains interact directly and catalyze hydride transfer reactions similar to those catalyzed by the wild-type enzyme. An extensive mutagenesis program has established several amino acid residues as important for both catalysis and proton pumping. Conformational changes mediating the redox-driven proton pumping by the enzyme are being characterized. With the cloned, well-characterized and easily accessible transhydrogenases from E. coli and Rhodospirillum rubrum at hand, the overall aim of the transhydrogenase research, the understanding of the conformationally driven proton pumping mechanism, is within reach.
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Affiliation(s)
- J Rydström
- Department of Chemistry, Göteborg University, Sweden
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21
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Sedgwick EG, Meuller J, Hou C, Rydström J, Bragg PD. Cross-linking and N-(1-pyrenyl)maleimide labeling of cysteine mutants of proton-pumping pyridine nucleotide transhydrogenase of Escherichia coli. Biochemistry 1997; 36:15285-93. [PMID: 9398257 DOI: 10.1021/bi9708996] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The pyridine nucleotide transhydrogenase of Escherichiacoli is a proton pump composed of two subunits (alpha and beta) organized as an alpha2beta2 tetramer. The enzyme contains seven cysteine residues, five in the alpha-subunit and two in the beta-subunit. The reaction of these residues with the cross-linking agent cupric 1, 10-phenanthrolinate and with the fluorescent thiol reagent N-(1-pyrenyl)maleimide was investigated in mutants in which one or more of these cysteine residues had been mutated to serine or threonine residues. Mutation of alphaCys395 and alphaCys397 prevented disulfide bond formation to give the cross-linked alpha2 dimer. We concluded that the two alpha-subunits of the holoenzyme interface in the region of these two cysteine residues. Pyrenylmaleimide reacted with detergent-washed cytoplasmic membrane vesicles containing high levels of transhydrogenase protein to show characteristic fluorescence emission bands at 378-379, 397-398, and 419-420 nm. At higher ratios of pyrenylmaleimide:transhydrogenase (>5:1) and longer times of reaction, an eximer band at 470 nm was formed. This was attributed to interaction between noncovalently bound molecules of pyrenylmaleimide. The cysteine residues of the beta-subunit (betaCys147 and betaCys260) were covalently modified by pyrenylmaleimide. betaCys147 reacted more strongly than betaCys260 with the fluorophore, and the pyrene derivative of betaCys147 was more accessible to quenching by 5-doxylstearate, suggesting a proximity to the surface of the membrane. Covalent modification of betaCys260 resulted in inhibition of enzyme activity. The inhibition was attributed to the introduction of the bulky pyrene group into the enzyme.
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Affiliation(s)
- E G Sedgwick
- Department of Biochemistry and Molecular Biology, University of British Columbia, 2146 Health Sciences Mall, Vancouver, British Columbia, Canada V6T 1Z3
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22
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Abstract
Nicotinamide nucleotide transhydrogenase from Escherichia coli was investigated with respect to the roles of its cysteine residues. This enzyme contains seven cysteines, of which five are located in the alpha subunit and two are in the beta subunit. All cysteines were replaced by site-directed mutagenesis. The final construct (alphaC292T, alphaC339T, alphaC395S, alphaC397T, alphaC435S, betaC147S, betaC260S) was inserted normally in the membrane and underwent the normal NADPH-dependent conformational change of the beta subunit to a trypsin-sensitive state. Reduction of NADP+ by NADH driven by ATP hydrolysis or respiration was between 32% and 65% of the corresponding wild-type activities. Likewise, the catalytic and proton pumping activities of the purified cysteine-free enzyme were at least 30% of the purified wild-type enzyme activities. The H+/H- ratio for both enzymes was 0.5, although the cysteine-free enzyme appeared to be more stable than the wild-type enzyme in proteoliposomes. No bound NADP(H) was detected in the enzymes. Modification of transhydrogenase by diethyl pyrocarbonate and the subsequent inhibition of the enzyme were unaffected by removal of the cysteines, indicating a lack of involvement of cysteines in this process. Replacement of cysteine residues in the alpha subunit resulted in no or little change in activity, suggesting that the basis for the decreased activity was probably the modification of the conserved beta-subunit residue Cys-260 or (less likely) the non-conserved beta-subunit residue Cys-147. It is concluded that the cysteine-free transhydrogenase is structurally and mechanistically very similar to the wild-type enzyme, with minor modifications of the properties of the NADP(H) site, possibly mediated by the betaC260S mutation. The cysteine-free construct will be a valuable tool for studying structure-function relationships of transhydrogenases.
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Affiliation(s)
- J Meuller
- Department of Biochemistry and Biophysics, Göteborg University, S-413 90 Göteborg, Sweden
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23
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Meuller J, Hu X, Bunthof C, Olausson T, Rydström J. Identification of an aspartic acid residue in the beta subunit which is essential for catalysis and proton pumping by transhydrogenase from Escherichia coli. Biochim Biophys Acta 1996; 1273:191-4. [PMID: 8616154 DOI: 10.1016/0005-2728(95)00154-9] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Based on the alignment of 7 unknown amino acid sequences, including the recently determined sequences for the mouse and human enzymes, a highly conserved acidic domain was identified which in the Escherichia coli enzyme is located close to the C-terminal end of the predicted NADP(H)-binding site of the beta subunit. The effect of replacing the four conserved acidic residues, betaE361, betaE374, betaD383 and betaD392, in this domain on catalytic and proton-pumping activity was tested by site-directed mutagenesis. In addition, betaE371, which is not conserved but located in the same domain, was also mutated. Of these residues, betaAsp 392 proved to be the only residue which is essential for both activities. However, two betaAsp 392 mutants were still partly active in catalyzing the cyclic reduction of 3-acetylpyridine-NAD+ by NADH in the presence of NADPH, suggesting that the mutations did not cause a global change but rather a subtle local change influencing the dissociation of NADP(H). It is proposed that betaAsp 392 together with th previously identified betaHis91 form part of a proton wire in transhydrogenase.
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Affiliation(s)
- J Meuller
- Department of Biochemistry, Lundberg Labortary, Goteborg University, Sweden
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24
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Olausson T, Fjellström O, Meuller J, Rydström J. Molecular biology of nicotinamide nucleotide transhydrogenase--a unique proton pump. Biochim Biophys Acta 1995; 1231:1-19. [PMID: 7640288 DOI: 10.1016/0005-2728(95)00058-q] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- T Olausson
- Department of Biochemistry and Biophysics, Chalmers University of Technology, Göteborg, Sweden
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