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Fitzpatrick PF, Daubner SC. Biochemical and biophysical approaches to characterization of the aromatic amino acid hydroxylases. Methods Enzymol 2024; 704:345-361. [PMID: 39300655 DOI: 10.1016/bs.mie.2024.05.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/22/2024]
Abstract
The aromatic amino acid hydroxylases phenylalanine hydroxylase, tyrosine hydroxylase, and tryptophan hydroxylase utilize a non-heme iron to catalyze the hydroxylation of the aromatic rings of their amino acid substrates, with a tetrahydropterin serving as the source of the electrons necessary for the monooxygenation reaction. These enzymes have been subjected to a variety of biochemical and biophysical approaches, resulting in a detailed understanding of their structures and mechanism. We summarize here the experimental approaches that have led to this understanding.
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Affiliation(s)
- Paul F Fitzpatrick
- Department of Biochemistry and Structural Biology, UT Health San Antonio, San Antonio, TX, United States.
| | - S Colette Daubner
- Department of Biochemistry and Structural Biology, UT Health San Antonio, San Antonio, TX, United States
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2
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Thöny B, Ng J, Kurian MA, Mills P, Martinez A. Mouse models for inherited monoamine neurotransmitter disorders. J Inherit Metab Dis 2024; 47:533-550. [PMID: 38168036 DOI: 10.1002/jimd.12710] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Revised: 11/07/2023] [Accepted: 12/19/2023] [Indexed: 01/05/2024]
Abstract
Several mouse models have been developed to study human defects of primary and secondary inherited monoamine neurotransmitter disorders (iMND). As the field continues to expand, current defects in corresponding mouse models include enzymes and a molecular co-chaperone involved in monoamine synthesis and metabolism (PAH, TH, PITX3, AADC, DBH, MAOA, DNAJC6), tetrahydrobiopterin (BH4) cofactor synthesis and recycling (adGTPCH1/DRD, arGTPCH1, PTPS, SR, DHPR), and vitamin B6 cofactor deficiency (ALDH7A1), as well as defective monoamine neurotransmitter packaging (VMAT1, VMAT2) and reuptake (DAT). No mouse models are available for human DNAJC12 co-chaperone and PNPO-B6 deficiencies, disorders associated with recessive variants that result in decreased stability and function of the aromatic amino acid hydroxylases and decreased neurotransmitter synthesis, respectively. More than one mutant mouse is available for some of these defects, which is invaluable as different variant-specific (knock-in) models may provide more insights into underlying mechanisms of disorders, while complete gene inactivation (knock-out) models often have limitations in terms of recapitulating complex human diseases. While these mouse models have common phenotypic traits also observed in patients, reflecting the defective homeostasis of the monoamine neurotransmitter pathways, they also present with disease-specific manifestations with toxic accumulation or deficiency of specific metabolites related to the specific gene affected. This review provides an overview of the currently available models and may give directions toward selecting existing models or generating new ones to investigate novel pathogenic mechanisms and precision therapies.
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Affiliation(s)
- Beat Thöny
- Division of Metabolism and Children's Research Center, University Children's Hospital Zurich, Zürich, Switzerland
| | - Joanne Ng
- Genetic Therapy Accelerator Centre, University College London, Queen Square Institute of Neurology, London, UK
| | - Manju A Kurian
- Zayed Centre for Research into Rare Disease in Children, GOS Institute of Child Health, University College London, London, UK
- Department of Neurology, Great Ormond Street Hospital, London, UK
| | - Philippa Mills
- Great Ormond Street Institute of Child Health, University College London, London, UK
| | - Aurora Martinez
- Department of Biomedicine and Center for Translational Research in Parkinson's Disease, University of Bergen, Bergen, Norway
- Neuro-SysMed, Department of Neurology, Haukeland University Hospital, Bergen, Norway
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3
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Sarodaya N, Tyagi A, Kim HJ, Colaco JC, Kang JS, Kim WJ, Kim KS, Ramakrishna S. Deubiquitinase USP19 enhances phenylalanine hydroxylase protein stability and its enzymatic activity. Cell Biol Toxicol 2023; 39:2295-2310. [PMID: 35449354 DOI: 10.1007/s10565-022-09719-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Accepted: 04/07/2022] [Indexed: 12/13/2022]
Abstract
Phenylalanine hydroxylase (PAH) is the key enzyme in phenylalanine metabolism, deficiency of which is associated with the most common metabolic phenotype of phenylketonuria (PKU) and hyperphenylalaninemia (HPA). A bulk of PKU disease-associated missense mutations in the PAH gene have been studied, and the consequence of each PAH variant vary immensely. Prior research established that PKU-associated variants possess defects in protein folding with reduced cellular stability leading to rapid degradation. However, recent evidence revealed that PAH tetramers exist as a mixture of resting state and activated state whose transition depends upon the phenylalanine concentration and certain PAH variants that fail to modulate the structural equilibrium are associated with PKU disease. Collectively, these findings framed our understanding of the complex genotype-phenotype correlation in PKU. In the current study, we substantiate a link between PAH protein stability and its degradation by the ubiquitin-mediated proteasomal degradation system. Here, we provide an evidence that PAH protein undergoes ubiquitination and proteasomal degradation, which can be reversed by deubiquitinating enzymes (DUBs). We identified USP19 as a novel DUB that regulates PAH protein stability. We found that ectopic expression of USP19 increased PAH protein level, whereas depletion of USP19 promoted PAH protein degradation. Our study indicates that USP19 interacts with PAH and prevents polyubiquitination of PAH subsequently extending the half-life of PAH protein. Finally, the increase in the level of PAH protein by the deubiquitinating activity of USP19 resulted in enhanced metabolic function of PAH. In summary, our study identifies the role of USP19 in regulating PAH protein stability and promotes its metabolic activity. Graphical highlights 1. E3 ligase Cdh1 promotes PAH protein degradation leading to insufficient cellular amount of PAH causing PKU. 2. A balance between E3 ligase and DUB is important to regulate the proteostasis of PAH. 3. USP19 deubiquitinates and stabilizes PAH further protecting it from rapid degradation. 4. USP19 increases the enzymatic activity of PAH, thus maintaining normal Phe levels.
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Affiliation(s)
- Neha Sarodaya
- Graduate School of Biomedical Science and Engineering, Hanyang University, Seoul, South Korea
| | - Apoorvi Tyagi
- Graduate School of Biomedical Science and Engineering, Hanyang University, Seoul, South Korea
| | - Hyun-Jin Kim
- Department of Pharmacology, College of Medicine, Hanyang University, Seoul, South Korea
| | - Jencia Carminha Colaco
- Graduate School of Biomedical Science and Engineering, Hanyang University, Seoul, South Korea
| | - Ju-Seop Kang
- Department of Pharmacology, College of Medicine, Hanyang University, Seoul, South Korea
| | - Woo Jin Kim
- Department of Internal Medicine and Environmental Health Center, Kangwon National University Hospital, Kangwon National University School of Medicine, Chuncheon, South Korea
| | - Kye-Seong Kim
- Graduate School of Biomedical Science and Engineering, Hanyang University, Seoul, South Korea.
- College of Medicine, Hanyang University, Seoul, South Korea.
| | - Suresh Ramakrishna
- Graduate School of Biomedical Science and Engineering, Hanyang University, Seoul, South Korea.
- College of Medicine, Hanyang University, Seoul, South Korea.
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4
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Carkaci-Salli N, Bewley MC, Tekin I, Flanagan JM, Vrana KE. The A328 V/E (rs2887147) polymorphisms in human tryptophan hydroxylase 2 compromise enzyme activity. Biochem Biophys Rep 2023; 35:101527. [PMID: 37608910 PMCID: PMC10440358 DOI: 10.1016/j.bbrep.2023.101527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 08/03/2023] [Accepted: 08/03/2023] [Indexed: 08/24/2023] Open
Abstract
Human tryptophan hydroxylase 2 (hTPH2) is the rate-limiting enzyme for serotonin biosynthesis in the brain. A number of naturally-occurring single nucleotide polymorphisms (SNPs) have been reported for hTPH2. We investigated the activity and kinetic characteristics of the most common missense polymorphism rs2887147 (A328 V/E; 0.92% allelic frequency for the two different reported SNPs at the same site) using bacterially expressed hTPH2. The recombinant full-length enzyme A328E had no measurable enzyme activity, but A328V displayed decreased enzyme activity (Vmax). A328V also displayed substrate inhibition and decreased stability compared to the wild-type enzyme. By contrast, in constructs lacking the N-terminal 150 amino acid regulatory domain, the A328V substitution had no effect; that is, there was no substrate inhibition, enzyme stabilities (for wild-type and A328V) were dramatically increased, and Vmax values were not different (while the A328E variant remained inactive). These findings, in combination with molecular modeling, suggest that substitutions at A328 affect catalytic activity by altering the conformational freedom of the regulatory domain. The reduced activity and substrate inhibition resulting from these polymorphisms may ultimately reduce serotonin synthesis and contribute to behavioral perturbations, emotional stress, and eating disorders.
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Affiliation(s)
- Nurgul Carkaci-Salli
- Departments of Pharmacology, Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA
| | - Maria C. Bewley
- Biochemistry and Molecular Biology, Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA
| | - Izel Tekin
- Departments of Pharmacology, Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA
| | - John M. Flanagan
- Biochemistry and Molecular Biology, Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA
| | - Kent E. Vrana
- Departments of Pharmacology, Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA
- Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA
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5
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Vedel IM, Prestel A, Zhang Z, Skawinska NT, Stark H, Harris P, Kragelund BB, Peters GHJ. Structural characterization of human tryptophan hydroxylase 2 reveals that L-Phe is superior to L-Trp as the regulatory domain ligand. Structure 2023:S0969-2126(23)00127-2. [PMID: 37119821 DOI: 10.1016/j.str.2023.04.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2022] [Revised: 03/03/2023] [Accepted: 04/04/2023] [Indexed: 05/01/2023]
Abstract
Tryptophan hydroxylase 2 (TPH2) catalyzes the rate-limiting step in serotonin biosynthesis in the brain. Consequently, regulation of TPH2 is relevant for serotonin-related diseases, yet the regulatory mechanism of TPH2 is poorly understood and structural and dynamical insights are missing. We use NMR spectroscopy to determine the structure of a 47 N-terminally truncated variant of the regulatory domain (RD) dimer of human TPH2 in complex with L-Phe, and show that L-Phe is the superior RD ligand compared with the natural substrate, L-Trp. Using cryo-EM, we obtain a low-resolution structure of a similarly truncated variant of the complete tetrameric enzyme with dimerized RDs. The cryo-EM two-dimensional (2D) class averages additionally indicate that the RDs are dynamic in the tetramer and likely exist in a monomer-dimer equilibrium. Our results provide structural information on the RD as an isolated domain and in the TPH2 tetramer, which will facilitate future elucidation of TPH2's regulatory mechanism.
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Affiliation(s)
- Ida M Vedel
- Department of Chemistry, Technical University of Denmark, Kemitorvet, 2800 Kgs. Lyngby, Denmark
| | - Andreas Prestel
- Department of Biology, University of Copenhagen, Ole Maaløes vej 5, 2200 Copenhagen N, Denmark
| | - Zhenwei Zhang
- Department of Structural Dynamics, Max Planck Institute for Multidisciplinary Sciences, Am Faßberg 11, 37077 Göttingen, Germany
| | - Natalia T Skawinska
- Department of Chemistry, Technical University of Denmark, Kemitorvet, 2800 Kgs. Lyngby, Denmark
| | - Holger Stark
- Department of Structural Dynamics, Max Planck Institute for Multidisciplinary Sciences, Am Faßberg 11, 37077 Göttingen, Germany
| | - Pernille Harris
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen Ø, Denmark
| | - Birthe B Kragelund
- Department of Biology, University of Copenhagen, Ole Maaløes vej 5, 2200 Copenhagen N, Denmark.
| | - Günther H J Peters
- Department of Chemistry, Technical University of Denmark, Kemitorvet, 2800 Kgs. Lyngby, Denmark.
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6
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Leandro P, Lino PR, Lopes R, Leandro J, Amaro MP, Sousa P, Vicente JB, Almeida AJ. Isothermal denaturation fluorimetry vs Differential scanning fluorimetry as tools for screening of stabilizers for protein freeze-drying: human phenylalanine hydroxylase as the case study. Eur J Pharm Biopharm 2023; 187:1-11. [PMID: 37011788 DOI: 10.1016/j.ejpb.2023.03.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 03/24/2023] [Accepted: 03/25/2023] [Indexed: 04/03/2023]
Abstract
The structural maintenance of therapeutic proteins during formulation and/or storage is a critical aspect, particularly for multi-domain and/or multimeric proteins which usually exhibit intrinsic structural dynamics leading to aggregation with concomitant loss-of-function. Protein freeze-drying is a widely used technique to preserve protein structure and function during storage. To minimize chemical/physical stresses occurring during this process, protein stabilizers are usually included, their effect being strongly dependent on the target protein. Therefore, they should be screened for on a time-consuming case-by-case basis. Herein, differential scanning fluorimetry (DSF) and isothermal denaturation fluorimetry (ITDF) were employed to screen, among different classes of freeze-drying additives, for the most effective stabilizer of the model protein human phenylalanine hydroxylase (hPAH). Correlation studies among retrieved DSF and ITDF parameters with recovered enzyme amount and activity indicated ITDF as the most appropriate screening method. Biochemical and biophysical characterization of hPAH freeze-dried with ITDF-selected stabilizers and a long-term storage study (12 months, 5 ± 3 °C) showed that the selected compounds prevented protein aggregation and preserved hPAH structural and functional properties throughout time storage. Our results provide a solid basis towards the choice of ITDF as a high-throughput screening step for the identification of protein freeze-drying protectors.
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Affiliation(s)
- Paula Leandro
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal.
| | - Paulo R Lino
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal
| | - Raquel Lopes
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal
| | - João Leandro
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal
| | - Mariana P Amaro
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal
| | - Paulo Sousa
- Sofarimex, Indústria Química e Farmacêutica SA, Av. das Indústrias, Alto de Colaride, 2735-521 Agualva, Portugal
| | - João B Vicente
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República 2780-157 Oeiras, Portugal
| | - António J Almeida
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal.
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7
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Fitzpatrick PF. The aromatic amino acid hydroxylases: Structures, catalysis, and regulation of phenylalanine hydroxylase, tyrosine hydroxylase, and tryptophan hydroxylase. Arch Biochem Biophys 2023; 735:109518. [PMID: 36639008 DOI: 10.1016/j.abb.2023.109518] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 01/01/2023] [Accepted: 01/06/2023] [Indexed: 01/12/2023]
Abstract
The aromatic amino acid hydroxylases phenylalanine hydroxylase, tyrosine hydroxylase, and tryptophan hydroxylase are non-heme iron enzymes that catalyze key physiological reactions. This review discusses the present understanding of the common catalytic mechanism of these enzymes and recent advances in understanding the relationship between their structures and their regulation.
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Affiliation(s)
- Paul F Fitzpatrick
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, 78229, USA.
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8
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Zhu K, Liu C, Gao Y, Lu J, Wang D, Zhang H. Cryo-EM Structure and Activator Screening of Human Tryptophan Hydroxylase 2. Front Pharmacol 2022; 13:907437. [PMID: 36046836 PMCID: PMC9420949 DOI: 10.3389/fphar.2022.907437] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Accepted: 06/23/2022] [Indexed: 02/06/2023] Open
Abstract
Human tryptophan hydroxylase 2 (TPH2) is the rate-limiting enzyme in the synthesis of serotonin. Its dysfunction has been implicated in various psychiatric disorders such as depression, autism, and bipolar disorder. TPH2 is typically decreased in stability and catalytic activity in patients; thus, screening of molecules capable of binding and stabilizing the structure of TPH2 in activated conformation is desired for drug development in mental disorder treatment. Here, we solved the 3.0 Å cryo-EM structure of the TPH2 tetramer. Then, based on the structure, we conducted allosteric site prediction and small-molecule activator screening to the obtained cavity. ZINC000068568685 was successfully selected as the best candidate with highest binding affinity. To better understand the driving forces and binding stability of the complex, we performed molecular dynamics simulation, which indicates that ZINC000068568685 has great potential to stabilize the folding of the TPH2 tetramer to facilitate its activity. The research might shed light on the development of novel drugs targeting TPH2 for the treatment of psychological disorders.
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Affiliation(s)
- Kongfu Zhu
- Department of Biomedical Engineering, Southern University of Science and Technology, Shenzhen, China
| | - Chao Liu
- Department of Biomedical Engineering, Southern University of Science and Technology, Shenzhen, China
| | - Yuanzhu Gao
- Cryo-EM Facility Center, Southern University of Science and Technology, Shenzhen, China
| | - Jianping Lu
- Department of Child and Adolescent Psychiatry, Shenzhen Kangning Hospital, Shenzhen Mental Health Center, Shenzhen, China
| | - Daping Wang
- Department of Biomedical Engineering, Southern University of Science and Technology, Shenzhen, China
- Department of Orthopedics, Shenzhen Intelligent Orthopaedics and Biomedical Innovation Platform, Guangdong Provincial Research Center for Artificial Intelligence and Digital Orthopedic Technology, Shenzhen Second People’s Hospital, The First Affiliated Hospital of Shenzhen University, Shenzhen, China
- *Correspondence: Daping Wang, ; Huawei Zhang,
| | - Huawei Zhang
- Department of Biomedical Engineering, Southern University of Science and Technology, Shenzhen, China
- Guangdong Provincial Key Laboratory of Advanced Biomaterials, Southern University of Science and Technology, Shenzhen, China
- *Correspondence: Daping Wang, ; Huawei Zhang,
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Park J, Hong J, Seok J, Hong H, Seo H, Kim KJ. Structural studies of a novel auxiliary-domain-containing phenylalanine hydroxylase from Bacillus cereus ATCC 14579. Acta Crystallogr D Struct Biol 2022; 78:586-598. [DOI: 10.1107/s2059798322002674] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Accepted: 03/08/2022] [Indexed: 11/11/2022] Open
Abstract
Phenylalanine hydroxylase (PAH), which belongs to the aromatic amino-acid hydroxylase family, is involved in protein synthesis and pyomelanine production through the hydroxylation of phenylalanine to tyrosine. In this study, the crystal structure of PAH from Bacillus cereus ATCC 14579 (BcPAH) with an additional 280 amino acids in the C-terminal region was determined. The structure of BcPAH consists of three distinct domains: a core domain with two additional inserted α-helices and two novel auxiliary domains: BcPAH-AD1 and BcPAH-AD2. Structural homologues of BcPAH-AD1 and BcPAH-AD2 are known to be involved in mRNA regulation and protein–protein interactions, and thus it was speculated that BcPAH might utilize the auxiliary domains for interaction with its partner proteins. Furthermore, phylogenetic tree analysis revealed that the three-domain PAHs, including BcPAH, are completely distinctive from both conventional prokaryotic PAHs and eukaryotic PAHs. Finally, biochemical studies of BcPAH showed that BcPAH-AD1 might be important for the structural integrity of the enzyme and that BcPAH-AD2 is related to enzyme stability and/or activity. Investigations into the intracellular functions of the two auxiliary domains and the relationship between these functions and the activity of PAH are required.
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Lin C, Li Y, Zhang E, Feillet F, Zhang S, Blau N. Importance of the long non-coding RNA (lncRNA) transcript HULC for the regulation of phenylalanine hydroxylase and treatment of phenylketonuria. Mol Genet Metab 2022; 135:171-178. [PMID: 35101330 DOI: 10.1016/j.ymgme.2022.01.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 01/18/2022] [Accepted: 01/18/2022] [Indexed: 12/12/2022]
Abstract
More than 1280 variants in the phenylalanine hydroxylase (PAH) gene are responsible for a broad spectrum of phenylketonuria (PKU) phenotypes. While the genotype-phenotype correlation is reaching 88%, for some inconsistent phenotypes with the same genotype additional factors like tetrahydrobiopterin (BH4), the PAH co-chaperone DNAJC12, phosphorylation of the PAH residues or epigenetic factors may play an important role. Very recently an additional player, the long non-coding RNA (lncRNA) transcript HULC, was described to regulate PAH activity and enhance residual enzyme activity of some PAH variants (e.g., the most common p.R408W) by using HULC mimics. In this review we present an overview of the lncRNA function and in particular the interplay of the HUCL transcript with the PAH and discuss potential applications for the future treatment of some PKU patients.
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Affiliation(s)
- Chunru Lin
- Department of Molecular and Cellular Oncology, Division of Basic Science Research, The University of Texas, MD Anderson Cancer Center, Houston, TX, United States of America
| | - Yajuan Li
- Department of Molecular and Cellular Oncology, Division of Basic Science Research, The University of Texas, MD Anderson Cancer Center, Houston, TX, United States of America
| | - Eric Zhang
- Department of Experimental Therapeutics, The University of Texas, MD Anderson Cancer Center, Houston, TX, United States of America
| | - François Feillet
- INSERM, U1256, NGERE - Nutrition, Genetics, and Environmental Risk Exposure, University of Lorraine, Nancy, France; Pediatric Department Reference Center for Inborn Errors of Metabolism Children University Hospital Nancy, Nancy, France
| | - Shuxing Zhang
- Department of Experimental Therapeutics, The University of Texas, MD Anderson Cancer Center, Houston, TX, United States of America
| | - Nenad Blau
- Division of Metabolism, University Children's Hospital Zürich, Zurich, Switzerland.
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11
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Bueno-Carrasco MT, Cuéllar J, Flydal MI, Santiago C, Kråkenes TA, Kleppe R, López-Blanco JR, Marcilla M, Teigen K, Alvira S, Chacón P, Martinez A, Valpuesta JM. Structural mechanism for tyrosine hydroxylase inhibition by dopamine and reactivation by Ser40 phosphorylation. Nat Commun 2022; 13:74. [PMID: 35013193 PMCID: PMC8748767 DOI: 10.1038/s41467-021-27657-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2020] [Accepted: 12/03/2021] [Indexed: 12/15/2022] Open
Abstract
Tyrosine hydroxylase (TH) catalyzes the rate-limiting step in the biosynthesis of dopamine (DA) and other catecholamines, and its dysfunction leads to DA deficiency and parkinsonisms. Inhibition by catecholamines and reactivation by S40 phosphorylation are key regulatory mechanisms of TH activity and conformational stability. We used Cryo-EM to determine the structures of full-length human TH without and with DA, and the structure of S40 phosphorylated TH, complemented with biophysical and biochemical characterizations and molecular dynamics simulations. TH presents a tetrameric structure with dimerized regulatory domains that are separated 15 Å from the catalytic domains. Upon DA binding, a 20-residue α-helix in the flexible N-terminal tail of the regulatory domain is fixed in the active site, blocking it, while S40-phosphorylation forces its egress. The structures reveal the molecular basis of the inhibitory and stabilizing effects of DA and its counteraction by S40-phosphorylation, key regulatory mechanisms for homeostasis of DA and TH. Tyrosine hydroxylase (TH) catalyzes the rate-limiting step in the synthesis of the catecholamine neurotransmitters and hormones dopamine (DA), adrenaline and noradrenaline. Here, the authors present the cryo-EM structures of full-length human TH in the apo form and bound with DA, as well as the structure of Ser40 phosphorylated TH, and discuss the inhibitory and stabilizing effects of DA on TH and its counteraction by Ser40-phosphorylation.
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Affiliation(s)
| | - Jorge Cuéllar
- Centro Nacional de Biotecnología (CNB-CSIC), Madrid, Spain.
| | - Marte I Flydal
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | - César Santiago
- Centro Nacional de Biotecnología (CNB-CSIC), Madrid, Spain
| | | | - Rune Kleppe
- Norwegian Centre for Maritime and Diving Medicine, Department of Occupational Medicine, Haukeland University Hospital, Bergen, Norway
| | | | | | - Knut Teigen
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | - Sara Alvira
- Centro Nacional de Biotecnología (CNB-CSIC), Madrid, Spain.,School of Biochemistry, University of Bristol, Bristol, BS8 1TD, UK
| | - Pablo Chacón
- Instituto de Química Física Rocasolano (IQFR-CSIC), Madrid, Spain
| | - Aurora Martinez
- Department of Biomedicine, University of Bergen, Bergen, Norway.
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12
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Personalized Medicine to Improve Treatment of Dopa-Responsive Dystonia-A Focus on Tyrosine Hydroxylase Deficiency. J Pers Med 2021; 11:jpm11111186. [PMID: 34834538 PMCID: PMC8625014 DOI: 10.3390/jpm11111186] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 11/08/2021] [Accepted: 11/09/2021] [Indexed: 11/25/2022] Open
Abstract
Dopa-responsive dystonia (DRD) is a rare movement disorder associated with defective dopamine synthesis. This impairment may be due to the fact of a deficiency in GTP cyclohydrolase I (GTPCHI, GCH1 gene), sepiapterin reductase (SR), tyrosine hydroxylase (TH), or 6-pyruvoyl tetrahydrobiopterin synthase (PTPS) enzyme functions. Mutations in GCH1 are most frequent, whereas fewer cases have been reported for individual SR-, PTP synthase-, and TH deficiencies. Although termed DRD, a subset of patients responds poorly to L-DOPA. As this is regularly observed in severe cases of TH deficiency (THD), there is an urgent demand for more adequate or personalized treatment options. TH is a key enzyme that catalyzes the rate-limiting step in catecholamine biosynthesis, and THD patients often present with complex and variable phenotypes, which results in frequent misdiagnosis and lack of appropriate treatment. In this expert opinion review, we focus on THD pathophysiology and ongoing efforts to develop novel therapeutics for this rare disorder. We also describe how different modeling approaches can be used to improve genotype to phenotype predictions and to develop in silico testing of treatment strategies. We further discuss the current status of mathematical modeling of catecholamine synthesis and how such models can be used together with biochemical data to improve treatment of DRD patients.
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13
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The Pah-R261Q mouse reveals oxidative stress associated with amyloid-like hepatic aggregation of mutant phenylalanine hydroxylase. Nat Commun 2021; 12:2073. [PMID: 33824313 PMCID: PMC8024259 DOI: 10.1038/s41467-021-22107-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 02/25/2021] [Indexed: 01/09/2023] Open
Abstract
Phenylketonuria (PKU) is caused by autosomal recessive variants in phenylalanine hydroxylase (PAH), leading to systemic accumulation of L-phenylalanine (L-Phe) that may reach neurotoxic levels. A homozygous Pah-R261Q mouse, with a highly prevalent misfolding variant in humans, reveals the expected hepatic PAH activity decrease, systemic L-Phe increase, L-tyrosine and L-tryptophan decrease, and tetrahydrobiopterin-responsive hyperphenylalaninemia. Pah-R261Q mice also present unexpected traits, including altered lipid metabolism, reduction of liver tetrahydrobiopterin content, and a metabolic profile indicative of oxidative stress. Pah-R261Q hepatic tissue exhibits large ubiquitin-positive, amyloid-like oligomeric aggregates of mutant PAH that colocalize with selective autophagy markers. Together, these findings reveal that PKU, customarily considered a loss-of-function disorder, can also have toxic gain-of-function contribution from protein misfolding and aggregation. The proteostasis defect and concomitant oxidative stress may explain the prevalence of comorbid conditions in adult PKU patients, placing this mouse model in an advantageous position for the discovery of mutation-specific biomarkers and therapies.
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14
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Arturo EC, Merkel GW, Hansen MR, Lisowski S, Almeida D, Gupta K, Jaffe EK. Manipulation of a cation-π sandwich reveals conformational flexibility in phenylalanine hydroxylase. Biochimie 2021; 183:63-77. [PMID: 33221376 PMCID: PMC9856217 DOI: 10.1016/j.biochi.2020.11.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 11/04/2020] [Accepted: 11/10/2020] [Indexed: 01/24/2023]
Abstract
Phenylalanine hydroxylase (PAH) is an allosteric enzyme that maintains phenylalanine (Phe) below neurotoxic levels; its failure results in phenylketonuria, an inborn error of amino acid metabolism. Wild type (WT) PAH equilibrates among resting-state (RS-PAH) and activated (A-PAH) conformations, whose equilibrium position depends upon allosteric Phe binding. The RS-PAH conformation of WT rat PAH (rPAH) contains a cation-π sandwich involving Phe80 that cannot exist in the A-PAH conformation. Phe80 variants F80A, F80D, F80L, and F80R were prepared and evaluated using native PAGE, size exclusion chromatography, ion exchange behavior, intrinsic protein fluorescence, enzyme kinetics, and limited proteolysis, each as a function of [Phe]. Like WT rPAH, F80A and F80D show allosteric activation by Phe while F80L and F80R are constitutively active. Maximal activity of all variants suggests relief of a rate-determining conformational change. Limited proteolysis of WT rPAH (minus Phe) reveals facile cleavage within a 4-helix bundle that is buried in the RS-PAH tetramer interface, reflecting dynamic dissociation of that tetramer. This cleavage is not seen for the Phe80 variants, which all show proteolytic hypersensitivity in a linker that repositions during the RS-PAH to A-PAH interchange. Hypersensitivity is corrected by addition of Phe such that all variants become like WT rPAH and achieve the A-PAH conformation. Thus, manipulation of Phe80 perturbs the conformational space sampled by PAH, increasing sampling of on-pathway intermediates in the RS-PAH and A-PAH interchange. The behavior of the Phe80 variants mimics that of disease-associated R68S and suggests a molecular basis for proteolytic susceptibility in PKU-associated human PAH variants.
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Affiliation(s)
- Emilia C. Arturo
- Molecular Therapeutics Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania, 10111,Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, PA 19102
| | - George W. Merkel
- Molecular Therapeutics Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania, 10111
| | - Michael R. Hansen
- Molecular Therapeutics Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania, 10111
| | - Sophia Lisowski
- Molecular Therapeutics Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania, 10111
| | - Deeanne Almeida
- Molecular Therapeutics Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania, 10111
| | - Kushol Gupta
- Department pf Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Eileen K. Jaffe
- Molecular Therapeutics Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania, 10111,To whom correspondence should be addressed: Eileen K. Jaffe: Molecular Therapeutics, Fox Chase Cancer Center, Philadelphia, PA 19111; ; Tel.(215) 728-3695; Fax. (215) 728-2412
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15
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Lopes RR, Tomé CS, Russo R, Paterna R, Leandro J, Candeias NR, Gonçalves LMD, Teixeira M, Sousa PMF, Guedes RC, Vicente JB, Gois PMP, Leandro P. Modulation of Human Phenylalanine Hydroxylase by 3-Hydroxyquinolin-2(1H)-One Derivatives. Biomolecules 2021; 11:biom11030462. [PMID: 33808760 PMCID: PMC8003416 DOI: 10.3390/biom11030462] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Revised: 02/08/2021] [Accepted: 03/13/2021] [Indexed: 01/14/2023] Open
Abstract
Phenylketonuria (PKU) is a genetic disease caused by deficient activity of human phenylalanine hydroxylase (hPAH) that, when untreated, can lead to severe psychomotor impairment. Protein misfolding is recognized as the main underlying pathogenic mechanism of PKU. Therefore, the use of stabilizers of protein structure and/or activity is an attractive therapeutic strategy for this condition. Here, we report that 3-hydroxyquinolin-2(1H)-one derivatives can act as protectors of hPAH enzyme activity. Electron paramagnetic resonance spectroscopy demonstrated that the 3-hydroxyquinolin-2(1H)-one compounds affect the coordination of the non-heme ferric center at the enzyme active-site. Moreover, surface plasmon resonance studies showed that these stabilizing compounds can be outcompeted by the natural substrate l-phenylalanine. Two of the designed compounds functionally stabilized hPAH by maintaining protein activity. This effect was observed on the recombinant purified protein and in a cellular model. Besides interacting with the catalytic iron, one of the compounds also binds to the N-terminal regulatory domain, although to a different location from the allosteric l-Phe binding site, as supported by the solution structures obtained by small-angle X-ray scattering.
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Affiliation(s)
- Raquel R. Lopes
- Research Institute for Medicines, Faculty of Pharmacy, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal; (R.R.L.); (C.S.T.); (R.R.); (R.P.); (J.L.); (L.M.D.G.); (R.C.G.)
| | - Catarina S. Tomé
- Research Institute for Medicines, Faculty of Pharmacy, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal; (R.R.L.); (C.S.T.); (R.R.); (R.P.); (J.L.); (L.M.D.G.); (R.C.G.)
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157 Oeiras, Portugal;
- Instituto de Biologia Experimental e Tecnológica, Quinta do Marquês, 2780-155 Oeiras, Portugal;
| | - Roberto Russo
- Research Institute for Medicines, Faculty of Pharmacy, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal; (R.R.L.); (C.S.T.); (R.R.); (R.P.); (J.L.); (L.M.D.G.); (R.C.G.)
| | - Roberta Paterna
- Research Institute for Medicines, Faculty of Pharmacy, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal; (R.R.L.); (C.S.T.); (R.R.); (R.P.); (J.L.); (L.M.D.G.); (R.C.G.)
| | - João Leandro
- Research Institute for Medicines, Faculty of Pharmacy, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal; (R.R.L.); (C.S.T.); (R.R.); (R.P.); (J.L.); (L.M.D.G.); (R.C.G.)
| | - Nuno R. Candeias
- Faculty of Engineering and Natural Sciences, Tampere University, Korkeakoulunkatu 8, 33101 Tampere, Finland;
- LAQV-REQUIMTE, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal
| | - Lídia M. D. Gonçalves
- Research Institute for Medicines, Faculty of Pharmacy, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal; (R.R.L.); (C.S.T.); (R.R.); (R.P.); (J.L.); (L.M.D.G.); (R.C.G.)
| | - Miguel Teixeira
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157 Oeiras, Portugal;
| | - Pedro M. F. Sousa
- Instituto de Biologia Experimental e Tecnológica, Quinta do Marquês, 2780-155 Oeiras, Portugal;
| | - Rita C. Guedes
- Research Institute for Medicines, Faculty of Pharmacy, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal; (R.R.L.); (C.S.T.); (R.R.); (R.P.); (J.L.); (L.M.D.G.); (R.C.G.)
| | - João B. Vicente
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157 Oeiras, Portugal;
- Correspondence: (J.B.V.); (P.M.P.G.); (P.L.); Tel.: +351-217946400 (P.L.)
| | - Pedro M. P. Gois
- Research Institute for Medicines, Faculty of Pharmacy, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal; (R.R.L.); (C.S.T.); (R.R.); (R.P.); (J.L.); (L.M.D.G.); (R.C.G.)
- Correspondence: (J.B.V.); (P.M.P.G.); (P.L.); Tel.: +351-217946400 (P.L.)
| | - Paula Leandro
- Research Institute for Medicines, Faculty of Pharmacy, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal; (R.R.L.); (C.S.T.); (R.R.); (R.P.); (J.L.); (L.M.D.G.); (R.C.G.)
- Correspondence: (J.B.V.); (P.M.P.G.); (P.L.); Tel.: +351-217946400 (P.L.)
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16
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Lino PR, Leandro J, Amaro M, Gonçalves LMD, Leandro P, Almeida AJ. In Silico and In Vitro Tailoring of a Chitosan Nanoformulation of a Human Metabolic Enzyme. Pharmaceutics 2021; 13:pharmaceutics13030329. [PMID: 33806405 PMCID: PMC8000282 DOI: 10.3390/pharmaceutics13030329] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 02/23/2021] [Accepted: 02/27/2021] [Indexed: 01/10/2023] Open
Abstract
Enzyme nanoencapsulation holds an enormous potential to develop new therapeutic approaches to a large set of human pathologies including cancer, infectious diseases and inherited metabolic disorders. However, enzyme formulation has been limited by the need to maintain the catalytic function, which is governed by protein conformation. Herein we report the rational design of a delivery system based on chitosan for effective encapsulation of a functionally and structurally complex human metabolic enzyme through ionic gelation with tripolyphosphate. The rationale was to use a mild methodology to entrap the multimeric multidomain 200 kDa human phenylalanine hydroxylase (hPAH) in a polyol-like matrix that would allow an efficient maintenance of protein structure and function, avoiding formulation stress conditions. Through an in silico and in vitro based development, the particulate system was optimized with modulation of nanomaterials protonation status, polymer, counterion and protein ratios, taking into account particle size, polydispersity index, surface charge, particle yield production, protein free energy of folding, electrostatic surface potential, charge, encapsulation efficiency, loading capacity and transmission electron microscopy morphology. Evaluation of the thermal stability, substrate binding profile, relative enzymatic activity, and substrate activation ratio of the encapsulated hPAH suggests that the formulation procedure does not affect protein stability, allowing an effective maintenance of hPAH biological function. Hence, this study provides an important framework for an enzyme formulation process.
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17
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Abstract
Molecular dynamics simulations can now routinely access the microsecond timescale, making feasible direct sampling of ligand association events. While Markov State Model (MSM) approaches offer a useful framework for analyzing such trajectory data to gain insight into binding mechanisms, accurate modeling of ligand association pathways and kinetics must be done carefully. We describe methods and good practices for constructing MSMs of ligand binding from unbiased trajectory data and discuss how to use time-lagged independent component analysis (tICA) to build informative models, using as an example recent simulation work to model the binding of phenylalanine to the regulatory ACT domain dimer of phenylalanine hydroxylase. We describe a variety of methods for estimating association rates from MSMs and discuss how to distinguish between conformational selection and induced-fit mechanisms using MSMs. In addition, we review some examples of MSMs constructed to elucidate the mechanisms by which p53 transactivation domain (TAD) and related peptides bind the oncoprotein MDM2.
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Affiliation(s)
- Yunhui Ge
- Department of Chemistry, Temple University, Philadelphia, PA, USA
| | - Vincent A Voelz
- Department of Chemistry, Temple University, Philadelphia, PA, USA.
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18
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Tyagi A, Sarodaya N, Kaushal K, Chandrasekaran AP, Antao AM, Suresh B, Rhie BH, Kim KS, Ramakrishna S. E3 Ubiquitin Ligase APC/C Cdh1 Regulation of Phenylalanine Hydroxylase Stability and Function. Int J Mol Sci 2020; 21:E9076. [PMID: 33260674 PMCID: PMC7729981 DOI: 10.3390/ijms21239076] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 11/18/2020] [Accepted: 11/25/2020] [Indexed: 12/20/2022] Open
Abstract
Phenylketonuria (PKU) is an autosomal recessive metabolic disorder caused by the dysfunction of the enzyme phenylalanine hydroxylase (PAH). Alterations in the level of PAH leads to the toxic accumulation of phenylalanine in the blood and brain. Protein degradation mediated by ubiquitination is a principal cellular process for maintaining protein homeostasis. Therefore, it is important to identify the E3 ligases responsible for PAH turnover and proteostasis. Here, we report that anaphase-promoting complex/cyclosome-Cdh1 (APC/C)Cdh1 is an E3 ubiquitin ligase complex that interacts and promotes the polyubiquitination of PAH through the 26S proteasomal pathway. Cdh1 destabilizes and declines the half-life of PAH. In contrast, the CRISPR/Cas9-mediated knockout of Cdh1 stabilizes PAH expression and enhances phenylalanine metabolism. Additionally, our current study demonstrates the clinical relevance of PAH and Cdh1 correlation in hepatocellular carcinoma (HCC). Overall, we show that PAH is a prognostic marker for HCC and Cdh1 could be a potential therapeutic target to regulate PAH-mediated physiological and metabolic disorders.
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Affiliation(s)
- Apoorvi Tyagi
- Department of Biomedical Science, Graduate School of Biomedical Science and Engineering, Hanyang University, Seoul 04763, Korea; (A.T.); (N.S.); (K.K.); (A.P.C.); (A.M.A.); ( (B.S.); (B.H.R.)
| | - Neha Sarodaya
- Department of Biomedical Science, Graduate School of Biomedical Science and Engineering, Hanyang University, Seoul 04763, Korea; (A.T.); (N.S.); (K.K.); (A.P.C.); (A.M.A.); ( (B.S.); (B.H.R.)
| | - Kamini Kaushal
- Department of Biomedical Science, Graduate School of Biomedical Science and Engineering, Hanyang University, Seoul 04763, Korea; (A.T.); (N.S.); (K.K.); (A.P.C.); (A.M.A.); ( (B.S.); (B.H.R.)
| | - Arun Pandian Chandrasekaran
- Department of Biomedical Science, Graduate School of Biomedical Science and Engineering, Hanyang University, Seoul 04763, Korea; (A.T.); (N.S.); (K.K.); (A.P.C.); (A.M.A.); ( (B.S.); (B.H.R.)
| | - Ainsley Mike Antao
- Department of Biomedical Science, Graduate School of Biomedical Science and Engineering, Hanyang University, Seoul 04763, Korea; (A.T.); (N.S.); (K.K.); (A.P.C.); (A.M.A.); ( (B.S.); (B.H.R.)
| | - Bharathi Suresh
- Department of Biomedical Science, Graduate School of Biomedical Science and Engineering, Hanyang University, Seoul 04763, Korea; (A.T.); (N.S.); (K.K.); (A.P.C.); (A.M.A.); ( (B.S.); (B.H.R.)
| | - Byung Ho Rhie
- Department of Biomedical Science, Graduate School of Biomedical Science and Engineering, Hanyang University, Seoul 04763, Korea; (A.T.); (N.S.); (K.K.); (A.P.C.); (A.M.A.); ( (B.S.); (B.H.R.)
| | - Kye Seong Kim
- Department of Biomedical Science, Graduate School of Biomedical Science and Engineering, Hanyang University, Seoul 04763, Korea; (A.T.); (N.S.); (K.K.); (A.P.C.); (A.M.A.); ( (B.S.); (B.H.R.)
- College of Medicine, Hanyang University, Seoul 04763, Korea
| | - Suresh Ramakrishna
- Department of Biomedical Science, Graduate School of Biomedical Science and Engineering, Hanyang University, Seoul 04763, Korea; (A.T.); (N.S.); (K.K.); (A.P.C.); (A.M.A.); ( (B.S.); (B.H.R.)
- College of Medicine, Hanyang University, Seoul 04763, Korea
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19
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Sarodaya N, Suresh B, Kim KS, Ramakrishna S. Protein Degradation and the Pathologic Basis of Phenylketonuria and Hereditary Tyrosinemia. Int J Mol Sci 2020; 21:ijms21144996. [PMID: 32679806 PMCID: PMC7404301 DOI: 10.3390/ijms21144996] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 07/10/2020] [Accepted: 07/13/2020] [Indexed: 12/15/2022] Open
Abstract
A delicate intracellular balance among protein synthesis, folding, and degradation is essential to maintaining protein homeostasis or proteostasis, and it is challenged by genetic and environmental factors. Molecular chaperones and the ubiquitin proteasome system (UPS) play a vital role in proteostasis for normal cellular function. As part of protein quality control, molecular chaperones recognize misfolded proteins and assist in their refolding. Proteins that are beyond repair or refolding undergo degradation, which is largely mediated by the UPS. The importance of protein quality control is becoming ever clearer, but it can also be a disease-causing mechanism. Diseases such as phenylketonuria (PKU) and hereditary tyrosinemia-I (HT1) are caused due to mutations in PAH and FAH gene, resulting in reduced protein stability, misfolding, accelerated degradation, and deficiency in functional proteins. Misfolded or partially unfolded proteins do not necessarily lose their functional activity completely. Thus, partially functional proteins can be rescued from degradation by molecular chaperones and deubiquitinating enzymes (DUBs). Deubiquitination is an important mechanism of the UPS that can reverse the degradation of a substrate protein by covalently removing its attached ubiquitin molecule. In this review, we discuss the importance of molecular chaperones and DUBs in reducing the severity of PKU and HT1 by stabilizing and rescuing mutant proteins.
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Affiliation(s)
- Neha Sarodaya
- Graduate School of Biomedical Science and Engineering, Hanyang University, Seoul 04763, Korea; (N.S.); (B.S.)
| | - Bharathi Suresh
- Graduate School of Biomedical Science and Engineering, Hanyang University, Seoul 04763, Korea; (N.S.); (B.S.)
| | - Kye-Seong Kim
- Graduate School of Biomedical Science and Engineering, Hanyang University, Seoul 04763, Korea; (N.S.); (B.S.)
- College of Medicine, Hanyang University, Seoul 04763, Korea
- Correspondence: (K.-S.K.); or (S.R.)
| | - Suresh Ramakrishna
- Graduate School of Biomedical Science and Engineering, Hanyang University, Seoul 04763, Korea; (N.S.); (B.S.)
- College of Medicine, Hanyang University, Seoul 04763, Korea
- Correspondence: (K.-S.K.); or (S.R.)
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20
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Tran ML, Génisson Y, Ballereau S, Dehoux C. Second-Generation Pharmacological Chaperones: Beyond Inhibitors. Molecules 2020; 25:molecules25143145. [PMID: 32660097 PMCID: PMC7397201 DOI: 10.3390/molecules25143145] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 06/29/2020] [Accepted: 07/05/2020] [Indexed: 02/06/2023] Open
Abstract
Protein misfolding induced by missense mutations is the source of hundreds of conformational diseases. The cell quality control may eliminate nascent misfolded proteins, such as enzymes, and a pathological loss-of-function may result from their early degradation. Since the proof of concept in the 2000s, the bioinspired pharmacological chaperone therapy became a relevant low-molecular-weight compound strategy against conformational diseases. The first-generation pharmacological chaperones were competitive inhibitors of mutant enzymes. Counterintuitively, in binding to the active site, these inhibitors stabilize the proper folding of the mutated protein and partially rescue its cellular function. The main limitation of the first-generation pharmacological chaperones lies in the balance between enzyme activity enhancement and inhibition. Recent research efforts were directed towards the development of promising second-generation pharmacological chaperones. These non-inhibitory ligands, targeting previously unknown binding pockets, limit the risk of adverse enzymatic inhibition. Their pharmacophore identification is however challenging and likely requires a massive screening-based approach. This review focuses on second-generation chaperones designed to restore the cellular activity of misfolded enzymes. It intends to highlight, for a selected set of rare inherited metabolic disorders, the strategies implemented to identify and develop these pharmacologically relevant small organic molecules as potential drug candidates.
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Affiliation(s)
| | | | | | - Cécile Dehoux
- Correspondence: (S.B.); (C.D.); Tel.: +33-5-6155-6127 (C.D.)
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21
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Tomé CS, Lopes RR, Sousa PMF, Amaro MP, Leandro J, Mertens HDT, Leandro P, Vicente JB. Structure of full-length wild-type human phenylalanine hydroxylase by small angle X-ray scattering reveals substrate-induced conformational stability. Sci Rep 2019; 9:13615. [PMID: 31541188 PMCID: PMC6754429 DOI: 10.1038/s41598-019-49944-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Accepted: 09/03/2019] [Indexed: 01/30/2023] Open
Abstract
Human phenylalanine hydroxylase (hPAH) hydroxylates L-phenylalanine (L-Phe) to L-tyrosine, a precursor for neurotransmitter biosynthesis. Phenylketonuria (PKU), caused by mutations in PAH that impair PAH function, leads to neurological impairment when untreated. Understanding the hPAH structural and regulatory properties is essential to outline PKU pathophysiological mechanisms. Each hPAH monomer comprises an N-terminal regulatory, a central catalytic and a C-terminal oligomerisation domain. To maintain physiological L-Phe levels, hPAH employs complex regulatory mechanisms. Resting PAH adopts an auto-inhibited conformation where regulatory domains block access to the active site. L-Phe-mediated allosteric activation induces a repositioning of the regulatory domains. Since a structure of activated wild-type hPAH is lacking, we addressed hPAH L-Phe-mediated conformational changes and report the first solution structure of the allosterically activated state. Our solution structures obtained by small-angle X-ray scattering support a tetramer with distorted P222 symmetry, where catalytic and oligomerisation domains form a core from which regulatory domains protrude, positioning themselves close to the active site entrance in the absence of L-Phe. Binding of L-Phe induces a large movement and dimerisation of regulatory domains, exposing the active site. Activated hPAH is more resistant to proteolytic cleavage and thermal denaturation, suggesting that the association of regulatory domains stabilises hPAH.
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Affiliation(s)
- Catarina S Tomé
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
- Instituto de Biologia Experimental e Tecnológica, Oeiras, Portugal
| | - Raquel R Lopes
- Research Institute for Medicines (iMed.ULisboa) and Department of Biochemistry and Human Biology, Faculty of Pharmacy, Universidade de Lisboa, Lisbon, Portugal
| | - Pedro M F Sousa
- Instituto de Biologia Experimental e Tecnológica, Oeiras, Portugal
| | - Mariana P Amaro
- Research Institute for Medicines (iMed.ULisboa) and Department of Biochemistry and Human Biology, Faculty of Pharmacy, Universidade de Lisboa, Lisbon, Portugal
- Department of Genetics and Genomic Sciences and Icahn Institute for Data Science and Genomic Technology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - João Leandro
- Research Institute for Medicines (iMed.ULisboa) and Department of Biochemistry and Human Biology, Faculty of Pharmacy, Universidade de Lisboa, Lisbon, Portugal
- Department of Genetics and Genomic Sciences and Icahn Institute for Data Science and Genomic Technology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | | | - Paula Leandro
- Research Institute for Medicines (iMed.ULisboa) and Department of Biochemistry and Human Biology, Faculty of Pharmacy, Universidade de Lisboa, Lisbon, Portugal.
| | - João B Vicente
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal.
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22
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Arturo EC, Gupta K, Hansen MR, Borne E, Jaffe EK. Biophysical characterization of full-length human phenylalanine hydroxylase provides a deeper understanding of its quaternary structure equilibrium. J Biol Chem 2019; 294:10131-10145. [PMID: 31076506 PMCID: PMC6664189 DOI: 10.1074/jbc.ra119.008294] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Revised: 05/09/2019] [Indexed: 11/06/2022] Open
Abstract
Dysfunction of human phenylalanine hydroxylase (hPAH, EC 1.14.16.1) is the primary cause of phenylketonuria, the most common inborn error of amino acid metabolism. The dynamic domain rearrangements of this multimeric protein have thwarted structural study of the full-length form for decades, until now. In this study, a tractable C29S variant of hPAH (C29S) yielded a 3.06 Å resolution crystal structure of the tetrameric resting-state conformation. We used size-exclusion chromatography in line with small-angle X-ray scattering (SEC-SAXS) to analyze the full-length hPAH solution structure both in the presence and absence of Phe, which serves as both substrate and allosteric activators. Allosteric Phe binding favors accumulation of an activated PAH tetramer conformation, which is biophysically distinct in solution. Protein characterization with enzyme kinetics and intrinsic fluorescence revealed that the C29S variant and hPAH are otherwise equivalent in their response to Phe, further supported by their behavior on various chromatography resins and by analytical ultracentrifugation. Modeling of resting-state and activated forms of C29S against SAXS data with available structural data created and evaluated several new models for the transition between the architecturally distinct conformations of PAH and highlighted unique intra- and inter-subunit interactions. Three best-fitting alternative models all placed the allosteric Phe-binding module 8-10 Å farther from the tetramer center than do all previous models. The structural insights into allosteric activation of hPAH reported here may help inform ongoing efforts to treat phenylketonuria with novel therapeutic approaches.
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Affiliation(s)
- Emilia C Arturo
- From the Molecular Therapeutics Program, Fox Chase Cancer Center, Temple University Health Systems, Philadelphia, Pennsylvania 19111
- the Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102, and
| | - Kushol Gupta
- the Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Michael R Hansen
- From the Molecular Therapeutics Program, Fox Chase Cancer Center, Temple University Health Systems, Philadelphia, Pennsylvania 19111
| | - Elias Borne
- From the Molecular Therapeutics Program, Fox Chase Cancer Center, Temple University Health Systems, Philadelphia, Pennsylvania 19111
| | - Eileen K Jaffe
- From the Molecular Therapeutics Program, Fox Chase Cancer Center, Temple University Health Systems, Philadelphia, Pennsylvania 19111,
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23
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Pecimonova M, Kluckova D, Csicsay F, Reblova K, Krahulec J, Procházkova D, Skultety L, Kadasi L, Soltysova A. Structural and Functional Impact of Seven Missense Variants of Phenylalanine Hydroxylase. Genes (Basel) 2019; 10:E459. [PMID: 31208052 PMCID: PMC6628251 DOI: 10.3390/genes10060459] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2019] [Revised: 06/12/2019] [Accepted: 06/13/2019] [Indexed: 11/17/2022] Open
Abstract
The molecular genetics of well-characterized inherited diseases, such as phenylketonuria (PKU) and hyperphenylalaninemia (HPA) predominantly caused by mutations in the phenylalanine hydroxylase (PAH) gene, is often complicated by the identification of many novel variants, often with no obvious impact on the associated disorder. To date, more than 1100 PAH variants have been identified of which a substantial portion have unknown clinical significance. In this work, we study the functionality of seven yet uncharacterized PAH missense variants p.Asn167Tyr, p.Thr200Asn, p.Asp229Gly, p.Gly239Ala, p.Phe263Ser, p.Ala342Pro, and p.Ile406Met first identified in the Czech PKU/HPA patients. From all tested variants, three of them, namely p.Asn167Tyr, p.Thr200Asn, and p.Ile406Met, exerted residual enzymatic activity in vitro similar to wild type (WT) PAH, however, when expressed in HepG2 cells, their protein level reached a maximum of 72.1% ± 4.9%, 11.2% ± 4.2%, and 36.6% ± 7.3% compared to WT PAH, respectively. Remaining variants were null with no enzyme activity and decreased protein levels in HepG2 cells. The chaperone-like effect of applied BH4 precursor increased protein level significantly for p.Asn167Tyr, p.Asp229Gly, p.Ala342Pro, and p.Ile406Met. Taken together, our results of functional characterization in combination with in silico prediction suggest that while p.Asn167Tyr, p.Thr200Asn, and p.Ile406Met PAH variants have a mild impact on the protein, p.Asp229Gly, p.Gly239Ala, p.Phe263Ser, and p.Ala342Pro severely affect protein structure and function.
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Affiliation(s)
- Martina Pecimonova
- Department of Molecular Biology, Faculty of Natural Sciences, Comenius University, Ilkovicova 6, 842 15 Bratislava, Slovakia.
| | - Daniela Kluckova
- Department of Molecular Biology, Faculty of Natural Sciences, Comenius University, Ilkovicova 6, 842 15 Bratislava, Slovakia.
| | - Frantisek Csicsay
- Insitute of Virology, Biomedical Research Center, Slovak Academy of Sciences, Dubravska cesta 9, 845 05 Bratislava, Slovakia.
| | - Kamila Reblova
- Central European Institute of Technology, Masaryk University, 625 00 Brno, Czech Republic.
| | - Jan Krahulec
- Department of Molecular Biology, Faculty of Natural Sciences, Comenius University, Ilkovicova 6, 842 15 Bratislava, Slovakia.
| | - Dagmar Procházkova
- Department of Pediatrics, Medical Faculty of Masaryk University and University Hospital Brno, Černopolní 9, 625 00 Brno, Czech Republic.
| | - Ludovit Skultety
- Insitute of Virology, Biomedical Research Center, Slovak Academy of Sciences, Dubravska cesta 9, 845 05 Bratislava, Slovakia.
| | - Ludevit Kadasi
- Department of Molecular Biology, Faculty of Natural Sciences, Comenius University, Ilkovicova 6, 842 15 Bratislava, Slovakia.
- Institute for Clinical and Translational Research, Biomedical Research Center, Slovak Academy of Sciences, Dubravska cesta 9, 845 05 Bratislava, Slovakia.
| | - Andrea Soltysova
- Department of Molecular Biology, Faculty of Natural Sciences, Comenius University, Ilkovicova 6, 842 15 Bratislava, Slovakia.
- Institute for Clinical and Translational Research, Biomedical Research Center, Slovak Academy of Sciences, Dubravska cesta 9, 845 05 Bratislava, Slovakia.
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24
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Flydal MI, Alcorlo-Pagés M, Johannessen FG, Martínez-Caballero S, Skjærven L, Fernandez-Leiro R, Martinez A, Hermoso JA. Structure of full-length human phenylalanine hydroxylase in complex with tetrahydrobiopterin. Proc Natl Acad Sci U S A 2019; 116:11229-11234. [PMID: 31118288 PMCID: PMC6561269 DOI: 10.1073/pnas.1902639116] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Phenylalanine hydroxylase (PAH) is a key enzyme in the catabolism of phenylalanine, and mutations in this enzyme cause phenylketonuria (PKU), a genetic disorder that leads to brain damage and mental retardation if untreated. Some patients benefit from supplementation with a synthetic formulation of the cofactor tetrahydrobiopterin (BH4) that partly acts as a pharmacological chaperone. Here we present structures of full-length human PAH (hPAH) both unbound and complexed with BH4 in the precatalytic state. Crystal structures, solved at 3.18-Å resolution, show the interactions between the cofactor and PAH, explaining the negative regulation exerted by BH4 BH4 forms several H-bonds with the N-terminal autoregulatory tail but is far from the catalytic FeII Upon BH4 binding a polar and salt-bridge interaction network links the three PAH domains, explaining the stability conferred by BH4 Importantly, BH4 binding modulates the interaction between subunits, providing information about PAH allostery. Moreover, we also show that the cryo-EM structure of hPAH in absence of BH4 reveals a highly dynamic conformation for the tetramers. Structural analyses of the hPAH:BH4 subunits revealed that the substrate-induced movement of Tyr138 into the active site could be coupled to the displacement of BH4 from the precatalytic toward the active conformation, a molecular mechanism that was supported by site-directed mutagenesis and targeted molecular dynamics simulations. Finally, comparison of the rat and human PAH structures show that hPAH is more dynamic, which is related to amino acid substitutions that enhance the flexibility of hPAH and may increase the susceptibility to PKU-associated mutations.
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Affiliation(s)
| | - Martín Alcorlo-Pagés
- Department of Crystallography and Structural Biology, Instituto de Química-Física "Rocasolano," Consejo Superior de Investigaciones Científicas (CSIC), 28006 Madrid, Spain
| | | | | | - Lars Skjærven
- Department of Biomedicine, University of Bergen, 5009 Bergen, Norway
| | - Rafael Fernandez-Leiro
- Structural Biology Programme, Spanish National Cancer Research Centre (CNIO), 28029 Madrid, Spain
| | - Aurora Martinez
- Department of Biomedicine, University of Bergen, 5009 Bergen, Norway;
| | - Juan A Hermoso
- Department of Crystallography and Structural Biology, Instituto de Química-Física "Rocasolano," Consejo Superior de Investigaciones Científicas (CSIC), 28006 Madrid, Spain;
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25
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Scheller R, Stein A, Nielsen SV, Marin FI, Gerdes AM, Di Marco M, Papaleo E, Lindorff-Larsen K, Hartmann-Petersen R. Toward mechanistic models for genotype-phenotype correlations in phenylketonuria using protein stability calculations. Hum Mutat 2019; 40:444-457. [PMID: 30648773 DOI: 10.1002/humu.23707] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Revised: 12/18/2018] [Accepted: 01/13/2019] [Indexed: 01/22/2023]
Abstract
Phenylketonuria (PKU) is a genetic disorder caused by variants in the gene encoding phenylalanine hydroxylase (PAH), resulting in accumulation of phenylalanine to neurotoxic levels. Here, we analyzed the cellular stability, localization, and interaction with wild-type PAH of 20 selected PKU-linked PAH protein missense variants. Several were present at reduced levels in human cells, and the levels increased in the presence of a proteasome inhibitor, indicating that proteins are proteasome targets. We found that all the tested PAH variants retained their ability to associate with wild-type PAH, and none formed aggregates, suggesting that they are only mildly destabilized in structure. In all cases, PAH variants were stabilized by the cofactor tetrahydrobiopterin (BH4 ), a molecule known to alleviate symptoms in certain PKU patients. Biophysical calculations on all possible single-site missense variants using the full-length structure of PAH revealed a strong correlation between the predicted protein stability and the observed stability in cells. This observation rationalizes previously observed correlations between predicted loss of protein destabilization and disease severity, a correlation that we also observed using new calculations. We thus propose that many disease-linked PAH variants are structurally destabilized, which in turn leads to proteasomal degradation and insufficient amounts of cellular PAH protein.
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Affiliation(s)
- Rasmus Scheller
- The Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Amelie Stein
- The Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Sofie V Nielsen
- The Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Frederikke I Marin
- The Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Anne-Marie Gerdes
- Department of Clinical Genetics, Rigshospitalet, Copenhagen, Denmark
| | - Miriam Di Marco
- Computational Biology Laboratory, Danish Cancer Society Research Center, Copenhagen, Denmark
| | - Elena Papaleo
- Computational Biology Laboratory, Danish Cancer Society Research Center, Copenhagen, Denmark
| | - Kresten Lindorff-Larsen
- The Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Rasmus Hartmann-Petersen
- The Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark
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26
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Khan CA, Meisburger SP, Ando N, Fitzpatrick PF. The phenylketonuria-associated substitution R68S converts phenylalanine hydroxylase to a constitutively active enzyme but reduces its stability. J Biol Chem 2019; 294:4359-4367. [PMID: 30674554 DOI: 10.1074/jbc.ra118.006477] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Revised: 01/15/2019] [Indexed: 11/06/2022] Open
Abstract
The naturally occurring R68S substitution of phenylalanine hydroxylase (PheH) causes phenylketonuria (PKU). However, the molecular basis for how the R68S variant leads to PKU remains unclear. Kinetic characterization of R68S PheH establishes that the enzyme is fully active in the absence of allosteric binding of phenylalanine, in contrast to the WT enzyme. Analytical ultracentrifugation establishes that the isolated regulatory domain of R68S PheH is predominantly monomeric in the absence of phenylalanine and dimerizes in its presence, similar to the regulatory domain of the WT enzyme. Fluorescence and small-angle X-ray scattering analyses establish that the overall conformation of the resting form of R68S PheH is different from that of the WT enzyme. The data are consistent with the substitution disrupting the interface between the catalytic and regulatory domains of the enzyme, shifting the equilibrium between the resting and activated forms ∼200-fold, so that the resting form of R68S PheH is ∼70% in the activated conformation. However, R68S PheH loses activity 2 orders of magnitude more rapidly than the WT enzyme at 37 °C and is significantly more sensitive to proteolysis. We propose that, even though this substitution converts the enzyme to a constitutively active enzyme, it results in PKU because of the decrease in protein stability.
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Affiliation(s)
- Crystal A Khan
- From the Department of Biochemistry and Structural Biology, UT Health San Antonio, San Antonio, Texas 78229 and
| | - Steve P Meisburger
- the Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853
| | - Nozomi Ando
- the Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853
| | - Paul F Fitzpatrick
- From the Department of Biochemistry and Structural Biology, UT Health San Antonio, San Antonio, Texas 78229 and
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27
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Szigetvari PD, Muruganandam G, Kallio JP, Hallin EI, Fossbakk A, Loris R, Kursula I, Møller LB, Knappskog PM, Kursula P, Haavik J. The quaternary structure of human tyrosine hydroxylase: effects of dystonia-associated missense variants on oligomeric state and enzyme activity. J Neurochem 2018; 148:291-306. [PMID: 30411798 PMCID: PMC6587854 DOI: 10.1111/jnc.14624] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Revised: 10/26/2018] [Accepted: 10/31/2018] [Indexed: 01/27/2023]
Abstract
Abstract Tyrosine hydroxylase (TH) is a multi‐domain, homo‐oligomeric enzyme that catalyses the rate‐limiting step of catecholamine neurotransmitter biosynthesis. Missense variants of human TH are associated with a recessive neurometabolic disease with low levels of brain dopamine and noradrenaline, resulting in a variable clinical picture, from progressive brain encephalopathy to adolescent onset DOPA‐responsive dystonia (DRD). We expressed isoform 1 of human TH (hTH1) and its dystonia‐associated missense variants in E. coli, analysed their quaternary structure and thermal stability using size‐exclusion chromatography, circular dichroism, multi‐angle light scattering, transmission electron microscopy, small‐angle X‐ray scattering and assayed hydroxylase activity. Wild‐type (WT) hTH1 was a mixture of enzymatically stable tetramers (85.6%) and octamers (14.4%), with little interconversion between these species. We also observed small amounts of higher order assemblies of long chains of enzyme by transmission electron microscopy. To investigate the role of molecular assemblies in the pathogenesis of DRD, we compared the structure of WT hTH1 with the DRD‐associated variants R410P and D467G that are found in vicinity of the predicted subunit interfaces. In contrast to WT hTH1, R410P and D467G were mixtures of tetrameric and dimeric species. Inspection of the available structures revealed that Arg‐410 and Asp‐467 are important for maintaining the stability and oligomeric structure of TH. Disruption of the normal quaternary enzyme structure by missense variants is a new molecular mechanism that may explain the loss of TH enzymatic activity in DRD. Unstable missense variants could be targets for pharmacological intervention in DRD, aimed to re‐establish the normal oligomeric state of TH. ![]()
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Affiliation(s)
- Peter D Szigetvari
- Department of Biomedicine, University of Bergen, Bergen, Norway.,K.G. Jebsen Centre for Research on Neuropsychiatric Disorders, University of Bergen, Bergen, Norway
| | - Gopinath Muruganandam
- VIB-VUB Center for Structural Biology, Vlaams Instituut voor Biotechnologie, Brussels, Belgium.,Structural Biology Brussels, Department of Bioengineering Sciences, Vrije Universiteit Brussel, Brussels, Belgium
| | - Juha P Kallio
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | - Erik I Hallin
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | - Agnete Fossbakk
- K.G. Jebsen Centre for Research on Neuropsychiatric Disorders, University of Bergen, Bergen, Norway
| | - Remy Loris
- VIB-VUB Center for Structural Biology, Vlaams Instituut voor Biotechnologie, Brussels, Belgium.,Structural Biology Brussels, Department of Bioengineering Sciences, Vrije Universiteit Brussel, Brussels, Belgium
| | - Inari Kursula
- Department of Biomedicine, University of Bergen, Bergen, Norway.,Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland.,Biocenter Oulu, University of Oulu, Oulu, Finland
| | - Lisbeth B Møller
- Applied Human Molecular Genetics, Kennedy Center, Department of Clinical Genetics, Copenhagen University Hospital, Rigshospitalet, Glostrup, Denmark
| | - Per M Knappskog
- K.G. Jebsen Centre for Research on Neuropsychiatric Disorders, University of Bergen, Bergen, Norway.,Department of Clinical Science, University of Bergen, Bergen, Norway.,Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway
| | - Petri Kursula
- Department of Biomedicine, University of Bergen, Bergen, Norway.,Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
| | - Jan Haavik
- Department of Biomedicine, University of Bergen, Bergen, Norway.,K.G. Jebsen Centre for Research on Neuropsychiatric Disorders, University of Bergen, Bergen, Norway.,Division of Psychiatry, Haukeland University Hospital, Bergen, Norway
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28
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Mutational and phenotypic spectrum of phenylalanine hydroxylase deficiency in Zhejiang Province, China. Sci Rep 2018; 8:17137. [PMID: 30459323 PMCID: PMC6244417 DOI: 10.1038/s41598-018-35373-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Accepted: 11/05/2018] [Indexed: 11/15/2022] Open
Abstract
Phenylalanine hydroxylase deficiency (PAHD), one of the genetic disorders resulting in hyperphenylalaninemia, has a complex phenotype with many variants and genotypes among different populations. Here, we describe the mutational and phenotypic spectrum of PAHD in a cohort of 420 patients from neonatal screening between 1999 and 2016. The observed phenotypes comprised 43.57% classic phenylketonuria, 33.10% mild PKU, and 23.33% mild hyperphenylalaninemia, with an overall PAHD incidence of 1 in 20,445. Genetic testing was performed for 209 patients and 72 variants including seven novel variants were identified. These included two synonymous and five pathogenic nonsynonymous variants (p.S36*, p.T186I, p.L255W, p.F302V and p.R413H). The most common variant among all patients was p.R243Q, followed by p.R241C, p.Y204C, p.R111* and c.442-1G > A. Variants p.R53H and p.F392I occurred only in MHP with 19.3% and 8.0% of the observed alleles respectively. The genotypes p.[R241C];[R243Q], p.[R243Q];[R243Q], and p.[Y204C];[R243Q] were abundant across all PAHD patients. The distributions of the null allele and the three defined genotypes, null/null, null/missense, and missense/missense, were significantly different between the cPKU and mPKU patients. However, no significant differences were found between mPKU and MHP patients, indicating that other modifier factors influence the phenotypic outcome in these patients. The data presented here will provide a valuable tool for improved genetic counseling and management of future cases of PAHD in China.
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29
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Khan CA, Fitzpatrick PF. Phosphorylation of Phenylalanine Hydroxylase Increases the Rate Constant for Formation of the Activated Conformation of the Enzyme. Biochemistry 2018; 57:6274-6277. [PMID: 30346142 DOI: 10.1021/acs.biochem.8b00919] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Liver phenylalanine hydroxylase (PheH) is an allosteric enzyme that is activated by phenylalanine. The enzyme is also phosphorylated by protein kinase A, but the effects of phosphorylation are unclear. Recent structural studies ( Meisburger et al. ( 2016 ) J. Amer. Chem. Soc. 138 , 6506 - 6516 ) support a model in which activation of the enzyme involves dimerization of the regulatory domains, creating the allosteric site for phenylalanine at the dimer interface. This conformational change also results in a change in the fluorescence of the protein that can be used to monitor activation. The kinetics of activation of PheH are biphasic over a range of phenylalanine concentrations. These data are well-described by a model involving an initial equilibrium between the resting form and the activated conformation, with a value of the equilibrium constant for formation of the activated conformation, L, equal to 0.007, followed by binding of two molecules of phenylalanine. Phosphorylation increases L 10-fold by increasing the rate constant for conversion of the resting form to the activated form. The results provide functional support for the previous structural model, identify the specific effect of phosphorylation on the enzyme, and rationalize the lack of change in the protein structure upon phosphorylation.
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Affiliation(s)
- Crystal A Khan
- Department of Biochemistry and Structural Biology , University of Texas Health Science Center , San Antonio , Texas 78229 , United States
| | - Paul F Fitzpatrick
- Department of Biochemistry and Structural Biology , University of Texas Health Science Center , San Antonio , Texas 78229 , United States
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30
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Ge Y, Borne E, Stewart S, Hansen MR, Arturo EC, Jaffe EK, Voelz VA. Simulations of the regulatory ACT domain of human phenylalanine hydroxylase (PAH) unveil its mechanism of phenylalanine binding. J Biol Chem 2018; 293:19532-19543. [PMID: 30287685 DOI: 10.1074/jbc.ra118.004909] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Revised: 09/17/2018] [Indexed: 12/20/2022] Open
Abstract
Phenylalanine hydroxylase (PAH) regulates phenylalanine (Phe) levels in mammals to prevent neurotoxicity resulting from high Phe concentrations as observed in genetic disorders leading to hyperphenylalaninemia and phenylketonuria. PAH senses elevated Phe concentrations by transient allosteric Phe binding to a protein-protein interface between ACT domains of different subunits in a PAH tetramer. This interface is present in an activated PAH (A-PAH) tetramer and absent in a resting-state PAH (RS-PAH) tetramer. To investigate this allosteric sensing mechanism, here we used the GROMACS molecular dynamics simulation suite on the Folding@home computing platform to perform extensive molecular simulations and Markov state model (MSM) analysis of Phe binding to ACT domain dimers. These simulations strongly implicated a conformational selection mechanism for Phe association with ACT domain dimers and revealed protein motions that act as a gating mechanism for Phe binding. The MSMs also illuminate a highly mobile hairpin loop, consistent with experimental findings also presented here that the PAH variant L72W does not shift the PAH structural equilibrium toward the activated state. Finally, simulations of ACT domain monomers are presented, in which spontaneous transitions between resting-state and activated conformations are observed, also consistent with a mechanism of conformational selection. These mechanistic details provide detailed insight into the regulation of PAH activation and provide testable hypotheses for the development of new allosteric effectors to correct structural and functional defects in PAH.
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Affiliation(s)
- Yunhui Ge
- From the Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122
| | - Elias Borne
- Fox Chase Cancer Center, Temple University Health System, Philadelphia, Pennsylvania 19111, and
| | - Shannon Stewart
- Fox Chase Cancer Center, Temple University Health System, Philadelphia, Pennsylvania 19111, and
| | - Michael R Hansen
- Fox Chase Cancer Center, Temple University Health System, Philadelphia, Pennsylvania 19111, and
| | - Emilia C Arturo
- Fox Chase Cancer Center, Temple University Health System, Philadelphia, Pennsylvania 19111, and.,Drexel University College of Medicine, Philadelphia, Pennsylvania 19129
| | - Eileen K Jaffe
- Fox Chase Cancer Center, Temple University Health System, Philadelphia, Pennsylvania 19111, and
| | - Vincent A Voelz
- From the Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122,
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31
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CHEN T, ZHAO Z, JIANG P, SHU Q. [Research progress on phenotype and genotype of hyperphenylalaninemia]. Zhejiang Da Xue Xue Bao Yi Xue Ban 2018; 47:219-226. [PMID: 30226320 PMCID: PMC10393690 DOI: 10.3785/j.issn.1008-9292.2018.06.01] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Accepted: 04/24/2018] [Indexed: 06/08/2023]
Abstract
Hyperphenylalaninemia(HPA), an autosomal recessive disease, is the most common inborn error of amino acid metabolism, caused by the deficiency of phenylalanine hydroxylase(PAH) or tetrahydrobiopterin(BH4) which induced by mutations of genes. The accumulation of the clinical database and genetic information will enhance the development of novel personalized medicine and to provide more accurate and timely diagnostic and therapeutic approaches for HPA. This paper summarizes the correlations between HPA metabolism and PAH, BH4, pathogenic genes and their distributions in HPA, as well as the phenotypes and genotypes of HPA, so as to provide reference for personalized medicine for HPA.
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Affiliation(s)
| | | | | | - Qiang SHU
- 舒强(1965-), 男, 博士, 主任医师, 教授, 博士生导师, 主要从事出生缺陷综合防治研究; E-mail:
;
https://orcid.org/0000-0002-4106-6255
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32
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Jaffe EK. New protein structures provide an updated understanding of phenylketonuria. Mol Genet Metab 2017; 121:289-296. [PMID: 28645531 PMCID: PMC5549558 DOI: 10.1016/j.ymgme.2017.06.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Accepted: 06/08/2017] [Indexed: 11/16/2022]
Abstract
Phenylketonuria (PKU) and less severe hyperphenylalaninemia (HPA) constitute the most common inborn error of amino acid metabolism, and is most often caused by defects in phenylalanine hydroxylase (PAH) function resulting in accumulation of Phe to neurotoxic levels. Despite the success of dietary intervention in preventing permanent neurological damage, individuals living with PKU clamor for additional non-dietary therapies. The bulk of disease-associated mutations are PAH missense variants, which occur throughout the entire 452 amino acid human PAH protein. While some disease-associated mutations affect protein structure (e.g. truncations) and others encode catalytically dead variants, most have been viewed as defective in protein folding/stability. Here we refine this view to address how PKU-associated missense variants can perturb the equilibrium among alternate native PAH structures (resting-state PAH and activated PAH), thus shifting the tipping point of this equilibrium to a neurotoxic Phe concentration. This refined view of PKU introduces opportunities for the design or discovery of therapeutic pharmacological chaperones that can help restore the tipping point to healthy Phe levels and how such a therapeutic might work with or without the inhibitory pharmacological chaperone BH4. Dysregulation of an equilibrium of architecturally distinct native PAH structures departs from the concept of "misfolding", provides an updated understanding of PKU, and presents an enhanced foundation for understanding genotype/phenotype relationships.
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Affiliation(s)
- Eileen K Jaffe
- Fox Chase Cancer Center - Temple University Health System, 333 Cottman Ave, Philadelphia, PA 19111, USA.
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33
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Leandro J, Stokka AJ, Teigen K, Andersen OA, Flatmark T. Substituting Tyr 138 in the active site loop of human phenylalanine hydroxylase affects catalysis and substrate activation. FEBS Open Bio 2017; 7:1026-1036. [PMID: 28680815 PMCID: PMC5494296 DOI: 10.1002/2211-5463.12243] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Revised: 04/27/2017] [Accepted: 05/10/2017] [Indexed: 11/22/2022] Open
Abstract
Mammalian phenylalanine hydroxylase (PAH) is a key enzyme in l‐phenylalanine (l‐Phe) metabolism and is active as a homotetramer. Biochemical and biophysical work has demonstrated that it cycles between two states with a variably low and a high activity, and that the substrate l‐Phe is the key player in this transition. X‐ray structures of the catalytic domain have shown mobility of a partially intrinsically disordered Tyr138‐loop to the active site in the presence of l‐Phe. The mechanism by which the loop dynamics are coupled to substrate binding at the active site in tetrameric PAH is not fully understood. We have here conducted functional studies of four Tyr138 point mutants. A high linear correlation (r2 = 0.99) was observed between their effects on the catalytic efficiency of the catalytic domain dimers and the corresponding effect on the catalytic efficiency of substrate‐activated full‐length tetramers. In the tetramers, a correlation (r2 = 0.96) was also observed between the increase in catalytic efficiency (activation) and the global conformational change (surface plasmon resonance signal response) at the same l‐Phe concentration. The new data support a similar functional importance of the Tyr138‐loop in the catalytic domain and the full‐length enzyme homotetramer.
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Affiliation(s)
- João Leandro
- Department of Biomedicine University of Bergen Norway.,Metabolism and Genetics Group Research Institute for Medicines (iMed.ULisboa) Faculty of Pharmacy University of Lisbon Portugal.,Present address: Department of Genetics and Genomic Sciences Icahn School of Medicine at Mount Sinai 1425 Madison Avenue, Box 1498 New York NY 10029 USA
| | - Anne J Stokka
- Department of Biomedicine University of Bergen Norway.,The Biotechnology Centre of Oslo University of Oslo Norway
| | - Knut Teigen
- Department of Biomedicine University of Bergen Norway
| | - Ole A Andersen
- Department of Biomedicine University of Bergen Norway.,Evotec (UK) Ltd .Abingdon UK
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34
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Abstract
X-ray scattering is uniquely suited to the study of disordered systems and thus has the potential to provide insight into dynamic processes where diffraction methods fail. In particular, while X-ray crystallography has been a staple of structural biology for more than half a century and will continue to remain so, a major limitation of this technique has been the lack of dynamic information. Solution X-ray scattering has become an invaluable tool in structural and mechanistic studies of biological macromolecules where large conformational changes are involved. Such systems include allosteric enzymes that play key roles in directing metabolic fluxes of biochemical pathways, as well as large, assembly-line type enzymes that synthesize secondary metabolites with pharmaceutical applications. Furthermore, crystallography has the potential to provide information on protein dynamics via the diffuse scattering patterns that are overlaid with Bragg diffraction. Historically, these patterns have been very difficult to interpret, but recent advances in X-ray detection have led to a renewed interest in diffuse scattering analysis as a way to probe correlated motions. Here, we will review X-ray scattering theory and highlight recent advances in scattering-based investigations of protein solutions and crystals, with a particular focus on complex enzymes.
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Affiliation(s)
- Steve P Meisburger
- Department of Chemistry, Princeton University , Princeton, New Jersey 08544, United States
| | - William C Thomas
- Department of Chemistry, Princeton University , Princeton, New Jersey 08544, United States
| | - Maxwell B Watkins
- Department of Chemistry, Princeton University , Princeton, New Jersey 08544, United States
| | - Nozomi Ando
- Department of Chemistry, Princeton University , Princeton, New Jersey 08544, United States
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35
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Leandro J, Saraste J, Leandro P, Flatmark T. PKU mutation p.G46S prevents the stereospecific binding of l-phenylalanine to the dimer of human phenylalanine hydroxylase regulatory domain. FEBS Open Bio 2017; 7:195-203. [PMID: 28174686 PMCID: PMC5292662 DOI: 10.1002/2211-5463.12175] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Revised: 12/01/2016] [Accepted: 12/03/2016] [Indexed: 11/23/2022] Open
Abstract
Mammalian phenylalanine hydroxylase (PAH) has a potential allosteric regulatory binding site for l‐phenylalanine (l‐Phe), in addition to its catalytic site. This arrangement is supported by a crystal structure of a homodimeric truncated form of the regulatory domain of human PAH (hPAH‐RD1–118/19–118) [Patel D et al. (2016) Sci Rep doi: 10.1038/srep23748]. In this study, a fusion protein of the domain (MBP‐(pepXa)‐hPAH‐RD1–120) was overexpressed and recovered in a metastable and soluble state, which allowed the isolation of a dimeric and a monomeric fusion protein. When cleaved from MBP, hPAH‐RD forms aggregates which are stereospecifically inhibited by l‐Phe (> 95%) at low physiological concentrations. Aggregation of the cleaved dimer of the mutant form hPAH‐G46S‐RD was not inhibited by l‐Phe, which is compatible with structurally/conformationally changed βαββαβ ACT domain folds in the mutant.
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Affiliation(s)
- João Leandro
- Department of Biomedicine University of Bergen Norway; Metabolism and Genetics Group Research Institute for Medicines and Pharmaceutical Sciences (iMed.UL) Faculty of Pharmacy University of Lisbon Portugal
| | | | - Paula Leandro
- Metabolism and Genetics Group Research Institute for Medicines and Pharmaceutical Sciences (iMed.UL) Faculty of Pharmacy University of Lisbon Portugal
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36
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Waløen K, Kleppe R, Martinez A, Haavik J. Tyrosine and tryptophan hydroxylases as therapeutic targets in human disease. Expert Opin Ther Targets 2016; 21:167-180. [PMID: 27973928 DOI: 10.1080/14728222.2017.1272581] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
INTRODUCTION The ancient and ubiquitous monoamine signalling molecules serotonin, dopamine, norepinephrine, and epinephrine are involved in multiple physiological functions. The aromatic amino acid hydroxylases tyrosine hydroxylase (TH), tryptophan hydroxylase 1 (TPH1), and tryptophan hydroxylase 2 (TPH2) catalyse the rate-limiting steps in the biosynthesis of these monoamines. Genetic variants of TH, TPH1, and TPH2 genes are associated with neuropsychiatric disorders. The interest in these enzymes as therapeutic targets is increasing as new roles of these monoamines have been discovered, not only in brain function and disease, but also in development, cardiovascular function, energy and bone homeostasis, gastrointestinal motility, hemostasis, and liver function. Areas covered: Physiological roles of TH, TPH1, and TPH2. Enzyme structures, catalytic and regulatory mechanisms, animal models, and associated diseases. Interactions with inhibitors, pharmacological chaperones, and regulatory proteins relevant for drug development. Expert opinion: Established inhibitors of these enzymes mainly target their amino acid substrate binding site, while tetrahydrobiopterin analogues, iron chelators, and allosteric ligands are less studied. New insights into monoamine biology and 3D-structural information and new computational/experimental tools have triggered the development of a new generation of more selective inhibitors and pharmacological chaperones. The enzyme complexes with their regulatory 14-3-3 proteins are also emerging as therapeutic targets.
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Affiliation(s)
- Kai Waløen
- a Department of Biomedicine and K.G. Jebsen Centre for Neuropsychiatric Disorders , University of Bergen , Bergen , Norway
| | - Rune Kleppe
- b Computational Biology Unit, Department of Informatics , University of Bergen , Bergen , Norway
| | - Aurora Martinez
- a Department of Biomedicine and K.G. Jebsen Centre for Neuropsychiatric Disorders , University of Bergen , Bergen , Norway
| | - Jan Haavik
- a Department of Biomedicine and K.G. Jebsen Centre for Neuropsychiatric Disorders , University of Bergen , Bergen , Norway
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37
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Trunzo R, Santacroce R, Shen N, Jung-Klawitter S, Leccese A, De Girolamo G, Margaglione M, Blau N. In vitro residual activity of phenylalanine hydroxylase variants and correlation with metabolic phenotypes in PKU. Gene 2016; 594:138-143. [PMID: 27620137 DOI: 10.1016/j.gene.2016.09.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 08/29/2016] [Accepted: 09/08/2016] [Indexed: 10/21/2022]
Abstract
Hyperphenylalaninemias (HPAs) are genetic diseases predominantly caused by a wide range of variants in the phenylalanine hydroxylase (PAH) gene. In vitro expression analysis of PAH variants offers the opportunity to elucidate the molecular mechanisms involved in HPAs and to clarify whether a disease-associated variant is genuinely pathogenic, while investigating the severity of a metabolic phenotype, and determining how a variant exerts its deleterious effects on the PAH enzyme. To study the effects of gene variants on PAH activity, we investigated eight variants: c.611A>G (p.Y204C), c.635T>C (p.L212P), c.746T>C (p.L249P), c.745C>T (p.L249F), c.809G>A (p.R270K), c.782G>C (p.R261P), c.587C>A (p.S196Y) and c.1139C>T (p.T380M), associated with different phenotypic groups. Transient expression of mutant full-length cDNAs in COS-7 cells yielded PAH proteins with PAH activity levels between 7% and 51% compared to the wild-type enzyme. With one exception (p.Y204C, which had no significant impact on PAH function), lower PAH activity was associated with a more severe phenotype (e.g. p.L249P with 7% PAH activity, 100% of classic PKU and no BH4 responsiveness), while higher activity correlated with milder phenotypes (e.g. p.T380M with 28% PAH activity, 97% of mild HPA and 83% of BH4 responsiveness). The results of the in vitro residual PAH activity have major implications, both for our understanding of genotype-phenotype correlations, and thereby existing inconsistencies, but also for the elucidation of the molecular basis of tetrahydrobiopterin (BH4) responsiveness.
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Affiliation(s)
- Roberta Trunzo
- Genetica Medica, Dipartimento di Medicina Clinica e Sperimentale, Università degli Studi di Foggia, Italy.
| | - Rosa Santacroce
- Genetica Medica, Dipartimento di Medicina Clinica e Sperimentale, Università degli Studi di Foggia, Italy
| | - Nan Shen
- Dietmar-Hopp Metabolic Center, University Children's Hospital, Department of General Pediatrics, Heidelberg, Germany
| | - Sabine Jung-Klawitter
- Dietmar-Hopp Metabolic Center, University Children's Hospital, Department of General Pediatrics, Heidelberg, Germany
| | - Angelica Leccese
- Genetica Medica, Dipartimento di Medicina Clinica e Sperimentale, Università degli Studi di Foggia, Italy
| | - Giuseppe De Girolamo
- Genetica Medica, Dipartimento di Medicina Clinica e Sperimentale, Università degli Studi di Foggia, Italy
| | - Maurizio Margaglione
- Genetica Medica, Dipartimento di Medicina Clinica e Sperimentale, Università degli Studi di Foggia, Italy
| | - Nenad Blau
- Dietmar-Hopp Metabolic Center, University Children's Hospital, Department of General Pediatrics, Heidelberg, Germany
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38
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Stable preparations of tyrosine hydroxylase provide the solution structure of the full-length enzyme. Sci Rep 2016; 6:30390. [PMID: 27462005 PMCID: PMC4961952 DOI: 10.1038/srep30390] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Accepted: 06/30/2016] [Indexed: 01/22/2023] Open
Abstract
Tyrosine hydroxylase (TH) catalyzes the rate-limiting step in the biosynthesis of catecholamine neurotransmitters. TH is a highly complex enzyme at mechanistic, structural, and regulatory levels, and the preparation of kinetically and conformationally stable enzyme for structural characterization has been challenging. Here, we report on improved protocols for purification of recombinant human TH isoform 1 (TH1), which provide large amounts of pure, stable, active TH1 with an intact N-terminus. TH1 purified through fusion with a His-tagged maltose-binding protein on amylose resin was representative of the iron-bound functional enzyme, showing high activity and stabilization by the natural feedback inhibitor dopamine. TH1 purified through fusion with a His-tagged ZZ domain on TALON is remarkably stable, as it was partially inhibited by resin-derived cobalt. This more stable enzyme preparation provided high-quality small-angle X-ray scattering (SAXS) data and reliable structural models of full-length tetrameric TH1. The SAXS-derived model reveals an elongated conformation (Dmax = 20 nm) for TH1, different arrangement of the catalytic domains compared with the crystal structure of truncated forms, and an N-terminal region with an unstructured tail that hosts the phosphorylation sites and a separated Ala-rich helical motif that may have a role in regulation of TH by interacting with binding partners.
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39
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Abstract
More than 950 phenylalanine hydroxylase (PAH) gene variants have been identified in people with phenylketonuria (PKU). These vary in their consequences for the residual level of PAH activity, from having little or no effect to abolishing PAH activity completely. Advances in genotyping technology and the availability of locus-specific and genotype databases have greatly expanded our understanding of the correlations between individual gene variant, residual PAH activity, tetrahydrobiopterin (BH4 ) responsiveness, and the clinical PKU phenotype. Most patients (∼76%) have compound heterozygous PAH gene variants and one mutated allele may markedly influence the activity of the second mutated allele, which in turn may influence either positively or negatively the activity of the biologically active heterotetrameric form of the PAH. While it is possible to predict the level of BH4 responsiveness (∼71%) and PKU severity (∼78%) from the nature of the underlying gene variants, these relationships remain complex and incompletely understood. A greater understanding of these relationships may increase the potential for individualized management of PKU in future. Inherited deficiencies in BH4 metabolism account for about 1%-2% of all hyperphenylalaninemias and are clinically more severe than PKU. Almost 90% of all patients are deficient in 6-pyruvoyl-tetrahydropterin synthase and dihydropteridine reductase.
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Affiliation(s)
- Nenad Blau
- Dietmar-Hopp-Metabolic Center, University Children's Hospital, Heidelberg, Germany
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40
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Meisburger SP, Taylor AB, Khan CA, Zhang S, Fitzpatrick PF, Ando N. Domain Movements upon Activation of Phenylalanine Hydroxylase Characterized by Crystallography and Chromatography-Coupled Small-Angle X-ray Scattering. J Am Chem Soc 2016; 138:6506-16. [PMID: 27145334 PMCID: PMC4896396 DOI: 10.1021/jacs.6b01563] [Citation(s) in RCA: 89] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Mammalian phenylalanine hydroxylase (PheH) is an allosteric enzyme that catalyzes the first step in the catabolism of the amino acid phenylalanine. Following allosteric activation by high phenylalanine levels, the enzyme catalyzes the pterin-dependent conversion of phenylalanine to tyrosine. Inability to control elevated phenylalanine levels in the blood leads to increased risk of mental disabilities commonly associated with the inherited metabolic disorder, phenylketonuria. Although extensively studied, structural changes associated with allosteric activation in mammalian PheH have been elusive. Here, we examine the complex allosteric mechanisms of rat PheH using X-ray crystallography, isothermal titration calorimetry (ITC), and small-angle X-ray scattering (SAXS). We describe crystal structures of the preactivated state of the PheH tetramer depicting the regulatory domains docked against the catalytic domains and preventing substrate binding. Using SAXS, we further describe the domain movements involved in allosteric activation of PheH in solution and present the first demonstration of chromatography-coupled SAXS with Evolving Factor Analysis (EFA), a powerful method for separating scattering components in a model-independent way. Together, these results support a model for allostery in PheH in which phenylalanine stabilizes the dimerization of the regulatory domains and exposes the active site for substrate binding and other structural changes needed for activity.
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Affiliation(s)
- Steve P. Meisburger
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA
| | - Alexander B. Taylor
- Department of Biochemistry, University of Texas Health Science Center, San Antonio, Texas 78229, USA
| | - Crystal A. Khan
- Department of Biochemistry, University of Texas Health Science Center, San Antonio, Texas 78229, USA
| | - Shengnan Zhang
- Department of Biochemistry, University of Texas Health Science Center, San Antonio, Texas 78229, USA
| | - Paul F. Fitzpatrick
- Department of Biochemistry, University of Texas Health Science Center, San Antonio, Texas 78229, USA
| | - Nozomi Ando
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA
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41
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Patel D, Kopec J, Fitzpatrick F, McCorvie TJ, Yue WW. Structural basis for ligand-dependent dimerization of phenylalanine hydroxylase regulatory domain. Sci Rep 2016; 6:23748. [PMID: 27049649 PMCID: PMC4822156 DOI: 10.1038/srep23748] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Accepted: 03/08/2016] [Indexed: 02/01/2023] Open
Abstract
The multi-domain enzyme phenylalanine hydroxylase (PAH) catalyzes the hydroxylation of dietary I-phenylalanine (Phe) to I-tyrosine. Inherited mutations that result in PAH enzyme deficiency are the genetic cause of the autosomal recessive disorder phenylketonuria. Phe is the substrate for the PAH active site, but also an allosteric ligand that increases enzyme activity. Phe has been proposed to bind, in addition to the catalytic domain, a site at the PAH N-terminal regulatory domain (PAH-RD), to activate the enzyme via an unclear mechanism. Here we report the crystal structure of human PAH-RD bound with Phe at 1.8 Å resolution, revealing a homodimer of ACT folds with Phe bound at the dimer interface. This work delivers the structural evidence to support previous solution studies that a binding site exists in the RD for Phe, and that Phe binding results in dimerization of PAH-RD. Consistent with our structural observation, a disease-associated PAH mutant impaired in Phe binding disrupts the monomer:dimer equilibrium of PAH-RD. Our data therefore support an emerging model of PAH allosteric regulation, whereby Phe binds to PAH-RD and mediates the dimerization of regulatory modules that would bring about conformational changes to activate the enzyme.
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Affiliation(s)
- Dipali Patel
- Structural Genomics Consortium, Nuffield Department of Clinical Medicine, University of Oxford, UK OX3 7DQ
| | - Jolanta Kopec
- Structural Genomics Consortium, Nuffield Department of Clinical Medicine, University of Oxford, UK OX3 7DQ
| | - Fiona Fitzpatrick
- Structural Genomics Consortium, Nuffield Department of Clinical Medicine, University of Oxford, UK OX3 7DQ
| | - Thomas J McCorvie
- Structural Genomics Consortium, Nuffield Department of Clinical Medicine, University of Oxford, UK OX3 7DQ
| | - Wyatt W Yue
- Structural Genomics Consortium, Nuffield Department of Clinical Medicine, University of Oxford, UK OX3 7DQ
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