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Gupta P, Kumar R. GTP cyclohydroxylase1 (GCH1): Role in neurodegenerative diseases. Gene 2023; 888:147749. [PMID: 37652170 DOI: 10.1016/j.gene.2023.147749] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Revised: 08/18/2023] [Accepted: 08/28/2023] [Indexed: 09/02/2023]
Abstract
GCH1 gene provides directions for the synthesis of GTP cyclohydrolase 1 which regulates the formation of Tetrahydrobiopterin (BH4). BH4 is a crucial cofactor for essential neurotransmitters synthesis such as dopamine, serotonin and nitric oxide synthases. Deficiency of GCH1 limits the synthesis of BH4 which is responsible for neuropsychiatric diseases such as dopa-responsive dystonia, hyperalaninemia, Parkinson's disease and depression. Few single nucleotide polymorphisms of GCH1 gene are also responsible for pain in sickle cell disease. Furthermore, GCH1 regulates NO activity which controls the blood pressure, vasodilatory functions and oxidative stress. Understanding the therapeutic implications of targeting GCH1 which holds promise for treating various diseases. Novel therapeutic strategies could involve small molecule drugs or gene therapy techniques that enhance GCH1 expression or activity.
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Affiliation(s)
- Parul Gupta
- ICMR-National Institute of Research in Tribal Health, India
| | - Ravindra Kumar
- ICMR-National Institute of Research in Tribal Health, India.
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2
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Bouly M, Bourguignon MP, Roesch S, Rigouin P, Gosgnach W, Bossard E, Royere E, Diguet N, Sansilvestri-Morel P, Bonnin A, Xuereb L, Berson P, Komajda M, Bernhardt P, Tyl B. Aging increases circulating BH 2 without modifying BH 4 levels and impairs peripheral vascular function in healthy adults. Transl Res 2021; 238:36-48. [PMID: 34332154 DOI: 10.1016/j.trsl.2021.07.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 06/23/2021] [Accepted: 07/23/2021] [Indexed: 11/17/2022]
Abstract
Little is known about the mechanisms of aging on vascular beds and its relationship with tetra and di-hydrobiopterin (BH4 and BH2) levels. This observational clinical study analyzed the impact of aging on plasma and platelet biopterins, cutaneous blood flow (CBF), and coronary flow reserve (CFR) in healthy adults. The study enrolled healthy adults in 3 age groups: 18-30, 50-59, and 60-70 years (n = 25/group). Biopterins were assessed by LC-MS/MS using newly defined pre-analytical conditions limiting BH4 oxidation and improving long-term stability. CBF was measured by Laser Speckle Contrast Imaging coupled with acetylcholine-iontophoresis and CFR by adenosine stress cardiac magnetic resonance. In healthy adults, aging (60-70 years vs 18-30 years) significantly increased platelet BH2 (+75%, P = 0.033) and BH2 + BH4 (+31%, P = 0.033), and to a lesser extent plasma BH2 (+29%, P = 0.009) without affecting BH4 and BH4/BH2. Simultaneously, CBF was decreased (-23%, P = 0.004) but not CFR, CBF being inversely correlated with platelet BH2 (r = -0.42, P = 0.001) and BH2 + BH4 (r = -0.41, P = 0.002). The proportion of adults with abnormal platelet BH2 increased with age (+28% in 60-70y). These abnormal BH2 levels were significantly associated with reduced CBF and CFR (-16%, P = 0.03 and -26%, P = 0.02). In conclusion, our study showed that age-related peripheral endothelial dysfunction was associated with an increase in circulating BH2 without decreasing BH4, the effect being more marked in platelets, the most relevant blood compartment to assess biopterin bioavailability. Peripheral but not coronary vascular function is progressively impaired with aging in healthy adults. All these findings support biopterins as therapeutic targets to improve vascular function.
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Affiliation(s)
- Muriel Bouly
- Cardiovascular & Metabolic Disease Centre for Therapeutic Innovation, Institut de Recherches Internationales Servier, Suresnes, France
| | - Marie-Pierre Bourguignon
- Cardiovascular & Metabolic Disease Centre for Therapeutic Innovation, Institut de Recherches Servier, Suresnes, France
| | - Susanne Roesch
- Centre of Excellence Clinical Operations, Institut de Recherches Internationales Servier, Suresnes, France
| | - Pascal Rigouin
- Biostatistics Department, Keyrus Life Science, Nantes, France
| | - Willy Gosgnach
- Centre of Excellence Biotechnology, Institut de Recherches Servier, Croissy, France
| | | | - Emilie Royere
- Cardiovascular & Metabolic Disease Centre for Therapeutic Innovation, Institut de Recherches Servier, Suresnes, France
| | - Nicolas Diguet
- Cardiovascular & Metabolic Disease Centre for Therapeutic Innovation, Institut de Recherches Servier, Suresnes, France
| | - Patricia Sansilvestri-Morel
- Cardiovascular & Metabolic Disease Centre for Therapeutic Innovation, Institut de Recherches Servier, Suresnes, France
| | - Ariane Bonnin
- Drug Safety & Pharmacokinetics Centre of Excellence, Biologie Servier, Gidy, France
| | - Laura Xuereb
- Centre of Excellence Methodology and Valorisation of Data, Institut de Recherches Internationales Servier, Suresnes, France
| | - Pascal Berson
- Cardiovascular & Metabolic Disease Centre for Therapeutic Innovation, Institut de Recherches Servier, Suresnes, France
| | - Michel Komajda
- Department of Cardiology, Hospital Saint Joseph, France/Paris Sorbonne Université France, Paris, France
| | | | - Benoit Tyl
- Cardiovascular & Metabolic Disease Centre for Therapeutic Innovation, Institut de Recherches Internationales Servier, Suresnes, France
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Khairallah A, Ross CJ, Tastan Bishop Ö. GTP Cyclohydrolase I as a Potential Drug Target: New Insights into Its Allosteric Modulation via Normal Mode Analysis. J Chem Inf Model 2021; 61:4701-4719. [PMID: 34450011 DOI: 10.1021/acs.jcim.1c00898] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Guanosine triphosphate (GTP) cyclohydrolase I (GCH1) catalyzes the conversion of GTP into dihydroneopterin triphosphate (DHNP). DHNP is the first intermediate of the folate de novo biosynthesis pathway in prokaryotic and lower eukaryotic microorganisms and the tetrahydrobiopterin (BH4) biosynthesis pathway in higher eukaryotes. The de novo folate biosynthesis provides essential cofactors for DNA replication, cell division, and synthesis of key amino acids in rapidly replicating pathogen cells, such as Plasmodium falciparum (P. falciparum), a causative agent of malaria. In eukaryotes, the product of the BH4 biosynthesis pathway is essential for the production of nitric oxide and several neurotransmitter precursors. An increased copy number of the malaria parasite P. falciparum GCH1 gene has been reported to influence antimalarial antifolate drug resistance evolution, whereas mutations in the human GCH1 are associated with neuropathic and inflammatory pain disorders. Thus, GCH1 stands as an important and attractive drug target for developing therapeutics. The GCH1 intrinsic dynamics that modulate its activity remains unclear, and key sites that exert allosteric effects across the structure are yet to be elucidated. This study employed the anisotropic network model to analyze the intrinsic motions of the GCH1 structure alone and in complex with its regulatory partner protein. We showed that the GCH1 tunnel-gating mechanism is regulated by a global shear motion and an outward expansion of the central five-helix bundle. We further identified hotspot residues within sites of structural significance for the GCH1 intrinsic allosteric modulation. The obtained results can provide a solid starting point to design novel antineuropathic treatments for humans and novel antimalarial drugs against the malaria parasite P. falciparum GCH1 enzyme.
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Affiliation(s)
- Afrah Khairallah
- Research Unit in Bioinformatics (RUBi), Department of Biochemistry and Microbiology, Rhodes University, Grahamstown 6140, South Africa
| | - Caroline J Ross
- Research Unit in Bioinformatics (RUBi), Department of Biochemistry and Microbiology, Rhodes University, Grahamstown 6140, South Africa
| | - Özlem Tastan Bishop
- Research Unit in Bioinformatics (RUBi), Department of Biochemistry and Microbiology, Rhodes University, Grahamstown 6140, South Africa
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Biophysical and structural investigation of the regulation of human GTP cyclohydrolase I by its regulatory protein GFRP. J Struct Biol 2020; 213:107691. [PMID: 33387654 DOI: 10.1016/j.jsb.2020.107691] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Revised: 12/22/2020] [Accepted: 12/24/2020] [Indexed: 11/23/2022]
Abstract
GTP Cyclohydrolase I (GCH1) catalyses the conversion of guanosine triphosphate (GTP) to dihydroneopterin triphosphate (H2NTP), the initiating step in the biosynthesis of tetrahydrobiopterin (BH4). BH4 functions as co-factor in neurotransmitter biosynthesis. BH4 homeostasis is a promising target to treat pain disorders in patients. The function of mammalian GCH1s is regulated by a metabolic sensing mechanism involving a regulator protein, GCH1 feedback regulatory protein (GFRP). Dependent on the relative cellular concentrations of effector ligands, BH4 and phenylalanine, GFRP binds GCH1 to form inhibited or activated complexes, respectively. We determined high-resolution structures of the ligand-free and -bound human GFRP and GCH1-GFRP complexes by X-ray crystallography. Highly similar binding modes of the substrate analogue 7-deaza-GTP to active and inhibited GCH1-GFRP complexes confirm a novel, dissociation rate-controlled mechanism of non-competitive inhibition to be at work. Further, analysis of all structures shows that upon binding of the effector molecules, the conformations of GCH1 or GFRP are altered and form highly complementary surfaces triggering a picomolar interaction of GFRP and GCH1 with extremely slow koff values, while GCH1-GFRP complexes rapidly disintegrate in absence of BH4 or phenylalanine. Finally, comparing behavior of full-length and N-terminally truncated GCH1 we conclude that the disordered GCH1 N-terminus does not have impact on complex formation and enzymatic activity. In summary, this comprehensive and methodologically diverse study helps to provide a better understanding of the regulation of GCH1 by GFRP and could thus stimulate research on GCH1 modulating drugs.
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Khairallah A, Ross CJ, Tastan Bishop Ö. Probing the Structural Dynamics of the Plasmodium falciparum Tunneling-Fold Enzyme 6-Pyruvoyl Tetrahydropterin Synthase to Reveal Allosteric Drug Targeting Sites. Front Mol Biosci 2020; 7:575196. [PMID: 33102524 PMCID: PMC7546909 DOI: 10.3389/fmolb.2020.575196] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 08/20/2020] [Indexed: 11/13/2022] Open
Abstract
The de novo folate synthesis pathway is a well-established drug target in the treatment of many infectious diseases. Antimalarial antifolate drugs have proven to be effective against malaria, however, rapid drug resistance has emerged on the two primary targeted enzymes: dihydrofolate reductase and dihydroptoreate synthase. The need to identify alternative antifolate drugs and novel metabolic targets is of imminent importance. The 6-pyruvol tetrahydropterin synthase (PTPS) enzyme belongs to the tunneling fold protein superfamily which is characterized by a distinct central tunnel/cavity. The enzyme catalyzes the second reaction step of the parasite’s de novo folate synthesis pathway and is responsible for the conversion of 7,8-dihydroneopterin to 6-pyruvoyl-tetrahydropterin. In this study, we examine the structural dynamics of Plasmodium falciparum PTPS using the anisotropic network model, to elucidate the collective motions that drive the function of the enzyme and identify potential sites for allosteric modulation of its binding properties. Based on our modal analysis, we identified key sites in the N-terminal domains and central helices which control the accessibility to the active site. Notably, the N-terminal domains were shown to regulate the open-to-closed transition of the tunnel, via a distinctive wringing motion that deformed the core of the protein. We, further, combined the dynamic analysis with motif discovery which revealed highly conserved motifs that are unique to the Plasmodium species and are located in the N-terminal domains and central helices. This provides essential structural information for the efficient design of drugs such as allosteric modulators that would have high specificity and low toxicity as they do not target the PTPS active site that is highly conserved in humans.
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Affiliation(s)
- Afrah Khairallah
- Research Unit in Bioinformatics (RUBi), Department of Biochemistry and Microbiology, Rhodes University, Grahamstown, South Africa
| | - Caroline J Ross
- Research Unit in Bioinformatics (RUBi), Department of Biochemistry and Microbiology, Rhodes University, Grahamstown, South Africa
| | - Özlem Tastan Bishop
- Research Unit in Bioinformatics (RUBi), Department of Biochemistry and Microbiology, Rhodes University, Grahamstown, South Africa
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Hussein D, Starr A, Heikal L, McNeill E, Channon KM, Brown PR, Sutton BJ, McDonnell JM, Nandi M. Validating the GTP-cyclohydrolase 1-feedback regulatory complex as a therapeutic target using biophysical and in vivo approaches. Br J Pharmacol 2015; 172:4146-57. [PMID: 26014146 PMCID: PMC4543619 DOI: 10.1111/bph.13202] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Revised: 05/12/2015] [Accepted: 05/13/2015] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND AND PURPOSE 6R-L-erythro-5,6,7,8-tetrahydrobiopterin (BH4 ) is an essential cofactor for nitric oxide biosynthesis. Substantial clinical evidence indicates that intravenous BH4 restores vascular function in patients. Unfortunately, oral BH4 has limited efficacy. Therefore, orally bioavailable pharmacological activators of endogenous BH4 biosynthesis hold significant therapeutic potential. GTP-cyclohydrolase 1 (GCH1), the rate limiting enzyme in BH4 synthesis, forms a protein complex with GCH1 feedback regulatory protein (GFRP). This complex is subject to allosteric feed-forward activation by L-phenylalanine (L-phe). We investigated the effects of L-phe on the biophysical interactions of GCH1 and GFRP and its potential to alter BH4 levels in vivo. EXPERIMENTAL APPROACH Detailed characterization of GCH1-GFRP protein-protein interactions were performed using surface plasmon resonance (SPR) with or without L-phe. Effects on systemic and vascular BH4 biosynthesis in vivo were investigated following L-phe treatment (100 mg·kg(-1) , p.o.). KEY RESULTS GCH1 and GFRP proteins interacted in the absence of known ligands or substrate but the presence of L-phe doubled maximal binding and enhanced binding affinity eightfold. Furthermore, the complex displayed very slow association and dissociation rates. In vivo, L-phe challenge induced a sustained elevation of aortic BH4 , an effect absent in GCH1(fl/fl)-Tie2Cre mice. CONCLUSIONS AND IMPLICATIONS Biophysical data indicate that GCH1 and GFRP are constitutively bound. In vivo, data demonstrated that L-phe elevated vascular BH4 in an endothelial GCH1 dependent manner. Pharmacological agents which mimic the allosteric effects of L-phe on the GCH1-GFRP complex have the potential to elevate endothelial BH4 biosynthesis for numerous cardiovascular disorders.
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Affiliation(s)
- D Hussein
- Institute of Pharmaceutical Science, Faculty of Life Sciences & Medicine, King's College LondonLondon, UK
| | - A Starr
- Institute of Pharmaceutical Science, Faculty of Life Sciences & Medicine, King's College LondonLondon, UK
| | - L Heikal
- Institute of Pharmaceutical Science, Faculty of Life Sciences & Medicine, King's College LondonLondon, UK
| | - E McNeill
- British Heart Foundation Centre of Research Excellence, Division of Cardiovascular Medicine, University of Oxford, John Radcliffe HospitalOxford, UK
| | - K M Channon
- British Heart Foundation Centre of Research Excellence, Division of Cardiovascular Medicine, University of Oxford, John Radcliffe HospitalOxford, UK
| | - P R Brown
- The Randall Division of Cell and Molecular Biophysics, Faculty of Life Sciences & Medicine, King's College LondonLondon, UK
| | - B J Sutton
- The Randall Division of Cell and Molecular Biophysics, Faculty of Life Sciences & Medicine, King's College LondonLondon, UK
| | - J M McDonnell
- The Randall Division of Cell and Molecular Biophysics, Faculty of Life Sciences & Medicine, King's College LondonLondon, UK
| | - M Nandi
- Institute of Pharmaceutical Science, Faculty of Life Sciences & Medicine, King's College LondonLondon, UK
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Biochemical and functional characterization of Plasmodium falciparum GTP cyclohydrolase I. Malar J 2014; 13:150. [PMID: 24745605 PMCID: PMC4005822 DOI: 10.1186/1475-2875-13-150] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Accepted: 12/17/2013] [Indexed: 12/12/2022] Open
Abstract
Background Antifolates are currently in clinical use for malaria preventive therapy and treatment. The drugs kill the parasites by targeting the enzymes in the de novo folate pathway. The use of antifolates has now been limited by the spread of drug-resistant mutations. GTP cyclohydrolase I (GCH1) is the first and the rate-limiting enzyme in the folate pathway. The amplification of the gch1 gene found in certain Plasmodium falciparum isolates can cause antifolate resistance and influence the course of antifolate resistance evolution. These findings showed the importance of P. falciparum GCH1 in drug resistance intervention. However, little is known about P. falciparum GCH1 in terms of kinetic parameters and functional assays, precluding the opportunity to obtain the key information on its catalytic reaction and to eventually develop this enzyme as a drug target. Methods Plasmodium falciparum GCH1 was cloned and expressed in bacteria. Enzymatic activity was determined by the measurement of fluorescent converted neopterin with assay validation by using mutant and GTP analogue. The genetic complementation study was performed in ∆folE bacteria to functionally identify the residues and domains of P. falciparum GCH1 required for its enzymatic activity. Plasmodial GCH1 sequences were aligned and structurally modeled to reveal conserved catalytic residues. Results Kinetic parameters and optimal conditions for enzymatic reactions were determined by the fluorescence-based assay. The inhibitor test against P. falciparum GCH1 is now possible as indicated by the inhibitory effect by 8-oxo-GTP. Genetic complementation was proven to be a convenient method to study the function of P. falciparum GCH1. A series of domain truncations revealed that the conserved core domain of GCH1 is responsible for its enzymatic activity. Homology modelling fits P. falciparum GCH1 into the classic Tunnelling-fold structure with well-conserved catalytic residues at the active site. Conclusions Functional assays for P. falciparum GCH1 based on enzymatic activity and genetic complementation were successfully developed. The assays in combination with a homology model characterized the enzymatic activity of P. falciparum GCH1 and the importance of its key amino acid residues. The potential to use the assay for inhibitor screening was validated by 8-oxo-GTP, a known GTP analogue inhibitor.
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Heinberg A, Siu E, Stern C, Lawrence EA, Ferdig MT, Deitsch KW, Kirkman LA. Direct evidence for the adaptive role of copy number variation on antifolate susceptibility in Plasmodium falciparum. Mol Microbiol 2013; 88:702-12. [PMID: 23347134 DOI: 10.1111/mmi.12162] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/20/2013] [Indexed: 11/29/2022]
Abstract
Resistance to antimalarials targeting the folate pathway is widespread. GTP-cyclohydrolase (gch1), the first enzyme in this pathway, exhibits extensive copy number variation (CN) in parasite isolates from areas with a history of longstanding antifolate use. Increased CN of gch1 is associated with a greater number of point mutations in enzymes targeted by the antifolates, pyrimethamine and sulphadoxine. While these observations suggest that increases in gch1 CN are an adaptation to drug pressure, changes in CN have not been experimentally demonstrated to directly alter drug susceptibility. To determine if changes in gch1 expression alone modify pyrimethamine sensitivity, we manipulated gch1 CN in several parasite lines to test the effect on drug sensitivity. We report that increases in gch1 CN alter pyrimethamine resistance in most parasites lines. However we find evidence of a detrimental effect of very high levels of gch1 overexpression in parasite lines with high endogenous levels of gch1 expression, revealing the importance of maintaining balance in the folate pathway and implicating changes in gch1 expression in preserving proper metabolic flux. This work expands our understanding of parasite adaptation to drug pressure and provides a possible mechanism for how specific mutations become fixed within parasite populations.
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Affiliation(s)
- Adina Heinberg
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY, USA
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Gräwert T, Fischer M, Bacher A. Structures and reaction mechanisms of GTP cyclohydrolases. IUBMB Life 2013; 65:310-22. [PMID: 23457054 DOI: 10.1002/iub.1153] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2013] [Accepted: 01/25/2013] [Indexed: 11/09/2022]
Abstract
GTP cyclohydrolases generate the first committed intermediates for the biosynthesis of certain vitamins/cofactors (folic acid, riboflavin, deazaflavin, and tetrahydrobiopterin), deazapurine antibiotics, some t-RNA bases (queuosine, archaeosine), and the phytotoxin, toxoflavin. They depend on divalent cations for hydrolytic opening of the imidazole ring of the substrate, guanosine triphosphate (GTP). Surprisingly, the ring opening reaction is not the rate-limiting step for GTP cyclohydrolases I and II whose mechanism have been studied in some detail. GTP cyclohydrolase I, Ib, and II are potential targets for novel anti-infectives. Genetic factors modulating the activity of human GTP cyclohydrolase are highly pleiotropic, since the signal transponders whose biosyntheses require their participation (nitric oxide, catecholamines) impact a very wide range of physiological phenomena. Recent studies suggest that human GTP cyclohydrolase may become an oncology target.
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Affiliation(s)
- Tobias Gräwert
- Hamburg School of Food Science, Institut für Lebensmittelchemie, Grindelallee 117, 20146 Hamburg, Germany
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Abstract
6R l-erythro-5,6,7,8-tetrahydrobiopterin (BH4) is an essential cofactor for several enzymes including phenylalanine hydroxylase and the nitric oxide synthases (NOS). Oral supplementation of BH4 has been successfully employed to treat subsets of patients with hyperphenylalaninaemia. More recently, research efforts have focussed on understanding whether BH4 supplementation may also be efficacious in cardiovascular disorders that are underpinned by reduced nitric oxide bioavailability. Whilst numerous preclinical and clinical studies have demonstrated a positive association between enhanced BH4 and vascular function, the efficacy of orally administered BH4 in human cardiovascular disease remains unclear. Furthermore, interventions that limit BH4 bioavailability may provide benefit in diseases where nitric oxide over production contributes to pathology. This review describes the pathways involved in BH4 bio-regulation and discusses other endogenous mechanisms that could be harnessed therapeutically to manipulate vascular BH4 levels.
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Affiliation(s)
- Anna Starr
- Pharmacology and Therapeutics Group, Institute of Pharmaceutical Science, School of Biomedical Sciences, King's College London, Franklin Wilkins Building, 150 Stamford Street,London SE1 9NH, United Kingdom
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Du J, Teng RJ, Lawrence M, Guan T, Xu H, Ge Y, Shi Y. The protein partners of GTP cyclohydrolase I in rat organs. PLoS One 2012; 7:e33991. [PMID: 22479495 PMCID: PMC3313957 DOI: 10.1371/journal.pone.0033991] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2012] [Accepted: 02/22/2012] [Indexed: 02/03/2023] Open
Abstract
Objective GTP cyclohydrolase I (GCH1) is the rate-limiting enzyme for tetrahydrobiopterin biosynthesis and has been shown to be a promising therapeutic target in ischemic heart disease, hypertension, atherosclerosis and diabetes. The endogenous GCH1-interacting partners have not been identified. Here, we determined endogenous GCH1-interacting proteins in rat. Methods and Results A pulldown and proteomics approach were used to identify GCH1 interacting proteins in rat liver, brain, heart and kidney. We demonstrated that GCH1 interacts with at least 17 proteins including GTP cyclohydrolase I feedback regulatory protein (GFRP) in rat liver by affinity purification followed by proteomics and validated six protein partners in liver, brain, heart and kidney by immunoblotting. GCH1 interacts with GFRP and very long-chain specific acyl-CoA dehydrogenase in the liver, tubulin beta-2A chain in the liver and brain, DnaJ homolog subfamily A member 1 and fatty aldehyde dehydrogenase in the liver, heart and kidney and eukaryotic translation initiation factor 3 subunit I (EIF3I) in all organs tested. Furthermore, GCH1 associates with mitochondrial proteins and GCH1 itself locates in mitochondria. Conclusion GCH1 interacts with proteins in an organ dependant manner and EIF3I might be a general regulator of GCH1. Our finding indicates GCH1 might have broader functions beyond tetrahydrobiopterin biosynthesis.
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Affiliation(s)
- Jianhai Du
- Department of Surgery, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
- Children's Research Institute, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
- * E-mail: (JD); (YS)
| | - Ru-Jeng Teng
- Children's Research Institute, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
- Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
- Department of Pediatrics, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
| | - Matt Lawrence
- Human Proteomics Program and Department of Physiology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Tongju Guan
- Department of Surgery, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
- Children's Research Institute, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
| | - Hao Xu
- Department of Surgery, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
- Children's Research Institute, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
- Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
| | - Ying Ge
- Human Proteomics Program and Department of Physiology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Yang Shi
- Department of Surgery, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
- Children's Research Institute, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
- Patient Centered Research, Aurora Health Care, Milwaukee, Wisconsin, United States of America
- * E-mail: (JD); (YS)
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Wang H, Yang B, Hao G, Feng Y, Chen H, Feng L, Zhao J, Zhang H, Chen YQ, Wang L, Chen W. Biochemical characterization of the tetrahydrobiopterin synthesis pathway in the oleaginous fungus Mortierella alpina. MICROBIOLOGY (READING, ENGLAND) 2011; 157:3059-3070. [PMID: 21852350 PMCID: PMC4811656 DOI: 10.1099/mic.0.051847-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2011] [Revised: 08/10/2011] [Accepted: 08/17/2011] [Indexed: 11/18/2022]
Abstract
We characterized the de novo biosynthetic pathway of tetrahydrobiopterin (BH₄) in the lipid-producing fungus Mortierella alpina. The BH₄ cofactor is essential for various cell processes, and is probably present in every cell or tissue of higher organisms. Genes encoding two copies of GTP cyclohydrolase I (GTPCH-1 and GTPCH-2) for the conversion of GTP to dihydroneopterin triphosphate (H₂-NTP), 6-pyruvoyltetrahydropterin synthase (PTPS) for the conversion of H₂-NTP to 6-pyruvoyltetrahydropterin (PPH₄), and sepiapterin reductase (SR) for the conversion of PPH₄ to BH₄, were expressed heterologously in Escherichia coli. The recombinant enzymes were produced as His-tagged fusion proteins and were purified to homogeneity to investigate their enzymic activities. Enzyme products were analysed by HPLC and electrospray ionization-MS. Kinetic parameters and other properties of GTPCH, PTPS and SR were investigated. Physiological roles of BH₄ in M. alpina are discussed, and comparative analyses between GTPCH, PTPS and SR proteins and other homologous proteins were performed. The presence of two functional GTPCH enzymes has, as far as we are aware, not been reported previously, reflecting the unique ability of this fungus to synthesize both BH₄ and folate, using the GTPCH product as a common substrate. To our knowledge, this study is the first to report the comprehensive characterization of a BH₄ biosynthesis pathway in a fungus.
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Affiliation(s)
- Hongchao Wang
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi 214122, PR China
| | - Bo Yang
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi 214122, PR China
| | - Guangfei Hao
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi 214122, PR China
| | - Yun Feng
- TEDA School of Biological Sciences and Biotechnology, Nankai University, Tianjin Economic-Technological Development Area, Tianjin 300457, PR China
| | - Haiqin Chen
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi 214122, PR China
| | - Lu Feng
- TEDA School of Biological Sciences and Biotechnology, Nankai University, Tianjin Economic-Technological Development Area, Tianjin 300457, PR China
| | - Jianxin Zhao
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi 214122, PR China
| | - Hao Zhang
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi 214122, PR China
| | - Yong Q. Chen
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi 214122, PR China
| | - Lei Wang
- TEDA School of Biological Sciences and Biotechnology, Nankai University, Tianjin Economic-Technological Development Area, Tianjin 300457, PR China
| | - Wei Chen
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi 214122, PR China
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