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Huang YH, Huang CY. The complexed crystal structure of dihydropyrimidinase reveals a potential interactive link with the neurotransmitter γ-aminobutyric acid (GABA). Biochem Biophys Res Commun 2024; 692:149351. [PMID: 38056157 DOI: 10.1016/j.bbrc.2023.149351] [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] [Received: 11/25/2023] [Accepted: 11/28/2023] [Indexed: 12/08/2023]
Abstract
Dihydropyrimidinase (DHPase) plays a crucial role in pyrimidine degradation, showcasing a broad substrate specificity that extends beyond pyrimidine catabolism, hinting at additional roles for this ancient enzyme. In this study, we solved the crystal structure of Pseudomonas aeruginosa DHPase (PaDHPase) complexed with the neurotransmitter γ-aminobutyric acid (GABA) at a resolution of 1.97 Å (PDB ID 8WQ9). Our structural analysis revealed two GABA binding sites in each monomer of PaDHPase. Interactions between PaDHPase and GABA molecules, involving residues within a contact distance of <4 Å, were examined. In silico analyses via PISA and PLIP software revealed hydrogen bonds formed between the side chain of Cys318 and GABA 1, as well as the main chains of Ser333, Ile335, and Asn337 with GABA 2. Comparative structural analysis between GABA-bound and unbound states unveiled significant conformational changes at the active site, particularly within dynamic loop I, supporting the conclusion that PaDHPase binds GABA through the loop-out mechanism. Building upon this molecular evidence, we discuss and propose a working model. The study expands the GABA interactome by identifying DHPase as a novel GABA-interacting protein and provides structural insight into the interaction between a dimetal center in the protein's active site and GABA. Further investigations are warranted to explore potential interactions of GABA with other DHPase-like proteins and to understand whether DHPase may have additional regulatory and physiological roles in the cell, extending beyond pyrimidine catabolism.
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Affiliation(s)
- Yen-Hua Huang
- Department of Biomedical Sciences, Chung Shan Medical University, No.110, Sec.1, Chien-Kuo N. Rd., Taichung City, Taiwan
| | - Cheng-Yang Huang
- Department of Biomedical Sciences, Chung Shan Medical University, No.110, Sec.1, Chien-Kuo N. Rd., Taichung City, Taiwan; Department of Medical Research, Chung Shan Medical University Hospital, No.110, Sec.1, Chien-Kuo N. Rd., Taichung City, Taiwan.
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2
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Albokhari D, Alharbi O, Blesson A, Jain M. The diagnostic odyssey of a patient with dihydropyrimidinase deficiency: a case report and review of the literature. Cold Spring Harb Mol Case Stud 2023; 9:a006319. [PMID: 38199782 PMCID: PMC10815279 DOI: 10.1101/mcs.a006319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2023] [Accepted: 12/05/2023] [Indexed: 01/12/2024] Open
Abstract
Dihydropyrimidinase (DHP) deficiency is an autosomal recessive metabolic disorder caused by biallelic pathogenic variants of DPYS Patients with DHP deficiency exhibit a broad spectrum of phenotypes, ranging from severe neurological and gastrointestinal involvement to cases with no apparent symptoms. The biochemical diagnosis of DHP deficiency is based on the detection of a significant amount of dihydropyrimidines in urine, plasma, and cerebrospinal fluid samples. Molecular genetic testing, specifically the identification of biallelic pathogenic variants in DPYS, has proven instrumental in confirming the diagnosis and facilitating family studies. This case study documents the diagnostic journey of an 18-yr-old patient with DHP deficiency, highlighting features at the severe end of the clinical spectrum. Notably, our patient exhibited previously unreported skeletal features that positively responded to bisphosphonate treatment, contributing valuable insights to the clinical characterization of DHP deficiency. Additionally, a novel DPYS variant was identified and confirmed pathogenicity through metabolic testing, further expanding the variant spectrum of the gene. Our case emphasizes the importance of a comprehensive diagnostic approach using genetic sequencing and metabolic testing for accurate diagnosis.
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Affiliation(s)
- Daniah Albokhari
- Department of Pediatrics, Taibah University College of Medicine, Medina 42353, Saudi Arabia
- King Faisal Specialist Hospital and Research Center, Medina 42523, Saudi Arabia
| | - Ohood Alharbi
- Taibah University College of Medicine, Medina 42353, Saudi Arabia
| | - Alyssa Blesson
- Department of Bone/Osteogenesis Imperfecta, Kennedy Krieger Institute, Baltimore, Maryland 21205, USA
| | - Mahim Jain
- Department of Bone/Osteogenesis Imperfecta, Kennedy Krieger Institute, Baltimore, Maryland 21205, USA;
- Department of Genetic Medicine, Johns Hopkins Medical Institute, Baltimore, Maryland 21205, USA
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Meelua W, Wanjai T, Thinkumrob N, Oláh J, Cairns JRK, Hannongbua S, Ryde U, Jitonnom J. A computational study of the reaction mechanism and stereospecificity of dihydropyrimidinase. Phys Chem Chem Phys 2023; 25:8767-8778. [PMID: 36912034 DOI: 10.1039/d2cp05262h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2023]
Abstract
Dihydropyrimidinase (DHPase) is a key enzyme in the pyrimidine pathway, the catabolic route for synthesis of β-amino acids. It catalyses the reversible conversion of 5,6-dihydrouracil (DHU) or 5,6-dihydrothymine (DHT) to the corresponding N-carbamoyl-β-amino acids. This enzyme has the potential to be used as a tool in the production of β-amino acids. Here, the reaction mechanism and origin of stereospecificity of DHPases from Saccharomyces kluyveri and Sinorhizobium meliloti CECT4114 were investigated and compared using a quantum mechanical cluster approach based on density functional theory. Two models of the enzyme active site were designed from the X-ray crystal structure of the native enzyme: a small cluster to characterize the mechanism and the stationary points and a large model to probe the stereospecificity and the role of stereo-gate-loop (SGL) residues. It is shown that a hydroxide ion first performs a nucleophilic attack on the substrate, followed by the abstraction of a proton by Asp358, which occurs concertedly with protonation of the ring nitrogen by the same residue. For the DHT substrate, the enzyme displays a preference for the L-configuration, in good agreement with experimental observation. Comparison of the reaction energetics of the two models reveals the importance of SGL residues in the stereospecificity of catalysis. The role of the conserved Tyr172 residue in transition-state stabilization is confirmed as the Tyr172Phe mutation increases the activation barrier of the reaction by ∼8 kcal mol-1. A detailed understanding of the catalytic mechanism of the enzyme could offer insight for engineering in order to enhance its activity and substrate scope.
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Affiliation(s)
- Wijitra Meelua
- Demonstration School, University of Phayao, Phayao 56000, Thailand
- Unit of Excellence in Computational Molecular Science and Catalysis, and Division of Chemistry, School of Science, University of Phayao, Phayao 56000, Thailand.
| | - Tanchanok Wanjai
- Unit of Excellence in Computational Molecular Science and Catalysis, and Division of Chemistry, School of Science, University of Phayao, Phayao 56000, Thailand.
| | - Natechanok Thinkumrob
- Unit of Excellence in Computational Molecular Science and Catalysis, and Division of Chemistry, School of Science, University of Phayao, Phayao 56000, Thailand.
| | - Julianna Oláh
- Department of Inorganic and Analytical Chemistry, Budapest University of Technology and Economics, Műegyetem rakpart 3, Budapest H-1111, Hungary
| | - James R Ketudat Cairns
- Center for Biomolecular Structure, Function and Application and School of Chemistry, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand
| | - Supa Hannongbua
- Department of Chemistry, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand
| | - Ulf Ryde
- Department of Theoretical Chemistry, Lund University, Chemical Centre, P.O. Box 124, Lund SE-221 00, Sweden
| | - Jitrayut Jitonnom
- Unit of Excellence in Computational Molecular Science and Catalysis, and Division of Chemistry, School of Science, University of Phayao, Phayao 56000, Thailand.
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Righetti S, Allcock RJN, Yaplito-Lee J, Adams L, Ellaway C, Jones KJ, Selvanathan A, Fletcher J, Pitt J, van Kuilenburg ABP, Delatycki MB, Laing NG, Kirk EP. The relationship between beta-ureidopropionase deficiency due to UPB1 variants and human phenotypes is uncertain. Mol Genet Metab 2022; 137:62-67. [PMID: 35926322 DOI: 10.1016/j.ymgme.2022.07.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 07/15/2022] [Accepted: 07/21/2022] [Indexed: 01/15/2023]
Abstract
BACKGROUND Beta-ureidopropionase deficiency, caused by variants in UPB1, has been reported in association with various neurodevelopmental phenotypes including intellectual disability, seizures and autism. AIM We aimed to reassess the relationship between variants in UPB1 and a clinical phenotype. METHODS Literature review, calculation of carrier frequencies from population databases, long-term follow-up of a previously published case and reporting of additional cases. RESULTS Fifty-three published cases were identified, and two additional cases are reported here. Of these, 14 were asymptomatic and four had transient neurological features; clinical features in the remainder were variable and included non-neurological presentations. Several of the variants previously reported as pathogenic are present in population databases at frequencies higher than expected for a rare condition. In particular, the variant most frequently reported as pathogenic, p.Arg326Gln, is very common among East Asians, with a carrier frequency of 1 in 19 and 1 in 907 being homozygous for the variant in gnomAD v2.1.1. CONCLUSION Pending the availability of further evidence, UPB1 should be considered a 'gene of uncertain clinical significance'. Caution should be used in ascribing clinical significance to biochemical features of beta-ureidopropionase deficiency and/or UPB1 variants in patients with neurodevelopmental phenotypes. UPB1 is not currently suitable for inclusion in gene panels for reproductive genetic carrier screening. SYNOPSIS The relationship between beta-ureidopropionase deficiency due to UPB1 variants and clinical phenotypes is uncertain.
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Affiliation(s)
| | | | - Joy Yaplito-Lee
- Department of Metabolic Medicine, Royal Children's Hospital, Melbourne, VIC, Australia
| | - Louisa Adams
- Sydney Children's Hospitals Network, Sydney, NSW, Australia
| | | | - Kristi J Jones
- Sydney Children's Hospitals Network, Sydney, NSW, Australia; University of Sydney, NSW, Australia
| | | | | | - James Pitt
- Victorian Clinical Genetics Service, Murdoch Children's Research Institute, Melbourne, VIC, Australia
| | - André B P van Kuilenburg
- Amsterdam UMC location, University of Amsterdam, Amsterdam Gastroenterology Endocrinology Metabolism, Cancer Center Amsterdam, Laboratory Genetic Metabolic Diseases, Amsterdam, the Netherlands; Amsterdam Gastroenterology Endocrinology Metabolism, Amsterdam, the Netherlands
| | - Martin B Delatycki
- Victorian Clinical Genetics Service, Murdoch Children's Research Institute, Melbourne, VIC, Australia
| | - Nigel G Laing
- Centre for Medical Research University of Western Australia, Harry Perkins Institute of Medical Research, Perth, WA, Australia
| | - Edwin P Kirk
- University of New South Wales, Sydney, NSW, Australia; Sydney Children's Hospitals Network, Sydney, NSW, Australia; New South Wales Health Pathology, Sydney, NSW, Australia.
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Campanella B, Lomonaco T, Benedetti E, Onor M, Nieri R, Marmorino F, Cremolini C, Bramanti E. Fast, Direct Dihydrouracil Quantitation in Human Saliva: Method Development, Validation, and Application. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:ijerph19106033. [PMID: 35627569 PMCID: PMC9140617 DOI: 10.3390/ijerph19106033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 05/11/2022] [Accepted: 05/14/2022] [Indexed: 12/04/2022]
Abstract
Background. Salivary metabolomics is garnering increasing attention in the health field because of easy, minimally invasive saliva sampling. Dihydrouracil (DHU) is a metabolite of pyrimidine metabolism present in urine, plasma, and saliva and of fluoropyrimidines-based chemotherapeutics. Its fast quantification would help in the identification of patients with higher risk of fluoropyrimidine-induced toxicity and inborn errors of pyrimidine metabolism. Few studies consider DHU as the main salivary metabolite, but reports of its concentration levels in saliva are scarce. We propose the direct determination of DHU in saliva by reversed-phase high-performance liquid chromatography (RP-HPLC-UV detector) as a simple, rapid procedure for non-invasive screening. Methods. The method used was validated and applied to 176 saliva samples collected from 21 nominally healthy volunteers and 4 saliva samples from metastatic colorectal cancer patients before and after receiving 5-fluorouracil chemotherapy. Results. DHU levels in all samples analyzed were in the μmol L−1 range or below proving that DHU is not the main metabolite in saliva and confirming the results found in the literature with LC-MS/MS instrumentation. Any increase of DHU due to metabolism dysfunctions can be suggestive of disease and easily monitored in saliva using common, low-cost instrumentation available also for population screening.
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Affiliation(s)
- Beatrice Campanella
- National Research Council of Italy, C.N.R., Institute of Chemistry of Organometallic Compounds—ICCOM, Via G. Moruzzi 1, 56124 Pisa, Italy; (B.C.); (M.O.); (R.N.)
| | - Tommaso Lomonaco
- Department of Chemistry and Industrial Chemistry, University of Pisa, Via G. Moruzzi 15, 56124 Pisa, Italy;
| | - Edoardo Benedetti
- Hematology Unit, Department of Oncology, Azienda Ospedaliero Universitaria Pisana, Via Roma 67, 56127 Pisa, Italy;
| | - Massimo Onor
- National Research Council of Italy, C.N.R., Institute of Chemistry of Organometallic Compounds—ICCOM, Via G. Moruzzi 1, 56124 Pisa, Italy; (B.C.); (M.O.); (R.N.)
| | - Riccardo Nieri
- National Research Council of Italy, C.N.R., Institute of Chemistry of Organometallic Compounds—ICCOM, Via G. Moruzzi 1, 56124 Pisa, Italy; (B.C.); (M.O.); (R.N.)
| | - Federica Marmorino
- Unity of Oncology, Department of Translational Research and New Technologies in Medicine, University of Pisa, Via Roma 67, 56127 Pisa, Italy; (F.M.); (C.C.)
| | - Chiara Cremolini
- Unity of Oncology, Department of Translational Research and New Technologies in Medicine, University of Pisa, Via Roma 67, 56127 Pisa, Italy; (F.M.); (C.C.)
| | - Emilia Bramanti
- National Research Council of Italy, C.N.R., Institute of Chemistry of Organometallic Compounds—ICCOM, Via G. Moruzzi 1, 56124 Pisa, Italy; (B.C.); (M.O.); (R.N.)
- Correspondence:
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Douglas TD, Newby LK, Eckstrand J, Wixted D, Singh RH. Lipid changes in the metabolome of a single case study with maple syrup urine disease (MSUD) after five days of improved diet adherence of controlled branched-chain amino acids (BCAA). Mol Genet Metab Rep 2020; 25:100651. [PMID: 33088714 PMCID: PMC7567947 DOI: 10.1016/j.ymgmr.2020.100651] [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: 09/17/2020] [Accepted: 09/19/2020] [Indexed: 11/19/2022] Open
Abstract
Background Distinguishing systemic metabolic disruptions in maple syrup urine disease (MSUD) beyond amino acid pathways is under-investigated, yet important to understanding disease pathology and treatment options. Methods An adolescent female (15 years) with MSUD without liver transplant, attended 2 study visits, 5 days apart. Medical diet adherence was determined based on her 3-day diet records and plasma branched-chain amino acid (BCAA) concentrations at both study visits. Plasma from a single age- and sex-matched control (MURDOCK Study, Duke University) and the case patient were analyzed with UPLC/MS/MS for intensity (m/z), annotated, and normalized against a median of 1 (Metabolon, Morrisville NC). Differences between case/control and 5-day comparisons were defined as ≥ ǀ 0.5 ǀ. Results 434 lipid metabolites were identified across samples; 90 (20.7%) were higher and 120 (27.6%) lower in the MSUD case at baseline compared with control. By study visit 2, plasma BCAA had declined, while 48 (53%) of elevated lipids and 14 (11.7%) of lower lipid values had moved to within ǀ 0.5 ǀ of control. Most shifts towards control by day 5 were seen in long-chain fatty acid intermediates (42%) and acylcarnitines (32%). Although androgenic (28%) and bile acid (23%) metabolites increased towards control, neither reached control level by day 5. Discussion This comparative metabolomics study in a single MSUD case and healthy control suggests intrinsic differences in MSUD lipid metabolism potentially influenced by therapeutic diet. Findings suggest influences on hormone regulation, fatty acid oxidation, and bile acid synthesis, but further studies are needed to confirm an association between MSUD and lipid dysregulation. Synopsis Within 5 days of improved dietary adherence, a single MSUD case experienced substantial changes in lipid markers potentially related to changes in plasma branched-chain amino acids.
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Affiliation(s)
- Teresa D. Douglas
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA, USA
- Corresponding author.
| | - L. Kristin Newby
- Duke Clinical and Translational Science Institute (CTSI), Duke University School of Medicine, Durham, NC, USA
| | - Julie Eckstrand
- Duke Clinical and Translational Science Institute (CTSI), Duke University School of Medicine, Durham, NC, USA
| | - Douglas Wixted
- Duke Clinical and Translational Science Institute (CTSI), Duke University School of Medicine, Durham, NC, USA
| | - Rani H. Singh
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA, USA
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Huang CY. Structure, catalytic mechanism, posttranslational lysine carbamylation, and inhibition of dihydropyrimidinases. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2020; 122:63-96. [PMID: 32951816 DOI: 10.1016/bs.apcsb.2020.05.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Dihydropyrimidinase catalyzes the reversible hydrolytic ring opening of dihydrouracil and dihydrothymine to N-carbamoyl-β-alanine and N-carbamyl-β-aminoisobutyrate, respectively. Dihydropyrimidinase from microorganisms is normally known as hydantoinase because of its role as a biocatalyst in the synthesis of d- and l-amino acids for the industrial production of antibiotic precursors and its broad substrate specificity. Dihydropyrimidinase belongs to the cyclic amidohydrolase family, which also includes imidase, allantoinase, and dihydroorotase. Although these metal-dependent enzymes share low levels of amino acid sequence homology, they possess similar active site architectures and may use a similar mechanism for catalysis. By contrast, the five human dihydropyrimidinase-related proteins possess high amino acid sequence identity and are structurally homologous to dihydropyrimidinase, but they are neuronal proteins with no dihydropyrimidinase activity. In this chapter, we summarize and discuss current knowledge and the recent advances on the structure, catalytic mechanism, and inhibition of dihydropyrimidinase.
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Affiliation(s)
- Cheng-Yang Huang
- School of Biomedical Sciences, Chung Shan Medical University, Taichung City, Taiwan; Department of Medical Research, Chung Shan Medical University Hospital, Taichung City, Taiwan
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