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Bisello G, Kusmierska K, Verbeek MM, Sykut-Cegielska J, Willemsen MAAP, Wevers RA, Szymańska K, Poznanski J, Drozak J, Wertheim-Tysarowska K, Rygiel AM, Bertoldi M. The novel P330L pathogenic variant of aromatic amino acid decarboxylase maps on the catalytic flexible loop underlying its crucial role. Cell Mol Life Sci 2022; 79:305. [PMID: 35593933 PMCID: PMC9121088 DOI: 10.1007/s00018-022-04343-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 04/13/2022] [Accepted: 05/01/2022] [Indexed: 12/14/2022]
Abstract
Aromatic amino acid decarboxylase (AADC) deficiency is a rare monogenic disease, often fatal in the first decade, causing severe intellectual disability, movement disorders and autonomic dysfunction. It is due to mutations in the gene coding for the AADC enzyme responsible for the synthesis of dopamine and serotonin. Using whole exome sequencing, we have identified a novel homozygous c.989C > T (p.Pro330Leu) variant of AADC causing AADC deficiency. Pro330 is part of an essential structural and functional element: the flexible catalytic loop suggested to cover the active site as a lid and properly position the catalytic residues. Our investigations provide evidence that Pro330 concurs in the achievement of an optimal catalytic competence. Through a combination of bioinformatic approaches, dynamic light scattering measurements, limited proteolysis experiments, spectroscopic and in solution analyses, we demonstrate that the substitution of Pro330 with Leu, although not determining gross conformational changes, results in an enzymatic species that is highly affected in catalysis with a decarboxylase catalytic efficiency decreased by 674- and 194-fold for the two aromatic substrates. This defect does not lead to active site structural disassembling, nor to the inability to bind the pyridoxal 5’-phosphate (PLP) cofactor. The molecular basis for the pathogenic effect of this variant is rather due to a mispositioning of the catalytically competent external aldimine intermediate, as corroborated by spectroscopic analyses and pH dependence of the kinetic parameters. Altogether, we determined the structural basis for the severity of the manifestation of AADC deficiency in this patient and discussed the rationale for a precision therapy.
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Affiliation(s)
- Giovanni Bisello
- Department of Neuroscience, Biomedicine and Movement Sciences, Section of Biochemistry, University of Verona, Strada Le Grazie 8, 37134, Verona, Italy
| | - Katarzyna Kusmierska
- Department of Screening and Metabolic Diagnostics, Institute of Mother and Child, Warsaw, Poland
| | - Marcel M Verbeek
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Centre, Geert Grooteplein 10, 6525 GA, Nijmegen, The Netherlands
- Translational Metabolic Laboratory, Department Laboratory Medicine, Radboud University Medical Cente, Geert Grooteplein 10, 6525 GA, Nijmegen, The Netherlands
| | - Jolanta Sykut-Cegielska
- Department of Inborn Errors of Metabolism and Paediatrics, Institute of Mother and Child, Warsaw, Poland
| | - Michèl A A P Willemsen
- Department of Pediatric Neurology, Radboud University Medical Centre, Geert Grooteplein 10, 6525 GA, Nijmegen, The Netherlands
| | - Ron A Wevers
- Translational Metabolic Laboratory, Department Laboratory Medicine, Radboud University Medical Cente, Geert Grooteplein 10, 6525 GA, Nijmegen, The Netherlands
| | - Krystyna Szymańska
- Department of Child and Adolescent Psychiatry, Medical University of Warsaw, Warsaw, Poland
| | - Jarosław Poznanski
- Department of Biophysics, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | - Jakub Drozak
- Department of Metabolic Regulation, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | | | | | - Mariarita Bertoldi
- Department of Neuroscience, Biomedicine and Movement Sciences, Section of Biochemistry, University of Verona, Strada Le Grazie 8, 37134, Verona, Italy.
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Wang Y, Chen X, Chen Q, Zhou N, Wang X, Zhang A, Chen K, Ouyang P. Construction of cell factory capable of efficiently converting L-tryptophan into 5-hydroxytryptamine. Microb Cell Fact 2022; 21:47. [PMID: 35331215 PMCID: PMC8944007 DOI: 10.1186/s12934-022-01745-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Accepted: 01/21/2022] [Indexed: 01/03/2023] Open
Abstract
BACKGROUND L-Tryptophan (L-Trp) derivatives such as 5-hydroxytryptophan (5-HTP) and 5-hydroxytryptamine (5-HT), N-Acetyl-5-hydroxytryptamine and melatonin are important molecules with pharmaceutical interest. Among, 5-HT is an inhibitory neurotransmitter with proven benefits for treating the symptoms of depression. At present, 5-HT depends on plant extraction and chemical synthesis, which limits its mass production and causes environmental problems. Therefore, it is necessary to develop an efficient, green and sustainable biosynthesis method to produce 5-HT. RESULTS Here we propose a one-pot production of 5-HT from L-Trp via two enzyme cascades for the first time. First, a chassis cell that can convert L-Trp into 5-HTP was constructed by heterologous expression of tryptophan hydroxylase from Schistosoma mansoni (SmTPH) and an artificial endogenous tetrahydrobiopterin (BH4) module. Then, dopa decarboxylase from Harminia axyridis (HaDDC), which can specifically catalyse 5-HTP to 5-HT, was used for 5-HT production. The cell factory, E. coli BL21(DE3)△tnaA/BH4/HaDDC-SmTPH, which contains SmTPH and HaDDC, was constructed for 5-HT synthesis. The highest concentration of 5-HT reached 414.5 ± 1.6 mg/L (with conversion rate of 25.9 mol%) at the optimal conditions (substrate concentration,2 g/L; induced temperature, 25℃; IPTG concentration, 0.5 mM; catalysis temperature, 30℃; catalysis time, 72 h). CONCLUSIONS This protocol provided an efficient one-pot method for converting. L-Trp into 5-HT production, which opens up possibilities for the practical biosynthesis of natural 5-HT at an industrial scale.
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Affiliation(s)
- Yingying Wang
- State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing, 211816, China.,College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, 211816, China
| | - Xueman Chen
- State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing, 211816, China.,College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, 211816, China
| | - Qiaoyu Chen
- State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing, 211816, China.,College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, 211816, China
| | - Ning Zhou
- State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing, 211816, China.,College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, 211816, China
| | - Xin Wang
- State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing, 211816, China.,College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, 211816, China
| | - Alei Zhang
- State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing, 211816, China.,College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, 211816, China
| | - Kequan Chen
- State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing, 211816, China. .,College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, 211816, China.
| | - Pingkai Ouyang
- State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing, 211816, China.,College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, 211816, China
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3
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Oxygen reactivity with pyridoxal 5'-phosphate enzymes: biochemical implications and functional relevance. Amino Acids 2020; 52:1089-1105. [PMID: 32844248 PMCID: PMC7497351 DOI: 10.1007/s00726-020-02885-6] [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: 05/06/2020] [Accepted: 08/18/2020] [Indexed: 12/29/2022]
Abstract
The versatility of reactions catalyzed by pyridoxal 5'-phosphate (PLP) enzymes is largely due to the chemistry of their extraordinary catalyst. PLP is necessary for many reactions involving amino acids. Reaction specificity is controlled by the orientation of the external aldimine intermediate that is formed upon addition of the amino acidic substrate to the coenzyme. The breakage of a specific bond of the external aldimine gives rise to a carbanionic intermediate. From this point, the different reaction pathways diverge leading to multiple activities: transamination, decarboxylation, racemization, elimination, and synthesis. A significant novelty appeared approximately 30 years ago when it was reported that some PLP-dependent decarboxylases are able to consume molecular oxygen transforming an amino acid into a carbonyl compound. These side paracatalytic reactions could be particularly relevant for human health, also considering that some of these enzymes are responsible for the synthesis of important neurotransmitters such as γ-aminobutyric acid, dopamine, and serotonin, whose dysregulation under oxidative conditions could have important implications in neurodegenerative states. However, the reactivity of PLP enzymes with dioxygen is not confined to mammals/animals. In fact, some plant PLP decarboxylases have been reported to catalyze oxidative reactions producing carbonyl compounds. Moreover, other recent reports revealed the existence of new oxidase activities catalyzed by new PLP enzymes, MppP, RohP, Ind4, CcbF, PvdN, Cap15, and CuaB. These PLP enzymes belong to the bacterial and fungal kingdoms and are present in organisms synthesizing bioactive compounds. These new PLP activities are not paracatalytic and could only scratch the surface on a wider and unexpected catalytic capability of PLP enzymes.
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Hoffarth ER, Rothchild KW, Ryan KS. Emergence of oxygen- and pyridoxal phosphate-dependent reactions. FEBS J 2020; 287:1403-1428. [PMID: 32142210 DOI: 10.1111/febs.15277] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 11/29/2019] [Accepted: 03/03/2020] [Indexed: 12/21/2022]
Abstract
Pyridoxal 5'-phosphate (PLP) is an organic cofactor employed by ~ 4% of enzymes. The structure of the PLP cofactor allows for the stabilization of carbanions through resonance. A small number of PLP-dependent enzymes employ molecular oxygen as a cosubstrate. Here, we review the biological roles and possible mechanisms of these enzymes, and we observe that these enzymes are found in multiple protein families, suggesting that reaction with oxygen might have emerged de novo in several protein families and thus could be directed to emerge again through laboratory evolution experiments.
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Affiliation(s)
- Elesha R Hoffarth
- Department of Chemistry, University of British Columbia, Vancouver, BC, Canada
| | | | - Katherine S Ryan
- Department of Chemistry, University of British Columbia, Vancouver, BC, Canada
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5
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Lan J, Liu Z, Liao C, Merkler DJ, Han Q, Li J. A Study for Therapeutic Treatment against Parkinson's Disease via Chou's 5-steps Rule. Curr Top Med Chem 2019; 19:2318-2333. [PMID: 31629395 DOI: 10.2174/1568026619666191019111528] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Revised: 08/05/2019] [Accepted: 08/22/2019] [Indexed: 11/22/2022]
Abstract
The enzyme L-DOPA decarboxylase (DDC), also called aromatic-L-amino-acid decarboxylase, catalyzes the biosynthesis of dopamine, serotonin, and trace amines. Its deficiency or perturbations in expression result in severe motor dysfunction or a range of neurodegenerative and psychiatric disorders. A DDC substrate, L-DOPA, combined with an inhibitor of the enzyme is still the most effective treatment for symptoms of Parkinson's disease. In this review, we provide an update regarding the structures, functions, and inhibitors of DDC, particularly with regards to the treatment of Parkinson's disease. This information will provide insight into the pharmacological treatment of Parkinson's disease.
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Affiliation(s)
- Jianqiang Lan
- Key Laboratory of Tropical Biological Resources of Ministry of Education, School of Life and Pharmaceutical Sciences, Hainan University, Haikou, Hainan 570228, China
| | - Zhongqiang Liu
- Key Laboratory of Tropical Biological Resources of Ministry of Education, School of Life and Pharmaceutical Sciences, Hainan University, Haikou, Hainan 570228, China
| | - Chenghong Liao
- Key Laboratory of Tropical Biological Resources of Ministry of Education, School of Life and Pharmaceutical Sciences, Hainan University, Haikou, Hainan 570228, China
| | - David J Merkler
- Department of Chemistry, University of South Florida, Tampa, FL, 33620, United States
| | - Qian Han
- Key Laboratory of Tropical Biological Resources of Ministry of Education, School of Life and Pharmaceutical Sciences, Hainan University, Haikou, Hainan 570228, China
| | - Jianyong Li
- Department of Biochemistry, Virginia Tech, Blacksburg, VA 24061, United States
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6
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McDonald AD, Perkins LJ, Buller AR. Facile in Vitro Biocatalytic Production of Diverse Tryptamines. Chembiochem 2019; 20:1939-1944. [PMID: 30864270 PMCID: PMC6800669 DOI: 10.1002/cbic.201900069] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 03/08/2019] [Indexed: 01/01/2023]
Abstract
Tryptamines are a medicinally important class of small molecules that serve as precursors to more complex, clinically used indole alkaloid natural products. Typically, tryptamine analogues are prepared from indoles through multistep synthetic routes. In the natural world, the desirable tryptamine synthon is produced in a single step by l-tryptophan decarboxylases (TDCs). However, no TDCs are known to combine high activity and substrate promiscuity, which might enable a practical biocatalytic route to tryptamine analogues. We have now identified the TDC from Ruminococcus gnavus as the first highly active and promiscuous member of this enzyme family. RgnTDC performs up to 96 000 turnovers and readily accommodates tryptophan analogues with substituents at the 4, 5, 6, and 7 positions, as well as alternative heterocycles, thus enabling the facile biocatalytic synthesis of >20 tryptamine analogues. We demonstrate the utility of this enzyme in a two-step biocatalytic sequence with an engineered tryptophan synthase to afford an efficient, cost-effective route to tryptamines from commercially available indole starting materials.
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Affiliation(s)
- Allwin D McDonald
- Department of Chemistry, University of Wisconsin, Madison, Madison, WI, 53705, USA
| | - Lydia J Perkins
- Department of Chemistry, University of Wisconsin, Madison, Madison, WI, 53705, USA
| | - Andrew R Buller
- Department of Chemistry, University of Wisconsin, Madison, Madison, WI, 53705, USA
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7
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Ren J, Zhang Y, Jin H, Yu J, Zhou Y, Wu F, Zhang W. Novel inhibitors of human DOPA decarboxylase extracted from Euonymus glabra Roxb. ACS Chem Biol 2014; 9:897-903. [PMID: 24471650 DOI: 10.1021/cb500009r] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Dopamine, a biogenic amine with important biological functions, is produced from l-DOPA by DOPA decarboxylase (DDC). DDC is a potential target to modulate the production of dopamine in several pathological states. Known inhibitors of DDC have been used for treatment of Parkinson's disease but suffered low specificity and diverse side effects. In the present study, we identified and characterized a novel class of natural-product-based selective inhibitors for DDC from the extract of Euonymus glabra Roxb. by a newly developed high-throughput enzyme assay. The structures of these inhibitors are dimeric diarylpropane, a unique chemical structure containing a divalent dopamine motif. The most effective inhibitors 5 and 6 have an IC50 of 11.5 ± 1.6 and 21.6 ± 2.7 μM in an in vitro purified enzyme assay, respectively, but did not inhibit other homologous enzymes. Compound 5 but not 6 dose-dependently suppressed the activity of hDDC and dopamine levels at low micromolar concentrations in cells. Furthermore, structure-activity relationship analyses revealed that p-benzoquinone might be a crucial moiety of these inhibitors for inhibiting hDDC. The natural-product-based selective inhibitors of hDDC could serve as a chemical lead for developing improved drugs for dopamine-related disease states.
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Affiliation(s)
| | - Yuanyuan Zhang
- Key
Laboratory of Exploration and Utilization of Aquatic Genetic Resources,
Ministry of Education, College of Fisheries and Life Science, Shanghai Ocean University, Shanghai 201306, China
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8
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Mammalian Dopa decarboxylase: structure, catalytic activity and inhibition. Arch Biochem Biophys 2014; 546:1-7. [PMID: 24407024 DOI: 10.1016/j.abb.2013.12.020] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2013] [Revised: 12/21/2013] [Accepted: 12/23/2013] [Indexed: 11/23/2022]
Abstract
Mammalian Dopa decarboxylase catalyzes the conversion of L-Dopa and L-5-hydroxytryptophan to dopamine and serotonin, respectively. Both of them are biologically active neurotransmitters whose levels should be finely tuned. In fact, an altered concentration of dopamine is the cause of neurodegenerative diseases, such as Parkinson's disease. The chemistry of the enzyme is based on the features of its coenzyme pyridoxal 5'-phosphate (PLP). The cofactor is highly reactive and able to perform multiple reactions, besides decarboxylation, such as oxidative deamination, half-transamination and Pictet-Spengler cyclization. The structure resolution shows that the enzyme has a dimeric arrangement and provides a molecular basis to identify the residues involved in each catalytic activity. This information has been combined with kinetic studies under steady-state and pre-steady-state conditions as a function of pH to shed light on residues important for catalysis. A great effort in DDC research is devoted to design efficient and specific inhibitors in addition to those already used in therapy that are not highly specific and are responsible for the side effects exerted by clinical approach to either Parkinson's disease or aromatic amino acid decarboxylase deficiency.
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9
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Cellini B, Montioli R, Oppici E, Voltattorni CB. Biochemical and computational approaches to improve the clinical treatment of dopa decarboxylase-related diseases: an overview. Open Biochem J 2012; 6:131-8. [PMID: 23264832 PMCID: PMC3528064 DOI: 10.2174/1874091x01206010131] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Revised: 10/12/2012] [Accepted: 10/23/2012] [Indexed: 11/22/2022] Open
Abstract
Dopa decarboxylase (DDC) is a pyridoxal 5’-phosphate (PLP)-dependent enzyme that by catalyzing the decarboxylation of L-Dopa and L-5-hydroxytryptophan produces the neurotransmitters dopamine and serotonin. The functional properties of pig kidney and human DDC enzymes have been extensively characterized, and the crystal structure of the enzyme in the holo- and apo-forms has been elucidated. DDC is a clinically relevant enzyme since it is involved in Parkinson’s disease (PD) and in aromatic amino acid decarboxylase (AADC) deficiency. PD, a chronic progressive neurological disorder characterized by tremor, bradykinesia, rigidity and postural instability, results from the degeneration of dopamine-producing cells in the substantia nigra of the brain. On the other hand, AADC deficiency is a rare debilitating recessive genetic disorder due to mutations in AADC gene leading to the inability to synthesize dopamine and serotonin. Development delay, abnormal movements, oculogyric crises and vegetative symptoms characterize this severe neurometabolic disease. This article is an up to date review of the therapies currently used in the treatment of PD and AADC deficiency as well as of the recent findings that, on one hand provide precious guidelines for the drug development process necessary to PD therapy, and, on the other, suggest an aimed therapeutic approach based on the elucidation of the molecular defects of each variant associated with AADC deficiency.
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Affiliation(s)
- Barbara Cellini
- Department of Life Sciences and Reproduction, Section of Biological Chemistry, University of Verona, Italy
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10
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Torrens-Spence MP, Liu P, Ding H, Harich K, Gillaspy G, Li J. Biochemical evaluation of the decarboxylation and decarboxylation-deamination activities of plant aromatic amino acid decarboxylases. J Biol Chem 2012. [PMID: 23204519 DOI: 10.1074/jbc.m112.401752] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Plant aromatic amino acid decarboxylase (AAAD) enzymes are capable of catalyzing either decarboxylation or decarboxylation-deamination on various combinations of aromatic amino acid substrates. These two different activities result in the production of arylalkylamines and the formation of aromatic acetaldehydes, respectively. Variations in product formation enable individual enzymes to play different physiological functions. Despite these catalytic variations, arylalkylamine and aldehyde synthesizing AAADs are indistinguishable without protein expression and characterization. In this study, extensive biochemical characterization of plant AAADs was performed to identify residues responsible for differentiating decarboxylation AAADs from aldehyde synthase AAADs. Results demonstrated that a tyrosine residue located on a catalytic loop proximal to the active site of plant AAADs is primarily responsible for dictating typical decarboxylase activity, whereas a phenylalanine at the same position is primarily liable for aldehyde synthase activity. Mutagenesis of the active site phenylalanine to tyrosine in Arabidopsis thaliana and Petroselinum crispum aromatic acetaldehyde synthases primarily converts the enzymes activity from decarboxylation-deamination to decarboxylation. The mutation of the active site tyrosine to phenylalanine in the Catharanthus roseus and Papaver somniferum aromatic amino acid decarboxylases changes the enzymes decarboxylation activity to a primarily decarboxylation-deamination activity. Generation of these mutant enzymes enables the production of unusual AAAD enzyme products including indole-3-acetaldehyde, 4-hydroxyphenylacetaldehyde, and phenylethylamine. Our data indicates that the tyrosine and phenylalanine in the catalytic loop region could serve as a signature residue to reliably distinguish plant arylalkylamine and aldehyde synthesizing AAADs. Additionally, the resulting data enables further insights into the mechanistic roles of active site residues.
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Daidone F, Montioli R, Paiardini A, Cellini B, Macchiarulo A, Giardina G, Bossa F, Borri Voltattorni C. Identification by virtual screening and in vitro testing of human DOPA decarboxylase inhibitors. PLoS One 2012; 7:e31610. [PMID: 22384042 PMCID: PMC3285636 DOI: 10.1371/journal.pone.0031610] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2011] [Accepted: 01/16/2012] [Indexed: 11/19/2022] Open
Abstract
Dopa decarboxylase (DDC), a pyridoxal 5'-phosphate (PLP) enzyme responsible for the biosynthesis of dopamine and serotonin, is involved in Parkinson's disease (PD). PD is a neurodegenerative disease mainly due to a progressive loss of dopamine-producing cells in the midbrain. Co-administration of L-Dopa with peripheral DDC inhibitors (carbidopa or benserazide) is the most effective symptomatic treatment for PD. Although carbidopa and trihydroxybenzylhydrazine (the in vivo hydrolysis product of benserazide) are both powerful irreversible DDC inhibitors, they are not selective because they irreversibly bind to free PLP and PLP-enzymes, thus inducing diverse side effects. Therefore, the main goals of this study were (a) to use virtual screening to identify potential human DDC inhibitors and (b) to evaluate the reliability of our virtual-screening (VS) protocol by experimentally testing the "in vitro" activity of selected molecules. Starting from the crystal structure of the DDC-carbidopa complex, a new VS protocol, integrating pharmacophore searches and molecular docking, was developed. Analysis of 15 selected compounds, obtained by filtering the public ZINC database, yielded two molecules that bind to the active site of human DDC and behave as competitive inhibitors with K(i) values ≥10 µM. By performing in silico similarity search on the latter compounds followed by a substructure search using the core of the most active compound we identified several competitive inhibitors of human DDC with K(i) values in the low micromolar range, unable to bind free PLP, and predicted to not cross the blood-brain barrier. The most potent inhibitor with a K(i) value of 500 nM represents a new lead compound, targeting human DDC, that may be the basis for lead optimization in the development of new DDC inhibitors. To our knowledge, a similar approach has not been reported yet in the field of DDC inhibitors discovery.
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Affiliation(s)
- Frederick Daidone
- Department of Biochemical Sciences “A. Rossi Fanelli”, University of Rome “La Sapienza”, Rome, Italy
| | - Riccardo Montioli
- Department of Life Sciences and Reproduction, University of Verona, Verona, Italy
| | - Alessandro Paiardini
- Department of Biochemical Sciences “A. Rossi Fanelli”, University of Rome “La Sapienza”, Rome, Italy
| | - Barbara Cellini
- Department of Life Sciences and Reproduction, University of Verona, Verona, Italy
| | - Antonio Macchiarulo
- Department of Chemistry and Drug Technology, University of Perugia, Perugia, Italy
| | - Giorgio Giardina
- Department of Biochemical Sciences “A. Rossi Fanelli”, University of Rome “La Sapienza”, Rome, Italy
| | - Francesco Bossa
- Department of Biochemical Sciences “A. Rossi Fanelli”, University of Rome “La Sapienza”, Rome, Italy
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12
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Montioli R, Cellini B, Borri Voltattorni C. Molecular insights into the pathogenicity of variants associated with the aromatic amino acid decarboxylase deficiency. J Inherit Metab Dis 2011; 34:1213-24. [PMID: 21541720 DOI: 10.1007/s10545-011-9340-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Revised: 03/21/2011] [Accepted: 04/11/2011] [Indexed: 10/18/2022]
Abstract
Dopa decarboxylase (DDC or AADC) is a pyridoxal 5'-phosphate (PLP)-dependent enzyme that catalyzes the decarboxylation of L-aromatic amino acids into the corresponding aromatic amines. AADC deficiency is an inborn error of neurotransmitters biosynthesis with an autosomal recessive inheritance. About 30 pathogenic mutations have been identified, but the enzymatic phenotypes causing AADC deficiency are unknown, and the therapeutic management is challenging. Here, we report biochemical and bioinformatic analyses of the human wild-type DDC and the pathogenic variants G102S, F309L, S147R and A275T whose mutations concern amino acid residues at or near the active site. We found that the mutations cause, even if to different extents, a decreased PLP binding affinity (in the range 1.4-170-fold), an altered state of the bound coenzyme and of its microenvironment, and a reduced catalytic efficiency (in the range 17-930-fold). Moreover, as compared to wild-type, the external aldimines formed by the variants with L-aromatic amino acids exhibit different spectroscopic features, do not protect against limited proteolysis, and lead to the formation, in addition to aromatic amines, of cyclic-substrate adducts. This suggests that these external Schiff bases are not properly oriented and anchored, i.e., in a conformation not completely productive for decarboxylation. The external aldimines that the variants form with D-Dopa also appear not to be correctly located at their active site, as suggested by the rate constants of PLP-L-Dopa adduct production higher than that of the wild-type. The possible therapeutic implications of the data are discussed in the light of the molecular defects of the pathogenic variants.
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Affiliation(s)
- Riccardo Montioli
- Dipartimento di Scienze della Vita e della Riproduzione, Sezione di Chimica Biologica, Facoltà di Medicina e Chirurgia, Università degli Studi di Verona, Strada Le Grazie, 8, 37134, Verona, Italy
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13
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Bunik VI, Schloss JV, Pinto JT, Dudareva N, Cooper AJL. A survey of oxidative paracatalytic reactions catalyzed by enzymes that generate carbanionic intermediates: implications for ROS production, cancer etiology, and neurodegenerative diseases. ADVANCES IN ENZYMOLOGY AND RELATED AREAS OF MOLECULAR BIOLOGY 2011; 77:307-60. [PMID: 21692372 DOI: 10.1002/9780470920541.ch7] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Victoria I Bunik
- School of Bioinformatics and Bioengineering, and Belozersky Institute of Physico-Chemical Biology, Moscow Lomonosov State University, Moscow, Russian Federation
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Chang C, Xu C. Transcriptome atlas of aromatic amino acid family metabolism-related genes in eight liver cell types uncovers the corresponding metabolic pathways in rat liver regeneration. Int J Biochem Cell Biol 2010; 42:1708-16. [DOI: 10.1016/j.biocel.2010.06.025] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2010] [Revised: 06/11/2010] [Accepted: 06/30/2010] [Indexed: 01/19/2023]
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15
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Bertoldi M, Voltattorni CB. Multiple roles of the active site lysine of Dopa decarboxylase. Arch Biochem Biophys 2009; 488:130-9. [PMID: 19580779 DOI: 10.1016/j.abb.2009.06.019] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2009] [Revised: 06/05/2009] [Accepted: 06/30/2009] [Indexed: 10/20/2022]
Abstract
The pyridoxal 5'-phosphate dependent-enzyme Dopa decarboxylase, responsible for the irreversible conversion of l-Dopa to dopamine, is an attractive drug target. The contribution of the pyridoxal-Lys303 to the catalytic mechanisms of decarboxylation and oxidative deamination is analyzed. The K303A variant binds the coenzyme with a 100-fold decreased apparent equilibrium binding affinity with respect to the wild-type enzyme. Unlike the wild-type, K303A in the presence of l-Dopa displays a parallel progress course of formation of both dopamine and 3,4-dihydroxyphenylacetaldehyde (plus ammonia) with a burst followed by a linear phase. Moreover, the finding that the catalytic efficiencies of decarboxylation and of oxidative deamination display a decrease of 1500- and 17-fold, respectively, with respect to the wild-type, is indicative of a different impact of Lys303 mutation on these reactions. Kinetic analyses reveal that Lys303 is involved in external aldimine formation and hydrolysis as well as in product release which affects the rate-determining step of decarboxylation.
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Affiliation(s)
- Mariarita Bertoldi
- Dipartimento di Scienze Morfologico-Biomediche, Sezione di Chimica Biologica, Facoltà di Medicina e Chirurgia, Università di Verona, 37134 Verona, Italy.
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16
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Bertoldi M, Cellini B, Montioli R, Borri Voltattorni C. Insights into the mechanism of oxidative deamination catalyzed by DOPA decarboxylase. Biochemistry 2008; 47:7187-95. [PMID: 18547057 DOI: 10.1021/bi800478s] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The unusual oxygen-consuming oxidative deamination reaction catalyzed by the pyridoxal 5'-phosphate (PLP) enzyme DOPA decarboxylase (DDC) was here investigated. Either wild-type or Y332F DDC variant is able to perform such oxidation toward aromatic amines or aromatic l-amino acids, respectively, without the aid of any cofactor related to oxygen chemistry. Oxidative deamination produces, in equivalent amounts, a carbonyl compound and ammonia, accompanied by dioxygen consumption in a 1:2 molar ratio with respect to the products. Kinetic studies either in the pre-steady or in the steady state, together with HPLC analyses of reaction mixtures under varying experimental conditions, revealed that a ketimine accumulates during the linear phase of product formation. This species is reactive since it is converted back to PLP when the substrate is consumed. Rapid-mixing chemical quench studies provide evidence that the ketimine is indeed an intermediate formed during the first catalytic cycle. Moreover, superoxide anion and hydrogen peroxide are both generated during the catalytic cycles. On this basis, a mechanism of oxidative deamination consistent with the present data is proposed. Furthermore, the catalytic properties of the T246A DDC mutant together with those previously obtained with H192Q mutant allow us to propose that the Thr246-His192 dyad could act as a general base in promoting the first step of the oxidative deamination of aromatic amines.
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Affiliation(s)
- Mariarita Bertoldi
- Dipartimento di Scienze Morfologico-Biomediche, sezione di Chimica Biologica, Facoltà di Medicina e Chirurgia, Strada Le Grazie, 8, 37134 Verona, Italy.
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17
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Abstract
Vitamin B6is a water-soluble vitamin, and is readily metabolized and excreted, so it has generally been assumed to have negligible toxicity, although at very high levels of intake it can cause peripheral nerve damage. Nutritional deficiency disease is extremely rare, although a significant proportion of the population shows biochemical evidence of inadequate status, despite apparently adequate levels of intake. The vitamin has been used to treat a wide variety of conditions, which may or may not be related to inadequate intake. In some conditions use of vitamin B6supplements has been purely empirical; in other conditions there is a reasonable physiological or metabolic mechanism to explain why supplements of the vitamin many times greater than average requirements may have therapeutic uses. However, even in such conditions there is little evidence of efficacy from properly conducted controlled trials.
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Bunik VI, Schloss JV, Pinto JT, Gibson GE, Cooper AJL. Enzyme-Catalyzed Side Reactions with Molecular Oxygen may Contribute to Cell Signaling and Neurodegenerative Diseases. Neurochem Res 2007; 32:871-91. [PMID: 17342415 DOI: 10.1007/s11064-006-9239-z] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2006] [Accepted: 11/22/2006] [Indexed: 02/07/2023]
Abstract
A link between neurodegeneration and well-characterized enzymatic and non-enzymatic reactions that produce reactive oxygen species (ROS) from O(2) is well established. Several enzymes that contain pyridoxal 5'-phosphate (PLP) or thiamine diphosphate (ThDP) catalyze side reactions (paracatalytic reactions) in the presence of ambient O(2). These side reactions produce oxidants such as hydrogen peroxide [H(2)O(2)] or extremely reactive peracids [RC(O)OOH]. We hypothesize that although these enzymes normally produce oxidants at low or undetectable levels, changes in substrate levels or disease-induced structural alterations may enhance interactions with O(2), thereby generating higher levels of reactive oxidants. These oxidants may damage the enzymes producing them, alter nearby macromolecules and/or destroy important metabolites/coenzymes. We propose that paracatalytic reactions with O(2) catalyzed by PLP-dependent decarboxylases and by ThDP-dependent enzymes within the alpha-keto acid dehydrogenase complexes may contribute to normal cellular signaling and to cellular damage in neurodegenerative diseases.
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Affiliation(s)
- Victoria I Bunik
- School of Bioengineering and Bioinformatics, and Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119992, Russia
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Bertoldi M, Cellini B, Maras B, Voltattorni CB. A quinonoid is an intermediate of oxidative deamination reaction catalyzed by Dopa decarboxylase. FEBS Lett 2005; 579:5175-80. [PMID: 16150447 DOI: 10.1016/j.febslet.2005.08.029] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2005] [Revised: 08/03/2005] [Accepted: 08/15/2005] [Indexed: 11/20/2022]
Abstract
The reactions of Dopa decarboxylase (DDC) with l- and d-enantiomers of tryptophan methyl ester are described. Although both the enantiomers bind to the active site of the enzyme with similar affinity, their binding modes are different. l-enantiomer binds in an unproductive mode, while d-enantiomer acts as an oxidative deamination substrate. For the first time a quinonoid has been detected as intermediate of this reaction. By using rapid-scanning stopped-flow kinetic technique rate constants for formation and decay of this species have been determined. All these data, besides validating the functional DDC active site model, represent an important step toward the elucidation of the catalytic pathway of oxidative deamination.
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Affiliation(s)
- Mariarita Bertoldi
- Dipartimento di Scienze Neurologiche e della Visione, Sezione di Chimica Biologica, Università di Verona, Italy
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20
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Bertoldi M, Borri Voltattorni C. Reaction and substrate specificity of recombinant pig kidney Dopa decarboxylase under aerobic and anaerobic conditions. BIOCHIMICA ET BIOPHYSICA ACTA 2003; 1647:42-7. [PMID: 12686106 DOI: 10.1016/s1570-9639(03)00046-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Dopa decarboxylase (DDC) catalyzes as main reaction the stereospecific CO(2) abstraction from L-Dopa and L-5-hydroxytryptophan (5-HTP), generating the corresponding aromatic amines, dopamine and serotonin, respectively. Side reactions with turnover time of minutes are also catalyzed by the enzyme. In particular, DDC exhibits half-transaminase activity toward D-aromatic amino acids and oxidative deaminase activity toward aromatic amines. The latter reaction could represent a new activity for this class of enzymes. Studies on the effect exerted by O(2) on reaction specificity of DDC revealed that under anaerobic conditions decarboxylation of L-aromatic amino acids takes place with a k(cat) approximately half of that measured in the presence of O(2), and is accompanied by a decarboxylation-dependent transamination, whereas oxidative deamination of aromatic amines is replaced by half-transamination. Half-transamination of D-aromatic amino acids is unaffected by the presence or absence of O(2). Some structural elements relevant for the control of reaction and substrate specificity of DDC have been identified by means of limited tryptic digestion and site-directed mutagenesis studies. All together, the data indicate that the chemical nature of the substrate, the presence of O(2), the integrity of a mobile loop, the absence of perturbation in the coenzyme-binding cleft and pH are important requirements for the achievement of a closed conformational state where the highest level of reaction specificity is reached.
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Affiliation(s)
- Mariarita Bertoldi
- Dipartimento di Scienze Neurologiche e della Visione, Sezione di Chimica Biologica, Università degli Studi di Verona, Strada Le Grazie, 8, 37134 Verona, Italy
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21
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Bertoldi M, Gonsalvi M, Contestabile R, Voltattorni CB. Mutation of tyrosine 332 to phenylalanine converts dopa decarboxylase into a decarboxylation-dependent oxidative deaminase. J Biol Chem 2002; 277:36357-62. [PMID: 12118007 DOI: 10.1074/jbc.m204867200] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A flexible loop (residues 328-339), presumably covering the active site upon substrate binding, has been revealed in 3,4-dihydroxyphenylalanine decarboxylase by means of kinetic and structural studies. The function of tyrosine 332 has been investigated by substituting it with phenylalanine. Y332F displays coenzyme content and spectroscopic features identical to those of the wild type. Unlike wild type, during reactions with l-aromatic amino acids under both aerobic and anaerobic conditions, Y332F does not catalyze the formation of aromatic amines. However, analysis of the products shows that in aerobiosis, l-aromatic amino acids are converted into the corresponding aromatic aldehydes, ammonia, and CO(2) with concomitant O(2) consumption. Therefore, substitution of Tyr-332 with phenylalanine results in the suppression of the original activity and in the generation of a decarboxylation-dependent oxidative deaminase activity. In anaerobiosis, Y332F catalyzes exclusively a decarboxylation-dependent transamination of l-aromatic amino acids. A role of Tyr-332 in the Calpha protonation step that catalyzes the formation of physiological products has been proposed. Furthermore, Y332F catalyzes oxidative deamination of aromatic amines and half-transamination of d-aromatic amino acids with k(cat) values comparable with those of the wild type. However, for all the mutant-catalyzed reactions, an increase in K(m) values is observed, suggesting that Y --> F replacement also affects substrate binding.
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Affiliation(s)
- Mariarita Bertoldi
- Dipartimento di Scienze Neurologiche e della Visione, Sezione di Chimica Biologica, Facoltà di Medicina e Chirurgia, Università degli Studi di Verona, Strada Le Grazie, 8, 37134 Verona, Italy
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22
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Bertoldi M, Castellani S, Bori Voltattorni C. Mutation of residues in the coenzyme binding pocket of Dopa decarboxylase. Effects on catalytic properties. ACTA ACUST UNITED AC 2001; 268:2975-81. [PMID: 11358515 DOI: 10.1046/j.1432-1327.2001.02187.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Residues D271, H192, H302 and N300 of L-3,4-dihydroxyphenylalanine decarboxylase (DDC), a homodimeric pyridoxal 5'-phosphate (PLP) enzyme, were mutated in order to acquire information on the catalytic mechanism. These residues are potential participants in catalysis because they belong to the common PLP-binding structural motif of group I, II and III decarboxylases and other PLP enzymes, and because they are among the putative active-site residues of structural modelled rat liver DDC. The spectroscopic features of the D271E, H192Q, H302Q and N300A mutants as well as their dissociation constants for PLP suggest that substitution of each of these residues causes alteration of the state of the bound coenzyme molecule and of the conformation of aromatic amino acids, possibly in the vicinity of the active site. This supports, but does not prove, the possibility that these residues are located in the coenzyme-binding cleft. Interestingly, mutation of each residue generates an oxidative decarboxylase activity towards L-3,4-dihydroxyphenylalanine (L-Dopa), not inherent in the wild-type in aerobiosis, and reduces the nonoxidative decarboxylase activity of L-Dopa from 3- to 390-fold. The partition ratio between oxidative and nonoxidative decarboxylation ranges from 5.7 x 10(-4) for N300A mutant to 946 x 10(-4) for H302Q mutant. Unlike wild-type enzyme, the mutants catalyse these two reactions to the same extent either in the presence or absence of O2. In addition, all four mutants exhibit an extremely low level of the oxidative deaminase activity towards serotonin with respect to wild-type. All these findings demonstrate that although D271, H192, H302 and N300 are not essential for catalysis, mutation of these residues alters the nature of catalysis. A possible relationship among the integrity of the PLP cleft, the productive binding of O2 and the transition to a closed conformational state of DDC is discussed.
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Affiliation(s)
- M Bertoldi
- Dipartimento di Scienze Neurologiche e della Visione, Sezione di Chimica Biologica, Facoltà di Medicina e Chirurgia, Università degli Studi di Verona, Strada Le Grazie, Verona, Italy
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23
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Bertoldi M, Gonsalvi M, Voltattorni CB. Green Tea Polyphenols: Novel Irreversible Inhibitors of Dopa Decarboxylase. Biochem Biophys Res Commun 2001; 284:90-3. [PMID: 11374875 DOI: 10.1006/bbrc.2001.4945] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The green tea gallocatechins, (-)-epigallocatechin-3-O-gallate (EGCG), and (-)-epigallocatechin (EGC) were found to be inhibitors of Dopa decarboxylase (DDC). EGCG and EGC inactivate the enzyme in both a time- and concentration-dependent manner and exhibit saturation of the rate of inactivation at high concentrations, with efficiency of inactivation values (k(inact)/K(i)) of 868 and 1511 M(-1) min(-1), respectively. In contrast, gallic acid behaves as a weak inhibitor of DDC. Protection against inactivation by EGCG and EGC was observed in the presence of the active site-directed inhibitor D-Dopa. Either EGCG or EGC induce changes in the absorbance and CD bands of the visible spectrum of enzyme-bound PLP. Taken together, these findings indicate the active site nature of the interaction of DDC with both polyphenols. On the basis of the properties of the EGCG-inactivated enzyme, it can be suggested that inactivation could be ascribed to a covalent modification of not yet identified residue(s) of the active site of DDC.
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Affiliation(s)
- M Bertoldi
- Dipartimento di Scienze Neurologiche e della Visione, Sezione di Chimica Biologica, Facoltà di Medicina e Chirurgia, Università degli Studi di Verona, Strada Le Grazie, 8, Verona, 37134, Italy
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24
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Bertoldi M, Voltattorni CB. Dopa decarboxylase exhibits low pH half-transaminase and high pH oxidative deaminase activities toward serotonin (5-hydroxytryptamine). Protein Sci 2001; 10:1178-86. [PMID: 11369856 PMCID: PMC2374013 DOI: 10.1110/ps.46601] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2000] [Revised: 03/19/2001] [Accepted: 03/20/2001] [Indexed: 10/14/2022]
Abstract
Dopa decarboxylase (DDC) catalyzes not only the decarboxylation of L-aromatic amino acids but also side reactions including half-transamination of D-aromatic amino acids and oxidative deamination of aromatic amines. The latter reaction produces, in equivalent amounts, an aromatic aldehyde or ketone (depending on the nature of the substrate), and ammonia, accompanied by O(2) consumption in a 1 : 2 molar ratio with respect to the products. The kinetic mechanism and the pH dependence of the kinetic parameters have been determined in order to obtain information on the chemical mechanism for this reaction toward 5-hydroxytryptamine (5-HT). The initial velocity studies indicate that 5-HT and O(2) bind to the enzyme sequentially, and that D-Dopa is a competitive inhibitor versus 5-HT and a noncompetitive inhibitor versus O(2). The results are consistent with a mechanism in which 5-HT binds to DDC before O(2). The pH dependency of log V for the oxidative deaminase reaction shows that the enzyme possesses a single ionizing group with a pK value of approximately 7.8 that must be unprotonated for catalysis. In addition to an ionizing residue with a pK value of 7.9 similar to that found in the V profile, the (V/K)(5-HT) profile exhibits a pK value of 9.8, identical to that of free substrate. This pK was therefore tentatively assigned to the alpha-amino group of 5-HT. No titratable ionizing residue was detected in the (V/K)(O2) profile, in the pH range examined. Surprisingly, at pH values lower than 7, where oxidative deamination does not occur to a significant extent, a half-transamination of 5-HT takes place. The rate constant of pyridoxamine 5'-phosphate formation increases below a single pK of approximately 6.7. This value mirrors the spectrophotometric pK(spec) of the shift 420-384 nm of the external aldimine between DDC and 5-HT. Nevertheless, the analysis of the reaction of DDC with 5-HT under anaerobic conditions indicates that only half-transamination occurs with a pH-independent rate constant over the pH range 6-8.5. A model accounting for these data is proposed that provides alternative pathways leading to oxidative deamination or half-transamination.
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Affiliation(s)
- M Bertoldi
- Dipartimento di Scienze Neurologiche e della Visione, Sezione di Chimica Biologica, Facoltà di Medicina e Chirurgia, Università degli Studi di Verona, Strada Le Grazie, 8, 37134 Verona, Italy
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25
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Tang L, Frank G. Identification and characterization of an aromatic amino acid decarboxylase from the filarial nematode, Dirofilaria immitis. Biol Chem 2001; 382:115-22. [PMID: 11258661 DOI: 10.1515/bc.2001.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
A novel secreted aromatic amino acid decarboxylase-like molecule was identified in the excretory/secretory products of L3/L4 larvae as well as in an extract of adult Dirofilaria immitis. The secretion of the enzyme was developmentally regulated. Peak enzyme activities were detected in the culture medium before and after the molting of L3 larvae in vitro. The enzyme was purified from D. immitis adult extracts and the excretory/secretory products of L3/L4 larvae using different chromatographic methods followed by isoelectric focusing and SDS-PAGE. The enzyme has a molecular mass of 48 kDa and a pI of 5.6, and shows a specific enzymatic activity towards the aromatic amino acid substrates phenylalanine, tyrosine and tryptophan. The enzyme's activity did not show an absolute requirement for exogenous pyridoxal-5-phosphate. However, addition of pyridoxal-5-phosphate at 5 microM in the reaction increased the enzyme activity greatly. The enzyme had the ability to catalyze the formation of dopamine from L-dopa. Studies on the effects of inhibitors on the enzyme activity showed that the enzyme was sensitive to Pefabloc and p-chloromercuribenzoic acid, but not to diisopropyl flurophosphate. The Km values of the enzyme for H-Phe-AMC, H-Tyr-AMC and H-Trp-AMC were calculated to be 32.1 microM, 35.1 microM and 29.1 microM, respectively.
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Affiliation(s)
- L Tang
- Heska Corporation, Fort Collins, Colorado 80525, USA
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26
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Facchini PJ, Huber-Allanach KL, Tari LW. Plant aromatic L-amino acid decarboxylases: evolution, biochemistry, regulation, and metabolic engineering applications. PHYTOCHEMISTRY 2000; 54:121-38. [PMID: 10872203 DOI: 10.1016/s0031-9422(00)00050-9] [Citation(s) in RCA: 166] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A comprehensive survey of the extensive literature relevant to the evolution, physiology, biochemistry, regulation, and genetic engineering applications of plant aromatic L-amino acid decarboxylases (AADCs) is presented. AADCs catalyze the pyridoxal-5'-phosphate (PLP)-dependent decarboxylation of select aromatic L-amino acids in plants, mammals, and insects. Two plant AADCs, L-tryptophan decarboxylase (TDC) and L-tyrosine decarboxylase (TYDC), have attracted considerable attention because of their role in the biosynthesis of pharmaceutically important monoterpenoid indole alkaloids and benzylisoquinoline alkaloids, respectively. Although plant and animal AADCs share extensive amino acid homology, the enzymes display striking differences in their substrate specificities. AADCs from mammals and insects accept a broad range of aromatic L-amino acids, whereas TDC and TYDC from plants exhibit exclusive substrate specificity for L-amino acids with either indole or phenol side chains, but not both. Recent biochemical and kinetic studies on animal AADCs support basic features of the classic AADC reaction mechanism. The catalytic mechanism involves the formation of a Schiff base between PLP and an invariable lysine residue, followed by a transaldimination reaction with an aromatic L-amino acid substrate. Both TDC and TYDC are primarily regulated at the transcriptional level by developmental and environmental factors. However, the putative post-translational regulation of TDC via the ubiquitin pathway, by an ATP-dependent proteolytic process, has also been suggested. Isolated TDC and TYDC genes have been used to genetically alter the regulation of secondary metabolic pathways derived from aromatic amino acids in several plant species. The metabolic modifications include increased serotonin levels, reduced indole glucosinolate levels, redirected shikimate metabolism, increased indole alkaloid levels, and increased cell wall-bound tyramine levels.
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Affiliation(s)
- P J Facchini
- Department of Biological Sciences, University of Calgary, Alta., Canada.
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27
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Bertoldi M, Frigeri P, Paci M, Voltattorni CB. Reaction specificity of native and nicked 3,4-dihydroxyphenylalanine decarboxylase. J Biol Chem 1999; 274:5514-21. [PMID: 10026165 DOI: 10.1074/jbc.274.9.5514] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
3,4-Dihydroxyphenylalanine (Dopa) decarboxylase is a stereospecific pyridoxal 5'-phosphate (PLP)-dependent alpha-decarboxylase that converts L-aromatic amino acids into their corresponding amines. We now report that reaction of the enzyme with D-5-hydroxytryptophan or D-Dopa results in a time-dependent inactivation and conversion of the PLP coenzyme to pyridoxamine 5'-phosphate and PLP-D-amino acid Pictet-Spengler adducts, which have been identified by high performance liquid chromatography. We also show that the reaction specificity of Dopa decarboxylase toward aromatic amines depends on the experimental conditions. Whereas oxidative deamination occurs under aerobic conditions (Bertoldi, M., Moore, P. S., Maras, B., Dominici, P., and Borri Voltattorni, C. (1996) J. Biol. Chem. 271, 23954-23959; Bertoldi, M., Dominici, P., Moore, P. S., Maras, B., and Borri Voltattorni, C. (1998) Biochemistry 37, 6552-6561), half-transamination and Pictet-Spengler reactions take place under anaerobic conditions. Moreover, we examined the reaction specificity of nicked Dopa decarboxylase, obtained by selective tryptic cleavage of the native enzyme between Lys334 and His335. Although this enzymatic species does not exhibit either decarboxylase or oxidative deamination activities, it retains a large percentage of the native transaminase activity toward D-aromatic amino acids and displays a slow transaminase activity toward aromatic amines. These transamination reactions occur concomitantly with the formation of cyclic coenzyme-substrate adducts. Together with additional data, we thus suggest that native Dopa decarboxylase can exist as an equilibrium among "open," "half-open," and "closed" forms.
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Affiliation(s)
- M Bertoldi
- Dipartimento di Scienze Neurologiche e della Visione, Sezione di Chimica Biologica, Facoltà di Medicina e Chirurgia, Università degli Studi di Verona, Strada Le Grazie, 8, 37134 Verona, Italy
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28
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Bertoldi M, Dominici P, Moore PS, Maras B, Voltattorni CB. Reaction of dopa decarboxylase with alpha-methyldopa leads to an oxidative deamination producing 3,4-dihydroxyphenylacetone, an active site directed affinity label. Biochemistry 1998; 37:6552-61. [PMID: 9572873 DOI: 10.1021/bi9718898] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Dopa decarboxylase (DDC) catalyzes the cleavage of alpha-methylDopa into 3,4-dihydroxyphenylacetone and ammonia, via the intermediate alpha-methyldopamine, which does not accumulate during catalysis. The ketone has been identified by high-performance liquid chromatography and mass spectroscopic analysis, and ammonia by means of glutamate dehydrogenase. Molecular oxygen is consumed during the reaction in a 1:2 molar ratio with respect to the products. The kcat and Km of this reaction were determined to be 5.68 min-1 and 45 microM, respectively. When the reaction is carried out under anaerobic conditions, alpha-methyldopamine is formed in a time-dependent manner and neither ammonia nor ketone is produced to a significant extent. The reaction is accompanied by a time- and concentration-dependent inactivation of the enzyme with kinact of 0. 012 min-1 and Ki of 39.3 microM. Free 3,4-dihydroxyphenylacetone binds to the active site of DDC and inactivates the enzyme in a time- and concentration-dependent manner with a kinact/Ki value similar to that of alpha-methylDopa. d-Dopa, a competitive inhibitor of DDC, protects the enzyme against inactivation. Taken together, these findings indicate the active site directed nature of the interaction of DDC with 3,4-dihydroxyphenylacetone and provide evidence that the ketone generated by the reaction of DDC with alpha-methylDopa dissociates from the active site before it inactivates the enzyme. Inactivation of the enzyme by ketone followed by NaB3H4 reduction and chymotryptic digestion revealed that the lysine residue which binds pyridoxal 5'-phosphate (PLP) in the native enzyme is the site of covalent modification. Together with the characterization of the adduct released from the inactivated DDC, these data suggest that the enzyme is inactivated by trapping the coenzyme in a ternary adduct with ketone and the active site lysine. As recently reported for serotonin (5-HT) [Bertoldi, M., Moore, P. S., Maras, B., Dominici, P., and Borri Voltattorni, C. (1996) J. Biol. Chem. 271, 23954-23959], the conversion of dopamine (DA) into 3,4-dihydroxyphenylacetaldehyde and ammonia catalyzed by DDC is accompanied by irreversible loss of decarboxylase activity. However, the comparison between the absorbance, fluorescence, and CD features of DDC after 5-HT- or 3, 4-dihydroxyphenylacetone-induced inactivation shows that a different covalent adduct is formed between either of these two molecules and DDC-bound PLP.
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Affiliation(s)
- M Bertoldi
- Istituto di Chimica Biologica, Facoltà di Medicina e Chirurgia, Università degli Studi di Verona, Strada Le Grazie, 8, 37134 Verona, Italy
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29
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Dominici P, Moore PS, Castellani S, Bertoldi M, Voltattorni CB. Mutation of cysteine 111 in Dopa decarboxylase leads to active site perturbation. Protein Sci 1997; 6:2007-15. [PMID: 9300500 PMCID: PMC2143786 DOI: 10.1002/pro.5560060921] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Cysteine 111 in Dopa decarboxylase (DDC) has been replaced by alanine or serine by site-directed mutagenesis. Compared to the wild-type enzyme, the resultant C111A and C111S mutant enzymes exhibit Kcat values of about 50% and 15%, respectively, at pH 6.8, while the K(m) values remain relatively unaltered for L-3,4-dihydroxyphenylalanine (L-Dopa) and L-5-hydroxytryptophan (L-5-HTP). While a significant decrease of the 280 nm optically active band present in the wild type is observed in mutant DDCs, their visible co-enzyme absorption and CD spectra are similar to those of the wild type. With respect to the wild type, the Cys-111-->Ala mutant displays a reduced affinity for pyridoxal 5'-phosphate (PLP), slower kinetics of reconstitution to holoenzyme, a decreased ability to anchor the external aldimine formed between D-Dopa and the bound co-enzyme, and a decreased efficiency of energy transfer between tryptophan residue(s) and reduced PLP. Values of pKa and pKb for the groups involved in catalysis were determined for the wild-type and the C111A mutant enzymes. The mutant showed a decrease in both pK values by about 1 pH unit, resulting in a shift of the pH of the maximum velocity from 7.2 (wild-type) to 6.2 (mutant). This change in maximum velocity is mirrored by a similar shift in the spectrophotometrically determined pK value of the 420-->390 nm transition of the external aldimine. These results demonstrate that the sulfhydryl group of Cys-111 is catalytically nonessential and provide strong support for previous suggestion that this residue is located at or near the PLP binding site (Dominici P, Maras B, Mei G, Borri Voltattorni C. 1991. Eur J Biochem 201:393-397). Moreover, our findings provide evidence that Cys-111 has a structural role in PLP binding and suggest that this residue is required for maintenance of proper active-site conformation.
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Affiliation(s)
- P Dominici
- Facoltà di Scienze Matematiche, Fisiche e Naturali, Università di Verona, Italy
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