1
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Rabattoni V, Motta Z, Miceli M, Molla G, Fissore A, Adinolfi S, Pollegioni L, Sacchi S. On the regulation of human D-aspartate oxidase. Protein Sci 2023; 32:e4802. [PMID: 37805834 PMCID: PMC10588558 DOI: 10.1002/pro.4802] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Revised: 09/14/2023] [Accepted: 10/03/2023] [Indexed: 10/09/2023]
Abstract
The human flavoenzyme D-aspartate oxidase (hDASPO) controls the level of D-aspartate in the brain, a molecule acting as an agonist of NMDA receptors and modulator of AMPA and mGlu5 receptors. hDASPO-induced D-aspartate degradation prevents age-dependent deterioration of brain functions and is related to psychiatric disorders such as schizophrenia and autism. Notwithstanding this crucial role, less is known about hDASPO regulation. Here, we report that hDASPO is nitrosylated in vitro, while no evidence of sulfhydration and phosphorylation is apparent: nitrosylation affects the activity of the human flavoenzyme to a limited extent. Furthermore, hDASPO interacts with the primate-specific protein pLG72 (a well-known negative chaperone of D-amino acid oxidase, the enzyme deputed to D-serine degradation in the human brain), yielding a ~114 kDa complex, with a micromolar dissociation constant, promoting the flavoenzyme inactivation. At the cellular level, pLG72 and hDASPO generate a cytosolic complex: the expression of pLG72 negatively affects the hDASPO level by reducing its half-life. We propose that pLG72 binding may represent a protective mechanism aimed at avoiding cytotoxicity due to H2 O2 produced by the hDASPO enzymatic degradation of D-aspartate, especially before the final targeting to peroxisomes.
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Affiliation(s)
- Valentina Rabattoni
- “The Protein Factory 2.0”, Dipartimento di Biotecnologie e Scienze della VitaUniversità degli studi dell'InsubriaVareseItaly
| | - Zoraide Motta
- “The Protein Factory 2.0”, Dipartimento di Biotecnologie e Scienze della VitaUniversità degli studi dell'InsubriaVareseItaly
| | - Matteo Miceli
- “The Protein Factory 2.0”, Dipartimento di Biotecnologie e Scienze della VitaUniversità degli studi dell'InsubriaVareseItaly
| | - Gianluca Molla
- “The Protein Factory 2.0”, Dipartimento di Biotecnologie e Scienze della VitaUniversità degli studi dell'InsubriaVareseItaly
| | - Alex Fissore
- Dipartimento di Scienza e Tecnologia del FarmacoUniversità di TorinoTorinoItaly
| | - Salvatore Adinolfi
- Dipartimento di Scienza e Tecnologia del FarmacoUniversità di TorinoTorinoItaly
| | - Loredano Pollegioni
- “The Protein Factory 2.0”, Dipartimento di Biotecnologie e Scienze della VitaUniversità degli studi dell'InsubriaVareseItaly
| | - Silvia Sacchi
- “The Protein Factory 2.0”, Dipartimento di Biotecnologie e Scienze della VitaUniversità degli studi dell'InsubriaVareseItaly
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2
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Wu S, Zhou J, Zhang H, Barger SW. Serine Racemase Expression Differentiates Aging from Alzheimer's Brain. Curr Alzheimer Res 2022; 19:494-502. [PMID: 35929621 DOI: 10.2174/1567205019666220805105106] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Revised: 06/27/2022] [Accepted: 06/29/2022] [Indexed: 01/27/2023]
Abstract
Aging is an inevitable process characterized by progressive loss of physiological integrity and increased susceptibility to cancer, diabetes, cardiovascular, and neurodegenerative diseases; aging is the primary risk factor for Alzheimer's disease (AD), the most common cause of dementia. AD is characterized by brain pathology, including extracellular deposition of amyloid aggregation and intracellular accumulation of neurofibrillary tangles composed of hyperphosphorylated tau protein. In addition, losses of synapses and a wide range of neurons are pivotal pathologies in the AD brain. Accumulating evidence demonstrates hypoactivation of hippocampal neural networks in the aging brain, whereas AD-related mild cognitive impairment (AD-MCI) begins with hyperactivation, followed by a diminution of hippocampal activity as AD develops. The biphasic trends of the activity of the hippocampal neural network are consistent with the alteration of N-methyl-D-aspartate receptor (NMDA-R) activity from aging to prodromal (AD-MCI) to mid-/late stage AD. D-serine, a product of racemization catalyzed by serine racemase (SR), is an important co-agonist of the NMDA-R which is involved in synaptic events including neurotransmission, synaptogenesis, long-term potentiation (LTP), development, and excitotoxicity. SR and D-serine are decreased in the hippocampus of the aging brain, correlating with impairment of cognitive function. By contrast, SR is increased in AD brain, which is associated with a greater degree of cognitive dysfunction. Emerging studies suggest that D-serine levels in the brain or in cerebral spinal fluid from AD patients are higher than in age-matched controls, but the results are inconsistent. Very recently, serum D-serine levels in AD were reported to correlate with sex and clinical dementia rating (CDR) stage. This review will discuss alterations of NMDA-R and SR in aging and AD brain, and the mechanisms underlying the differential regulation of SR will be probed. Collectively, we propose that SR may be a molecular switch that distinguishes the effects of aging from those of AD on the brain.
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Affiliation(s)
- Shengzhou Wu
- School of Optometry and Ophthalmology and the Eye Hospital, Wenzhou Medical University, State Key Laboratory of Optometry, Wenzhou, Zhejiang 325003, P.R. China
| | - Jing Zhou
- School of Optometry and Ophthalmology and the Eye Hospital, Wenzhou Medical University, State Key Laboratory of Optometry, Wenzhou, Zhejiang 325003, P.R. China
| | - He Zhang
- School of Optometry and Ophthalmology and the Eye Hospital, Wenzhou Medical University, State Key Laboratory of Optometry, Wenzhou, Zhejiang 325003, P.R. China.,College of Life and Environmental Sciences, Wenzhou University, Wenzhou, Zhejiang, P.R. China
| | - Steven W Barger
- Department of Geriatrics, University of Arkansas for Medical Sciences, Little Rock AR, USA.,Geriatric Research, Education & Clinical Center, Central Arkansas Veterans Healthcare System, Little Rock AR, USA
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3
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Human Serine Racemase Weakly Binds the Third PDZ Domain of PSD-95. Int J Mol Sci 2022; 23:ijms23094959. [PMID: 35563349 PMCID: PMC9105370 DOI: 10.3390/ijms23094959] [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: 03/15/2022] [Revised: 04/13/2022] [Accepted: 04/27/2022] [Indexed: 11/16/2022] Open
Abstract
Human serine racemase (hSR) is a pyridoxal-5'-phosphate (PLP)-dependent dimer that catalyzes the formation of D-serine from L-serine, as well as the dehydration of both L- and D-serine to pyruvate and ammonia. As D-serine is a co-agonist of N-methyl-D-aspartate receptors (NMDARs), hSR is a key enzyme in glutamatergic neurotransmission. hSR activity is finely regulated by Mg2+, ATP, post-translational modifications, and the interaction with protein partners. In particular, the C-terminus of murine SR binds the third PDZ domain (PDZ3) of postsynaptic density protein 95 (PSD-95), a member of the membrane-associated guanylate kinase (MAGUK) family involved in the trafficking and localization of glutamate receptors. The structural details of the interaction and the stability of the complex have not been elucidated yet. We evaluated the binding of recombinant human PSD-95 PDZ3 to hSR by glutaraldehyde cross-linking, pull-down assays, isothermal titration calorimetry, nuclear magnetic resonance, and enzymatic assays. Overall, a weak interaction was observed, confirming the binding for the human orthologs but supporting the hypothesis that a third protein partner (i.e., stargazin) is required for the regulation of hSR activity by PSD-95 and to stabilize their interaction.
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4
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Koulouris CR, Gardiner SE, Harris TK, Elvers KT, Mark Roe S, Gillespie JA, Ward SE, Grubisha O, Nicholls RA, Atack JR, Bax BD. Tyrosine 121 moves revealing a ligandable pocket that couples catalysis to ATP-binding in serine racemase. Commun Biol 2022; 5:346. [PMID: 35410329 PMCID: PMC9001717 DOI: 10.1038/s42003-022-03264-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Accepted: 03/14/2022] [Indexed: 11/23/2022] Open
Abstract
Human serine racemase (hSR) catalyses racemisation of L-serine to D-serine, the latter of which is a co-agonist of the NMDA subtype of glutamate receptors that are important in synaptic plasticity, learning and memory. In a 'closed' hSR structure containing the allosteric activator ATP, the inhibitor malonate is enclosed between the large and small domains while ATP is distal to the active site, residing at the dimer interface with the Tyr121 hydroxyl group contacting the α-phosphate of ATP. In contrast, in 'open' hSR structures, Tyr121 sits in the core of the small domain with its hydroxyl contacting the key catalytic residue Ser84. The ability to regulate SR activity by flipping Tyr121 from the core of the small domain to the dimer interface appears to have evolved in animals with a CNS. Multiple X-ray crystallographic enzyme-fragment structures show Tyr121 flipped out of its pocket in the core of the small domain. Data suggest that this ligandable pocket could be targeted by molecules that inhibit enzyme activity.
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Affiliation(s)
- Chloe R Koulouris
- Sussex Drug Discovery Centre, University of Sussex, Brighton, BN1 9QG, UK
| | - Sian E Gardiner
- Medicines Discovery Institute, Cardiff University, Cardiff, CF10 3AT, UK
| | - Tessa K Harris
- Medicines Discovery Institute, Cardiff University, Cardiff, CF10 3AT, UK
| | - Karen T Elvers
- Medicines Discovery Institute, Cardiff University, Cardiff, CF10 3AT, UK
| | - S Mark Roe
- Department of Biochemistry and Biomedicine, University of Sussex, Brighton, BN1 9QJ, UK
| | - Jason A Gillespie
- Medicines Discovery Institute, Cardiff University, Cardiff, CF10 3AT, UK
| | - Simon E Ward
- Medicines Discovery Institute, Cardiff University, Cardiff, CF10 3AT, UK
| | - Olivera Grubisha
- Medicines Discovery Institute, Cardiff University, Cardiff, CF10 3AT, UK
| | - Robert A Nicholls
- MRC Laboratory of Molecular Biology, Francis Crick Ave, CB2 0QH, Cambridge, UK
| | - John R Atack
- Medicines Discovery Institute, Cardiff University, Cardiff, CF10 3AT, UK.
| | - Benjamin D Bax
- Medicines Discovery Institute, Cardiff University, Cardiff, CF10 3AT, UK.
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5
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Marchesani F, Zangelmi E, Bruno S, Bettati S, Peracchi A, Campanini B. A Novel Assay for Phosphoserine Phosphatase Exploiting Serine Acetyltransferase as the Coupling Enzyme. Life (Basel) 2021; 11:life11060485. [PMID: 34073563 PMCID: PMC8229081 DOI: 10.3390/life11060485] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 05/21/2021] [Accepted: 05/23/2021] [Indexed: 01/01/2023] Open
Abstract
Phosphoserine phosphatase (PSP) catalyzes the final step of de novo L-serine biosynthesis—the hydrolysis of phosphoserine to serine and inorganic phosphate—in humans, bacteria, and plants. In published works, the reaction is typically monitored through the discontinuous malachite green phosphate assay or, more rarely, through a continuous assay that couples phosphate release to the phosphorolysis of a chromogenic nucleoside by the enzyme purine nucleoside phosphorylase (PNP). These assays suffer from numerous drawbacks, and both rely on the detection of phosphate. We describe a new continuous assay that monitors the release of serine by exploiting bacterial serine acetyltransferase (SAT) as a reporter enzyme. SAT acetylates serine, consuming acetyl-CoA and releasing CoA-SH. CoA-SH spontaneously reacts with Ellman’s reagent to produce a chromophore that absorbs light at 412 nm. The catalytic parameters estimated through the SAT-coupled assay are fully consistent with those obtained with the published methods, but the new assay exhibits several advantages. Particularly, it depletes L-serine, thus allowing more prolonged linearity in the kinetics. Moreover, as the SAT-coupled assay does not rely on phosphate detection, it can be used to investigate the inhibitory effect of phosphate on PSP.
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Affiliation(s)
- Francesco Marchesani
- Department of Food and Drug, University of Parma, 43124 Parma, Italy; (F.M.); (S.B.)
| | - Erika Zangelmi
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, 43124 Parma, Italy;
| | - Stefano Bruno
- Department of Food and Drug, University of Parma, 43124 Parma, Italy; (F.M.); (S.B.)
| | - Stefano Bettati
- Department of Medicine and Surgery, University of Parma, 43125 Parma, Italy;
- Institute of Biophysics, National Research Council, 56124 Pisa, Italy
| | - Alessio Peracchi
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, 43124 Parma, Italy;
- Correspondence: (A.P.); (B.C.); Tel.: +39-0521-905137 (A.P.); +39-0521-906333 (B.C.)
| | - Barbara Campanini
- Department of Food and Drug, University of Parma, 43124 Parma, Italy; (F.M.); (S.B.)
- Correspondence: (A.P.); (B.C.); Tel.: +39-0521-905137 (A.P.); +39-0521-906333 (B.C.)
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6
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Lloyd MD, Yevglevskis M, Nathubhai A, James TD, Threadgill MD, Woodman TJ. Racemases and epimerases operating through a 1,1-proton transfer mechanism: reactivity, mechanism and inhibition. Chem Soc Rev 2021; 50:5952-5984. [PMID: 34027955 PMCID: PMC8142540 DOI: 10.1039/d0cs00540a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Indexed: 12/12/2022]
Abstract
Racemases and epimerases catalyse changes in the stereochemical configurations of chiral centres and are of interest as model enzymes and as biotechnological tools. They also occupy pivotal positions within metabolic pathways and, hence, many of them are important drug targets. This review summarises the catalytic mechanisms of PLP-dependent, enolase family and cofactor-independent racemases and epimerases operating by a deprotonation/reprotonation (1,1-proton transfer) mechanism and methods for measuring their catalytic activity. Strategies for inhibiting these enzymes are reviewed, as are specific examples of inhibitors. Rational design of inhibitors based on substrates has been extensively explored but there is considerable scope for development of transition-state mimics and covalent inhibitors and for the identification of inhibitors by high-throughput, fragment and virtual screening approaches. The increasing availability of enzyme structures obtained using X-ray crystallography will facilitate development of inhibitors by rational design and fragment screening, whilst protein models will facilitate development of transition-state mimics.
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Affiliation(s)
- Matthew D Lloyd
- Drug & Target Discovery, Department of Pharmacy & Pharmacology, University of Bath, Claverton Down, Bath BA2 7AY, UK.
| | - Maksims Yevglevskis
- Drug & Target Discovery, Department of Pharmacy & Pharmacology, University of Bath, Claverton Down, Bath BA2 7AY, UK. and CatSci Ltd., CBTC2, Capital Business Park, Wentloog, Cardiff CF3 2PX, UK
| | - Amit Nathubhai
- Drug & Target Discovery, Department of Pharmacy & Pharmacology, University of Bath, Claverton Down, Bath BA2 7AY, UK. and University of Sunderland, School of Pharmacy & Pharmaceutical Sciences, Sciences Complex, Sunderland SR1 3SD, UK
| | - Tony D James
- Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK and School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang 453007, People's Republic of China
| | - Michael D Threadgill
- Drug & Target Discovery, Department of Pharmacy & Pharmacology, University of Bath, Claverton Down, Bath BA2 7AY, UK. and Institute of Biological, Environmental & Rural Sciences, Aberystwyth University, Aberystwyth SY23 3BY, UK
| | - Timothy J Woodman
- Drug & Target Discovery, Department of Pharmacy & Pharmacology, University of Bath, Claverton Down, Bath BA2 7AY, UK.
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7
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Marchesani F, Gianquinto E, Autiero I, Michielon A, Campanini B, Faggiano S, Bettati S, Mozzarelli A, Spyrakis F, Bruno S. The allosteric interplay between S-nitrosylation and glycine binding controls the activity of human serine racemase. FEBS J 2020; 288:3034-3054. [PMID: 33249721 DOI: 10.1111/febs.15645] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 11/06/2020] [Accepted: 11/09/2020] [Indexed: 12/15/2022]
Abstract
Human serine racemase (hSR) catalyzes the biosynthesis of D-serine, an obligatory co-agonist of the NMDA receptors. It was previously found that the reversible S-nitrosylation of Cys113 reduces hSR activity. Here, we show by site-directed mutagenesis, fluorescence spectroscopy, mass spectrometry, and molecular dynamics that S-nitrosylation stabilizes an open, less-active conformation of the enzyme. The reaction of hSR with either NO or nitroso donors is conformation-dependent and occurs only in the conformation stabilized by the allosteric effector ATP, in which the ε-amino group of Lys114 acts as a base toward the thiol group of Cys113. In the closed conformation stabilized by glycine-an active-site ligand of hSR-the side chain of Lys114 moves away from that of Cys113, while the carboxyl side-chain group of Asp318 moves significantly closer, increasing the thiol pKa and preventing the reaction. We conclude that ATP binding, glycine binding, and S-nitrosylation constitute a three-way regulation mechanism for the tight control of hSR activity. We also show that Cys113 undergoes H2 O2 -mediated oxidation, with loss of enzyme activity, a reaction also dependent on hSR conformation.
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Affiliation(s)
- Francesco Marchesani
- Dipartimento di Scienze degli Alimenti e del Farmaco, Università degli Studi di Parma, Italy
| | - Eleonora Gianquinto
- Dipartimento di Scienza e Tecnologia del Farmaco, Università degli Studi di Torino, Italy
| | - Ida Autiero
- Molecular Horizon Srl, Bettona, PG, Italy.,Consiglio Nazionale delle Ricerche, Istituto di Biostrutture e Bioimmagini, Napoli, Italy
| | - Annalisa Michielon
- Dipartimento di Scienze degli Alimenti e del Farmaco, Università degli Studi di Parma, Italy
| | - Barbara Campanini
- Dipartimento di Scienze degli Alimenti e del Farmaco, Università degli Studi di Parma, Italy
| | - Serena Faggiano
- Dipartimento di Scienze degli Alimenti e del Farmaco, Università degli Studi di Parma, Italy.,Consiglio Nazionale delle Ricerche, Istituto di Biofisica, Pisa, Italy
| | - Stefano Bettati
- Consiglio Nazionale delle Ricerche, Istituto di Biofisica, Pisa, Italy.,Dipartimento di Medicina e Chirurgia, Parma, Italy
| | - Andrea Mozzarelli
- Dipartimento di Scienze degli Alimenti e del Farmaco, Università degli Studi di Parma, Italy.,Consiglio Nazionale delle Ricerche, Istituto di Biofisica, Pisa, Italy
| | - Francesca Spyrakis
- Dipartimento di Scienza e Tecnologia del Farmaco, Università degli Studi di Torino, Italy
| | - Stefano Bruno
- Dipartimento di Scienze degli Alimenti e del Farmaco, Università degli Studi di Parma, Italy
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8
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Michielon A, Marchesani F, Faggiano S, Giaccari R, Campanini B, Bettati S, Mozzarelli A, Bruno S. Human serine racemase is inhibited by glyceraldehyde 3-phosphate, but not by glyceraldehyde 3-phosphate dehydrogenase. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2020; 1869:140544. [PMID: 32971286 DOI: 10.1016/j.bbapap.2020.140544] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Revised: 09/14/2020] [Accepted: 09/19/2020] [Indexed: 11/28/2022]
Abstract
Murine serine racemase (SR), the enzyme responsible for the biosynthesis of the neuromodulator d-serine, was reported to form a complex with glyceraldehyde 3-phosphate dehydrogenase (GAPDH), resulting in SR inhibition. In this work, we investigated the interaction between the two human orthologues. We were not able to observe neither the inhibition nor the formation of the SR-GAPDH complex. Rather, hSR is inhibited by the hGAPDH substrate glyceraldehyde 3-phosphate (G3P) in a time- and concentration-dependent fashion, likely through a covalent reaction of the aldehyde functional group. The inhibition was similar for the two G3P enantiomers but it was not observed for structurally similar aldehydes. We ruled out a mechanism of inhibition based on the competition with either pyridoxal phosphate (PLP) - described for other PLP-dependent enzymes when incubated with small aldehydes - or ATP. Nevertheless, the inhibition time course was affected by the presence of hSR allosteric and orthosteric ligands, suggesting a conformation-dependence of the reaction.
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Affiliation(s)
- Annalisa Michielon
- Dipartimento di Scienze degli Alimenti e del Farmaco, Università degli Studi di Parma, Parco Area delle Scienze 27/A, 43124 Parma, Italy
| | - Francesco Marchesani
- Dipartimento di Scienze degli Alimenti e del Farmaco, Università degli Studi di Parma, Parco Area delle Scienze 27/A, 43124 Parma, Italy
| | - Serena Faggiano
- Dipartimento di Scienze degli Alimenti e del Farmaco, Università degli Studi di Parma, Parco Area delle Scienze 27/A, 43124 Parma, Italy; Istituto di Biofisica, CNR, Via G. Moruzzi 1, 56124 Pisa, Italy
| | - Roberta Giaccari
- Dipartimento di Scienze degli Alimenti e del Farmaco, Università degli Studi di Parma, Parco Area delle Scienze 27/A, 43124 Parma, Italy
| | - Barbara Campanini
- Dipartimento di Scienze degli Alimenti e del Farmaco, Università degli Studi di Parma, Parco Area delle Scienze 27/A, 43124 Parma, Italy
| | - Stefano Bettati
- Dipartimento di Medicina e Chirurgia, Via Volturno 39, 43125 Parma, Italy
| | - Andrea Mozzarelli
- Dipartimento di Scienze degli Alimenti e del Farmaco, Università degli Studi di Parma, Parco Area delle Scienze 27/A, 43124 Parma, Italy; Istituto di Biofisica, CNR, Via G. Moruzzi 1, 56124 Pisa, Italy
| | - Stefano Bruno
- Dipartimento di Scienze degli Alimenti e del Farmaco, Università degli Studi di Parma, Parco Area delle Scienze 27/A, 43124 Parma, Italy.
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9
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Raboni S, Marchetti M, Faggiano S, Campanini B, Bruno S, Marchesani F, Margiotta M, Mozzarelli A. The Energy Landscape of Human Serine Racemase. Front Mol Biosci 2019; 5:112. [PMID: 30687716 PMCID: PMC6333871 DOI: 10.3389/fmolb.2018.00112] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Accepted: 11/26/2018] [Indexed: 12/17/2022] Open
Abstract
Human serine racemase is a pyridoxal 5′-phosphate (PLP)-dependent dimeric enzyme that catalyzes the reversible racemization of L-serine and D-serine and their dehydration to pyruvate and ammonia. As D-serine is the co-agonist of the N-methyl-D-aspartate receptors for glutamate, the most abundant excitatory neurotransmitter in the brain, the structure, dynamics, function, regulation and cellular localization of serine racemase have been investigated in detail. Serine racemase belongs to the fold-type II of the PLP-dependent enzyme family and structural models from several orthologs are available. The comparison of structures of serine racemase co-crystallized with or without ligands indicates the presence of at least one open and one closed conformation, suggesting that conformational flexibility plays a relevant role in enzyme regulation. ATP, Mg2+, Ca2+, anions, NADH and protein interactors, as well as the post-translational modifications nitrosylation and phosphorylation, finely tune the racemase and dehydratase activities and their relative reaction rates. Further information on serine racemase structure and dynamics resulted from the search for inhibitors with potential therapeutic applications. The cumulative knowledge on human serine racemase allowed obtaining insights into its conformational landscape and into the mechanisms of cross-talk between the effector binding sites and the active site.
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Affiliation(s)
- Samanta Raboni
- Department of Food and Drug, University of Parma, Parma, Italy
| | | | - Serena Faggiano
- Department of Food and Drug, University of Parma, Parma, Italy.,Institute of Biophysics, National Research Council, Pisa, Italy
| | | | - Stefano Bruno
- Department of Food and Drug, University of Parma, Parma, Italy
| | | | | | - Andrea Mozzarelli
- Department of Food and Drug, University of Parma, Parma, Italy.,Institute of Biophysics, National Research Council, Pisa, Italy.,National Institute of Biostructures and Biosystems, Rome, Italy
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