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Kim H, Choi S, Lee E, Koh W, Lee CJ. Tonic NMDA Receptor Currents in the Brain: Regulation and Cognitive Functions. Biol Psychiatry 2024; 96:164-175. [PMID: 38490367 DOI: 10.1016/j.biopsych.2024.03.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 02/20/2024] [Accepted: 03/04/2024] [Indexed: 03/17/2024]
Abstract
Synaptically localized NMDA receptors (NMDARs) play a crucial role in important cognitive functions by mediating synaptic transmission and plasticity. In contrast, a tonic NMDAR current, thought to be mediated by extrasynaptic NMDARs, has a less clear function. This review provides a comprehensive overview of tonic NMDAR currents, focusing on their roles in synaptic transmission/plasticity and their impact on cognitive functions and psychiatric disorders. We discuss the roles of 3 endogenous ligands (i.e., glutamate, glycine, and D-serine) and receptors in mediating tonic NMDAR currents and explore the diverse mechanisms that regulate tonic NMDAR currents. In light of recent controversies surrounding the source of D-serine, we highlight the recent findings suggesting that astrocytes release D-serine to modulate tonic NMDAR currents and control cognitive flexibility. Furthermore, we propose distinct roles of neuronal and astrocytic D-serine in different locations and their implications for synaptic regulation and cognitive functions. The potential roles of tonic NMDAR currents in various psychiatric disorders, such as schizophrenia and autism spectrum disorder, are discussed in the context of the NMDAR hypofunction hypothesis. By presenting the mechanisms by which various cells, particularly astrocytes, regulate tonic NMDAR currents, we aim to stimulate future research in NMDAR hypofunction- or hyperfunction-related psychiatric disorders. This review not only provides a better understanding of the complex interplay between tonic NMDAR currents and cognitive functions but also sheds light on its potential therapeutic target for the treatment of various psychiatric disorders.
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Affiliation(s)
- Hayoung Kim
- Center for Cognition and Sociality, Life Science Institute, Institute for Basic Science, Daejeon, South Korea
| | - Sunyeong Choi
- Center for Cognition and Sociality, Life Science Institute, Institute for Basic Science, Daejeon, South Korea
| | - Euisun Lee
- Center for Cognition and Sociality, Life Science Institute, Institute for Basic Science, Daejeon, South Korea
| | - Wuhyun Koh
- Center for Cognition and Sociality, Life Science Institute, Institute for Basic Science, Daejeon, South Korea.
| | - C Justin Lee
- Center for Cognition and Sociality, Life Science Institute, Institute for Basic Science, Daejeon, South Korea.
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2
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Mott PD, Zea AH, Lewis J, Mirzalieva O, Aiyar AA. Serine deamination by human serine racemase synergizes with antibiotics to curtail the replication of Chlamydia trachomatis. J Biol Chem 2024; 300:107350. [PMID: 38718865 PMCID: PMC11140210 DOI: 10.1016/j.jbc.2024.107350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 04/28/2024] [Accepted: 04/30/2024] [Indexed: 05/28/2024] Open
Abstract
The obligate intracellular bacterium, Chlamydia trachomatis, has evolved to depend on its human host for many metabolites, including most amino acids and three of the four nucleotides. Given this, it is not surprising that depletion of a single amino acid in the host cell growth medium blocks chlamydial replication. Paradoxically, supra-normal levels of some amino acids also block productive replication of Chlamydia. Here, we have determined how elevated serine levels, generated by exogenous supplementation, impede chlamydial inclusion development and reduce the generation of infectious progeny. Our findings reveal that human serine racemase, which is broadly expressed in multiple tissues, potentiates the anti-chlamydial effect of elevated serine concentrations. In addition to reversibly converting l-serine to d-serine, serine racemase also deaminates serine via β-elimination. We have determined that d-serine does not directly impact Chlamydia; rather, ammonia generated by serine deamination limits the productive chlamydial replication. Our findings imply that ammonia produced within host cells can traverse the chlamydial inclusion membrane. Further, this property of serine deaminase can be exploited to sensitize Chlamydia to concentrations of doxycycline that are otherwise not bactericidal. Because exogenously elevated levels of serine can be tolerated over extended periods, the broad expression pattern of serine racemase indicates it to be a host enzyme whose activity can be directed against multiple intracellular bacterial pathogens. From a therapeutic perspective, demonstrating host metabolism can be skewed to generate an anti-bacterial metabolite that synergizes with antibiotics, we believe our results provide a new approach to target intracellular pathogens.
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Affiliation(s)
- Patricia D Mott
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA.
| | - Arnold H Zea
- Department of Microbiology, Immunology, & Parasitology, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA
| | - Jamiya Lewis
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA
| | - Oygul Mirzalieva
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA
| | - Ashok A Aiyar
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA.
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3
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Katane M, Homma H. Biosynthesis and Degradation of Free D-Amino Acids and Their Physiological Roles in the Periphery and Endocrine Glands. Biol Pharm Bull 2024; 47:562-579. [PMID: 38432912 DOI: 10.1248/bpb.b23-00485] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/05/2024]
Abstract
It was long believed that D-amino acids were either unnatural isomers or laboratory artifacts, and that the important functions of amino acids were exerted only by L-amino acids. However, recent investigations have revealed a variety of D-amino acids in mammals that play important roles in physiological functions, including free D-serine and D-aspartate that are crucial in the central nervous system. The functions of several D-amino acids in the periphery and endocrine glands are also receiving increasing attention. Here, we present an overview of recent advances in elucidating the physiological roles of D-amino acids, especially in the periphery and endocrine glands.
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Affiliation(s)
- Masumi Katane
- Medicinal Research Laboratories, Graduate School of Pharmaceutical Sciences, Kitasato University
| | - Hiroshi Homma
- Laboratory of Analytical Chemistry, Graduate School of Pharmaceutical Sciences, Kitasato University
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Fryar-Williams S, Strobel J, Clements P. Molecular Mechanisms Provide a Landscape for Biomarker Selection for Schizophrenia and Schizoaffective Psychosis. Int J Mol Sci 2023; 24:15296. [PMID: 37894974 PMCID: PMC10607016 DOI: 10.3390/ijms242015296] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2023] [Revised: 10/07/2023] [Accepted: 10/11/2023] [Indexed: 10/29/2023] Open
Abstract
Research evaluating the role of the 5,10-methylenetetrahydrofolate reductase (MTHFR C677T) gene in schizophrenia has not yet provided an extended understanding of the proximal pathways contributing to the 5-10-methylenetetrahydrofolate reductase (MTHFR) enzyme's activity and the distal pathways being affected by its activity. This review investigates these pathways, describing mechanisms relevant to riboflavin availability, trace mineral interactions, and the 5-methyltetrahydrofolate (5-MTHF) product of the MTHFR enzyme. These factors remotely influence vitamin cofactor activation, histamine metabolism, catecholamine metabolism, serotonin metabolism, the oxidative stress response, DNA methylation, and nicotinamide synthesis. These biochemical components form a broad interactive landscape from which candidate markers can be drawn for research inquiry into schizophrenia and other forms of mental illness. Candidate markers drawn from this functional biochemical background have been found to have biomarker status with greater than 90% specificity and sensitivity for achieving diagnostic certainty in schizophrenia and schizoaffective psychosis. This has implications for achieving targeted treatments for serious mental illness.
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Affiliation(s)
- Stephanie Fryar-Williams
- Youth in Mind Research Institute, Unley Annexe, Mary Street, Unley, SA 5061, Australia
- Department of Nanoscale BioPhotonics, School of Biomedicine, Faculty of Health and Medical Sciences, The University of Adelaide, Adelaide, SA 5000, Australia
| | - Jörg Strobel
- Department of Psychiatry, Adelaide Medical School, Faculty of Health and Medical Sciences, The University of Adelaide, Adelaide, SA 5000, Australia;
| | - Peter Clements
- Department of Paediatrics, Adelaide Medical School, Faculty of Health and Medical Sciences, The University of Adelaide, Adelaide, SA 5000, Australia;
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5
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Beesley S, Kumar SS. The t-N-methyl-d-aspartate receptor: Making the case for d-Serine to be considered its inverse co-agonist. Neuropharmacology 2023:109654. [PMID: 37437688 DOI: 10.1016/j.neuropharm.2023.109654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Revised: 06/22/2023] [Accepted: 07/06/2023] [Indexed: 07/14/2023]
Abstract
The N-methyl-d-aspartate receptor (NMDAR) is an enigmatic macromolecule that has garnered a good deal of attention on account of its involvement in the cellular processes that underlie learning and memory, following its discovery in the mid twentieth century (Baudry and Davis, 1991). Yet, despite advances in knowledge about its function, there remains much more to be uncovered regarding the receptor's biophysical properties, subunit composition, and role in CNS physiology and pathophysiology. The motivation for this review stems from the need for synthesizing new information gathered about these receptors that sheds light on their role in synaptic plasticity and their dichotomous relationship with the amino acid d-serine through which they influence the pathogenesis of neurodegenerative diseases like temporal lobe epilepsy (TLE), the most common type of adult epilepsies (Beesley et al., 2020a). This review will outline pertinent ideas relating structure and function of t-NMDARs (GluN3 subunit-containing triheteromeric NMDARs) for which d-serine might serve as an inverse co-agonist. We will explore how tracing d-serine's origins blends glutamate-receptor biology with glial biology to help provide fresh perspectives on how neurodegeneration might interlink with neuroinflammation to initiate and perpetuate the disease state. Taken together, we envisage the review to deepen our understanding of endogenous d-serine's new role in the brain while also recognizing its therapeutic potential in the treatment of TLE that is oftentimes refractory to medications.
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Affiliation(s)
- Stephen Beesley
- Department of Biomedical Sciences, College of Medicine & Program in Neuroscience Florida State University, 1115 W. Call Street, Tallahassee, FL, 32306-4300, USA
| | - Sanjay S Kumar
- Department of Biomedical Sciences, College of Medicine & Program in Neuroscience Florida State University, 1115 W. Call Street, Tallahassee, FL, 32306-4300, USA.
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Krishnan KS, Billups B. ASC Transporters Mediate D-Serine Transport into Astrocytes Adjacent to Synapses in the Mouse Brain. Biomolecules 2023; 13:biom13050819. [PMID: 37238689 DOI: 10.3390/biom13050819] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 05/08/2023] [Accepted: 05/09/2023] [Indexed: 05/28/2023] Open
Abstract
D-serine is an important signalling molecule, which activates N-methyl D-aspartate receptors (NMDARs) in conjunction with its fellow co-agonist, the neurotransmitter glutamate. Despite its involvement in plasticity and memory related to excitatory synapses, its cellular source and sink remain a question. We hypothesise that astrocytes, a type of glial cell that surrounds synapses, are likely candidates to control the extracellular concentration of D-Serine by removing it from the synaptic space. Using in situ patch clamp recordings and pharmacological manipulation of astrocytes in the CA1 region of the mouse hippocampal brain slices, we investigated the transport of D-serine across the plasma membrane. We observed the D-serine-induced transport-associated currents upon puff-application of 10 mM D-serine on astrocytes. Further, O-benzyl-L-serine and trans-4-hydroxy-proline, known substrate inhibitors of the alanine serine cysteine transporters (ASCT), reduced D-serine uptake. These results indicate that ASCT is a central mediator of astrocytic D-serine transport and plays a role in regulating its synaptic concentration by sequestration into astrocytes. Similar results were observed in astrocytes of the somatosensory cortex and Bergmann glia in the cerebellum, indicative of a general mechanism expressed across a range of brain areas. This removal of synaptic D-serine and its subsequent metabolic degradation are expected to reduce its extracellular availability, influencing NMDAR activation and NMDAR-dependent synaptic plasticity.
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Affiliation(s)
- Karthik Subramanian Krishnan
- Eccles Institute of Neuroscience, The John Curtin School of Medical Research, The Australian National University, 131 Garran Road, Canberra, ACT 2601, Australia
| | - Brian Billups
- Eccles Institute of Neuroscience, The John Curtin School of Medical Research, The Australian National University, 131 Garran Road, Canberra, ACT 2601, Australia
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Shen D, Deng Z, Liu W, Zhou F, Fang Y, Shan D, Wang G, Qian K, Yu M, Zhang Y, Ju L, Xiao Y, Wang X. Melatonin inhibits bladder tumorigenesis by suppressing PPARγ/ENO1-mediated glycolysis. Cell Death Dis 2023; 14:246. [PMID: 37024456 PMCID: PMC10079981 DOI: 10.1038/s41419-023-05770-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 03/22/2023] [Accepted: 03/23/2023] [Indexed: 04/08/2023]
Abstract
Melatonin is a well-known natural hormone, which shows a potential anticancer effect in many human cancers. Bladder cancer (BLCA) is one of the most malignant human cancers in the world. Chemoresistance is an increasingly prominent phenomenon that presents an obstacle to the clinical treatment of BLCA. There is an urgent need to investigate novel drugs to improve the current clinical status. In our study, we comprehensively explored the inhibitory effect of melatonin on BLCA and found that it could suppress glycolysis process. Moreover, we discovered that ENO1, a glycolytic enzyme involved in the ninth step of glycolysis, was the downstream effector of melatonin and could be a predictive biomarker of BLCA. We also proved that enhanced glycolysis simulated by adding exogenous pyruvate could induce gemcitabine resistance, and melatonin treatment or silencing of ENO1 could intensify the cytotoxic effect of gemcitabine on BLCA cells. Excessive accumulation of reactive oxygen species (ROS) mediated the inhibitory effect of melatonin on BLCA cells. Additionally, we uncovered that PPARγ was a novel upstream regulator of ENO1, which mediated the downregulation of ENO1 caused by melatonin. Our study offers a fresh perspective on the anticancer effect of melatonin and encourages further studies on clinical chemoresistance.
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Affiliation(s)
- Dexin Shen
- Department of Urology, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Zhao Deng
- Department of Urology, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Wei Liu
- Department of Urology, Aerospace Center Hospital, Peking University Aerospace School of Clinical Medicine, Beijing, China
| | - Fenfang Zhou
- Department of Radiology, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Yayun Fang
- Department of Biological Repositories, Zhongnan Hospital of Wuhan University, Wuhan, China
- Human Genetic Resources Preservation Center of Hubei Province, Wuhan, China
| | - Danni Shan
- Department of Biological Repositories, Zhongnan Hospital of Wuhan University, Wuhan, China
- Human Genetic Resources Preservation Center of Hubei Province, Wuhan, China
| | - Gang Wang
- Department of Biological Repositories, Zhongnan Hospital of Wuhan University, Wuhan, China
- Human Genetic Resources Preservation Center of Hubei Province, Wuhan, China
| | - Kaiyu Qian
- Department of Biological Repositories, Zhongnan Hospital of Wuhan University, Wuhan, China
- Human Genetic Resources Preservation Center of Hubei Province, Wuhan, China
| | - Mengxue Yu
- Department of Biological Repositories, Zhongnan Hospital of Wuhan University, Wuhan, China
- Human Genetic Resources Preservation Center of Hubei Province, Wuhan, China
| | - Yi Zhang
- Euler Technology, ZGC Life Sciences Park, Beijing, China
- Center for Quantitative Biology, School of Life Sciences, Peking University, Beijing, China
| | - Lingao Ju
- Department of Biological Repositories, Zhongnan Hospital of Wuhan University, Wuhan, China.
- Human Genetic Resources Preservation Center of Hubei Province, Wuhan, China.
| | - Yu Xiao
- Department of Urology, Zhongnan Hospital of Wuhan University, Wuhan, China.
- Department of Biological Repositories, Zhongnan Hospital of Wuhan University, Wuhan, China.
- Human Genetic Resources Preservation Center of Hubei Province, Wuhan, China.
| | - Xinghuan Wang
- Department of Urology, Zhongnan Hospital of Wuhan University, Wuhan, China.
- Wuhan Research Center for Infectious Diseases and Cancer, Chinese Academy of Medical Sciences, Wuhan, China.
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8
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Toikumo S, Xu H, Gelernter J, Kember RL, Kranzler HR. Integrating human brain proteomic data with genome-wide association study findings identifies novel brain proteins in substance use traits. Neuropsychopharmacology 2022; 47:2292-2299. [PMID: 35941285 PMCID: PMC9630289 DOI: 10.1038/s41386-022-01406-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 06/13/2022] [Accepted: 07/16/2022] [Indexed: 11/09/2022]
Abstract
Despite the identification of a growing number of genetic risk loci for substance use traits (SUTs), the impact of these loci on protein abundance and the potential utility of relevant proteins as therapeutic targets are unknown. We conducted a proteome-wide association study (PWAS) in which we integrated human brain proteomes from discovery (Banner; N = 152) and validation (ROSMAP; N = 376) datasets with genome-wide association study (GWAS) summary statistics for 4 SUTs. The 4 samples comprised GWAS of European-ancestry individuals for smoking initiation [Smk] (N = 1,232,091), alcohol use disorder [AUD] (N = 313,959), cannabis use disorder [CUD] (N = 384,032), and opioid use disorder [OUD] (N = 302,585). We conducted transcriptome-wide association studies (TWAS) with human brain transcriptomic data to examine the overlap of genetic effects at the proteomic and transcriptomic levels and characterize significant genes through conditional, colocalization, and fine-mapping analyses. We identified 27 genes (Smk = 21, AUD = 3, CUD = 2, OUD = 1) that were significantly associated with cis-regulated brain protein abundance. Of these, 7 showed evidence for causality (Smk: NT5C2, GMPPB, NQO1, RHOT2, SRR and ACTR1B; and AUD: CTNND1). Cis-regulated transcript levels for 8 genes (Smk = 6, CUD = 1, OUD = 1) were associated with SUTs, indicating that genetic loci could confer risk for these SUTs by modulating both gene expression and proteomic abundance. Functional studies of the high-confidence risk proteins identified here are needed to determine whether they are modifiable targets and useful in developing medications and biomarkers for these SUTs.
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Affiliation(s)
- Sylvanus Toikumo
- Department of Psychiatry, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
- Mental Illness Research, Education and Clinical Center, Crescenz VAMC, Philadelphia, PA, USA
| | - Heng Xu
- Department of Psychiatry, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Joel Gelernter
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA
| | - Rachel L Kember
- Department of Psychiatry, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA.
- Mental Illness Research, Education and Clinical Center, Crescenz VAMC, Philadelphia, PA, USA.
| | - Henry R Kranzler
- Department of Psychiatry, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA.
- Mental Illness Research, Education and Clinical Center, Crescenz VAMC, Philadelphia, PA, USA.
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9
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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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Tanaka Y, Yoshimura T, Hakamata M, Saito C, Sumitani M, Sezutsu H, Hemmi H, Ito T. Identification and characterization of a serine racemase in the silkworm Bombyx mori. J Biochem 2022; 172:17-28. [PMID: 35325141 DOI: 10.1093/jb/mvac026] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Accepted: 03/17/2022] [Indexed: 11/12/2022] Open
Abstract
The pupae of lepidopterans contain high concentrations of endogenous d-serine. In the silkworm Bombyx mori, d-serine is negligible during the larval stage but increases markedly during the pupal stage, reaching 50% of the total free serine. However, the physiological function of d-serine and the enzyme responsible for its production are unknown. Herein, we identified a new type of pyridoxal 5'-phosphate (PLP)-dependent serine racemase (SR) that catalyzes the racemization of l-serine to d-serine in B. mori. This silkworm SR (BmSR) has an N-terminal PLP-binding domain that is homologous to mammalian SR and a C-terminal putative ligand-binding regulatory-like domain (ACT-like domain) that is absent in mammalian SR. Similar to mammalian SRs, BmSR catalyzes the racemization and dehydration of both serine isomers. However, BmSR is different from mammalian SRs as evidenced by its insensitivity to Mg2+/Ca2+ and Mg-ATP-which are required for activation of mammalian SRs-and high d-serine dehydration activity. At the pupal stage, the SR activity was predominantly detected in the fat body, which was consistent with the timing and localization of BmSR expression. The results are an important first step in elucidating the physiological significance of d-serine in lepidopterans.
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Affiliation(s)
- Yui Tanaka
- Department of Applied Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furou-chou, Chikusa, Nagoya, Aichi, Japan
| | - Tohru Yoshimura
- Department of Applied Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furou-chou, Chikusa, Nagoya, Aichi, Japan
| | - Maho Hakamata
- Department of Applied Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furou-chou, Chikusa, Nagoya, Aichi, Japan
| | - Chiaki Saito
- Department of Applied Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furou-chou, Chikusa, Nagoya, Aichi, Japan
| | - Megumi Sumitani
- Silkworm Research Group, Division of Silk-Producing Insect Biotechnology, Institute of Agrobiological Sciences, National Agriculture and Food Research Organization, Owashi, Tsukuba 305-8634, Japan
| | - Hideki Sezutsu
- Silkworm Research Group, Division of Silk-Producing Insect Biotechnology, Institute of Agrobiological Sciences, National Agriculture and Food Research Organization, Owashi, Tsukuba 305-8634, Japan
| | - Hisashi Hemmi
- Department of Applied Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furou-chou, Chikusa, Nagoya, Aichi, Japan
| | - Tomokazu Ito
- Department of Applied Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furou-chou, Chikusa, Nagoya, Aichi, Japan
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Sherwood MW, Oliet SHR, Panatier A. NMDARs, Coincidence Detectors of Astrocytic and Neuronal Activities. Int J Mol Sci 2021; 22:7258. [PMID: 34298875 PMCID: PMC8307462 DOI: 10.3390/ijms22147258] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 06/30/2021] [Accepted: 06/30/2021] [Indexed: 12/18/2022] Open
Abstract
Synaptic plasticity is an extensively studied cellular correlate of learning and memory in which NMDARs play a starring role. One of the most interesting features of NMDARs is their ability to act as a co-incident detector. It is unique amongst neurotransmitter receptors in this respect. Co-incident detection is possible because the opening of NMDARs requires membrane depolarisation and the binding of glutamate. Opening of NMDARs also requires a co-agonist. Although the dynamic regulation of glutamate and membrane depolarization have been well studied in coincident detection, the role of the co-agonist site is unexplored. It turns out that non-neuronal glial cells, astrocytes, regulate co-agonist availability, giving them the ability to influence synaptic plasticity. The unique morphology and spatial arrangement of astrocytes at the synaptic level affords them the capacity to sample and integrate information originating from unrelated synapses, regardless of any pre-synaptic and post-synaptic commonality. As astrocytes are classically considered slow responders, their influence at the synapse is widely recognized as modulatory. The aim herein is to reconsider the potential of astrocytes to participate directly in ongoing synaptic NMDAR activity and co-incident detection.
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Affiliation(s)
- Mark W. Sherwood
- University of Bordeaux, INSERM, Neurocentre Magendie, U1215, F-3300 Bordeaux, France;
| | | | - Aude Panatier
- University of Bordeaux, INSERM, Neurocentre Magendie, U1215, F-3300 Bordeaux, France;
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12
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Kurita K, Ohta H, Shirakawa I, Tanaka M, Kitaura Y, Iwasaki Y, Matsuzaka T, Shimano H, Aoe S, Arima H, Ogawa Y, Ito A, Suganami T. Macrophages rely on extracellular serine to suppress aberrant cytokine production. Sci Rep 2021; 11:11137. [PMID: 34045514 PMCID: PMC8160356 DOI: 10.1038/s41598-021-90086-w] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Accepted: 05/06/2021] [Indexed: 01/08/2023] Open
Abstract
A growing body of evidence indicates that cellular metabolism is involved in immune cell functions, including cytokine production. Serine is a nutritionally non-essential amino acid that can be generated by de novo synthesis and conversion from glycine. Serine contributes to various cellular responses, but the role in inflammatory responses remains poorly understood. Here, we show that macrophages rely on extracellular serine to suppress aberrant cytokine production. Depleting serine from the culture media reduced the cellular serine content in macrophages markedly, suggesting that macrophages depend largely on extracellular serine rather than cellular synthesis. Under serine deprivation, macrophages stimulated with lipopolysaccharide showed aberrant cytokine expression patterns, including a marked reduction of anti-inflammatory interleukin-10 expression and sustained expression of interleukine-6. Transcriptomic and metabolomics analyses revealed that serine deprivation causes mitochondrial dysfunction: reduction in the pyruvate content, the NADH/NAD+ ratio, the oxygen consumption rate, and the mitochondrial production of reactive oxygen species (ROS). We also found the role of mitochondrial ROS in appropriate cytokine production. Thus, our results indicate that cytokine production in macrophages is tightly regulated by the nutritional microenvironment.
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Affiliation(s)
- Kento Kurita
- Department of Molecular Medicine and Metabolism, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Aichi, Japan.,Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, Aichi, Japan
| | - Hiroya Ohta
- Department of Molecular Medicine and Metabolism, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Aichi, Japan.,Department of Immunometabolism, Nagoya University Graduate School of Medicine, Nagoya, Aichi, Japan.,Department of Pharmacology, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima, Japan
| | - Ibuki Shirakawa
- Department of Molecular Medicine and Metabolism, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Aichi, Japan.,Department of Immunometabolism, Nagoya University Graduate School of Medicine, Nagoya, Aichi, Japan
| | - Miyako Tanaka
- Department of Molecular Medicine and Metabolism, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Aichi, Japan.,Department of Immunometabolism, Nagoya University Graduate School of Medicine, Nagoya, Aichi, Japan
| | - Yasuyuki Kitaura
- Laboratory Nutritional Biochemistry, Department of Applied Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi, Japan
| | - Yorihiro Iwasaki
- Center for Diabetes and Endocrinology, The Tazuke Kofukai Medical Research Institute Kitano Hospital, Osaka, Osaka, Japan
| | - Takashi Matsuzaka
- Department of Endocrinology and Metabolism, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Hitoshi Shimano
- Department of Endocrinology and Metabolism, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Seiichiro Aoe
- Department of Home Economics, Otsuma Women's University, Tokyo, Japan
| | - Hiroshi Arima
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, Aichi, Japan
| | - Yoshihiro Ogawa
- Department of Molecular Medicine and Metabolism, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Aichi, Japan.,Department of Medicine and Bioregulatory Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Fukuoka, Japan
| | - Ayaka Ito
- Department of Molecular Medicine and Metabolism, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Aichi, Japan. .,Department of Immunometabolism, Nagoya University Graduate School of Medicine, Nagoya, Aichi, Japan.
| | - Takayoshi Suganami
- Department of Molecular Medicine and Metabolism, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Aichi, Japan. .,Department of Immunometabolism, Nagoya University Graduate School of Medicine, Nagoya, Aichi, Japan.
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13
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Identification and biochemical characterization of threonine dehydratase from the hyperthermophile Thermotoga maritima. Amino Acids 2021; 53:903-915. [PMID: 33938999 DOI: 10.1007/s00726-021-02993-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Accepted: 04/21/2021] [Indexed: 01/14/2023]
Abstract
The peptidoglycan of the hyperthermophile Thermotoga maritima contains an unusual component, D-lysine (D-Lys), in addition to the typical D-alanine (D-Ala) and D-glutamate (D-Glu). In a previous study, we identified a Lys racemase that is presumably associated with D-Lys biosynthesis. However, our understanding of D-amino acid metabolism in T. maritima and other bacteria remains limited, although D-amino acids in the peptidoglycan are crucial for preserving bacterial cell structure and resistance to environmental threats. Herein, we characterized enzymatic and structural properties of TM0356 that shares a high amino acid sequence identity with serine (Ser) racemase. The results revealed that TM0356 forms a tetramer with each subunit containing a pyridoxal 5'-phosphate as a cofactor. The enzyme did not exhibit racemase activity toward various amino acids including Ser, and dehydratase activity was highest toward L-threonine (L-Thr). It also acted on L-Ser and L-allo-Thr, but not on the corresponding D-amino acids. The catalytic mechanism did not follow typical Michaelis-Menten kinetics; it displayed a sigmoidal dependence on substrate concentration, with highest catalytic efficiency (kcat/K0.5) toward L-Thr. Interestingly, dehydratase activity was insensitive to allosteric regulators L-valine and L-isoleucine (L-Ile) at low concentrations, while these L-amino acids are inhibitors at high concentrations. Thus, TM0356 is a biosynthetic Thr dehydratase responsible for the conversion of L-Thr to α-ketobutyrate and ammonia, which is presumably involved in the first step of the biosynthesis of L-Ile.
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14
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Promiscuous enzymes generating d-amino acids in mammals: Why they may still surprise us? Biochem J 2021; 478:1175-1178. [PMID: 33710333 DOI: 10.1042/bcj20200988] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 02/22/2021] [Accepted: 02/23/2021] [Indexed: 11/17/2022]
Abstract
Promiscuous catalysis is a common property of enzymes, particularly those using pyridoxal 5'-phosphate as a cofactor. In a recent issue of this journal, Katane et al. Biochem. J. 477, 4221-4241 demonstrate the synthesis and accumulation of d-glutamate in mammalian cells by promiscuous catalysis mediated by a pyridoxal 5'-phosphate enzyme, the serine/threonine dehydratase-like (SDHL). The mechanism of SDHL resembles that of serine racemase, which synthesizes d-serine, a well-established signaling molecule in the mammalian brain. d-Glutamate is present in body fluids and is degraded by the d-glutamate cyclase at the mitochondria. This study demonstrates a biochemical pathway for d-glutamate synthesis in mammalian cells and advances our knowledge on this little-studied d-amino acid in mammals. d-Amino acids may still surprise us by their unique roles in biochemistry, intercellular signaling, and as potential biomarkers of disease.
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15
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Dyakin VV, Wisniewski TM, Lajtha A. Racemization in Post-Translational Modifications Relevance to Protein Aging, Aggregation and Neurodegeneration: Tip of the Iceberg. Symmetry (Basel) 2021; 13:455. [PMID: 34350031 PMCID: PMC8330555 DOI: 10.3390/sym13030455] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Homochirality of DNA and prevalent chirality of free and protein-bound amino acids in a living organism represents the challenge for modern biochemistry and neuroscience. The idea of an association between age-related disease, neurodegeneration, and racemization originated from the studies of fossils and cataract disease. Under the pressure of new results, this concept has a broader significance linking protein folding, aggregation, and disfunction to an organism's cognitive and behavioral functions. The integrity of cognitive function is provided by a delicate balance between the evolutionarily imposed molecular homo-chirality and the epigenetic/developmental impact of spontaneous and enzymatic racemization. The chirality of amino acids is the crucial player in the modulation the structure and function of proteins, lipids, and DNA. The collapse of homochirality by racemization is the result of the conformational phase transition. The racemization of protein-bound amino acids (spontaneous and enzymatic) occurs through thermal activation over the energy barrier or by the tunnel transfer effect under the energy barrier. The phase transition is achieved through the intermediate state, where the chirality of alpha carbon vanished. From a thermodynamic consideration, the system in the homo-chiral (single enantiomeric) state is characterized by a decreased level of entropy. The oscillating protein chirality is suggesting its distinct significance in the neurotransmission and flow of perceptual information, adaptive associative learning, and cognitive laterality. The common pathological hallmarks of neurodegenerative disorders include protein misfolding, aging, and the deposition of protease-resistant protein aggregates. Each of the landmarks is influenced by racemization. The brain region, cell type, and age-dependent racemization critically influence the functions of many intracellular, membrane-bound, and extracellular proteins including amyloid precursor protein (APP), TAU, PrP, Huntingtin, α-synuclein, myelin basic protein (MBP), and collagen. The amyloid cascade hypothesis in Alzheimer's disease (AD) coexists with the failure of amyloid beta (Aβ) targeting drug therapy. According to our view, racemization should be considered as a critical factor of protein conformation with the potential for inducing order, disorder, misfolding, aggregation, toxicity, and malfunctions.
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Affiliation(s)
- Victor V. Dyakin
- Virtual Reality Perception Lab (VRPL), The Nathan S. Kline Institute for Psychiatric Research (NKI), Orangeburg, NY 10962, USA
| | - Thomas M. Wisniewski
- Departments of Neurology, Pathology and Psychiatry, Center for Cognitive Neurology, New York University School of Medicine, New York, NY 10016, USA
| | - Abel Lajtha
- Center for Neurochemistry, The Nathan S. Kline Institute for Psychiatric Research (NKI), Orangeburg, NY 10962, USA
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16
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Ohshima K, Morii E. Metabolic Reprogramming of Cancer Cells during Tumor Progression and Metastasis. Metabolites 2021; 11:metabo11010028. [PMID: 33401771 PMCID: PMC7824065 DOI: 10.3390/metabo11010028] [Citation(s) in RCA: 94] [Impact Index Per Article: 31.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 12/30/2020] [Accepted: 12/30/2020] [Indexed: 01/10/2023] Open
Abstract
Cancer cells face various metabolic challenges during tumor progression, including growth in the nutrient-altered and oxygen-deficient microenvironment of the primary site, intravasation into vessels where anchorage-independent growth is required, and colonization of distant organs where the environment is distinct from that of the primary site. Thus, cancer cells must reprogram their metabolic state in every step of cancer progression. Metabolic reprogramming is now recognized as a hallmark of cancer cells and supports cancer growth. Elucidating the underlying mechanisms of metabolic reprogramming in cancer cells may help identifying cancer targets and treatment strategies. This review summarizes our current understanding of metabolic reprogramming during cancer progression and metastasis, including cancer cell adaptation to the tumor microenvironment, defense against oxidative stress during anchorage-independent growth in vessels, and metabolic reprogramming during metastasis.
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17
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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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18
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Raza W, Ghafoor S, Abbas SZ, Muhammad SA. Polymorphic evaluation of NFKBIA and SRR with type 2 diabetes mellitus in population of southern Punjab. Meta Gene 2020. [DOI: 10.1016/j.mgene.2020.100803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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19
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Identification of an l-serine/l-threonine dehydratase with glutamate racemase activity in mammals. Biochem J 2020; 477:4221-4241. [DOI: 10.1042/bcj20200721] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Revised: 10/12/2020] [Accepted: 10/20/2020] [Indexed: 02/02/2023]
Abstract
Recent investigations have shown that multiple d-amino acids are present in mammals and these compounds have distinctive physiological functions. Free d-glutamate is present in various mammalian tissues and cells and in particular, it is presumably correlated with cardiac function, and much interest is growing in its unique metabolic pathways. Recently, we first identified d-glutamate cyclase as its degradative enzyme in mammals, whereas its biosynthetic pathway in mammals is unclear. Glutamate racemase is a most probable candidate, which catalyzes interconversion between d-glutamate and l-glutamate. Here, we identified the cDNA encoding l-serine dehydratase-like (SDHL) as the first mammalian clone with glutamate racemase activity. This rat SDHL had been deposited in mammalian databases as a protein of unknown function and its amino acid sequence shares ∼60% identity with that of l-serine dehydratase. Rat SDHL was expressed in Escherichia coli, and the enzymatic properties of the recombinant were characterized. The results indicated that rat SDHL is a multifunctional enzyme with glutamate racemase activity in addition to l-serine/l-threonine dehydratase activity. This clone is hence abbreviated as STDHgr. Further experiments using cultured mammalian cells confirmed that d-glutamate was synthesized and l-serine and l-threonine were decomposed. It was also found that SDHL (STDHgr) contributes to the homeostasis of several other amino acids.
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20
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Takagi S, Balu DT, Coyle JT. Factors regulating serine racemase and d-amino acid oxidase expression in the mouse striatum. Brain Res 2020; 1751:147202. [PMID: 33171153 DOI: 10.1016/j.brainres.2020.147202] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 10/23/2020] [Accepted: 11/03/2020] [Indexed: 10/23/2022]
Abstract
d-Serine plays an important role in modulating N-methyl-d-aspartate receptor (NMDAR) neurotransmission in the mammalian brain by binding to the receptor's glycine modulatory site (GMS). The cytosolic enzyme serine racemase (SR) converts L-serine to d-serine, while the peroxisomal enzyme d-amino acid oxidase (DAAO) catalyzes the breakdown of d-serine. Although it is important to understand how the activities of SR and DAAO regulate d-serine levels, very little is known about the mechanisms that regulate the expression of SR and DAAO. In this study, we investigated whether the different centrally active drugs affect the expression of SR and DAAO in adult mouse brain. We found that the NMDAR antagonist, MK801, and cocaine, psychotropic drugs that both augment glutamate release, reduce the expression of SR and DAAO. This regulation is brain region selective, and in the case of cocaine, is reversed in part byα-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) antagonist 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo[f]quinoxaline-2,3-dione (NBQX). However, d-serine and antipsychotics do not regulate SR and DAAO protein levels. In a genetic model of SR disruption, we found that DAAO expression was unaltered in SR conditional knockout mice, in which tissue d-serine content remains fairly stable despite marked reduction in SR expression. This study reveals a new mechanism by which AMPAR activity could regulate NMDAR function via d-serine availability.
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Affiliation(s)
- Shunsuke Takagi
- Department of Psychiatry and Behavioral Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan; Laboratory for Psychiatric and Molecular Neuroscience, McLean Hospital, Belmont, MA 02478, USA.
| | - Darrick T Balu
- Department of Psychiatry, Harvard Medical School, Boston, MA 02115, USA; Laboratory for Psychiatric and Molecular Neuroscience, McLean Hospital, Belmont, MA 02478, USA
| | - Joseph T Coyle
- Department of Psychiatry, Harvard Medical School, Boston, MA 02115, USA; Laboratory for Psychiatric and Molecular Neuroscience, McLean Hospital, Belmont, MA 02478, USA
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21
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Lee A, Arachchige BJ, Henderson R, Pow D, Reed S, Aylward J, McCombe PA. Elevated plasma levels of D-serine in some patients with amyotrophic lateral sclerosis. Amyotroph Lateral Scler Frontotemporal Degener 2020; 22:206-210. [PMID: 33908331 DOI: 10.1080/21678421.2020.1832120] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
D-serine is an endogenous co-agonist with glutamate for activation of the N-methyl-D-aspartate receptor (NMDAR). D-serine exacerbates neuronal death and is elevated in the spinal cord from patients with sporadic/familial ALS. The present study was undertaken to examine whether plasma levels of D-serine of patients with ALS are different from those of healthy controls. Levels of D-serine in plasma (30 patients and 30 controls) were measured by high-performance liquid chromatography mass spectrometry. Plasma levels of D-serine in ALS patients (mean 39.27 ± 28.61 ng/ml) were significantly higher (p = 0.0293) than those of healthy control subjects (mean 21.07 ± 14.03 ng/ml) as well as previously reported values for healthy controls; ∼43% of patients had plasma D-serine levels that were 2 to 4-folds higher than those of controls. There was no association of plasma D-serine levels with disability, the duration of disease or with the age of subjects. In conclusion, we show that D-serine levels are elevated in the plasma of some ALS patients. Since D-serine serves as a co-agonist/activator of NMDAR, increases in D-serine could have a direct influence on glutamatergic neurotransmission and potentially contribute to excitotoxicity in some ALS patients.
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Affiliation(s)
- Aven Lee
- Centre for Clinical Research, The University of Queensland, Brisbane, Australia
| | | | - Robert Henderson
- Department of Neurology, Royal Brisbane & Women's Hospital, Brisbane, Australia and
| | - David Pow
- Centre for Clinical Research, The University of Queensland, Brisbane, Australia
| | - Sarah Reed
- Mass Spectrometry Facility, Centre for Clinical Research, The University of Queensland, Brisbane, Australia
| | - James Aylward
- Wesley Medical Research, The Wesley Hospital, Auchenflower, Australia
| | - Pamela Ann McCombe
- Centre for Clinical Research, The University of Queensland, Brisbane, Australia.,Wesley Medical Research, The Wesley Hospital, Auchenflower, Australia
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22
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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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23
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Maugard M, Vigneron PA, Bolaños JP, Bonvento G. l-Serine links metabolism with neurotransmission. Prog Neurobiol 2020; 197:101896. [PMID: 32798642 DOI: 10.1016/j.pneurobio.2020.101896] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Revised: 07/20/2020] [Accepted: 08/09/2020] [Indexed: 12/12/2022]
Abstract
Brain energy metabolism is often considered as a succession of biochemical steps that metabolize the fuel (glucose and oxygen) for the unique purpose of providing sufficient ATP to maintain the huge information processing power of the brain. However, a significant fraction (10-15 %) of glucose is shunted away from the ATP-producing pathway (oxidative phosphorylation) and may be used to support other functions. Recent studies have pointed to the marked compartmentation of energy metabolic pathways between neurons and glial cells. Here, we focused our attention on the biosynthesis of l-serine, a non-essential amino acid that is formed exclusively in glial cells (mostly astrocytes) by re-routing the metabolic fate of the glycolytic intermediate, 3-phosphoglycerate (3PG). This metabolic pathway is called the phosphorylated pathway and transforms 3PG into l-serine via three enzymatic reactions. We first compiled the available data on the mechanisms that regulate the flux through this metabolic pathway. We then reviewed the current evidence that is beginning to unravel the roles of l-serine both in the healthy and diseased brain, leading to the notion that this specific metabolic pathway connects glial metabolism with synaptic activity and plasticity. We finally suggest that restoring astrocyte-mediated l-serine homeostasis may provide new therapeutic strategies for brain disorders.
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Affiliation(s)
- Marianne Maugard
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoire des Maladies Neurodégénératives, Fontenay-aux-Roses, France
| | - Pierre-Antoine Vigneron
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoire des Maladies Neurodégénératives, Fontenay-aux-Roses, France
| | - Juan P Bolaños
- Institute of Functional Biology and Genomics (IBFG), Universidad de Salamanca, CSIC, Salamanca, Spain; Centro de Investigación Biomédica en Red sobre Fragilidad y Envejecimiento Saludable (CIBERFES), Institute of Biomedical Research of Salamanca, 37007, Salamanca, Spain
| | - Gilles Bonvento
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoire des Maladies Neurodégénératives, Fontenay-aux-Roses, France.
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24
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Solid-state vibrational circular dichroism studies on the conformation of an amino acid molecule in crystalline state. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2020; 1868:140439. [DOI: 10.1016/j.bbapap.2020.140439] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Revised: 04/18/2020] [Accepted: 04/29/2020] [Indexed: 11/20/2022]
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25
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Gu SX, Wang HF, Zhu YY, Chen FE. Natural Occurrence, Biological Functions, and Analysis of D-Amino Acids. PHARMACEUTICAL FRONTS 2020. [DOI: 10.1055/s-0040-1713820] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
AbstractThis review covers the recent development on the natural occurrence, functional elucidations, and analysis of amino acids of the D (dextro) configuration. In the pharmaceutical field, amino acids are not only used directly as clinical drugs and nutriments, but also widely applied as starting materials, catalysts, or chiral ligands for the synthesis of active pharmaceutical ingredients. Earler belief hold that only L-amino acids exist in nature and D-amino acids were artificial products. However, increasing evidence indicates that D-amino acids are naturally occurring in living organisms including human beings, plants, and microorganisms, playing important roles in biological processes. While D-amino acids have similar physical and chemical characteristics with their respective L-enantiomers in an achiral measurement, the biological functions of D-amino acids are remarkably different from those of L-ones. With the rapid development of chiral analytical techniques for D-amino acids, studies on the existence, formation mechanisms, biological functions as well as relevant physiology and pathology of D-amino acids have achieved great progress; however, they are far from being sufficiently explored.
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Affiliation(s)
- Shuang-Xi Gu
- Pharmaceutical Research Institute, Wuhan Institute of Technology, Wuhan, People's Republic of China
- Key Laboratory for Green Chemical Process of Ministry of Education, School of Chemical Engineering & Pharmacy, Wuhan Institute of Technology, Wuhan, People's Republic of China
| | - Hai-Feng Wang
- Pharmaceutical Research Institute, Wuhan Institute of Technology, Wuhan, People's Republic of China
- Key Laboratory for Green Chemical Process of Ministry of Education, School of Chemical Engineering & Pharmacy, Wuhan Institute of Technology, Wuhan, People's Republic of China
| | - Yuan-Yuan Zhu
- School of Chemistry & Environmental Engineering, Wuhan Institute of Technology, Wuhan, People's Republic of China
| | - Fen-Er Chen
- Pharmaceutical Research Institute, Wuhan Institute of Technology, Wuhan, People's Republic of China
- Department of Chemistry, Fudan University, Shanghai, People's Republic of China
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26
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Ito T, Matsuoka M, Goto M, Watanabe S, Mizobuchi T, Matsushita K, Nasu R, Hemmi H, Yoshimura T. Mechanism of eukaryotic serine racemase-catalyzed serine dehydration. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2020; 1868:140460. [PMID: 32474107 DOI: 10.1016/j.bbapap.2020.140460] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 05/14/2020] [Accepted: 05/26/2020] [Indexed: 12/30/2022]
Abstract
Eukaryotic serine racemase (SR) is a pyridoxal 5'-phosphate enzyme belonging to the Fold-type II group, which catalyzes serine racemization and is responsible for the synthesis of D-Ser, a co-agonist of the N-methyl-d-aspartate receptor. In addition to racemization, SR catalyzes the dehydration of D- and L-Ser to pyruvate and ammonia. The bifuctionality of SR is thought to be important for D-Ser homeostasis. SR catalyzes the racemization of D- and L-Ser with almost the same efficiency. In contrast, the rate of L-Ser dehydration catalyzed by SR is much higher than that of D-Ser dehydration. This has caused the argument that SR does not catalyze the direct D-Ser dehydration and that D-Ser is first converted to L-Ser, then dehydrated. In this study, we investigated the substrate and solvent isotope effect of dehydration of D- and L-Ser catalyzed by SR from Dictyostelium discoideum (DdSR) and demonstrated that the enzyme catalyzes direct D-Ser dehydration. Kinetic studies of dehydration of four Thr isomers catalyzed by D. discoideum and mouse SRs suggest that SR discriminates the substrate configuration at C3 but not at C2. This is probably the reason for the difference in efficiency between L- and D-Ser dehydration catalyzed by SR.
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Affiliation(s)
- Tomokazu Ito
- Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furou-chou, Chikusa, Nagoya, Aichi 464-8601, Japan
| | - Mai Matsuoka
- Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furou-chou, Chikusa, Nagoya, Aichi 464-8601, Japan
| | - Masaru Goto
- Department of Biomolecular Science, Faculty of Science, Toho University, Miyama 2-2-1, Funabashi, Chiba 274-8510, Japan.
| | - Soichiro Watanabe
- Department of Biomolecular Science, Faculty of Science, Toho University, Miyama 2-2-1, Funabashi, Chiba 274-8510, Japan
| | - Taichi Mizobuchi
- Department of Biomolecular Science, Faculty of Science, Toho University, Miyama 2-2-1, Funabashi, Chiba 274-8510, Japan
| | - Kazuma Matsushita
- Department of Biomolecular Science, Faculty of Science, Toho University, Miyama 2-2-1, Funabashi, Chiba 274-8510, Japan
| | - Ryoma Nasu
- Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furou-chou, Chikusa, Nagoya, Aichi 464-8601, Japan
| | - Hisashi Hemmi
- Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furou-chou, Chikusa, Nagoya, Aichi 464-8601, Japan
| | - Tohru Yoshimura
- Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furou-chou, Chikusa, Nagoya, Aichi 464-8601, Japan.
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27
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Koulouris CR, Bax BD, Atack JR, Roe SM. Conformational flexibility within the small domain of human serine racemase. Acta Crystallogr F Struct Biol Commun 2020; 76:65-73. [PMID: 32039887 PMCID: PMC7010357 DOI: 10.1107/s2053230x20001193] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 01/28/2020] [Indexed: 01/28/2023] Open
Abstract
Serine racemase (SR) is a pyridoxal 5'-phosphate (PLP)-containing enzyme that converts L-serine to D-serine, an endogenous co-agonist for the N-methyl-D-aspartate receptor (NMDAR) subtype of glutamate ion channels. SR regulates D-serine levels by the reversible racemization of L-serine to D-serine, as well as the catabolism of serine by α,β-elimination to produce pyruvate. The modulation of SR activity is therefore an attractive therapeutic approach to disorders associated with abnormal glutamatergic signalling since it allows an indirect modulation of NMDAR function. In the present study, a 1.89 Å resolution crystal structure of the human SR holoenzyme (including the PLP cofactor) with four subunits in the asymmetric unit is described. Comparison of this new structure with the crystal structure of human SR with malonate (PDB entry 3l6b) shows an interdomain cleft that is open in the holo structure but which disappears when the inhibitor malonate binds and is enclosed. This is owing to a shift of the small domain (residues 78-155) in human SR similar to that previously described for the rat enzyme. This domain movement is accompanied by changes within the twist of the central four-stranded β-sheet of the small domain, including changes in the φ-ψ angles of all three residues in the C-terminal β-strand (residues 149-151). In the malonate-bound structure, Ser84 (a catalytic residue) points its side chain at the malonate and is preceded by a six-residue β-strand (residues 78-83), but in the holoenzyme the β-strand is only four residues (78-81) and His82 has φ-ψ values in the α-helical region of the Ramachandran plot. These data therefore represent a crystallographic platform that enables the structure-guided design of small-molecule modulators for this important but to date undrugged target.
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Affiliation(s)
- Chloe R. Koulouris
- Sussex Drug Discovery Centre, University of Sussex, Falmer, Brighton BN1 9QG, England
| | - Benjamin D. Bax
- Medicines Discovery Institute, School of Biosciences, University of Cardiff, Park Place, Cardiff CF10 3AT, Wales
| | - John R. Atack
- Medicines Discovery Institute, School of Biosciences, University of Cardiff, Park Place, Cardiff CF10 3AT, Wales
| | - S. Mark Roe
- Department of Biochemistry and Biomedicine, School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QJ, England
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28
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Ohshima K, Nojima S, Tahara S, Kurashige M, Kawasaki K, Hori Y, Taniguchi M, Umakoshi Y, Okuzaki D, Wada N, Ikeda JI, Fukusaki E, Morii E. Serine racemase enhances growth of colorectal cancer by producing pyruvate from serine. Nat Metab 2020; 2:81-96. [PMID: 32694681 DOI: 10.1038/s42255-019-0156-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Accepted: 11/29/2019] [Indexed: 11/09/2022]
Abstract
Serine racemase (SRR) catalyses not only the racemization but also the dehydration of L-serine and D-serine, resulting in the formation of pyruvate and ammonia. Although SRR activity is important in the central nervous system, SRR has not been linked to cancer metabolism before. Here we show that SRR supports proliferation of colorectal-cancer cells. We find that SRR expression is upregulated in colorectal adenoma and adenocarcinoma lesions compared with non-neoplastic mucosa in human colorectal-cancer specimens. SRR-mediated dehydration of serine contributes to the pyruvate pool in colon-cancer cells, enhances proliferation, maintains mitochondrial mass and increases basal reactive oxygen species production, which has anti-apoptotic effects. Moreover, SRR promotes acetylation of histone H3 by maintaining intracellular acetyl-CoA levels. Inhibition of SRR suppresses growth of colorectal tumours in mice and augments the efficacy of 5-fluorouracil treatment. Our findings highlight a previously unknown mechanism through which a racemase supports cancer-cell growth and suggest that SRR might be a molecular target for colorectal-cancer therapy.
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Affiliation(s)
- Kenji Ohshima
- Department of Pathology, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Satoshi Nojima
- Department of Pathology, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Shinichiro Tahara
- Department of Pathology, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Masako Kurashige
- Department of Pathology, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Keisuke Kawasaki
- Department of Pathology, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Yumiko Hori
- Department of Pathology, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Moyu Taniguchi
- Department of Biotechnology, Osaka University Graduate School of Engineering, Suita, Osaka, Japan
| | - Yutaka Umakoshi
- Department of Biotechnology, Osaka University Graduate School of Engineering, Suita, Osaka, Japan
| | - Daisuke Okuzaki
- Genome Information Research Center, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka, Japan
- Single Cell Genomics, Human Immunology, WPI Immunology Frontier Research Center, Osaka University, Osaka, Japan
- Institute for Open and Transdisciplinary Research Initiatives, Osaka University, Osaka, Japan
| | - Naoki Wada
- Department of Pathology, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
- Department of Diagnostic Pathology, Osaka City University, Osaka, Osaka, Japan
| | - Jun-Ichiro Ikeda
- Department of Diagnostic Pathology, Chiba University Graduate School of Medicine, Chiba, Chiba, Japan
| | - Eiichiro Fukusaki
- Department of Biotechnology, Osaka University Graduate School of Engineering, Suita, Osaka, Japan
| | - Eiichi Morii
- Department of Pathology, Osaka University Graduate School of Medicine, Suita, Osaka, Japan.
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29
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The NMDA receptor activation by d-serine and glycine is controlled by an astrocytic Phgdh-dependent serine shuttle. Proc Natl Acad Sci U S A 2019; 116:20736-20742. [PMID: 31548413 DOI: 10.1073/pnas.1909458116] [Citation(s) in RCA: 76] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Astrocytes express the 3-phosphoglycerate dehydrogenase (Phgdh) enzyme required for the synthesis of l-serine from glucose. Astrocytic l-serine was proposed to regulate NMDAR activity by shuttling to neurons to sustain d-serine production, but this hypothesis remains untested. We now report that inhibition of astrocytic Phgdh suppressed the de novo synthesis of l-and d-serine and reduced the NMDAR synaptic potentials and long-term potentiation (LTP) at the Schaffer collaterals-CA1 synapse. Likewise, enzymatic removal of extracellular l-serine impaired LTP, supporting an l-serine shuttle mechanism between glia and neurons in generating the NMDAR coagonist d-serine. Moreover, deletion of serine racemase (SR) in glutamatergic neurons abrogated d-serine synthesis to the same extent as Phgdh inhibition, suggesting that neurons are the predominant source of the newly synthesized d-serine. We also found that the synaptic NMDAR activation in adult SR-knockout (KO) mice requires Phgdh-derived glycine, despite the sharp decline in the postnatal glycine levels as a result of the emergence of the glycine cleavage system. Unexpectedly, we also discovered that glycine regulates d-serine metabolism by a dual mechanism. The first consists of tonic inhibition of SR by intracellular glycine observed in vitro, primary cultures, and in vivo microdialysis. The second involves a transient glycine-induce d-serine release through the Asc-1 transporter, an effect abolished in Asc-1 KO mice and diminished by deleting SR in glutamatergic neurons. Our observations suggest that glycine is a multifaceted regulator of d-serine metabolism and implicate both d-serine and glycine in mediating NMDAR synaptic activation at the mature hippocampus through a Phgdh-dependent shuttle mechanism.
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30
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Bastings JJ, van Eijk HM, Olde Damink SW, Rensen SS. d-amino Acids in Health and Disease: A Focus on Cancer. Nutrients 2019; 11:nu11092205. [PMID: 31547425 PMCID: PMC6770864 DOI: 10.3390/nu11092205] [Citation(s) in RCA: 82] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 09/06/2019] [Accepted: 09/09/2019] [Indexed: 01/09/2023] Open
Abstract
d-amino acids, the enantiomeric counterparts of l-amino acids, were long considered to be non-functional or not even present in living organisms. Nowadays, d-amino acids are acknowledged to play important roles in numerous physiological processes in the human body. The most commonly studied link between d-amino acids and human physiology concerns the contribution of d-serine and d-aspartate to neurotransmission. These d-amino acids and several others have also been implicated in regulating innate immunity and gut barrier function. Importantly, the presence of certain d-amino acids in the human body has been linked to several diseases including schizophrenia, amyotrophic lateral sclerosis, and age-related disorders such as cataract and atherosclerosis. Furthermore, increasing evidence supports a role for d-amino acids in the development, pathophysiology, and treatment of cancer. In this review, we aim to provide an overview of the various sources of d-amino acids, their metabolism, as well as their contribution to physiological processes and diseases in man, with a focus on cancer.
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Affiliation(s)
- Jacco J.A.J. Bastings
- Department of Surgery, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University, 6200 MD Maastricht, The Netherlands (H.M.v.E.); (S.W.O.D.)
- Department of Human Biology, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University, 6200 MD Maastricht, The Netherlands
| | - Hans M. van Eijk
- Department of Surgery, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University, 6200 MD Maastricht, The Netherlands (H.M.v.E.); (S.W.O.D.)
| | - Steven W. Olde Damink
- Department of Surgery, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University, 6200 MD Maastricht, The Netherlands (H.M.v.E.); (S.W.O.D.)
- Department of General, Visceral and Transplantation Surgery, RWTH University Hospital Aachen, 52074 Aachen, Germany
| | - Sander S. Rensen
- Department of Surgery, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University, 6200 MD Maastricht, The Netherlands (H.M.v.E.); (S.W.O.D.)
- Correspondence:
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31
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Kawamura I, Sato H. Solid-state vibrational circular dichroism studies of L- and D-serine. Anal Biochem 2019; 580:14-20. [PMID: 31153871 DOI: 10.1016/j.ab.2019.05.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2019] [Revised: 04/26/2019] [Accepted: 05/29/2019] [Indexed: 02/06/2023]
Abstract
d-Serine is considered a key endogenous substance involved in several enzymatic reactions in the human body. In this study, solid-state vibrational circular dichroism (VCD) measurements of enantiomeric serine were performed for spectroscopic distinction between d- and l-serine. The mirror-image VCD signals of the isomers in the KBr pellets were observed in the mid-infrared range of 1800-1250 cm-1. The calculated infrared (IR) and VCD spectra for the optimized serine structures were in good agreement with the corresponding observed spectra. In addition, the chemical shift values estimated from the shielding constants of the optimized structure of serine corresponded with the observed values in 13C and 15N solid-state nuclear magnetic resonance spectra, supporting the VCD assignments. Our results suggest the need for further study of VCD to develop a sensitive and high-resolution spectroscopic technique for the detection of d-amino acids.
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Affiliation(s)
- Izuru Kawamura
- Graduate School of Engineering, Yokohama National University, 240-8501, Yokohama, Japan.
| | - Hisako Sato
- (b)Graduate School of Science and Engineering, Ehime University, 790-8577, Matsuyama, Japan.
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32
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D-Serine made by serine racemase in Drosophila intestine plays a physiological role in sleep. Nat Commun 2019; 10:1986. [PMID: 31064979 PMCID: PMC6504911 DOI: 10.1038/s41467-019-09544-9] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Accepted: 03/14/2019] [Indexed: 12/21/2022] Open
Abstract
Natural D-serine (D-Ser) has been detected in animals more than two decades ago, but little is known about the physiological functions of D-Ser. Here we reveal sleep regulation by endogenous D-Ser. Sleep was decreased in mutants defective in D-Ser synthesis or its receptor the N-methyl-D-aspartic receptor 1 (NMDAR1), but increased in mutants defective in D-Ser degradation. D-Ser but not L-Ser rescued the phenotype of mutants lacking serine racemase (SR), the key enzyme for D-Ser synthesis. Pharmacological and triple gene knockout experiments indicate that D-Ser functions upstream of NMDAR1. Expression of SR was detected in both the nervous system and the intestines. Strikingly, reintroduction of SR into specific intestinal epithelial cells rescued the sleep phenotype of sr mutants. Our results have established a novel physiological function for endogenous D-Ser and a surprising role for intestinal cells. The physiological function of endogenous D-serine remains a mystery. Here the authors show that endogenous D-serine plays an important role in regulating sleep and that, while the D-serine synthesizing enzyme serine racemase (SR) is expressed both in the nervous system and the intestines, the SR in the intestine is shown to be functionally sufficient for sleep regulation.
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33
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Mothet JP, Billard JM, Pollegioni L, Coyle JT, Sweedler JV. Investigating brain d-serine: Advocacy for good practices. Acta Physiol (Oxf) 2019; 226:e13257. [PMID: 30650253 PMCID: PMC6462235 DOI: 10.1111/apha.13257] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 01/09/2019] [Accepted: 01/10/2019] [Indexed: 12/31/2022]
Abstract
The last two decades have witnessed remarkable advance in our understanding the role of d-amino acids in the mammalian nervous system: from the unknown, to known molecules with unknown functions, to potential central players in health and disease. d-Amino acids have emerged as an important class of signaling molecules. In particular, the exploration of the roles of d-serine in brain physiopathology is a vibrant field that is growing at an accelerating pace. However, disentangling the functions of a chiral molecule in a complex chemical matrice as the brain requires specific measurement and detection methods but is also a challenging task as many molecular tools and models investigators are using can lead to confounded observations. Thus, study of d-amino acids demands accurate methodologies and specific controls, and these have often been lacking. Here we outline best practices for d-amino acid research, with a special emphasis on d-serine. We hope these concepts help move the field to greater rigor and reproducibility, allowing the field to advance.
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Affiliation(s)
- Jean-Pierre Mothet
- Team Gliotransmission & Synaptopathies, Aix Marseille University, Centre de Recherche en Neurobiologie et Neurophysiologie de Marseille UMR7286 CNRS, Marseille, France
| | | | - Loredano Pollegioni
- Dipartimento di Biotecnologie e Scienze della Vita, Università degli Studi dell’Insubria, Varese, Italy
| | - Joseph T Coyle
- Department of Psychiatry, Harvard Medical School, Boston, MA, USA
| | - Jonathan V Sweedler
- Department of Chemistry and the Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
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34
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Graham DL, Beio ML, Nelson DL, Berkowitz DB. Human Serine Racemase: Key Residues/Active Site Motifs and Their Relation to Enzyme Function. Front Mol Biosci 2019; 6:8. [PMID: 30918891 PMCID: PMC6424897 DOI: 10.3389/fmolb.2019.00008] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Accepted: 02/12/2019] [Indexed: 01/06/2023] Open
Abstract
Serine racemase (SR) is the first racemase enzyme to be identified in human biology and converts L-serine to D-serine, an important neuronal signaling molecule that serves as a co-agonist of the NMDA (N-methyl-D-aspartate) receptor. This overview describes key molecular features of the enzyme, focusing on the side chains and binding motifs that control PLP (pyridoxal phosphate) cofactor binding as well as activity modulation through the binding of both divalent cations and ATP, the latter showing allosteric modulation. Discussed are catalytically important residues in the active site including K56 and S84—the si- and re-face bases, respectively,—and R135, a residue that appears to play a critical role in the binding of both negatively charged alternative substrates and inhibitors. The interesting bifurcated mechanism followed by this enzyme whereby substrate L-serine can be channeled either into D-serine (racemization pathway) or into pyruvate (β-elimination pathway) is discussed extensively, as are studies that focus on a key loop region (the so-called “triple serine loop”), the modification of which can be used to invert the normal in vitro preference of this enzyme for the latter pathway over the former. The possible cross-talk between the PLP enzymes hSR and hCBS (human cystathionine β-synthase) is discussed, as the former produces D-serine and the latter produces H2S, both of which stimulate the NMDAR and both of which have been implicated in neuronal infarction pursuant to ischemic stroke. Efforts to gain a more complete mechanistic understanding of these PLP enzymes are expected to provide valuable insights for the development of specific small molecule modulators of these enzymes as tools to study their roles in neuronal signaling and in modulation of NMDAR function.
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Affiliation(s)
- Danielle L Graham
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE, United States
| | - Matthew L Beio
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE, United States
| | - David L Nelson
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE, United States
| | - David B Berkowitz
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE, United States
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35
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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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36
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Shad KF, Luqman N, Simpson AM, Lal S. Peripheral Biomarker for Vascular Disorders. Biomark Insights 2018; 13:1177271918812467. [PMID: 30546256 PMCID: PMC6287300 DOI: 10.1177/1177271918812467] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Accepted: 10/19/2018] [Indexed: 11/15/2022] Open
Abstract
Atherosclerosis is the underlying cause of most myocardial infarction (MI) and ischaemic stroke episodes. An early sign of atherosclerosis is hypertrophy of the arterial wall. It is known that increased intima media thickness (IMT) is a non-invasive marker of arterial wall alteration, which can easily be assessed in the carotid arteries by high-resolution B-mode ultrasound. Similarly, the other key element of MI and ischaemic strokes is the N-methyl-D-aspartate (NMDA) receptor which is an ionotropic glutamate receptor that mediates the vast majority of excitatory neurotransmission in the brain. NMDA activation requires the binding of both glutamate and a coagonist like D-serine to its glycine site. A special enzyme, serine racemase (SR), is required for the conversion of L-serine into D-serine, and alterations in SR activities lead to a variety of physiological and pathological conditions ranging from synaptic plasticity to ischemia, MI, and stroke. The amount of D-serine available for the activation of glutamatergic signalling is largely determined by SR and we have developed ways to estimate its levels in human blood samples and correlate it with the IMT. This research based short communication describes our pilot study, which clearly suggests that there is a direct relationship between the SR, D-serine, and IMT. In this article, we will discuss whether the activity of SR can determine the future consequences resulting from vascular pathologies such as MI and stroke.
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Affiliation(s)
- Kaneez Fatima Shad
- School of Life Sciences and Centre for Health Technologies, University of Technology Sydney, Broadway, NSW, Australia.,PAPRSB Institute of Health Sciences, University of Brunei Darussalam, Gadong, Brunei Darussalam
| | - Nazar Luqman
- PAPRSB Institute of Health Sciences, University of Brunei Darussalam, Gadong, Brunei Darussalam.,Cardiology Department, RIPAS Hospital, Bandar Seri Begawan, Brunei Darussalam
| | - Ann M Simpson
- School of Life Sciences and Centre for Health Technologies, University of Technology Sydney, Broadway, NSW, Australia
| | - Sara Lal
- School of Life Sciences and Centre for Health Technologies, University of Technology Sydney, Broadway, NSW, Australia.,Neuroscience Research Unit, School of Life Sciences, University of Technology Sydney, Broadway, NSW, Australia
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Billard JM. Changes in Serine Racemase-Dependent Modulation of NMDA Receptor: Impact on Physiological and Pathological Brain Aging. Front Mol Biosci 2018; 5:106. [PMID: 30555832 PMCID: PMC6282039 DOI: 10.3389/fmolb.2018.00106] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Accepted: 11/09/2018] [Indexed: 02/02/2023] Open
Abstract
The N-methyl-D-Aspartate glutamate receptors (NMDARs) are pivotal for the functional and morphological plasticity that are required in neuronal networks for efficient brain activities and notably for cognitive-related abilities. Because NMDARs are heterogeneous in subunit composition and associated with multiple functional regulatory sites, their efficacy is under the tonic influence of numerous allosteric modulations, whose dysfunction generally represents the first step generating pathological states. Among the enzymatic candidates, serine racemase (SR) has recently gathered an increasing interest considering that it tightly regulates the production of d-serine, an amino acid now viewed as the main endogenous co-agonist necessary for NMDAR activation. Nowadays, SR deregulation is associated with a wide range of neurological and psychiatric diseases including schizophrenia, amyotrophic lateral sclerosis, and depression. This review aims at compelling the most recent experimental evidences indicating that changes in SR-related modulation of NMDARs also govern opposite functional dysfunctions in physiological and pathological (Alzheimer's disease) aging that finally results in memory disabilities in both cases. It also highlights SR as a relevant alternative target for new pharmacological strategies aimed at preventing functional alterations and cognitive impairments linked to the aging process.
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38
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Permissiveness to form pluripotent stem cells may be an evolutionarily derived characteristic in Mus musculus. Sci Rep 2018; 8:14706. [PMID: 30279419 PMCID: PMC6168588 DOI: 10.1038/s41598-018-32116-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Accepted: 09/03/2018] [Indexed: 01/06/2023] Open
Abstract
Mus musculus is the only known species from which embryonic stem cells (ESC) can be isolated under conditions requiring only leukemia inhibitory factor (LIF). Other species are non-permissive in LIF media, and form developmentally primed epiblast stem cells (EpiSC) similar to cells derived from post-implantation, egg cylinders. To evaluate whether non-permissiveness extends to induced pluripotent stem cells (iPSC), we derived iPSC from the eight founder strains of the mouse Collaborative Cross. Two strains, NOD/ShiLtJ and the WSB/EiJ, were non-permissive, consistent with the previous classification of NOD/ShiLtJ as non-permissive to ESC derivation. We determined non-permissiveness is recessive, and that non-permissive genomes do not compliment. We overcame iPSC non-permissiveness by using GSK3B and MEK inhibitors with serum, a technique we termed 2iS reprogramming. Although used for ESC derivation, GSK3B and MEK inhibitors have not been used during iPSC reprogramming because they inhibit survival of progenitor differentiated cells. iPSC derived in 2iS are more transcriptionally similar to ESC than EpiSC, indicating that 2iS reprogramming acts to overcome genetic background constraints. Finally, of species tested for ESC or iPSC derivation, only some M. musculus strains are permissive under LIF culture conditions suggesting that this is an evolutionarily derived characteristic in the M. musculus lineage.
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Kumar A, Foster TC. Alteration in NMDA Receptor Mediated Glutamatergic Neurotransmission in the Hippocampus During Senescence. Neurochem Res 2018; 44:38-48. [PMID: 30209673 DOI: 10.1007/s11064-018-2634-4] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Revised: 09/07/2018] [Accepted: 09/08/2018] [Indexed: 12/17/2022]
Abstract
Glutamate is the primary excitatory neurotransmitter in neurons and glia. N-methyl-D-aspartate (NMDA), α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), and kainate receptors are major ionotropic glutamate receptors. Glutamatergic neurotransmission is strongly linked with Ca2+ homeostasis. Research has provided ample evidence that brain aging is associated with altered glutamatergic neurotransmission and Ca2+ dysregulation. Much of the work has focused on the hippocampus, a brain region critically involved in learning and memory, which is particularly susceptible to dysfunction during senescence. The current review examines Ca2+ regulation with a focus on the NMDA receptors in the hippocampus. Integrating the knowledge of the complexity of age-related alterations in Ca2+ homeostasis and NMDA receptor-mediated glutamatergic neurotransmission will positively shape the development of highly effective therapeutics to treat brain disorders including cognitive impairment.
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Affiliation(s)
- Ashok Kumar
- Department of Neuroscience, McKnight Brain Institute, University of Florida, PO Box 100244, Gainesville, FL, 32610-0244, USA.
| | - Thomas C Foster
- Department of Neuroscience, McKnight Brain Institute, University of Florida, PO Box 100244, Gainesville, FL, 32610-0244, USA.
- Genetics and Genomics Program, University of Florida, Gainesville, FL, 32611, USA.
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40
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Glutamine 89 is a key residue in the allosteric modulation of human serine racemase activity by ATP. Sci Rep 2018; 8:9016. [PMID: 29899358 PMCID: PMC5998037 DOI: 10.1038/s41598-018-27227-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Accepted: 05/25/2018] [Indexed: 11/17/2022] Open
Abstract
Serine racemase (SR) catalyses two reactions: the reversible racemisation of L-serine and the irreversible dehydration of L- and D-serine to pyruvate and ammonia. SRs are evolutionarily related to serine dehydratases (SDH) and degradative threonine deaminases (TdcB). Most SRs and TdcBs – but not SDHs – are regulated by nucleotides. SR binds ATP cooperatively and the nucleotide allosterically stimulates the serine dehydratase activity of the enzyme. A H-bond network comprising five residues (T52, N86, Q89, E283 and N316) and water molecules connects the active site with the ATP-binding site. Conservation analysis points to Q89 as a key residue for the allosteric communication, since its mutation to either Met or Ala is linked to the loss of control of activity by nucleotides. We verified this hypothesis by introducing the Q89M and Q89A point mutations in the human SR sequence. The allosteric communication between the active site and the allosteric site in both mutants is almost completely abolished. Indeed, the stimulation of the dehydratase activity by ATP is severely diminished and the binding of the nucleotide is no more cooperative. Ancestral state reconstruction suggests that the allosteric control by nucleotides established early in SR evolution and has been maintained in most eukaryotic lineages.
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41
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Marchesani F, Bruno S, Paredi G, Raboni S, Campanini B, Mozzarelli A. Human serine racemase is nitrosylated at multiple sites. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2018; 1866:813-821. [PMID: 29410194 DOI: 10.1016/j.bbapap.2018.01.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Revised: 01/18/2018] [Accepted: 01/29/2018] [Indexed: 11/26/2022]
Abstract
Serine racemase is a pyridoxal 5'‑phosphate dependent enzyme responsible for the synthesis of d‑serine, a neuromodulator of the NMDA receptors. Its activity is modulated by several ligands, including ATP, divalent cations and protein interactors. The murine orthologue is inhibited by S-nitrosylation at Cys113, a residue adjacent to the ATP binding site. We found that the time course of inhibition of human serine racemase by S-nitrosylation is markedly biphasic, with a fast phase associated with the reaction of Cys113. Unlike the murine enzyme, two additional cysteine residues, Cys269, unique to the human orthologue, and Cys128 were also recognized as S-nitrosylation sites through mass spectrometry and site-directed mutagenesis. The effect of S-nitrosylation on the fluorescence of tryptophan residues and on that of the pyridoxal phosphate cofactor indicated that S-nitrosylation produces a partial interruption of the cross-talk between the ATP binding site and the active site. Overall, it appears that the inhibition results from a conformational change rather than the direct displacement of ATP.
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Affiliation(s)
- Francesco Marchesani
- Dipartimento di Scienze degli Alimenti e del Farmaco, Università di Parma, Parma, Italy
| | - Stefano Bruno
- Dipartimento di Scienze degli Alimenti e del Farmaco, Università di Parma, Parma, Italy.
| | - Gianluca Paredi
- Dipartimento di Scienze degli Alimenti e del Farmaco, Università di Parma, Parma, Italy
| | - Samanta Raboni
- Dipartimento di Scienze degli Alimenti e del Farmaco, Università di Parma, Parma, Italy
| | - Barbara Campanini
- Dipartimento di Scienze degli Alimenti e del Farmaco, Università di Parma, Parma, Italy
| | - Andrea Mozzarelli
- Dipartimento di Scienze degli Alimenti e del Farmaco, Università di Parma, Parma, Italy; Istituto di Biofisica, Consiglio Nazionale delle Ricerche, Pisa, Italy
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42
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Tao H, Zhou X, Xie Q, Ma Z, Sun F, Cui L, Cai Y, Ma G, Fu J, Liu Z, Li Y, Zhou H, Zhao J, Chen Y, Mai H, Chen Y, Chen J, Qi W, Sun C, Zhao B, Li K. SRR intronic variation inhibits expression of its neighbouring SMG6 gene and protects against temporal lobe epilepsy. J Cell Mol Med 2018; 22:1883-1893. [PMID: 29363864 PMCID: PMC5824374 DOI: 10.1111/jcmm.13473] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Accepted: 10/30/2017] [Indexed: 01/05/2023] Open
Abstract
D‐serine is a predominant N‐methyl‐D‐aspartate receptor co‐agonist with glutamate, and excessive activation of the receptor plays a substantial role in epileptic seizures. Serine racemase (SRR) is responsible for transforming L‐serine to D‐serine. In this study, we aimed to investigate the genetic roles of SRR and a neighbouring gene, nonsense‐mediated mRNA decay factor (SMG6), in temporal lobe epilepsy (TLE). Here, a total of 496 TLE patients and 528 healthy individuals were successfully genotyped for three SRR tag single nucleotide polymorphisms. The frequencies of the GG genotype at rs4523957 T > G were reduced in the TLE cases in the initial cohort (cohort 1) and were confirmed in the independent cohort (cohort 2). An analysis of all TLE cases in cohort 1 + 2 revealed that the seizure frequency and drug‐resistant incidence were significantly decreased in carriers of the GG genotype at rs4523957. Intriguingly, the activity of the SMG6 promoter with the mutant allele at rs4523957 decreased by 22% in the dual‐luciferase assay, and up‐regulated expression of SMG6 was observed in an epilepsy rat model. This study provides the first demonstration that the GG genotype is a protective marker against TLE. In particular, variation at rs4523957 likely inhibits SMG6 transcription and plays a key role against susceptibility to and severity of TLE. The significance of SMG6 hyperfunction in epileptic seizures deserves to be investigated in future studies.
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Affiliation(s)
- Hua Tao
- Department of Neurology, Affiliated Hospital of Guangdong Medical University, Zhanjiang, Guangdong, China.,Guangdong Key Laboratory of Age-related Cardiac and Cerebral Diseases, Guangdong Medical University, Zhanjiang, Guangdong, China
| | - Xu Zhou
- Clinical Research Center, Guangdong Medical University, Zhanjiang, Guangdong, China
| | - Qian Xie
- Emergency Department, Affiliated Hospital of Guangdong Medical University, Zhanjiang, Guangdong, China
| | - Zhonghua Ma
- Department of Neurology, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Fuhai Sun
- Department of Neurology, the First People's Hospital of Pingdingshan, Pingdingshan, Hebei, China
| | - Lili Cui
- Guangdong Key Laboratory of Age-related Cardiac and Cerebral Diseases, Guangdong Medical University, Zhanjiang, Guangdong, China
| | - Yujie Cai
- Guangdong Key Laboratory of Age-related Cardiac and Cerebral Diseases, Guangdong Medical University, Zhanjiang, Guangdong, China
| | - Guoda Ma
- Guangdong Key Laboratory of Age-related Cardiac and Cerebral Diseases, Guangdong Medical University, Zhanjiang, Guangdong, China
| | - Jiawu Fu
- Department of Neurology, Affiliated Hospital of Guangdong Medical University, Zhanjiang, Guangdong, China
| | - Zhou Liu
- Guangdong Key Laboratory of Age-related Cardiac and Cerebral Diseases, Guangdong Medical University, Zhanjiang, Guangdong, China
| | - You Li
- Guangdong Key Laboratory of Age-related Cardiac and Cerebral Diseases, Guangdong Medical University, Zhanjiang, Guangdong, China
| | - Haihong Zhou
- Department of Neurology, Affiliated Hospital of Guangdong Medical University, Zhanjiang, Guangdong, China
| | - Jianghao Zhao
- Department of Neurology, Affiliated Hospital of Guangdong Medical University, Zhanjiang, Guangdong, China
| | - Yanyan Chen
- Guangdong Key Laboratory of Age-related Cardiac and Cerebral Diseases, Guangdong Medical University, Zhanjiang, Guangdong, China
| | - Hui Mai
- Department of Neurology, Affiliated Hospital of Guangdong Medical University, Zhanjiang, Guangdong, China
| | - Ying Chen
- Department of Neurology, Central People's Hospital of Zhanjiang, Zhanjiang, Guangdong, China
| | - Jun Chen
- Department of Neurology, Affiliated Hospital of Guangdong Medical University, Zhanjiang, Guangdong, China
| | - Wei Qi
- Department of Neurology, Affiliated Hospital of Guangdong Medical University, Zhanjiang, Guangdong, China
| | - Chaowen Sun
- Department of Neurology, Affiliated Hospital of Guangdong Medical University, Zhanjiang, Guangdong, China
| | - Bin Zhao
- Guangdong Key Laboratory of Age-related Cardiac and Cerebral Diseases, Guangdong Medical University, Zhanjiang, Guangdong, China
| | - Keshen Li
- Institute of Neurology, Guangdong Medical University, Zhanjiang, Guangdong, China.,Stroke Center, Neurology& Neurosurgery Division, Clinical Medicine Research Institute & the First Affiliated Hospital, Jinan University, Guangzhou, Guangdong, China
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43
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44
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Mizobuchi T, Nonaka R, Yoshimura M, Abe K, Takahashi S, Kera Y, Goto M. Crystal structure of a pyridoxal 5'-phosphate-dependent aspartate racemase derived from the bivalve mollusc Scapharca broughtonii. Acta Crystallogr F Struct Biol Commun 2017; 73:651-656. [PMID: 29199985 PMCID: PMC5713669 DOI: 10.1107/s2053230x17015813] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Accepted: 10/30/2017] [Indexed: 11/10/2022] Open
Abstract
Aspartate racemase (AspR) is a pyridoxal 5'-phosphate (PLP)-dependent enzyme that is responsible for D-aspartate biosynthesis in vivo. To the best of our knowledge, this is the first study to report an X-ray crystal structure of a PLP-dependent AspR, which was resolved at 1.90 Å resolution. The AspR derived from the bivalve mollusc Scapharca broughtonii (SbAspR) is a type II PLP-dependent enzyme that is similar to serine racemase (SR) in that SbAspR catalyzes both racemization and dehydration. Structural comparison of SbAspR and SR shows a similar arrangement of the active-site residues and nucleotide-binding site, but a different orientation of the metal-binding site. Superposition of the structures of SbAspR and of rat SR bound to the inhibitor malonate reveals that Arg140 recognizes the β-carboxyl group of the substrate aspartate in SbAspR. It is hypothesized that the aromatic proline interaction between the domains, which favours the closed form of SbAspR, influences the arrangement of Arg140 at the active site.
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Affiliation(s)
- Taichi Mizobuchi
- Department of Biomolecular Science, Graduate School of Science, Toho University, 2-2-1 Miyama, Funabashi, Chiba 274-8510, Japan
| | - Risako Nonaka
- Department of Biomolecular Science, Graduate School of Science, Toho University, 2-2-1 Miyama, Funabashi, Chiba 274-8510, Japan
| | - Motoki Yoshimura
- Department of Environmental Systems Engineering, Nagaoka University of Technology, Nagaoka, Niigata 940-2188, Japan
| | - Katsumasa Abe
- Department of Environmental Systems Engineering, Nagaoka University of Technology, Nagaoka, Niigata 940-2188, Japan
| | - Shouji Takahashi
- Department of Environmental Systems Engineering, Nagaoka University of Technology, Nagaoka, Niigata 940-2188, Japan
| | - Yoshio Kera
- Department of Environmental Systems Engineering, Nagaoka University of Technology, Nagaoka, Niigata 940-2188, Japan
| | - Masaru Goto
- Department of Biomolecular Science, Faculty of Science, Toho University, 2-2-1 Miyama, Funabashi, Chiba 274-8510, Japan
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45
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Triple serine loop region regulates the aspartate racemase activity of the serine/aspartate racemase family. Amino Acids 2017; 49:1743-1754. [PMID: 28744579 DOI: 10.1007/s00726-017-2472-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Accepted: 07/20/2017] [Indexed: 02/02/2023]
Abstract
Recently, we cloned and characterized eleven serine and aspartate racemases (SerR and AspR, respectively) from animals. These SerRs and AspRs are not separated by their racemase functions and form a serine/aspartate racemase family cluster based on phylogenetic analysis. Moreover, we have proposed that the AspR-specific triple serine loop region at amino acid positions 150-152 may be responsible for the large AspR activity. In the present study, to test this hypothesis, we prepared and characterized fourteen mutants in this region of animal SerRs and AspRs. The large AspR activity in Acropora and Crassostrea AspR was reduced to <0.04% of wild-type after substitution of the triple serine loop region. Conversely, introducing the triple serine loop region into Acropora, Crassostrea, and Penaeus SerR drastically increased the AspR activity. Those mutants showed similar or higher substrate affinity for aspartate than serine and showed 11-683-fold higher k cat and 28-351-fold higher k cat/K m values for aspartate than serine racemization. Furthermore, we introduced serine residues in all combinations at position 150-152 in mouse SerR. These mutants revealed that a change in the enzyme function from SerR to AspR can be caused by introduction of Ser151 and Ser152, and addition of the third serine residue at position 150 further enhances the enzyme specificity for aspartate due to a decrease in the serine racemase and serine dehydratase activity. Here, we provide convincing evidence that the AspR gene has evolved from the SerR gene by acquisition of the triple serine loop region.
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46
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Nelson DL, Applegate GA, Beio ML, Graham DL, Berkowitz DB. Human serine racemase structure/activity relationship studies provide mechanistic insight and point to position 84 as a hot spot for β-elimination function. J Biol Chem 2017; 292:13986-14002. [PMID: 28696262 DOI: 10.1074/jbc.m117.777904] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Revised: 06/26/2017] [Indexed: 11/06/2022] Open
Abstract
There is currently great interest in human serine racemase, the enzyme responsible for producing the NMDA co-agonist d-serine. Reported correlation of d-serine levels with disorders including Alzheimer's disease, ALS, and ischemic brain damage (elevated d-serine) and schizophrenia (reduced d-serine) has further piqued this interest. Reported here is a structure/activity relationship study of position Ser84, the putative re-face base. In the most extreme case of functional reprogramming, the S84D mutant displays a dramatic reversal of β-elimination substrate specificity in favor of l-serine over the normally preferred l-serine-O-sulfate (∼1200-fold change in kcat/Km ratios) and l (l-THA; ∼5000-fold change in kcat/Km ratios) alternative substrates. On the other hand, the S84T (which performs l-Ser racemization activity), S84A (good kcat but high Km for l-THA elimination), and S84N mutants (nearly WT efficiency for l-Ser elimination) displayed intermediate activity, all showing a preference for the anionic substrates, but generally attenuated compared with the native enzyme. Inhibition studies with l-erythro-β-hydroxyaspartate follow this trend, with both WT serine racemase and the S84N mutant being competitively inhibited, with Ki = 31 ± 1.5 μm and 1.5 ± 0.1 mm, respectively, and the S84D being inert to inhibition. Computational modeling pointed to a key role for residue Arg-135 in binding and properly positioning the l-THA and l-serine-O-sulfate substrates and the l-erythro-β-hydroxyaspartate inhibitor. Examination of available sequence data suggests that Arg-135 may have originated for l-THA-like β-elimination function in earlier evolutionary variants, and examination of available structural data suggests that a Ser84-H2O-Lys114 hydrogen-bonding network in human serine racemase lowers the pKa of the Ser84re-face base.
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Affiliation(s)
- David L Nelson
- From the Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588
| | - Greg A Applegate
- From the Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588
| | - Matthew L Beio
- From the Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588
| | - Danielle L Graham
- From the Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588
| | - David B Berkowitz
- From the Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588.
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Abstract
More than half a century ago researchers thought that D-amino acids had a minor function compared to L-enantiomers in biological processes. Many evidences have shown that D-amino acids are present in high concentration in microorganisms, plants, mammals and humans and fulfil specific biological functions. In the brain of mammals, D-serine (D-Ser) acts as a co-agonist of the N-methyl-D-aspartate (NMDA)-type glutamate receptors, responsible for learning, memory and behaviour. D-Ser metabolism is relevant for disorders associated with an altered function of the NMDA receptor, such as schizophrenia, ischemia, epilepsy and neurodegenerative disorders. On the other hand, D-aspartate (D-Asp) is one of the major regulators of adult neurogenesis and plays an important role in the development of endocrine function. D-Asp is present in the neuroendocrine and endocrine tissues and testes, and regulates the synthesis and secretion of hormones and spermatogenesis. Also food proteins contain D-amino acids that are naturally originated or processing-induced under conditions such as high temperatures, acid and alkali treatments and fermentation processes. The presence of D-amino acids in dairy products denotes thermal and alkaline treatments and microbial contamination. Two enzymes are involved in the metabolism of D-amino acids: amino acid racemase in the synthesis and D-amino acid oxidase in the degradation.
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48
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D-Glutamate is metabolized in the heart mitochondria. Sci Rep 2017; 7:43911. [PMID: 28266638 PMCID: PMC5339696 DOI: 10.1038/srep43911] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Accepted: 01/31/2017] [Indexed: 12/30/2022] Open
Abstract
D-Amino acids are enantiomers of L-amino acids and have recently been recognized as biomarkers and bioactive substances in mammals, including humans. In the present study, we investigated functions of the novel mammalian mitochondrial protein 9030617O03Rik and showed decreased expression under conditions of heart failure. Genomic sequence analyses showed partial homology with a bacterial aspartate/glutamate/hydantoin racemase. Subsequent determinations of all free amino acid concentrations in 9030617O03Rik-deficient mice showed high accumulations of D-glutamate in heart tissues. This is the first time that a significant amount of D-glutamate was detected in mammalian tissue. Further analysis of D-glutamate metabolism indicated that 9030617O03Rik is a D-glutamate cyclase that converts D-glutamate to 5-oxo-D-proline. Hence, this protein is the first identified enzyme responsible for mammalian D-glutamate metabolism, as confirmed in cloning analyses. These findings suggest that D-glutamate and 5-oxo-D-proline have bioactivities in mammals through the metabolism by D-glutamate cyclase.
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49
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Cox PA, Metcalf JS. Traditional Food Items in Ogimi, Okinawa: l-Serine Content and the Potential for Neuroprotection. Curr Nutr Rep 2017; 6:24-31. [PMID: 28331770 PMCID: PMC5343079 DOI: 10.1007/s13668-017-0191-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Purpose of Review Ogimi village is renowned for its aging population. We sought to determine if the l-serine content of their diet could account for their neurological health. Recent Findings The most frequently consumed food items, including tofu and seaweeds, are rich in the dietary amino acid l-serine. l-serine content of the Ogimi diet >8 grams/day for Ogimi women significantly exceeds the average American dietary intake of 2.5 grams/day for women >70 years old. Summary Our hypothesis that the high l-serine content of the Ogimi diet is related to the paucity of tangle diseases among villagers is buttressed by in vivo results with non-human primates where dietary l-serine slowed development of neurofibrillary tangles and β-amyloid plaques by up to 85% and a human clinical trial finding that l-serine at 15 grams/day twice daily slows functional decline in ALS patients. Analysis of the Ogimi diet suggests that l-serine should be evaluated for therapeutic potential as a neuroprotective agent.
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Affiliation(s)
- Paul Alan Cox
- Brain Chemistry Labs, Institute for Ethnomedicine, Box 3464, Jackson, WY 83001 USA
| | - James S Metcalf
- Brain Chemistry Labs, Institute for Ethnomedicine, Box 3464, Jackson, WY 83001 USA
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50
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Bruno S, Margiotta M, Marchesani F, Paredi G, Orlandi V, Faggiano S, Ronda L, Campanini B, Mozzarelli A. Magnesium and calcium ions differentially affect human serine racemase activity and modulate its quaternary equilibrium toward a tetrameric form. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2017; 1865:381-387. [PMID: 28089597 DOI: 10.1016/j.bbapap.2017.01.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Revised: 12/21/2016] [Accepted: 01/05/2017] [Indexed: 11/18/2022]
Abstract
Serine racemase is the pyridoxal 5'-phosphate dependent enzyme that catalyzes both production and catabolism of d-serine, a co-agonist of the NMDA glutamate receptors. Mg2+, or, alternatively, Ca2+, activate human serine racemase by binding both at a specific site and - as ATP-metal complexes - at a distinct ATP binding site. We show that Mg2+ and Ca2+ bind at the metal binding site with a 4.5-fold difference in affinity, producing a similar thermal stabilization and partially shifting the dimer-tetramer equilibrium in favour of the latter. The ATP-Ca2+ complex produces a 2-fold lower maximal activation in comparison to the ATP-Mg2+ complex and exhibits a 3-fold higher EC50. The co-presence of ATP and metals further stabilizes the tetramer. In consideration of the cellular concentrations of Mg2+ and Ca2+, even taking into account the fluctuations of the latter, these results point to Mg2+ as the sole physiologically relevant ligand both at the metal binding site and at the ATP binding site. The stabilization of the tetramer by both metals and ATP-metal complexes suggests a quaternary activation mechanism mediated by 5'-phosphonucleotides similar to that observed in the distantly related prokaryotic threonine deaminases. This allosteric mechanism has never been observed before in mammalian fold type II pyridoxal 5'-phosphate dependent enzymes.
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Affiliation(s)
| | | | | | - Gianluca Paredi
- Interdepartment Center SITEIA.PARMA, University of Parma, Italy
| | | | | | - Luca Ronda
- Department of Neurosciences, University of Parma, Italy
| | | | - Andrea Mozzarelli
- Department of Pharmacy, University of Parma, Italy; Institute of Biophysics, CNR, Pisa, Italy; National Institute of Biostructures and Biomolecules, Rome, Italy
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