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Meng-yang Zhu - One of the best experts on this subject based on the ideXlab platform.
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Repeated immobilization stress alters rat hippocampal and prefrontal cortical morphology in parallel with endogenous agmatine and Arginine Decarboxylase levels.
Neurochemistry international, 2008Co-Authors: Meng-yang Zhu, Wei-ping Wang, Jingjing Huang, Yang-zheng Feng, Soundar Regunathan, Garth BissetteAbstract:Agmatine, an endogenous amine derived from decarboxylation of L-Arginine catalyzed by Arginine Decarboxylase, has been proposed as a neurotransmitter or neuromodulator in the brain. In the present study, we examined whether agmatine has neuroprotective effects against repeated immobilization-induced morphological changes in brain tissues and possible effects of immobilization stress on endogenous agmatine levels and Arginine Decarboxylase expression in rat brains. Sprague-Dawley rats were subjected to 2h immobilization stress daily for 7 days. This paradigm significantly increased plasma corticosterone levels, and the glutamate efflux in the hippocampus as measured by in vivo microdialysis. Immunohistochemical staining with beta-tubulin III showed that repeated immobilization caused marked morphological alterations in the hippocampus and medial prefrontal cortex that were prevented by simultaneous treatment with agmatine (50mg/kg/day), i.p.). Likewise, endogenous agmatine levels measured by high-performance liquid chromatography in the prefrontal cortex, hippocampus, striatum and hypothalamus were significantly increased by immobilization, as compared to controls. The increased endogenous agmatine levels, ranging from 92 to 265% of controls, were accompanied by a significant increase of Arginine Decarboxylase protein levels in the same regions. These results demonstrate that the administration of exogenous agmatine protects the hippocampus and medial prefrontal cortex against neuronal insults caused by repeated immobilization. The parallel increase in endogenous brain agmatine and Arginine Decarboxylase protein levels triggered by repeated immobilization indicates that the endogenous agmatine system may play an important role in adaptation to stress as a potential neuronal self-protection mechanism.
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Repeated immobilization stress alters rat hippocampal and prefrontal cortical morphology in parallel with endogenous agmatine and Arginine Decarboxylase levels.
Neurochemistry International, 2008Co-Authors: Meng-yang Zhu, Wei-ping Wang, Jingjing Huang, Yang-zheng Feng, Soundar Regunathan, Garth BissetteAbstract:Abstract Agmatine, an endogenous amine derived from decarboxylation of l -Arginine catalyzed by Arginine Decarboxylase, has been proposed as a neurotransmitter or neuromodulator in the brain. In the present study, we examined whether agmatine has neuroprotective effects against repeated immobilization-induced morphological changes in brain tissues and possible effects of immobilization stress on endogenous agmatine levels and Arginine Decarboxylase expression in rat brains. Sprague–Dawley rats were subjected to 2 h immobilization stress daily for 7 days. This paradigm significantly increased plasma corticosterone levels, and the glutamate efflux in the hippocampus as measured by in vivo microdialysis. Immunohistochemical staining with β-tubulin III showed that repeated immobilization caused marked morphological alterations in the hippocampus and medial prefrontal cortex that were prevented by simultaneous treatment with agmatine (50 mg/kg/day), i.p.). Likewise, endogenous agmatine levels measured by high-performance liquid chromatography in the prefrontal cortex, hippocampus, striatum and hypothalamus were significantly increased by immobilization, as compared to controls. The increased endogenous agmatine levels, ranging from 92 to 265% of controls, were accompanied by a significant increase of Arginine Decarboxylase protein levels in the same regions. These results demonstrate that the administration of exogenous agmatine protects the hippocampus and medial prefrontal cortex against neuronal insults caused by repeated immobilization. The parallel increase in endogenous brain agmatine and Arginine Decarboxylase protein levels triggered by repeated immobilization indicates that the endogenous agmatine system may play an important role in adaptation to stress as a potential neuronal self-protection mechanism.
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Expression of Arginine Decarboxylase in brain regions and neuronal cells
Journal of neurochemistry, 2006Co-Authors: Abiye H. Iyo, Meng-yang Zhu, Gregory A. Ordway, Soundar RegunathanAbstract:After our initial report of a mammalian gene for Arginine Decarboxylase, an enzyme for the synthesis of agmatine from Arginine, we have determined the regional expression of ADC in rat. We have analyzed the expression of ADC in rat brain regions by activity, protein and mRNA levels, and the regulation of expression in neuronal cells by RNA interference. In rat brain, ADC was widely expressed in major brain regions, with a substantial amount in hypothalamus, followed by cortex, and with least amounts in locus coeruleus and medulla. ADC mRNA was detected in primary astrocytes and C6 glioma cells. While no ADC message was detected in fresh neurons (3 days old), significant message appeared in differentiated neurons (3 weeks old). PC12 cells, treated with nerve growth factor, had higher ADC mRNA compared with naive cells. The siRNA mixture directed towards the N-terminal regions of ADC cDNA down-regulated the levels of mRNA and protein in cultured neurons/C6 glioma cells and these cells produced lower agmatine. Thus, this study demonstrates that ADC message is expressed in rat brain regions, that it is regulated in neuronal cells and that the down-regulation of ADC activity by specific siRNA leads to lower agmatine production.
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Expression of human Arginine Decarboxylase, the biosynthetic enzyme for agmatine
Biochimica et biophysica acta, 2004Co-Authors: Meng-yang Zhu, Abiye H. Iyo, John E. Piletz, Soundar RegunathanAbstract:Agmatine, an amine formed by decarboxylation of L-Arginine by Arginine Decarboxylase (ADC), has been recently discovered in mammalian brain and other tissues. While the cloning and sequencing of ADC from plant and bacteria have been reported extensively, the structure of mammalian enzyme is not known. Using homology screening approach, we have identified a human cDNA clone that exhibits ADC activity when expressed in COS-7 cells. The cDNA and deduced amino acid sequence of this human ADC clone is distinct from ADC of other forms. Human ADC is a 460-amino acid protein that shows about 48% identity to mammalian ornithine Decarboxylase (ODC) but has no ODC activity. While naive COS-7 cells do not make agmatine, these cells are able to produce agmatine, as measured by HPLC, when transfected with ADC cDNA. Northern blot analysis using the cDNA probe indicated the expression of ADC message in selective human brain regions and other human tissues.
Garth Bissette - One of the best experts on this subject based on the ideXlab platform.
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Repeated immobilization stress alters rat hippocampal and prefrontal cortical morphology in parallel with endogenous agmatine and Arginine Decarboxylase levels.
Neurochemistry international, 2008Co-Authors: Meng-yang Zhu, Wei-ping Wang, Jingjing Huang, Yang-zheng Feng, Soundar Regunathan, Garth BissetteAbstract:Agmatine, an endogenous amine derived from decarboxylation of L-Arginine catalyzed by Arginine Decarboxylase, has been proposed as a neurotransmitter or neuromodulator in the brain. In the present study, we examined whether agmatine has neuroprotective effects against repeated immobilization-induced morphological changes in brain tissues and possible effects of immobilization stress on endogenous agmatine levels and Arginine Decarboxylase expression in rat brains. Sprague-Dawley rats were subjected to 2h immobilization stress daily for 7 days. This paradigm significantly increased plasma corticosterone levels, and the glutamate efflux in the hippocampus as measured by in vivo microdialysis. Immunohistochemical staining with beta-tubulin III showed that repeated immobilization caused marked morphological alterations in the hippocampus and medial prefrontal cortex that were prevented by simultaneous treatment with agmatine (50mg/kg/day), i.p.). Likewise, endogenous agmatine levels measured by high-performance liquid chromatography in the prefrontal cortex, hippocampus, striatum and hypothalamus were significantly increased by immobilization, as compared to controls. The increased endogenous agmatine levels, ranging from 92 to 265% of controls, were accompanied by a significant increase of Arginine Decarboxylase protein levels in the same regions. These results demonstrate that the administration of exogenous agmatine protects the hippocampus and medial prefrontal cortex against neuronal insults caused by repeated immobilization. The parallel increase in endogenous brain agmatine and Arginine Decarboxylase protein levels triggered by repeated immobilization indicates that the endogenous agmatine system may play an important role in adaptation to stress as a potential neuronal self-protection mechanism.
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Repeated immobilization stress alters rat hippocampal and prefrontal cortical morphology in parallel with endogenous agmatine and Arginine Decarboxylase levels.
Neurochemistry International, 2008Co-Authors: Meng-yang Zhu, Wei-ping Wang, Jingjing Huang, Yang-zheng Feng, Soundar Regunathan, Garth BissetteAbstract:Abstract Agmatine, an endogenous amine derived from decarboxylation of l -Arginine catalyzed by Arginine Decarboxylase, has been proposed as a neurotransmitter or neuromodulator in the brain. In the present study, we examined whether agmatine has neuroprotective effects against repeated immobilization-induced morphological changes in brain tissues and possible effects of immobilization stress on endogenous agmatine levels and Arginine Decarboxylase expression in rat brains. Sprague–Dawley rats were subjected to 2 h immobilization stress daily for 7 days. This paradigm significantly increased plasma corticosterone levels, and the glutamate efflux in the hippocampus as measured by in vivo microdialysis. Immunohistochemical staining with β-tubulin III showed that repeated immobilization caused marked morphological alterations in the hippocampus and medial prefrontal cortex that were prevented by simultaneous treatment with agmatine (50 mg/kg/day), i.p.). Likewise, endogenous agmatine levels measured by high-performance liquid chromatography in the prefrontal cortex, hippocampus, striatum and hypothalamus were significantly increased by immobilization, as compared to controls. The increased endogenous agmatine levels, ranging from 92 to 265% of controls, were accompanied by a significant increase of Arginine Decarboxylase protein levels in the same regions. These results demonstrate that the administration of exogenous agmatine protects the hippocampus and medial prefrontal cortex against neuronal insults caused by repeated immobilization. The parallel increase in endogenous brain agmatine and Arginine Decarboxylase protein levels triggered by repeated immobilization indicates that the endogenous agmatine system may play an important role in adaptation to stress as a potential neuronal self-protection mechanism.
Soundar Regunathan - One of the best experts on this subject based on the ideXlab platform.
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Repeated immobilization stress alters rat hippocampal and prefrontal cortical morphology in parallel with endogenous agmatine and Arginine Decarboxylase levels.
Neurochemistry international, 2008Co-Authors: Meng-yang Zhu, Wei-ping Wang, Jingjing Huang, Yang-zheng Feng, Soundar Regunathan, Garth BissetteAbstract:Agmatine, an endogenous amine derived from decarboxylation of L-Arginine catalyzed by Arginine Decarboxylase, has been proposed as a neurotransmitter or neuromodulator in the brain. In the present study, we examined whether agmatine has neuroprotective effects against repeated immobilization-induced morphological changes in brain tissues and possible effects of immobilization stress on endogenous agmatine levels and Arginine Decarboxylase expression in rat brains. Sprague-Dawley rats were subjected to 2h immobilization stress daily for 7 days. This paradigm significantly increased plasma corticosterone levels, and the glutamate efflux in the hippocampus as measured by in vivo microdialysis. Immunohistochemical staining with beta-tubulin III showed that repeated immobilization caused marked morphological alterations in the hippocampus and medial prefrontal cortex that were prevented by simultaneous treatment with agmatine (50mg/kg/day), i.p.). Likewise, endogenous agmatine levels measured by high-performance liquid chromatography in the prefrontal cortex, hippocampus, striatum and hypothalamus were significantly increased by immobilization, as compared to controls. The increased endogenous agmatine levels, ranging from 92 to 265% of controls, were accompanied by a significant increase of Arginine Decarboxylase protein levels in the same regions. These results demonstrate that the administration of exogenous agmatine protects the hippocampus and medial prefrontal cortex against neuronal insults caused by repeated immobilization. The parallel increase in endogenous brain agmatine and Arginine Decarboxylase protein levels triggered by repeated immobilization indicates that the endogenous agmatine system may play an important role in adaptation to stress as a potential neuronal self-protection mechanism.
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Repeated immobilization stress alters rat hippocampal and prefrontal cortical morphology in parallel with endogenous agmatine and Arginine Decarboxylase levels.
Neurochemistry International, 2008Co-Authors: Meng-yang Zhu, Wei-ping Wang, Jingjing Huang, Yang-zheng Feng, Soundar Regunathan, Garth BissetteAbstract:Abstract Agmatine, an endogenous amine derived from decarboxylation of l -Arginine catalyzed by Arginine Decarboxylase, has been proposed as a neurotransmitter or neuromodulator in the brain. In the present study, we examined whether agmatine has neuroprotective effects against repeated immobilization-induced morphological changes in brain tissues and possible effects of immobilization stress on endogenous agmatine levels and Arginine Decarboxylase expression in rat brains. Sprague–Dawley rats were subjected to 2 h immobilization stress daily for 7 days. This paradigm significantly increased plasma corticosterone levels, and the glutamate efflux in the hippocampus as measured by in vivo microdialysis. Immunohistochemical staining with β-tubulin III showed that repeated immobilization caused marked morphological alterations in the hippocampus and medial prefrontal cortex that were prevented by simultaneous treatment with agmatine (50 mg/kg/day), i.p.). Likewise, endogenous agmatine levels measured by high-performance liquid chromatography in the prefrontal cortex, hippocampus, striatum and hypothalamus were significantly increased by immobilization, as compared to controls. The increased endogenous agmatine levels, ranging from 92 to 265% of controls, were accompanied by a significant increase of Arginine Decarboxylase protein levels in the same regions. These results demonstrate that the administration of exogenous agmatine protects the hippocampus and medial prefrontal cortex against neuronal insults caused by repeated immobilization. The parallel increase in endogenous brain agmatine and Arginine Decarboxylase protein levels triggered by repeated immobilization indicates that the endogenous agmatine system may play an important role in adaptation to stress as a potential neuronal self-protection mechanism.
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Expression of Arginine Decarboxylase in brain regions and neuronal cells
Journal of neurochemistry, 2006Co-Authors: Abiye H. Iyo, Meng-yang Zhu, Gregory A. Ordway, Soundar RegunathanAbstract:After our initial report of a mammalian gene for Arginine Decarboxylase, an enzyme for the synthesis of agmatine from Arginine, we have determined the regional expression of ADC in rat. We have analyzed the expression of ADC in rat brain regions by activity, protein and mRNA levels, and the regulation of expression in neuronal cells by RNA interference. In rat brain, ADC was widely expressed in major brain regions, with a substantial amount in hypothalamus, followed by cortex, and with least amounts in locus coeruleus and medulla. ADC mRNA was detected in primary astrocytes and C6 glioma cells. While no ADC message was detected in fresh neurons (3 days old), significant message appeared in differentiated neurons (3 weeks old). PC12 cells, treated with nerve growth factor, had higher ADC mRNA compared with naive cells. The siRNA mixture directed towards the N-terminal regions of ADC cDNA down-regulated the levels of mRNA and protein in cultured neurons/C6 glioma cells and these cells produced lower agmatine. Thus, this study demonstrates that ADC message is expressed in rat brain regions, that it is regulated in neuronal cells and that the down-regulation of ADC activity by specific siRNA leads to lower agmatine production.
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Expression of human Arginine Decarboxylase, the biosynthetic enzyme for agmatine
Biochimica et biophysica acta, 2004Co-Authors: Meng-yang Zhu, Abiye H. Iyo, John E. Piletz, Soundar RegunathanAbstract:Agmatine, an amine formed by decarboxylation of L-Arginine by Arginine Decarboxylase (ADC), has been recently discovered in mammalian brain and other tissues. While the cloning and sequencing of ADC from plant and bacteria have been reported extensively, the structure of mammalian enzyme is not known. Using homology screening approach, we have identified a human cDNA clone that exhibits ADC activity when expressed in COS-7 cells. The cDNA and deduced amino acid sequence of this human ADC clone is distinct from ADC of other forms. Human ADC is a 460-amino acid protein that shows about 48% identity to mammalian ornithine Decarboxylase (ODC) but has no ODC activity. While naive COS-7 cells do not make agmatine, these cells are able to produce agmatine, as measured by HPLC, when transfected with ADC cDNA. Northern blot analysis using the cDNA probe indicated the expression of ADC message in selective human brain regions and other human tissues.
I.d. Algranati - One of the best experts on this subject based on the ideXlab platform.
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Post-translational processing, metabolic stability and catalytic efficiency of oat Arginine Decarboxylase expressed in Trypanosoma cruzi epimastigotes
Experimental parasitology, 2008Co-Authors: María P. Serra, Alejandro M. Senn, I.d. AlgranatiAbstract:Abstract Trypanosoma cruzi epimastigotes are auxotrophic for polyamines because they are unable to synthesize putrescine de novo. This deficiency is due to the absence of ornithine and Arginine Decarboxylase genes in the parasite genome. We have been able to obtain transgenic T. cruzi expressing heterologous genes coding for these enzymes. Since Arginine Decarboxylase normal expression in oat requires a post-translational proteolytic cleavage of an enzyme precursor, we have investigated whether a similar processing occurs inside the transformed protozoa expressing oat Arginine Decarboxylase or the same enzyme attached to a C-terminal (his) 6 -tag. We were able to demonstrate that the post-translational processing also takes place inside the transgenic parasites. This cleavage is probably the result of a general proteolytic activity of T. cruzi acting on a protease-sensitive region of the protein. Interestingly, the (his) 6 -tagged enzyme expressed in the transformed parasites showed considerably increased metabolic stability and catalytic efficiency.
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Heterologous expression of a plant Arginine Decarboxylase gene in Trypanosoma cruzi.
Biochimica et biophysica acta, 2004Co-Authors: Carolina Carrillo, María P. Serra, Alejandra Huber, Nélida S. González, Claudio A. Pereira, I.d. AlgranatiAbstract:Wild-type Trypanosoma cruzi epimastigotes lack Arginine Decarboxylase (ADC) enzymatic activity. However, the transformation of these parasites with a recombinant plasmid containing the oat ADC cDNA coding region gave rise to the transient heterologous expression of the enzyme, suggesting the absence of endogenous mechanisms that could inhibit the expression of a hypothetical own ADC gene or the assay used to measure its enzymatic activity. The foreign ADC enzyme expressed in the transgenic T. cruzi was characterized by identification of the products, the stoichiometry of the catalysed reaction, the specific inhibition by a-difluoromethylArginine (DFMA) and the study of its metabolic turnover. The half-life of the heterologous ADC activity in T. cruzi was about 150 min. Bioinformatics studies and polymerase chain reaction (PCR) analyses seem to indicate the absence of ADC-like DNA sequences in the wild-type T. cruzi genome. D 2004 Published by Elsevier B.V.
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Lack of Arginine Decarboxylase in Trypanosoma cruzi Epimastigotes
The Journal of eukaryotic microbiology, 2003Co-Authors: Carolina Carrillo, Silvina Cejas, Alejandra Huber, Nélida S. González, I.d. AlgranatiAbstract:Abstract The presence of Arginine Decarboxylase (ADC) enzymatic activity in Trypanosoma cruzi epimastigotes is still a matter of controversy due to conflicting results published during the last few years. We have investigated whether Arginine might indeed be a precursor of putrescine via agmatine in these parasites. We have shown that wild-type T. cruzi epimastigotes cultivated in a medium almost free of polyamines stopped their growth after several repeated passages of cultures in the same medium, and that neither Arginine nor ornithine were able to support or reinitiate parasite multiplication. In contrast, normal growth was quickly resumed after adding exogenous putrescine or spermidine. The in vivo labelling of parasites with radioactive Arginine showed no conversion of this amino acid into agmatine, and attempts to detect ADC activity measured by the release of CO2 under different conditions in T. cruzi extracts gave negligible values for all strains assayed. The described data clearly indicate that ...
David E. Graham - One of the best experts on this subject based on the ideXlab platform.
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Crenarchaeal Arginine Decarboxylase Evolved from an S-Adenosylmethionine Decarboxylase Enzyme
The Journal of biological chemistry, 2008Co-Authors: Teresa N. Giles, David E. GrahamAbstract:The crenarchaeon Sulfolobus solfataricus uses Arginine to produce putrescine for polyamine biosynthesis. However, genome sequences from S. solfataricus and most crenarchaea have no known homologs of the previously characterized pyridoxal 5′-phosphate or pyruvoyl-dependent Arginine Decarboxylases that catalyze the first step in this pathway. Instead they have two paralogs of the S-adenosylmethionine Decarboxylase (AdoMetDC). The gene at locus SSO0585 produces an AdoMetDC enzyme, whereas the gene at locus SSO0536 produces a novel Arginine Decarboxylase (ArgDC). Both thermostable enzymes self-cleave at conserved serine residues to form amino-terminal β-domains and carboxyl-terminal α-domains with reactive pyruvoyl cofactors. The ArgDC enzyme specifically catalyzed Arginine decarboxylation more efficiently than previously studied pyruvoyl enzymes. α-DifluoromethylArginine significantly reduced the ArgDC activity of purified enzyme, and treating growing S. solfataricus cells with this inhibitor reduced the cells' ratio of spermidine to norspermine by decreasing the putrescine pool. The crenarchaeal ArgDC had no AdoMetDC activity, whereas its AdoMetDC paralog had no ArgDC activity. A chimeric protein containing the β-subunit of SSO0536 and the α-subunit of SSO0585 had ArgDC activity, implicating residues responsible for substrate specificity in the amino-terminal domain. This crenarchaeal ArgDC is the first example of alternative substrate specificity in the AdoMetDC family. ArgDC activity has evolved through convergent evolution at least five times, demonstrating the utility of this enzyme and the plasticity of amino acid Decarboxylases.
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Characterization of an Acid-Dependent Arginine Decarboxylase Enzyme from Chlamydophila pneumoniae
Journal of bacteriology, 2007Co-Authors: Teresa N. Giles, David E. GrahamAbstract:Genome sequences from members of the Chlamydiales encode diverged homologs of a pyruvoyl-dependent Arginine Decarboxylase enzyme that nonpathogenic euryarchaea use in polyamine biosynthesis. The Chlamydiales lack subsequent genes required for polyamine biosynthesis and probably obtain polyamines from their host cells. To identify the function of this protein, the CPn1032 homolog from the respiratory pathogen Chlamydophila pneumoniae was heterologously expressed and purified. This protein self-cleaved to form a reactive pyruvoyl group, and the subunits assembled into a thermostable (αβ)3 complex. The mature enzyme specifically catalyzed the decarboxylation of l-Arginine, with an unusually low pH optimum of 3.4. The CPn1032 gene complemented a mutation in the Escherichia coli adiA gene, which encodes a pyridoxal 5′-phosphate-dependent Arginine Decarboxylase, restoring Arginine-dependent acid resistance. Acting together with a putative Arginine-agmatine antiporter, the CPn1032 homologs may have evolved convergently to form an Arginine-dependent acid resistance system. These genes are the first evidence that obligately intracellular chlamydiae may encounter acidic conditions. Alternatively, this system could reduce the host cell Arginine concentration and produce inhibitors of nitric oxide synthase.
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Pyruvoyl-Dependent Arginine Decarboxylase from Methanococcus jannaschii: Crystal Structures of the Self-Cleaved and S53A Proenzyme Forms
Structure (London England : 1993), 2003Co-Authors: W. David Tolbert, David E. Graham, Robert H. White, Steven E. EalickAbstract:Abstract The three-dimensional structure of pyruvoyl-dependent Arginine Decarboxylase from Methanococcus jannaschii was determined at 1.4 A resolution. The pyruvoyl group of Arginine Decarboxylase is generated by an autocatalytic internal serinolysis reaction at Ser53 in the proenzyme resulting in two polypeptide chains. The structure of the nonprocessing S53A mutant was also determined. The active site of the processed enzyme unexpectedly contained the reaction product agmatine. The crystal structure confirms that Arginine Decarboxylase is a homotrimer. The protomer fold is a four-layer αββα sandwich with topology similar to pyruvoyl-dependent histidine Decarboxylase. Highly conserved residues Asn47, Ser52, Ser53, Ile54, and Glu109 are proposed to play roles in the self-processing reaction. Agmatine binding residues include the C terminus of the β chain (Ser52) from one protomer and the Asp35 side chain and the Gly44 and Val46 carbonyl oxygen atoms from an adjacent protomer. Glu109 is proposed to play a catalytic role in the decarboxylation reaction.
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Methanococcus jannaschii uses a pyruvoyl-dependent Arginine Decarboxylase in polyamine biosynthesis.
The Journal of biological chemistry, 2002Co-Authors: David E. Graham, Robert H. WhiteAbstract:Abstract The genome sequence of the hyperthermophilic methanogen Methanococcus jannaschii contains homologs of most genes required for spermidine polyamine biosynthesis. Yet genomes from neither this organism nor any other euryarchaeon have orthologs of the pyridoxal 5′-phosphate-dependent ornithine or Arginine Decarboxylase genes, required to produce putrescine. Instead, as shown here, these organisms have a new class of Arginine Decarboxylase (PvlArgDC) formed by the self-cleavage of a proenzyme into a 5-kDa subunit and a 12-kDa subunit that contains a reactive pyruvoyl group. Although this extremely thermostable enzyme has no significant sequence similarity to previously characterized proteins, conserved active site residues are similar to those of the pyruvoyl-dependent histidine Decarboxylase enzyme, and its subunits form a similar (αβ)3 complex. Homologs of PvlArgDC are found in several bacterial genomes, including those of Chlamydiaspp., which have no agmatine ureohydrolase enzyme to convert agmatine (decarboxylated Arginine) into putrescine. In these intracellular pathogens, PvlArgDC may function analogously to pyruvoyl-dependent histidine Decarboxylase; the cells are proposed to import Arginine and export agmatine, increasing the pH and affecting the host cell's metabolism. Phylogenetic analysis of Pvl- ArgDC proteins suggests that this gene has been recruited from the euryarchaeal polyamine biosynthetic pathway to function as a degradative enzyme in bacteria.