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Pinske C, Bönn M, Krüger S, Lindenstrauß U, Sawers RG. Metabolic deficiences revealed in the biotechnologically important model bacterium Escherichia coli BL21(DE3). PLoS One 2011; 6:e22830. [PMID: 21826210 PMCID: PMC3149613 DOI: 10.1371/journal.pone.0022830] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Accepted: 07/01/2011] [Indexed: 11/26/2022] Open
Abstract
The Escherichia coli B strain BL21(DE3) has had a profound impact on biotechnology through its use in the production of recombinant proteins. Little is understood, however, regarding the physiology of this important E. coli strain. We show here that BL21(DE3) totally lacks activity of the four [NiFe]-hydrogenases, the three molybdenum- and selenium-containing formate dehydrogenases and molybdenum-dependent nitrate reductase. Nevertheless, all of the structural genes necessary for the synthesis of the respective anaerobic metalloenzymes are present in the genome. However, the genes encoding the high-affinity molybdate transport system and the molybdenum-responsive transcriptional regulator ModE are absent from the genome. Moreover, BL21(DE3) has a nonsense mutation in the gene encoding the global oxygen-responsive transcriptional regulator FNR. The activities of the two hydrogen-oxidizing hydrogenases, therefore, could be restored to BL21(DE3) by supplementing the growth medium with high concentrations of Ni²⁺ (Ni²⁺-transport is FNR-dependent) or by introducing a wild-type copy of the fnr gene. Only combined addition of plasmid-encoded fnr and high concentrations of MoO₄²⁻ ions could restore hydrogen production to BL21(DE3); however, to only 25-30% of a K-12 wildtype. We could show that limited hydrogen production from the enzyme complex responsible for formate-dependent hydrogen evolution was due solely to reduced activity of the formate dehydrogenase (FDH-H), not the hydrogenase component. The activity of the FNR-dependent formate dehydrogenase, FDH-N, could not be restored, even when the fnr gene and MoO₄²⁻ were supplied; however, nitrate reductase activity could be recovered by combined addition of MoO₄²⁻ and the fnr gene. This suggested that a further component specific for biosynthesis or activity of formate dehydrogenases H and N was missing. Re-introduction of the gene encoding ModE could only partially restore the activities of both enzymes. Taken together these results demonstrate that BL21(DE3) has major defects in anaerobic metabolism, metal ion transport and metalloprotein biosynthesis.
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Affiliation(s)
- Constanze Pinske
- Institute for Microbiology, Martin-Luther University Halle-Wittenberg, Halle (Saale), Germany
| | - Markus Bönn
- Institute of Computer Science, Martin-Luther University Halle-Wittenberg, Halle (Saale), Germany
| | - Sara Krüger
- Institute for Microbiology, Martin-Luther University Halle-Wittenberg, Halle (Saale), Germany
| | - Ute Lindenstrauß
- Institute for Microbiology, Martin-Luther University Halle-Wittenberg, Halle (Saale), Germany
| | - R. Gary Sawers
- Institute for Microbiology, Martin-Luther University Halle-Wittenberg, Halle (Saale), Germany
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202
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Pavin NF, Donato F, Cibin FW, Jesse CR, Schneider PH, de Salles HD, Soares LDA, Alves D, Savegnago L. Antinociceptive and anti-hypernociceptive effects of Se-phenyl thiazolidine-4-carboselenoate in mice. Eur J Pharmacol 2011; 668:169-76. [PMID: 21756899 DOI: 10.1016/j.ejphar.2011.06.038] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2010] [Revised: 06/17/2011] [Accepted: 06/27/2011] [Indexed: 11/20/2022]
Abstract
In this study, the antinociceptive, anti-hypernociceptive and toxic effects of orally administered (R)-Se-phenyl thiazolidine-4-carboselenoate (Se-PTC, 1-50 mg/kg) were evaluated in mice. Se-PTC did not change plasma aspartate (AST) and alanine aminotransferase (ALT) activities or urea and creatinine levels. Furthermore, in an open field test, Se-PTC did not alter the number of crossings and rearing. Se-PTC significantly reduced the amount of writhing when assessed by acetic acid-induced visceral nociception and attenuated the licking time of the injected paw in the early and late phases of a formalin test. In addition, Se-PTC reduced nociception produced by intra-plantar (i.pl.) injection of glutamate, capsaicin, cinnalmaldehyde, bradykinin, phorbol myristate acetate and 8-Bromo-cAMP. Se-PTC caused a significant increase in hot plate and tail-immersion response latencies, but the antinociceptive effect of Se-PTC in the tail immersion was not abolished by pretreatment with the non-selective opioid receptor antagonist, naloxone. Se-PTC (25 mg/kg) significantly inhibited nociceptive behavior induced by intrathecal (i.t.) injection of glutamate, N-methyl-D-aspartate (NMDA) and (±)-1-aminocyclopentane-trans-1,3-dicarboxylic acid (trans-ACPD), but failed to affect nociception induced by kainate and α-amino-3-hydroxy-5-mehtyl-4-isoxazolepropionic acid (AMPA). Mechanical hypernociception induced by carrageenan and Complete Freund's Adjuvant was attenuated by Se-PTC administration. These results indicate that Se-PTC produces antinociception in several models of nociception.
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Affiliation(s)
- Natasha Frasson Pavin
- Universidade Federal do Pampa, BR 472, KM 582, Uruguaiana, CEP 97500-970, RS, Brazil
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203
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Toxicology and pharmacology of selenium: emphasis on synthetic organoselenium compounds. Arch Toxicol 2011; 85:1313-59. [DOI: 10.1007/s00204-011-0720-3] [Citation(s) in RCA: 330] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2011] [Accepted: 05/18/2011] [Indexed: 02/07/2023]
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204
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Beta-glucuronidase as a sensitive and versatile reporter in actinomycetes. Appl Environ Microbiol 2011; 77:5370-83. [PMID: 21685164 DOI: 10.1128/aem.00434-11] [Citation(s) in RCA: 145] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Here we describe a versatile and sensitive reporter system for actinomycetes that is based on gusA, which encodes the β-glucuronidase enzyme. A series of gusA-containing transcriptional and translational fusion vectors were constructed and utilized to study the regulatory cascade of the phenalinolactone biosynthetic gene cluster. Furthermore, these vectors were used to study the efficiency of translation initiation at the ATG, GTG, TTG, and CTG start codons. Surprisingly, constructs using a TTG start codon showed the best activity, whereas those using ATG or GTG were approximately one-half or one-third as active, respectively. The CTG fusion showed only 5% of the activity of the TTG fusion. A suicide vector, pKGLP2, carrying gusA in its backbone was used to visually detect merodiploid formation and resolution, making gene targeting in actinomycetes much faster and easier. Three regulatory genes, plaR1, plaR2, and plaR3, involved in phenalinolactone biosynthesis were efficiently replaced with an apramycin resistance marker using this system. Finally, we expanded the genetic code of actinomycetes by introducing the nonproteinogenic amino acid N-epsilon-cyclopentyloxycarbonyl-l-lysine with the GusA protein as a reporter.
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205
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Site-specific protein modifications through pyrroline-carboxy-lysine residues. Proc Natl Acad Sci U S A 2011; 108:10437-42. [PMID: 21670250 DOI: 10.1073/pnas.1105197108] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Pyrroline-carboxy-lysine (Pcl) is a demethylated form of pyrrolysine that is generated by the pyrrolysine biosynthetic enzymes when the growth media is supplemented with D-ornithine. Pcl is readily incorporated by the unmodified pyrrolysyl-tRNA/tRNA synthetase pair into proteins expressed in Escherichia coli and in mammalian cells. Here, we describe a broadly applicable conjugation chemistry that is specific for Pcl and orthogonal to all other reactive groups on proteins. The reaction of Pcl with 2-amino-benzaldehyde or 2-amino-acetophenone reagents proceeds to near completion at neutral pH with high efficiency. We illustrate the versatility of the chemistry by conjugating Pcl proteins with poly(ethylene glycol)s, peptides, oligosaccharides, oligonucleotides, fluorescence, and biotin labels and other small molecules. Because Pcl is genetically encoded by TAG codons, this conjugation chemistry enables enhancements of the pharmacology and functionality of proteins through site-specific conjugation.
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206
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Zhang Y, Gladyshev VN. Comparative genomics of trace element dependence in biology. J Biol Chem 2011; 286:23623-9. [PMID: 21566146 DOI: 10.1074/jbc.r110.172833] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Biological trace elements are needed in small quantities but are used by all living organisms. A growing list of trace element-dependent proteins and trace element utilization pathways highlights the importance of these elements for life. In this minireview, we focus on recent advances in comparative genomics of trace elements and explore the evolutionary dynamics of the dependence of user proteins on these elements. Many zinc protein families evolved representatives that lack this metal, whereas selenocysteine in proteins is dynamically exchanged with cysteine. Several other elements, such as molybdenum and nickel, have a limited number of user protein families, but they are strictly dependent on these metals. Comparative genomics of trace elements provides a foundation for investigating the fundamental properties, functions, and evolutionary dynamics of trace element dependence in biology.
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Affiliation(s)
- Yan Zhang
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
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207
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Yu H, Kim KS. The involvement of SelB in the expression of cytotoxic necrotizing factor 1 in Escherichia coli. FEBS Lett 2011; 585:1934-40. [DOI: 10.1016/j.febslet.2011.05.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2011] [Revised: 04/25/2011] [Accepted: 05/02/2011] [Indexed: 11/27/2022]
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208
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Curreem SO, Teng JL, Tse H, Yuen KY, Lau SK, Woo PC. General metabolism of Laribacter hongkongensis: a genome-wide analysis. Cell Biosci 2011; 1:16. [PMID: 21711917 PMCID: PMC3125206 DOI: 10.1186/2045-3701-1-16] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2010] [Accepted: 04/19/2011] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND Laribacter hongkongensis is associated with community-acquired gastroenteritis and traveler's diarrhea. In this study, we performed an in-depth annotation of the genes and pathways of the general metabolism of L. hongkongensis and correlated them with its phenotypic characteristics. RESULTS The L. hongkongensis genome possesses the pentose phosphate and gluconeogenesis pathways and tricarboxylic acid and glyoxylate cycles, but incomplete Embden-Meyerhof-Parnas and Entner-Doudoroff pathways, in agreement with its asaccharolytic phenotype. It contains enzymes for biosynthesis and β-oxidation of saturated fatty acids, biosynthesis of all 20 universal amino acids and selenocysteine, the latter not observed in Neisseria gonorrhoeae, Neisseria meningitidis and Chromobacterium violaceum. The genome contains a variety of dehydrogenases, enabling it to utilize different substrates as electron donors. It encodes three terminal cytochrome oxidases for respiration using oxygen as the electron acceptor under aerobic and microaerophilic conditions and four reductases for respiration with alternative electron acceptors under anaerobic conditions. The presence of complete tetrathionate reductase operon may confer survival advantage in mammalian host in association with diarrhea. The genome contains CDSs for incorporating sulfur and nitrogen by sulfate assimilation, ammonia assimilation and nitrate reduction. The existence of both glutamate dehydrogenase and glutamine synthetase/glutamate synthase pathways suggests an importance of ammonia metabolism in the living environments that it may encounter. CONCLUSIONS The L. hongkongensis genome possesses a variety of genes and pathways for carbohydrate, amino acid and lipid metabolism, respiratory chain and sulfur and nitrogen metabolism. These allow the bacterium to utilize various substrates for energy production and survive in different environmental niches.
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Affiliation(s)
- Shirly O Curreem
- Department of Microbiology, The University of Hong Kong, Hong Kong.
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210
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Arnér ES, Holmgren A. Measurement of thioredoxin and thioredoxin reductase. ACTA ACUST UNITED AC 2011; Chapter 7:Unit 7.4.. [PMID: 20954152 DOI: 10.1002/0471140856.tx0704s05] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The thioredoxin system is ubiquitous, providing reducing equivalents to essential biosynthetic enzymes like ribonucleotide reductase. It is essential for cellular redox regulation, control of oxidative stress, and protection against oxidative damage. This unit includes protocols for measuring thioredoxin or thioredoxin reductase in biological preparations or as purified enzymes.
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Affiliation(s)
- E S Arnér
- Karolinska Institutet, Stockholm, Sweden
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211
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Makiyama A, Komatsu I, Iwaoka M, Yatagai M. One-Pot Conversion of Serine and α-Methylserine Derivatives to the Corresponding Cysteines and Selenocystines by Using Chalcogenophosphate Reagents. PHOSPHORUS SULFUR 2011. [DOI: 10.1080/10426507.2010.485155] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Akira Makiyama
- a Department of Chemistry, School of Science , Tokai University , Kanagawa, Japan
| | - Itsuki Komatsu
- a Department of Chemistry, School of Science , Tokai University , Kanagawa, Japan
| | - Michio Iwaoka
- a Department of Chemistry, School of Science , Tokai University , Kanagawa, Japan
| | - Masanobu Yatagai
- b AminoScience Laboratories , Ajinomoto Co., Inc. , Kanagawa, Japan
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212
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Baltazar CSA, Marques MC, Soares CM, DeLacey AM, Pereira IAC, Matias PM. Nickel–Iron–Selenium Hydrogenases – An Overview. Eur J Inorg Chem 2011. [DOI: 10.1002/ejic.201001127] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Carla S. A. Baltazar
- Protein Modeling Laboratory, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Av. da República, EAN, 2780‐157 Oeiras, Portugal, Fax: +351‐21‐443‐3644
| | - Marta C. Marques
- Bacterial Energy Metabolism Laboratory, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Av. da República, EAN, 2780‐157 Oeiras, Portugal, Fax: +351‐21‐441‐1277
- Laboratory of Industry and Medicine Applied Crystallography, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Av. da República, EAN, 2780‐157 Oeiras, Portugal, Fax: +351‐21‐443‐3644
| | - Cláudio M. Soares
- Protein Modeling Laboratory, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Av. da República, EAN, 2780‐157 Oeiras, Portugal, Fax: +351‐21‐443‐3644
| | - Antonio M. DeLacey
- Instituto de Catálisis y Petroleoquímica, CSIC, C/Marie Curie 2, 28049 Madrid, Spain, Fax: +34‐915854760
| | - Inês A. C. Pereira
- Bacterial Energy Metabolism Laboratory, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Av. da República, EAN, 2780‐157 Oeiras, Portugal, Fax: +351‐21‐441‐1277
| | - Pedro M. Matias
- Laboratory of Industry and Medicine Applied Crystallography, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Av. da República, EAN, 2780‐157 Oeiras, Portugal, Fax: +351‐21‐443‐3644
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213
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Kim MJ, Lee BC, Jeong J, Lee KJ, Hwang KY, Gladyshev VN, Kim HY. Tandem use of selenocysteine: adaptation of a selenoprotein glutaredoxin for reduction of selenoprotein methionine sulfoxide reductase. Mol Microbiol 2011; 79:1194-203. [PMID: 21210868 DOI: 10.1111/j.1365-2958.2010.07500.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Several engineered selenocysteine (Sec)-containing glutaredoxins (Grxs) and their enzymatic properties have been reported, but natural selenoprotein Grxs have not been previously characterized. We expressed a bacterial selenoprotein Grx from Clostridium sp. (also known as Alkaliphilus oremlandii) OhILAs in Escherichia coli and characterized this selenoenzyme and its natural Cys homologues in Clostridium and E. coli. The selenoprotein Grx had a 200-fold higher activity than its Sec-to-Cys mutant form, suggesting that Sec is essential for catalysis by this thiol-disulfide oxidoreductase. Kinetic analysis also showed that the selenoprotein Grx had a 10-fold lower K(m) than Cys homologues. Interestingly, this selenoenzyme efficiently reduced a Clostridium selenoprotein methionine sulfoxide reductase A (MsrA), suggesting that it is the natural reductant for the protein that is not reducible by thioredoxin, a common reductant for Cys-containing MsrAs. We also found that the selenoprotein Grx could not efficiently reduce a Cys version of Clostridium MsrA, whereas natural Clostridium and E. coli Cys-containing Grxs, which efficiently reduce Cys-containing MsrAs, poorly acted on the selenoprotein MsrA. This specificity for MsrA reduction could explain why Sec is utilized in Clostridium Grx and more generally provides a novel example of the use of Sec in biological systems.
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Affiliation(s)
- Moon-Jung Kim
- Department of Biochemistry and Molecular Biology, Yeungnam University College of Medicine, Daegu 705-717, Korea
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214
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215
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Snider G, Grout L, Ruggles EL, Hondal RJ. Methaneseleninic acid is a substrate for truncated mammalian thioredoxin reductase: implications for the catalytic mechanism and redox signaling. Biochemistry 2010; 49:10329-38. [PMID: 21038895 DOI: 10.1021/bi101130t] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Mammalian thioredoxin reductase is a homodimeric pyridine nucleotide disulfide oxidoreductase that contains the rare amino acid selenocysteine (Sec) on a C-terminal extension. We previously have shown that a truncated version of mouse mitochondrial thioredoxin reductase missing this C-terminal tail will catalyze the reduction of a number of small molecules. Here we show that the truncated thioredoxin reductase will catalyze the reduction of methaneseleninic acid. This reduction is fast at pH 6.1 and is only 4-fold slower than that of the full-length enzyme containing Sec. This finding suggested to us that if the C-terminal Sec residue in the holoenzyme became oxidized to the seleninic acid form (Sec-SeO(2)(-)) that it would be quickly reduced back to an active state by enzymic thiols and further suggested to us that the enzyme would be very resistant to irreversible inactivation by oxidation. We tested this hypothesis by reducing the enzyme with NADPH and subjecting it to high concentrations of H(2)O(2) (up to 50 mM). The results show that the enzyme strongly resisted inactivation by 50 mM H(2)O(2). To determine the redox state of the C-terminal Sec residue, we attempted to inhibit the enzyme with dimedone. Dimedone alkylates protein sulfenic acid residues and presumably will alkylate selenenic acid (Sec-SeOH) residues as well. The enzyme was not inhibited by dimedone even when a 150-fold excess was added to the reaction mixture containing the enzyme and H(2)O(2). We also tested the ability of the truncated enzyme to resist inactivation by oxidation as well and found that it also was resistant to high concentrations of H(2)O(2). One assumption for the use of Sec in enzymes is that it is catalytically superior to the use of cysteine. We and others have previously suggested that there are reasons for the use of Sec in enzymes that are unrelated to the conversion of substrate to product. The data presented here support this assertion. The results also imply that the redox signaling function of the thioredoxin system can remain active under oxidative stress.
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Affiliation(s)
- Gregg Snider
- Department of Biochemistry, 89 Beaumont Avenue, Burlington, VT 05405, USA
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216
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Selenocysteine, pyrrolysine, and the unique energy metabolism of methanogenic archaea. ARCHAEA-AN INTERNATIONAL MICROBIOLOGICAL JOURNAL 2010; 2010. [PMID: 20847933 PMCID: PMC2933860 DOI: 10.1155/2010/453642] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/15/2010] [Accepted: 07/13/2010] [Indexed: 01/21/2023]
Abstract
Methanogenic archaea are a group of strictly anaerobic microorganisms characterized by their strict dependence on the process of methanogenesis for energy conservation. Among the archaea, they are also the only known group synthesizing proteins containing selenocysteine or pyrrolysine. All but one of the known archaeal pyrrolysine-containing and all but two of the confirmed archaeal selenocysteine-containing protein are involved in methanogenesis. Synthesis of these proteins proceeds through suppression of translational stop codons but otherwise the two systems are fundamentally different. This paper highlights these differences and summarizes the recent developments in selenocysteine- and pyrrolysine-related research on archaea and aims to put this knowledge into the context of their unique energy metabolism.
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217
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Lukashenko NP. Expanding genetic code: Amino acids 21 and 22, selenocysteine and pyrrolysine. RUSS J GENET+ 2010. [DOI: 10.1134/s1022795410080016] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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218
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Chiba S, Itoh Y, Sekine SI, Yokoyama S. Structural Basis for the Major Role of O-Phosphoseryl-tRNA Kinase in the UGA-Specific Encoding of Selenocysteine. Mol Cell 2010; 39:410-20. [DOI: 10.1016/j.molcel.2010.07.018] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2010] [Revised: 04/23/2010] [Accepted: 06/23/2010] [Indexed: 01/23/2023]
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219
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Chennakrishnareddy G, Nagendra G, Hemantha HP, Das U, Guru Row TN, Sureshbabu VV. Isoselenocyanates derived from Boc/Z-amino acids: synthesis, isolation, characterization, and application to the efficient synthesis of unsymmetrical selenoureas and selenoureidopeptidomimetics. Tetrahedron 2010. [DOI: 10.1016/j.tet.2010.06.082] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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220
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Würthner F, Bräse S, Sewald N, Herges R, Senge MO, Bach T, Gottwald T, Kopf T, Ŝpehar K, Hartung J, Plattner D, Gansäuer A, Oestreich M, Brückner R, Pietruszka J, Süßmuth R, Müller M, Weinhold E, Jäschke A, Albrecht M, Priepke H, Roth G, Ditrich K, Ernst A, Wortmann L, Ag S. Organische Chemie 2002. ACTA ACUST UNITED AC 2010. [DOI: 10.1002/nadc.20030510309] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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221
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Forchhammer K, Böck A. Selenocystein: Katalytische Funktion und spezifischer Einbau in Proteine. ACTA ACUST UNITED AC 2010. [DOI: 10.1002/nadc.19910390906] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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222
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Wilhelm EA, Jesse CR, Prigol M, Alves D, Schumacher RF, Nogueira CW. 3-Alkynyl selenophene protects against carbon-tetrachloride-induced and 2-nitropropane-induced hepatic damage in rats. Cell Biol Toxicol 2010; 26:569-77. [PMID: 20397041 DOI: 10.1007/s10565-010-9164-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2009] [Accepted: 03/31/2010] [Indexed: 11/24/2022]
Abstract
The aim of this study was to investigate the protective effect of 3-alkynyl selenophene (3-ASP) on acute liver injury induced by carbon tetrachloride (CCl(4)) and 2-nitropropane (2-NP) in rats. On the first day of treatment, the animals received 3-ASP (25 mg/kg, p.o.). On the second day, the rats received CCl(4) (1 mg/kg, i.p.) or 2-NP (100 mg/kg, p.o.). Twenty-four hours after CCl(4) or 2-NP administration, the animals were euthanized, and their plasma and liver were removed for biochemical and histological analyses. The histological analysis revealed extensive injury in the liver of CCl(4)-exposed and 2-NP-exposed rats, which was attenuated by 3-ASP. 3-ASP significantly attenuated (1) the increase in plasmatic aspartate and alanine aminotransferase activities and lipid peroxidation levels induced by CCl(4) and 2-NP; (2) the inhibition of δ-aminolevulinic dehydratase activity caused by 2-NP; and (3) the decrease in ascorbic acid (AA) levels and catalase (CAT) activity caused by CCl(4). AA levels and CAT activity remained unaltered in the liver of rats exposed to 2-NP. The protective effect of 3-ASP on acute liver injury induced by CCl(4) and 2-NP in rats was demonstrated.
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Affiliation(s)
- Ethel Antunes Wilhelm
- Programa de Pós-Graduação em Bioquímica Toxicológica, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, CEP 97105-900, RS, Brazil
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223
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Nunn PB, Bell EA, Watson AA, Nash RJ. Toxicity of Non-protein Amino Acids to Humans and Domestic Animals. Nat Prod Commun 2010. [DOI: 10.1177/1934578x1000500329] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Non-protein amino acids are common in plants and are present in widely consumed animal feeds and human foods such as alfalfa ( Medicago sativa), which contains canavanine, and lentil ( Lens culinaris), which contains homoarginine. Some occur in wild species that are inadvertently harvested with crop species. Some nonprotein amino acids and metabolites can be toxic to humans, e.g. Lathyrus species contain a neurotoxic oxalyl-amino acid. Some potential toxins may be passed along a food chain via animal intermediates. The increased interest in herbal medicines in the Western countries will increase exposure to such compounds.
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Affiliation(s)
- Peter B. Nunn
- School of Pharmacy and Biomedical Sciences, St Michael's Building, University of Portsmouth, Portsmouth, PO1 2DT, UK
| | - E. Arthur Bell
- Formerly at the School of Biomedical Sciences, King's College London, WC2R 2LS, England, UK
| | - Alison A. Watson
- Phytoquest Limited, Aberystwyth University, Plas Gogerddan, Aberystwyth, Ceredigion, SY23 3EB, UK
| | - Robert J. Nash
- Phytoquest Limited, Aberystwyth University, Plas Gogerddan, Aberystwyth, Ceredigion, SY23 3EB, UK
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224
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Diphenyl diselenide and diphenyl ditelluride: neurotoxic effect in brain of young rats, in vitro. Mol Cell Biochem 2010; 340:179-85. [DOI: 10.1007/s11010-010-0416-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2009] [Accepted: 02/10/2010] [Indexed: 11/27/2022]
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225
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Hondal RJ, Ruggles EL. Differing views of the role of selenium in thioredoxin reductase. Amino Acids 2010; 41:73-89. [PMID: 20397034 DOI: 10.1007/s00726-010-0494-6] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2009] [Accepted: 01/21/2010] [Indexed: 12/01/2022]
Abstract
This review covers three different chemical explanations that could account for the requirement of selenium in the form of selenocysteine in the active site of mammalian thioredoxin reductase. These views are the following: (1) the traditional view of selenocysteine as a superior nucleophile relative to cysteine, (2) the superior leaving group ability of a selenol relative to a thiol due to its significantly lower pK (a) and, (3) the superior ability of selenium to accept electrons (electrophilicity) relative to sulfur. We term these chemical explanations as the "chemico-enzymatic" function of selenium in an enzyme. We formally define the chemico-enzymatic function of selenium as its specific chemical property that allows a selenoenzyme to catalyze its individual reaction. However we, and others, question whether selenocysteine is chemically necessary to catalyze an enzymatic reaction since cysteine-homologs of selenocysteine-containing enzymes catalyze their specific enzymatic reactions with high catalytic efficiency. There must be a unique chemical reason for the presence of selenocysteine in enzymes that explains the biological pressure on the genome to maintain the complex selenocysteine-insertion machinery. We term this biological pressure the "chemico-biological" function of selenocysteine. We discuss evidence that this chemico-biological function is the ability of selenoenzymes to resist inactivation by irreversible oxidation. The way in which selenocysteine confers resistance to oxidation could be due to the superior ability of the oxidized form of selenocysteine (Sec-SeO(2)(-), seleninic acid) to be recycled back to its parent form (Sec-SeH, selenocysteine) in comparison to the same cycling of cysteine-sulfinic acid to cysteine (Cys-SO(2)(-) to Cys-SH).
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Affiliation(s)
- Robert J Hondal
- Department of Biochemistry, College of Medicine, University of Vermont, Burlington, 05405, USA.
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226
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Abstract
UNLABELLED Biological trace elements are required for numerous biological processes and by all organisms. We describe a database, dbTEU (DataBase of Trace Element Utilization), that features known transporters and user proteins for five trace elements (copper, molybdenum, nickel, cobalt and selenium) and represents sequenced organisms from the three domains of life. The manually curated dbTEU currently includes approximately 16,500 proteins from >700 organisms, and offers interactive trace element, protein, organism and sequence search and browse tools. AVAILABILITY AND IMPLEMENTATION dbTEU is freely available at http://gladyshevlab.bwh.harvard.edu/trace_element/
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Affiliation(s)
- Yan Zhang
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA
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227
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Goedhart AC, Bindels JG. The composition of human milk as a model for the design of infant formulas: recent findings and possible applications. Nutr Res Rev 2009; 7:1-23. [PMID: 19094290 DOI: 10.1079/nrr19940004] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- A C Goedhart
- Nutricia Research, P. O. Box 1, 2700 MA Zoetermeer, The Netherlands
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228
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Mobli M, deâ
Araújo A, Lambert L, Pierens G, Windley M, Nicholson G, Alewood P, King G. Direct Visualization of Disulfide Bonds through Diselenide Proxies Using77Se NMR Spectroscopy. Angew Chem Int Ed Engl 2009. [DOI: 10.1002/ange.200905206] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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229
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Mobli M, de Araújo AD, Lambert LK, Pierens GK, Windley MJ, Nicholson GM, Alewood PF, King GF. Direct Visualization of Disulfide Bonds through Diselenide Proxies Using77Se NMR Spectroscopy. Angew Chem Int Ed Engl 2009; 48:9312-4. [PMID: 19890933 DOI: 10.1002/anie.200905206] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Mehdi Mobli
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia QLD 4072, Australia
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230
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Zhang Y, Gladyshev VN. General trends in trace element utilization revealed by comparative genomic analyses of Co, Cu, Mo, Ni, and Se. J Biol Chem 2009; 285:3393-405. [PMID: 19887375 DOI: 10.1074/jbc.m109.071746] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Trace elements are used by all organisms and provide proteins with unique coordination and catalytic and electron transfer properties. Although many trace element-containing proteins are well characterized, little is known about the general trends in trace element utilization. We carried out comparative genomic analyses of copper, molybdenum, nickel, cobalt (in the form of vitamin B(12)), and selenium (in the form of selenocysteine) in 747 sequenced organisms at the following levels: (i) transporters and transport-related proteins, (ii) cofactor biosynthesis traits, and (iii) trace element-dependent proteins. Few organisms were found to utilize all five trace elements, whereas many symbionts, parasites, and yeasts used only one or none of these elements. Investigation of metalloproteomes and selenoproteomes revealed examples of increased utilization of proteins that use copper in land plants, cobalt in Dehalococcoides and Dictyostelium, and selenium in fish and algae, whereas nematodes were found to have great diversity of copper transporters. These analyses also characterized trace element metabolism in common model organisms and suggested new model organisms for experimental studies of individual trace elements. Mismatches in the occurrence of user proteins and corresponding transport systems revealed deficiencies in our understanding of trace element biology. Biological interactions among some trace elements were observed; however, such links were limited, and trace elements generally had unique utilization patterns. Finally, environmental factors, such as oxygen requirement and habitat, correlated with the utilization of certain trace elements. These data provide insights into the general features of utilization and evolution of trace elements in the three domains of life.
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Affiliation(s)
- Yan Zhang
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA
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231
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Pearce CI, Pattrick RAD, Law N, Charnock JM, Coker VS, Fellowes JW, Oremland RS, Lloyd JR. Investigating different mechanisms for biogenic selenite transformations: Geobacter sulfurreducens, Shewanella oneidensis and Veillonella atypica. ENVIRONMENTAL TECHNOLOGY 2009; 30:1313-26. [PMID: 19950474 DOI: 10.1080/09593330902984751] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
The metal-reducing bacteria Geobacter sulfurreducens, Shewanella oneidensis and Veillonella atypica, use different mechanisms to transform toxic, bioavailable sodium selenite to less toxic, non-mobile elemental selenium and then to selenide in anaerobic environments, offering the potential for in situ and ex situ bioremediation of contaminated soils, sediments, industrial effluents, and agricultural drainage waters. The products of these reductive transformations depend on both the organism involved and the reduction conditions employed, in terms of electron donor and exogenous extracellular redox mediator. The intermediary phase involves the precipitation of elemental selenium nanospheres and the potential role of proteins in the formation of these structures is discussed. The bionanomineral phases produced during these transformations, including both elemental selenium nanospheres and metal selenide nanoparticles, have catalytic, semiconducting and light-emitting properties, which may have unique applications in the realm of nanophotonics. This research offers the potential to combine remediation of contaminants with the development of environmentally friendly manufacturing pathways for novel bionanominerals.
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Affiliation(s)
- Carolyn I Pearce
- School of Earth, Atmospheric and Environmental Sciences, University of Manchester, Manchester, UK.
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232
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Flohé L. The labour pains of biochemical selenology: The history of selenoprotein biosynthesis. Biochim Biophys Acta Gen Subj 2009; 1790:1389-403. [DOI: 10.1016/j.bbagen.2009.03.031] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2009] [Revised: 03/29/2009] [Accepted: 03/31/2009] [Indexed: 11/17/2022]
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233
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Kabiri M, Amoozegar MA, Tabebordbar M, Gilany K, Salekdeh GH. Effects of selenite and tellurite on growth, physiology, and proteome of a moderately halophilic bacterium. J Proteome Res 2009; 8:3098-108. [PMID: 19334765 DOI: 10.1021/pr900005h] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We isolated a moderately halophilic bacterium with high level of tolerance to two toxic oxyanions, selenite and tellurite, from hypersaline soil in Garmsar, Iran. 16s rRNA sequence analysis revealed that the isolate, strain MAM, had 98% similarity with Halomonas elongate, and is closely related to other species of the genus Halomonas. We observed that the tolerance to tellurite and its removal increased significantly when both selenite and tellurite were added to the culture media, suggesting a positive synergism of selenite on tellurite tolerance and removal. We applied a proteomic approach to study the proteome response of Halomonas sp. strain MAM to selenite, tellurite, and selenite + tellurite. Out of approximately 800 protein spots detected on 2-DE gels, 208 spots were differentially expressed in response to at least one of treatments. Of them, 70 CBB stained spots were analyzed by MALDI TOF/TOF mass spectrometry, leading to identification of 36 proteins. Our results revealed that several mechanisms including fatty acid synthesis, energy production, cell transport, oxidative stress detoxification, DNA replication, transcription and translation contributed in bacterial response and/or adaptation. These results provided new insights into the general mechanisms on the tolerance of halophilic bacteria to these two toxic oxyanions and the use of them for bioremediation of contaminated saline soils and wastes discharge sites.
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Affiliation(s)
- Mahboubeh Kabiri
- Agricultural Biotechnology Research Institute of Iran, Karaj, Iran
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234
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Itoh Y, Chiba S, Sekine SI, Yokoyama S. Crystal structure of human selenocysteine tRNA. Nucleic Acids Res 2009; 37:6259-68. [PMID: 19692584 PMCID: PMC2764427 DOI: 10.1093/nar/gkp648] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022] Open
Abstract
Selenocysteine (Sec) is the 21st amino acid in translation. Sec tRNA (tRNASec) has an anticodon complementary to the UGA codon. We solved the crystal structure of human tRNASec. tRNASec has a 9-bp acceptor stem and a 4-bp T stem, in contrast with the 7-bp acceptor stem and the 5-bp T stem in the canonical tRNAs. The acceptor stem is kinked between the U6:U67 and G7:C66 base pairs, leading to a bent acceptor-T stem helix. tRNASec has a 6-bp D stem and a 4-nt D loop. The long D stem includes unique A14:U21 and G15:C20a pairs. The D-loop:T-loop interactions include the base pairs G18:U55 and U16:U59, and a unique base triple, U20:G19:C56. The extra arm comprises of a 6-bp stem and a 4-nt loop. Remarkably, the D stem and the extra arm do not form tertiary interactions in tRNASec. Instead, tRNASec has an open cavity, in place of the tertiary core of a canonical tRNA. The linker residues, A8 and U9, connecting the acceptor and D stems, are not involved in tertiary base pairing. Instead, U9 is stacked on the first base pair of the extra arm. These features might allow tRNASec to be the target of the Sec synthesis/incorporation machineries.
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Affiliation(s)
- Yuzuru Itoh
- Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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235
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Lothrop AP, Ruggles EL, Hondal RJ. No selenium required: reactions catalyzed by mammalian thioredoxin reductase that are independent of a selenocysteine residue. Biochemistry 2009; 48:6213-23. [PMID: 19366212 DOI: 10.1021/bi802146w] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Mammalian thioredoxin reductase (TR) contains a rare selenocysteine (Sec) residue in a conserved redox-active tetrapeptide of sequence Gly-Cys(1)-Sec(2)-Gly. The high chemical reactivity of the Sec residue is thought to confer broad substrate specificity to the enzyme. In addition to utilizing thioredoxin (Trx) as a substrate, other substrates are protein disulfide isomerase, glutaredoxin, glutathione peroxidase, NK-lysin/granulysin, HIV Tat protein, H(2)O(2), lipid hydroperoxides, vitamin K, ubiquinone, juglone, ninhydrin, alloxan, dehydroascorbate, DTNB, lipoic acid/lipoamide, S-nitrosoglutathione, selenodiglutathione, selenite, methylseleninate, and selenocystine. Here we show that the Cys(2) mutant enzyme or the N-terminal reaction center alone can reduce Se-containing substrates selenocystine and selenite with only slightly less activity than the wild-type enzyme, in stark contrast to when Trx is used as the substrate when the enzyme suffers a 175-550-fold reduction in k(cat). Our data support the use of alternative mechanistic pathways for the Se-containing substrates that bypass a critical ring-forming step when Trx is the substrate. We also show that lipoic acid can be reduced through a Sec-independent mechanism that involves the N-terminal reaction center. These results show that the broad substrate specificity of the mammalian enzyme is not due to the presence of the rare Sec residue but is due to the catalytic power of the N-terminal reaction center. We hypothesize that the N-terminal reaction center can reduce substrates (i) with good leaving groups such as DTNB, (ii) that are highly electrophilic such as selenite, or (iii) that are activated by strain such as lipoic acid/lipoamide. We also show that the absence of Sec only changed the IC(50) for aurothioglucose by a factor of 1.7 in the full-length mammalian enzyme (83-142 nM), but surprisingly the truncated enzyme showed much stronger inhibition (25 nM). This contrasts with auranofin, where the absence of Sec more strongly perturbed inhibition.
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Affiliation(s)
- Adam P Lothrop
- Department of Biochemistry, University of Vermont, 89 Beaumont Avenue, Given Building Room B413, Burlington, Vermont 05405, USA
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236
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Abstract
Nicotinate dehydrogenase (NDH) from Eubacterium barkeri is a molybdoenzyme catalyzing the hydroxylation of nicotinate to 6-hydroxynicotinate. Reactivity of NDH critically depends on the presence of labile (nonselenocysteine) selenium with an as-yet-unidentified form and function. We have determined the crystal structure of NDH and analyzed its active site by multiple wavelengths anomalous dispersion methods. We show that selenium is bound as a terminal Mo=Se ligand to molybdenum and that it occupies the position of the terminal sulfido ligand in other molybdenum hydroxylases. The role of selenium in catalysis has been assessed by model calculations, which indicate an acceleration of the critical hydride transfer from the substrate to the selenido ligand in the course of substrate hydroxylation when compared with an active site containing a sulfido ligand. The MoO(OH)Se active site of NDH shows a novel type of utilization and reactivity of selenium in nature.
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237
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Zhang Y, Gladyshev VN. Comparative Genomics of Trace Elements: Emerging Dynamic View of Trace Element Utilization and Function. Chem Rev 2009; 109:4828-61. [DOI: 10.1021/cr800557s] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Yan Zhang
- Department of Biochemistry and Redox Biology Center, University of Nebraska, Lincoln, Nebraska 68588-0664
| | - Vadim N. Gladyshev
- Department of Biochemistry and Redox Biology Center, University of Nebraska, Lincoln, Nebraska 68588-0664
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238
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Wilhelm EA, Jesse CR, Nogueira CW, Savegnago L. Introduction of trifluoromethyl group into diphenyl diselenide molecule alters its toxicity and protective effect against damage induced by 2-nitropropane in rats. ACTA ACUST UNITED AC 2009; 61:197-203. [DOI: 10.1016/j.etp.2008.08.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2008] [Revised: 08/18/2008] [Accepted: 08/27/2008] [Indexed: 10/21/2022]
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239
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ST-scale as a novel amino acid descriptor and its application in QSAM of peptides and analogues. Amino Acids 2009; 38:805-16. [PMID: 19373543 DOI: 10.1007/s00726-009-0287-y] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2008] [Accepted: 03/25/2009] [Indexed: 10/20/2022]
Abstract
In this study, structural topology scale (ST-scale) was recruited as a novel structural topological descriptor derived from principal component analysis on 827 structural variables of 167 amino acids. By using partial least squares (PLS), we applied ST-scale for the study of quantitative sequence-activity models (QSAMs) on three peptide datasets (58 angiotensin-converting enzyme (ACE) inhibitors, 34 antimicrobial peptides (AMPs) and 89 elastase substrates (ES)). The results of QSAMs were superior to that of the earlier studies, with determination coefficient (r(2)) and cross-validated (q(2)) equal to 0.855, 0.774; 0.79, 0.371 (OSC-PLS: 0.995, 0.848) and 0.846, 0.747, respectively. Therefore, ST-scale descriptors were considered to be competent to extract information from 827 structural variables and relate with their bioactivities.
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240
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Rengby O, Cheng Q, Vahter M, Jörnvall H, Arnér ESJ. Highly active dimeric and low-activity tetrameric forms of selenium-containing rat thioredoxin reductase 1. Free Radic Biol Med 2009; 46:893-904. [PMID: 19146949 DOI: 10.1016/j.freeradbiomed.2008.12.017] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2008] [Revised: 12/16/2008] [Accepted: 12/18/2008] [Indexed: 10/21/2022]
Abstract
Mammalian thioredoxin reductase 1 (TrxR1) is a selenoprotein that contains a selenocysteine (Sec) residue at the penultimate C-terminal position. When rat TrxR1 is expressed recombinantly in Escherichia coli, partial truncation at the Sec-encoding UGA gives rise to additional protein species that lack Sec. Phenylarsine oxide (PAO) Sepharose can subsequently be used to enrich the Sec-containing protein and yield activity corresponding to that of native enzyme. Herein we extensively purified recombinant rat TrxR1 over PAO Sepharose, which gave an enzyme with about 53 U/mg specific activity. Surprisingly, only about 65% of the subunits of this TrxR1 preparation contained Sec, whereas about 35% were protein products derived from UGA truncation. Further analyses revealed a theoretical maximal specific activity of 70-80 U/mg for the homodimeric enzyme with full Sec content, i.e., significantly higher than that reported for native TrxR1. We also discovered the formation of highly stable noncovalently linked tetrameric forms of TrxR1, having full FAD content but about half the specific activity in relation to the selenium content compared to the dimeric protein. The characterization of these different forms of recombinant TrxR1 revealed that inherent turnover capacity of the enzyme must be revised, that multimeric states of the protein may be formed, and that the yield of bacterial selenoprotein production may be lower than earlier reported. The biological significance of the hitherto unsurpassed high specific activity of the enzyme involves the capacity to support a higher turnover in vivo than previously believed. The tetrameric forms of the protein could represent hitherto unknown regulatory states of the enzyme.
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Affiliation(s)
- Olle Rengby
- Division of Biochemistry, Medical Nobel Institute for Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-171 77 Stockholm, Sweden
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241
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242
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Stock T, Rother M. Selenoproteins in Archaea and Gram-positive bacteria. Biochim Biophys Acta Gen Subj 2009; 1790:1520-32. [PMID: 19344749 DOI: 10.1016/j.bbagen.2009.03.022] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2009] [Revised: 03/23/2009] [Accepted: 03/23/2009] [Indexed: 01/23/2023]
Abstract
Selenium is an essential trace element for many organisms by serving important catalytic roles in the form of the 21st co-translationally inserted amino acid selenocysteine. It is mostly found in redox-active proteins in members of all three domains of life and analysis of the ever-increasing number of genome sequences has facilitated identification of the encoded selenoproteins. Available data from biochemical, sequence, and structure analyses indicate that Gram-positive bacteria synthesize and incorporate selenocysteine via the same pathway as enterobacteria. However, recent in vivo studies indicate that selenocysteine-decoding is much less stringent in Gram-positive bacteria than in Escherichia coli. For years, knowledge about the pathway of selenocysteine synthesis in Archaea and Eukarya was only fragmentary, but genetic and biochemical studies guided by analysis of genome sequences of Sec-encoding archaea has not only led to the characterization of the pathways but has also shown that they are principally identical. This review summarizes current knowledge about the metabolic pathways of Archaea and Gram-positive bacteria where selenium is involved, about the known selenoproteins, and about the respective pathways employed in selenoprotein synthesis.
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Affiliation(s)
- Tilmann Stock
- Molekulare Mikrobiologie und Bioenergetik, Institut für Molekulare Biowissenschaften, Goethe-Universität Frankfurt am Main, Max-von-Laue-Str. 9, D-60438 Frankfurt am Main, Germany
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243
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Wang Q, Parrish AR, Wang L. Expanding the genetic code for biological studies. CHEMISTRY & BIOLOGY 2009; 16:323-36. [PMID: 19318213 PMCID: PMC2696486 DOI: 10.1016/j.chembiol.2009.03.001] [Citation(s) in RCA: 172] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2009] [Revised: 02/25/2009] [Accepted: 03/03/2009] [Indexed: 11/15/2022]
Abstract
Using an orthogonal tRNA-synthetase pair, unnatural amino acids can be genetically encoded with high efficiency and fidelity, and over 40 unnatural amino acids have been site-specifically incorporated into proteins in Escherichia coli, yeast, or mammalian cells. Novel chemical or physical properties embodied in these amino acids enable new means for tailored manipulation of proteins. This review summarizes the methodology and recent progress in expanding this technology to eukaryotic cells. Applications of genetically encoded unnatural amino acids are highlighted with reports on labeling and modifying proteins, probing protein structure and function, identifying and regulating protein activity, and generating proteins with new properties. Genetic incorporation of unnatural amino acids provides a powerful method for investigating a wide variety of biological processes both in vitro and in vivo.
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Affiliation(s)
- Qian Wang
- The Jack H. Skirball Center for Chemical Biology & Proteomics, The Salk Institute for Biological Studies, 10010 N. Torrey Pines Road, La Jolla, CA 92037, USA
| | - Angela R. Parrish
- The Jack H. Skirball Center for Chemical Biology & Proteomics, The Salk Institute for Biological Studies, 10010 N. Torrey Pines Road, La Jolla, CA 92037, USA
| | - Lei Wang
- The Jack H. Skirball Center for Chemical Biology & Proteomics, The Salk Institute for Biological Studies, 10010 N. Torrey Pines Road, La Jolla, CA 92037, USA
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244
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Kim HY, Zhang Y, Lee BC, Kim JR, Gladyshev VN. The selenoproteome of Clostridium sp. OhILAs: characterization of anaerobic bacterial selenoprotein methionine sulfoxide reductase A. Proteins 2009; 74:1008-17. [PMID: 18767149 DOI: 10.1002/prot.22212] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Selenocysteine (Sec) is incorporated into proteins in response to UGA codons. This residue is frequently found at the catalytic sites of oxidoreductases. In this study, we characterized the selenoproteome of an anaerobic bacterium, Clostridium sp. (also known as Alkaliphilus oremlandii) OhILA, and identified 13 selenoprotein genes, five of which have not been previously described. One of the detected selenoproteins was methionine sulfoxide reductase A (MsrA), an antioxidant enzyme that repairs oxidatively damaged methionines in a stereospecific manner. To date, little is known about MsrA from anaerobes. We characterized this selenoprotein MsrA which had a single Sec residue at the catalytic site but no cysteine (Cys) residues in the protein sequence. Its SECIS (Sec insertion sequence) element did not resemble those in Escherichia coli. Although with low translational efficiency, the expression of the Clostridium selenoprotein msrA gene in E. coli could be demonstrated by (75)Se metabolic labeling, immunoblot analyses, and enzyme assays, indicating that its SECIS element was recognized by the E. coli Sec insertion machinery. We found that the Sec-containing MsrA exhibited at least a 20-fold higher activity than its Cys mutant form, indicating a critical role of Sec in the catalytic activity of the enzyme. Furthermore, our data revealed that the Clostridium MsrA was inefficiently reducible by thioredoxin, which is a typical reducing agent for MsrA, suggesting the use of alternative electron donors in this anaerobic bacterium that directly act on the selenenic acid intermediate and do not require resolving Cys residues.
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Affiliation(s)
- Hwa-Young Kim
- Department of Biochemistry and Molecular Biology, Aging-associated Vascular Disease Research Center, Yeungnam University College of Medicine, Daegu 705-717, Republic of Korea.
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245
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Howell JA. DFT investigation of the interaction between gold(I) complexes and the active site of thioredoxin reductase. J Organomet Chem 2009. [DOI: 10.1016/j.jorganchem.2008.10.029] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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246
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Novel approaches for selenium speciation in foodstuffs and biological specimens: A review. Anal Chim Acta 2009; 634:135-52. [DOI: 10.1016/j.aca.2008.12.026] [Citation(s) in RCA: 206] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2008] [Revised: 11/06/2008] [Accepted: 12/15/2008] [Indexed: 11/21/2022]
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247
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Gärtner R. Selenium and thyroid hormone axis in critical ill states: an overview of conflicting view points. J Trace Elem Med Biol 2009; 23:71-4. [PMID: 19398053 DOI: 10.1016/j.jtemb.2009.01.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2009] [Accepted: 01/15/2009] [Indexed: 11/23/2022]
Abstract
In critical ill states the plasma selenium levels are low and inversely correlated with the severity and outcome of the disease. The plasma selenium levels indicate the amount of circulating selenoproteins and selenoenzymes. These are important for the maintenance of the redox system, modulating the immune system and also for thyroid hormone metabolism. Not only all three deiodinases (D1-3) are selenoenzymes, but within the thyroid gland there are several other selenoenzymes, which are important for the maintenance of normal thyroid function. In critical ill states also triodothyronine (T3) is low and reverse T3 elevated, and also TSH and thyroxin (T4) are low, correlating like low plasma selenium with the severity of the disease. Subsequently, several intervention trials had been performed to evaluate whether an adjuvant selenium supplementation might attenuate the course of the disease and improve outcome. The selenium supplementation improved outcome and even reduced mortality in some but not all prospective randomized trials. A few prospective randomized intervention trials with selenium supplementation had also been performed to evaluate the hypothesis, whether low selenium is the cause of low-T3-syndrome, however, with conflicting results and no clear evidence that low D1 activity is due to the selenium deficiency in critical illness. Because D1 catalyses the conversion of T4 to T3 and also the clearance of reverse T3, low D1 activity would sufficiently explain low plasma T3 and elevated reverse T3. It had been, however, clearly shown that cytokines are responsible for the inhibition of D1 activity, but D2 and D3 are even higher during acute inflammation in critically ill patients. One of the most important effects of selenium on the immune system seems to be the reduction of cytokine release and therefore an indirect connection between low selenium and low D1 activity has to be postulated and not a lower D1 activity due to lower availability of selenium for the D1 expression.
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Affiliation(s)
- Roland Gärtner
- Medizinische Klinik Innenstadt der Universität München, München, Germany.
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Muttenthaler M, Alewood PF. Selenocystine Peptides – Synthesis, Folding and Applications. OXIDATIVE FOLDING OF PEPTIDES AND PROTEINS 2008. [DOI: 10.1039/9781847559265-00396] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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Pappas A, Zoidis E, Surai P, Zervas G. Selenoproteins and maternal nutrition. Comp Biochem Physiol B Biochem Mol Biol 2008; 151:361-72. [DOI: 10.1016/j.cbpb.2008.08.009] [Citation(s) in RCA: 135] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2008] [Revised: 08/13/2008] [Accepted: 08/20/2008] [Indexed: 11/24/2022]
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