Artykuły w czasopismach: „Amino acid selenocysteine”

1

Böck, A., K. Forchhammer, J. Heider, W. Leinfelder, G. Sawers, B. Veprek i F. Zinoni. "Selenocysteine: the 21st amino acid". Molecular Microbiology 5, nr 3 (marzec 1991): 515–20. http://dx.doi.org/10.1111/j.1365-2958.1991.tb00722.x.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

2

Gonzalez-Flores, Jonathan N., Sumangala P. Shetty, Aditi Dubey i Paul R. Copeland. "The molecular biology of selenocysteine". BioMolecular Concepts 4, nr 4 (1.08.2013): 349–65. http://dx.doi.org/10.1515/bmc-2013-0007.

Pełny tekst źródła

Streszczenie:

AbstractSelenium is an essential trace element that is incorporated into 25 human proteins as the amino acid selenocysteine (Sec). The incorporation of this amino acid turns out to be a fascinating problem in molecular biology because Sec is encoded by a stop codon, UGA. Layered on top of the canonical translation elongation machinery is a set of factors that exist solely to incorporate this important amino acid. The mechanism by which this process occurs, put into the context of selenoprotein biology, is the focus of this review.

Style APA, Harvard, Vancouver, ISO itp.

3

Baclaocos, Janinah, i John James Mackrill. "Why Multiples of 21? Why does Selenoprotein P Contain Multiple Selenocysteine Residues?" Current Nutraceuticals 1, nr 1 (29.04.2020): 42–53. http://dx.doi.org/10.2174/2665978601666200213120929.

Pełny tekst źródła

Streszczenie:

Background: In animals, the 21st amino acid selenocysteine is incorporated into a restricted subset of proteins by recoding of a UGA stop codon. This recoding requires a distinctive selenocysteine insertion sequence in selenoprotein encoding mRNAs, trans-acting factors and in most cases, adequate dietary intake of selenium. With one exception, selenoproteins contain a single selenocysteine, which is incorporated with low translational efficiency. The exception is selenoprotein P, which in some species is predicted to contain as many as 132 selenocysteines and which is considered to play roles in selenium transport and storage. Objective: This study aimed to develop comparative physiological and evolutionary perspectives on the function(s) of selenoprotein P. Method: The review of the literature on the roles of selenoprotein P in diverse animals. Results: Selenoprotein P contains multiple selenocysteines, making it energetically costly to produce. Furthermore, it is often associated with detrimental effects to the animals that produce it. Possible benefits that outweigh these costs include the general storage and transport of selenium; the transport of both toxic and useful metal ions; and specific functions in reproduction and in the nervous system. Conclusion: A probable reconciliation of the negative effects of producing Selenoprotein P is its benefit in terms of promoting reproductive success.

Style APA, Harvard, Vancouver, ISO itp.

4

Seale, Lucia A., Vedbar S. Khadka, Mark Menor, Guoxiang Xie, Ligia M. Watanabe, Alexandru Sasuclark, Kyrillos Guirguis i in. "Combined Omics Reveals That Disruption of the Selenocysteine Lyase Gene Affects Amino Acid Pathways in Mice". Nutrients 11, nr 11 (26.10.2019): 2584. http://dx.doi.org/10.3390/nu11112584.

Pełny tekst źródła

Streszczenie:

Selenium is a nonmetal trace element that is critical for several redox reactions and utilized to produce the amino acid selenocysteine (Sec), which can be incorporated into selenoproteins. Selenocysteine lyase (SCL) is an enzyme which decomposes Sec into selenide and alanine, releasing the selenide to be further utilized to synthesize new selenoproteins. Disruption of the selenocysteine lyase gene (Scly) in mice (Scly−/− or Scly KO) led to obesity with dyslipidemia, hyperinsulinemia, glucose intolerance and lipid accumulation in the hepatocytes. As the liver is a central regulator of glucose and lipid homeostasis, as well as selenium metabolism, we aimed to pinpoint hepatic molecular pathways affected by the Scly gene disruption. Using RNA sequencing and metabolomics, we identified differentially expressed genes and metabolites in the livers of Scly KO mice. Integrated omics revealed that biological pathways related to amino acid metabolism, particularly alanine and glycine metabolism, were affected in the liver by disruption of Scly in mice with selenium adequacy. We further confirmed that hepatic glycine levels are elevated in male, but not in female, Scly KO mice. In conclusion, our results reveal that Scly participates in the modulation of hepatic amino acid metabolic pathways.

Style APA, Harvard, Vancouver, ISO itp.

5

Longtin, R. "A Forgotten Debate: Is Selenocysteine the 21st Amino Acid?" JNCI Journal of the National Cancer Institute 96, nr 7 (6.04.2004): 504–5. http://dx.doi.org/10.1093/jnci/96.7.504.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

6

Copeland, Paul R., i Michael T. Howard. "Ribosome Fate during Decoding of UGA-Sec Codons". International Journal of Molecular Sciences 22, nr 24 (8.12.2021): 13204. http://dx.doi.org/10.3390/ijms222413204.

Pełny tekst źródła

Streszczenie:

Decoding of genetic information into polypeptides occurs during translation, generally following the codon assignment rules of the organism’s genetic code. However, recoding signals in certain mRNAs can overwrite the normal rules of translation. An exquisite example of this occurs during translation of selenoprotein mRNAs, wherein UGA codons are reassigned to encode for the 21st proteogenic amino acid, selenocysteine. In this review, we will examine what is known about the mechanisms of UGA recoding and discuss the fate of ribosomes that fail to incorporate selenocysteine.

Style APA, Harvard, Vancouver, ISO itp.

7

Hendrickson, Tamara L., Whitney N. Wood i Udumbara M. Rathnayake. "Did Amino Acid Side Chain Reactivity Dictate the Composition and Timing of Aminoacyl-tRNA Synthetase Evolution?" Genes 12, nr 3 (12.03.2021): 409. http://dx.doi.org/10.3390/genes12030409.

Pełny tekst źródła

Streszczenie:

The twenty amino acids in the standard genetic code were fixed prior to the last universal common ancestor (LUCA). Factors that guided this selection included establishment of pathways for their metabolic synthesis and the concomitant fixation of substrate specificities in the emerging aminoacyl-tRNA synthetases (aaRSs). In this conceptual paper, we propose that the chemical reactivity of some amino acid side chains (e.g., lysine, cysteine, homocysteine, ornithine, homoserine, and selenocysteine) delayed or prohibited the emergence of the corresponding aaRSs and helped define the amino acids in the standard genetic code. We also consider the possibility that amino acid chemistry delayed the emergence of the glutaminyl- and asparaginyl-tRNA synthetases, neither of which are ubiquitous in extant organisms. We argue that fundamental chemical principles played critical roles in fixation of some aspects of the genetic code pre- and post-LUCA.

Style APA, Harvard, Vancouver, ISO itp.

8

Seeher, Sandra, Bradley A. Carlson, Angela C. Miniard, Eva K. Wirth, Yassin Mahdi, Dolph L. Hatfield, Donna M. Driscoll i Ulrich Schweizer. "Impaired selenoprotein expression in brain triggers striatal neuronal loss leading to co-ordination defects in mice". Biochemical Journal 462, nr 1 (24.07.2014): 67–75. http://dx.doi.org/10.1042/bj20140423.

Pełny tekst źródła

Streszczenie:

Selenoproteins contain the rare amino acid selenocysteine. Reduced selenium levels in the brain lead to a complex neurological phenotype affecting cortical and hippocampal GABAergic interneurons. Here we show that striatal interneuron density is reduced in mice with impaired selenoprotein expression.

Style APA, Harvard, Vancouver, ISO itp.

9

Li, Chuang, Myriam Reches i Hanna Engelberg-Kulka. "The Bulged Nucleotide in the Escherichia coli Minimal Selenocysteine Insertion Sequence Participates in Interaction with SelB: a Genetic Approach". Journal of Bacteriology 182, nr 22 (15.11.2000): 6302–7. http://dx.doi.org/10.1128/jb.182.22.6302-6307.2000.

Pełny tekst źródła

Streszczenie:

ABSTRACT The UGA codon, which usually acts as a stop codon, can also direct the incorporation into a protein of the amino acid selenocysteine. This UGA decoding process requires acis-acting mRNA element called the selenocysteine insertion sequence (SECIS), which can form a stem-loop structure. InEscherichia coli, selenocysteine incorporation requires only the 17-nucleotide-long upper stem-loop structure of thefdhF SECIS. This structure carries a bulged nucleotide U at position 17. Here we asked whether the single bulged nucleotide located in the upper stem-loop structure of the E. coli fdhF SECIS is involved in the in vivo interaction with SelB. We used a genetic approach, generating and characterizingselB mutations that suppress mutations of the bulged nucleotide in the SECIS. All the selB suppressor mutations isolated were clustered in a region corresponding to 28 amino acids in the SelB C-terminal subdomain 4b. These selBsuppressor mutations were also found to suppress mutations in either the loop or the upper stem of the E. coli SECIS. Thus, the E. coli SECIS upper stem-loop structure can be considered a “single suppressible unit,” suggesting that there is some flexibility to the nature of the interaction between this element and SelB.

Style APA, Harvard, Vancouver, ISO itp.

10

Castellano, S., A. M. Andres, E. Bosch, M. Bayes, R. Guigo i A. G. Clark. "Low Exchangeability of Selenocysteine, the 21st Amino Acid, in Vertebrate Proteins". Molecular Biology and Evolution 26, nr 9 (1.06.2009): 2031–40. http://dx.doi.org/10.1093/molbev/msp109.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

11

Granold, Matthias, Parvana Hajieva, Monica Ioana Toşa, Florin-Dan Irimie i Bernd Moosmann. "Modern diversification of the amino acid repertoire driven by oxygen". Proceedings of the National Academy of Sciences 115, nr 1 (19.12.2017): 41–46. http://dx.doi.org/10.1073/pnas.1717100115.

Pełny tekst źródła

Streszczenie:

All extant life employs the same 20 amino acids for protein biosynthesis. Studies on the number of amino acids necessary to produce a foldable and catalytically active polypeptide have shown that a basis set of 7–13 amino acids is sufficient to build major structural elements of modern proteins. Hence, the reasons for the evolutionary selection of the current 20 amino acids out of a much larger available pool have remained elusive. Here, we have analyzed the quantum chemistry of all proteinogenic and various prebiotic amino acids. We find that the energetic HOMO–LUMO gap, a correlate of chemical reactivity, becomes incrementally closer in modern amino acids, reaching the level of specialized redox cofactors in the late amino acids tryptophan and selenocysteine. We show that the arising prediction of a higher reactivity of the more recently added amino acids is correct as regards various free radicals, particularly oxygen-derived peroxyl radicals. Moreover, we demonstrate an immediate survival benefit conferred by the enhanced redox reactivity of the modern amino acids tyrosine and tryptophan in oxidatively stressed cells. Our data indicate that in demanding building blocks with more versatile redox chemistry, biospheric molecular oxygen triggered the selective fixation of the last amino acids in the genetic code. Thus, functional rather than structural amino acid properties were decisive during the finalization of the universal genetic code.

Style APA, Harvard, Vancouver, ISO itp.

12

Seale, Lucia A. "Selenocysteine β-Lyase: Biochemistry, Regulation and Physiological Role of the Selenocysteine Decomposition Enzyme". Antioxidants 8, nr 9 (1.09.2019): 357. http://dx.doi.org/10.3390/antiox8090357.

Pełny tekst źródła

Streszczenie:

The enzyme selenocysteine β-lyase (SCLY) was first isolated in 1982 from pig livers, followed by its identification in bacteria. SCLY works as a homodimer, utilizing pyridoxal 5’-phosphate as a cofactor, and catalyzing the specific decomposition of the amino acid selenocysteine into alanine and selenide. The enzyme is thought to deliver its selenide as a substrate for selenophosphate synthetases, which will ultimately be reutilized in selenoprotein synthesis. SCLY subcellular localization is unresolved, as it has been observed both in the cytosol and in the nucleus depending on the technical approach used. The highest SCLY expression and activity in mammals is found in the liver and kidneys. Disruption of the Scly gene in mice led to obesity, hyperinsulinemia, glucose intolerance, and hepatic steatosis, with SCLY being suggested as a participant in the regulation of energy metabolism in a sex-dependent manner. With the physiological role of SCLY still not fully understood, this review attempts to discuss the available literature regarding SCLY in animals and provides avenues for possible future investigation.

Style APA, Harvard, Vancouver, ISO itp.

13

Small-Howard, A. L., i M. J. Berry. "Unique features of selenocysteine incorporation function within the context of general eukaryotic translational processes". Biochemical Society Transactions 33, nr 6 (26.10.2005): 1493–97. http://dx.doi.org/10.1042/bst0331493.

Pełny tekst źródła

Streszczenie:

Unlike other essential dietary trace elements, selenium exerts its biological actions through its direct incorporation into selenoproteins, as a part of the 21st amino acid, selenocysteine. Fundamental studies have elucidated the unique structures and putative functions of multiple co-translational factors required for the incorporation of selenocysteine into selenoproteins. The current challenge is to understand how these selenocysteine incorporation factors function within the framework of translation. In eukaryotes, co-ordinating nuclear transcription with cytoplasmic translation of genes is a challenge involving complex spatial and temporal regulation. Selenoproteins utilize the common cellular machinery required for synthesis of non-selenoproteins. This machinery includes the elements involved in transcription, mRNA splicing and transport, and translational processes. Many investigators have emphasized the differences between the expression of selenoproteins and other eukaryotic proteins, whereas this review will attempt to highlight common themes and point out where additional interactions may be discovered.

Style APA, Harvard, Vancouver, ISO itp.

14

Milanovic, Svetlana, Ivan Jovanovic i Olivera Valcic. "Selenoproteins". Veterinarski glasnik 69, nr 1-2 (2015): 75–89. http://dx.doi.org/10.2298/vetgl1502075m.

Pełny tekst źródła

Streszczenie:

Selenium is an essential trace element with multi significant role in the body. In contrast to other trace elements that appear as cofactors of certain enzymes, its physiological role is directly related to functions of proteins in composition of which it is cotranslationally installed by atypical amino acid selenocysteine. The group of proteins, in which composition selenocysteine is an integral functional part of polypeptides, are referred to as selenoproteins. The first enzyme that has been proven to have selenocysteine incorporated in its composition, is glutathione peroxidase (GPx). So far there have been identified 5 isoenzyme forms of GPx which reduce hydrogen peroxide and organic hydroperoxides, protecting cells from oxidative damage. Iodothyronine deiodinases (ID) are among the most important selenopoteins, being responsible for both activation and deactivation of thyroid hormones. So far there have been found over twenty selenoproteins, but only for some of them a physiological role is known.

Style APA, Harvard, Vancouver, ISO itp.

15

ITOH, Yuzuru, i Shigeyuki YOKOYAMA. "The Molecular Mechanism of the Synthesis of the 21st Amino Acid, Selenocysteine". Nihon Kessho Gakkaishi 56, nr 3 (2014): 186–93. http://dx.doi.org/10.5940/jcrsj.56.186.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

16

Lee, B. J., M. Rajagopalan, Y. S. Kim, K. H. You, K. B. Jacobson i D. Hatfield. "Selenocysteine tRNA[Ser]Sec gene is ubiquitous within the animal kingdom". Molecular and Cellular Biology 10, nr 5 (maj 1990): 1940–49. http://dx.doi.org/10.1128/mcb.10.5.1940-1949.1990.

Pełny tekst źródła

Streszczenie:

Recently, a mammalian tRNA which was previously designated as an opal suppressor seryl-tRNA and phosphoseryl-tRNA was shown to be a selenocysteyl-tRNA (B. J. Lee, P. J. Worland, J. N. Davis, T. C. Stadtman, and D. Hatfield, J. Biol. Chem. 264:9724-9727, 1989). Hence, this tRNA is now designated as selenocysteyl-tRNA[Ser]Sec, and its function is twofold, to serve as (i) a carrier molecule upon which selenocysteine is biosynthesized and (ii) as a donor of selenocysteine, which is the 21st naturally occurring amino acid of protein, to the nascent polypeptide chain in response to specific UGA codons. In the present study, the selenocysteine tRNA gene was sequenced from Xenopus laevis, Drosophila melanogaster, and Caenorhabditis elegans. The tRNA product of this gene was also identified within the seryl-tRNA population of a number of higher and lower animals, and the human tRNA[Ser]Sec gene was used as a probe to identify homologous sequences within genomic DNAs of organisms throughout the animal kingdom. The studies showed that the tRNA[Ser]Sec gene has undergone evolutionary change and that it is ubiquitous in the animal kingdom. Further, we conclude that selenocysteine-containing proteins, as well as the use of UGA as a codon for selenocysteine, are far more widespread in nature than previously thought.

Style APA, Harvard, Vancouver, ISO itp.

17

Lee, B. J., M. Rajagopalan, Y. S. Kim, K. H. You, K. B. Jacobson i D. Hatfield. "Selenocysteine tRNA[Ser]Sec gene is ubiquitous within the animal kingdom." Molecular and Cellular Biology 10, nr 5 (maj 1990): 1940–49. http://dx.doi.org/10.1128/mcb.10.5.1940.

Pełny tekst źródła

Streszczenie:

Recently, a mammalian tRNA which was previously designated as an opal suppressor seryl-tRNA and phosphoseryl-tRNA was shown to be a selenocysteyl-tRNA (B. J. Lee, P. J. Worland, J. N. Davis, T. C. Stadtman, and D. Hatfield, J. Biol. Chem. 264:9724-9727, 1989). Hence, this tRNA is now designated as selenocysteyl-tRNA[Ser]Sec, and its function is twofold, to serve as (i) a carrier molecule upon which selenocysteine is biosynthesized and (ii) as a donor of selenocysteine, which is the 21st naturally occurring amino acid of protein, to the nascent polypeptide chain in response to specific UGA codons. In the present study, the selenocysteine tRNA gene was sequenced from Xenopus laevis, Drosophila melanogaster, and Caenorhabditis elegans. The tRNA product of this gene was also identified within the seryl-tRNA population of a number of higher and lower animals, and the human tRNA[Ser]Sec gene was used as a probe to identify homologous sequences within genomic DNAs of organisms throughout the animal kingdom. The studies showed that the tRNA[Ser]Sec gene has undergone evolutionary change and that it is ubiquitous in the animal kingdom. Further, we conclude that selenocysteine-containing proteins, as well as the use of UGA as a codon for selenocysteine, are far more widespread in nature than previously thought.

Style APA, Harvard, Vancouver, ISO itp.

18

Cubas-Gaona, Liliana L., Patricia de Francisco, Ana Martín-González i Juan Carlos Gutiérrez. "Tetrahymena Glutathione Peroxidase Family: A Comparative Analysis of These Antioxidant Enzymes and Differential Gene Expression to Metals and Oxidizing Agents". Microorganisms 8, nr 7 (5.07.2020): 1008. http://dx.doi.org/10.3390/microorganisms8071008.

Pełny tekst źródła

Streszczenie:

In the present work, an extensive analysis of the putative glutathione peroxidases (GPx) of the eukaryotic microorganism model Tetrahymena thermophila is carried out. A comparative analysis with GPx present in other Tetrahymena species and other very taxonomically diverse ciliates is also performed. A majority of ciliate GPx have replaced the selenocysteine (Sec) by Cys in its catalytic center, so they can be considered as phospholipid hydroperoxide glutathione peroxidases (PHGPx). Selenocysteine insertion sequence (SECIS) elements have been detected in several ciliate GPx that do not incorporate Sec in their amino acid sequences, and conversely, in other ciliate GPx with Sec, no SECIS elements are detected. These anomalies are analyzed and discussed. From the phylogenetic analysis using the ciliate GPx amino acid sequences, the existence of extensive intra- and interspecific gene duplications that produced multiple GPx isoforms in each species is inferred. The ancestral character of the selenoproteins is also corroborated. The analysis by qRT-PCR of six selected T. thermophila GPx genes has shown a quantitative differential expression between them, depending on the stressor (oxidizing agents, apoptotic inducer or metals) and the time of exposure.

Style APA, Harvard, Vancouver, ISO itp.

19

Santesmasses, Didac, i Vadim N. Gladyshev. "Pathogenic Variants in Selenoproteins and Selenocysteine Biosynthesis Machinery". International Journal of Molecular Sciences 22, nr 21 (27.10.2021): 11593. http://dx.doi.org/10.3390/ijms222111593.

Pełny tekst źródła

Streszczenie:

Selenium is incorporated into selenoproteins as the 21st amino acid selenocysteine (Sec). There are 25 selenoproteins encoded in the human genome, and their synthesis requires a dedicated machinery. Most selenoproteins are oxidoreductases with important functions in human health. A number of disorders have been associated with deficiency of selenoproteins, caused by mutations in selenoprotein genes or Sec machinery genes. We discuss mutations that are known to cause disease in humans and report their allele frequencies in the general population. The occurrence of protein-truncating variants in the same genes is also presented. We provide an overview of pathogenic variants in selenoproteins genes from a population genomics perspective.

Style APA, Harvard, Vancouver, ISO itp.

20

Mohanta, Tapan Kumar, Yugal Kishore Mohanta, Satya Kumar Avula, Amilia Nongbet i Ahmed Al-Harrasi. "Virtual 2D map of cyanobacterial proteomes". PLOS ONE 17, nr 10 (3.10.2022): e0275148. http://dx.doi.org/10.1371/journal.pone.0275148.

Pełny tekst źródła

Streszczenie:

Cyanobacteria are prokaryotic Gram-negative organisms prevalent in nearly all habitats. A detailed proteomics study of Cyanobacteria has not been conducted despite extensive study of their genome sequences. Therefore, we conducted a proteome-wide analysis of the Cyanobacteria proteome and found Calothrix desertica as the largest (680331.825 kDa) and Candidatus synechococcus spongiarum as the smallest (42726.77 kDa) proteome of the cyanobacterial kingdom. A Cyanobacterial proteome encodes 312.018 amino acids per protein, with a molecular weight of 182173.1324 kDa per proteome. The isoelectric point (pI) of the Cyanobacterial proteome ranges from 2.13 to 13.32. It was found that the Cyanobacterial proteome encodes a greater number of acidic-pI proteins, and their average pI is 6.437. The proteins with higher pI are likely to contain repetitive amino acids. A virtual 2D map of Cyanobacterial proteome showed a bimodal distribution of molecular weight and pI. Several proteins within the Cyanobacterial proteome were found to encode Selenocysteine (Sec) amino acid, while Pyrrolysine amino acids were not detected. The study can enable us to generate a high-resolution cell map to monitor proteomic dynamics. Through this computational analysis, we can gain a better understanding of the bias in codon usage by analyzing the amino acid composition of the Cyanobacterial proteome.

Style APA, Harvard, Vancouver, ISO itp.

21

Fradejas, Noelia, Bradley A. Carlson, Eddy Rijntjes, Niels-Peter Becker, Ryuta Tobe i Ulrich Schweizer. "Mammalian Trit1 is a tRNA[Ser]Sec-isopentenyl transferase required for full selenoprotein expression". Biochemical Journal 450, nr 2 (15.02.2013): 427–32. http://dx.doi.org/10.1042/bj20121713.

Pełny tekst źródła

Streszczenie:

Selenoproteins are proteins carrying the rare amino acid Sec (selenocysteine). Full expression of selenoproteins requires modification of tRNA[Ser]Sec, including N6-isopentenylation of base A37. We show that Trit1 is a dimethylallyl:tRNA[Ser]Sec transferase. Knockdown of Trit1 reduces expression of selenoproteins. Incubation of in vitro transcribed tRNA[Ser]Sec with recombinant Trit1 transfers [14C]dimethylallyl pyrophosphate to tRNA[Ser]Sec. 37A>G tRNA[Ser]Sec is resistant to isopentenylation by Trit1.

Style APA, Harvard, Vancouver, ISO itp.

22

Skaff, Ojia, David I. Pattison, Philip E. Morgan, Rushad Bachana, Vimal K. Jain, K. Indira Priyadarsini i Michael J. Davies. "Selenium-containing amino acids are targets for myeloperoxidase-derived hypothiocyanous acid: determination of absolute rate constants and implications for biological damage". Biochemical Journal 441, nr 1 (14.12.2011): 305–16. http://dx.doi.org/10.1042/bj20101762.

Pełny tekst źródła

Streszczenie:

Elevated MPO (myeloperoxidase) levels are associated with multiple human inflammatory pathologies. MPO catalyses the oxidation of Cl−, Br− and SCN− by H2O2 to generate the powerful oxidants hypochlorous acid (HOCl), hypobromous acid (HOBr) and hypothiocyanous acid (HOSCN) respectively. These species are antibacterial agents, but misplaced or excessive production is implicated in tissue damage at sites of inflammation. Unlike HOCl and HOBr, which react with multiple targets, HOSCN targets cysteine residues with considerable selectivity. In the light of this reactivity, we hypothesized that Sec (selenocysteine) residues should also be rapidly oxidized by HOSCN, as selenium atoms are better nucleophiles than sulfur. Such oxidation might inactivate critical Sec-containing cellular protective enzymes such as GPx (glutathione peroxidase) and TrxR (thioredoxin reductase). Stopped-flow kinetic studies indicate that seleno-compounds react rapidly with HOSCN with rate constants, k, in the range 2.8×103–5.8×106 M−1·s−1 (for selenomethionine and selenocystamine respectively). These values are ~6000-fold higher than the corresponding values for H2O2, and are also considerably larger than for the reaction of HOSCN with thiols (16-fold for cysteine and 80-fold for selenocystamine). Enzyme studies indicate that GPx and TrxR, but not glutathione reductase, are inactivated by HOSCN in a concentration-dependent manner; k for GPx has been determined as ~5×105 M−1·s−1. Decomposed HOSCN did not induce inactivation. These data indicate that selenocysteine residues are oxidized rapidly by HOSCN, with this resulting in the inhibition of the critical intracellular Sec-dependent protective enzymes GPx and TrxR.

Style APA, Harvard, Vancouver, ISO itp.

23

Birk, Ohad S. "Selenocysteinopathies: progressive cerebello–cerebral atrophy and other diseases of the 21st amino acid, selenocysteine". Future Neurology 6, nr 2 (marzec 2011): 135–38. http://dx.doi.org/10.2217/fnl.11.2.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

24

Welegedara, Adarshi P., Luke A. Adams, Thomas Huber, Bim Graham i Gottfried Otting. "Site-Specific Incorporation of Selenocysteine by Genetic Encoding as a Photocaged Unnatural Amino Acid". Bioconjugate Chemistry 29, nr 7 (6.06.2018): 2257–64. http://dx.doi.org/10.1021/acs.bioconjchem.8b00254.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

25

Ma, Chi, Verena Martinez-Rodriguez i Peter R. Hoffmann. "Roles for Selenoprotein I and Ethanolamine Phospholipid Synthesis in T Cell Activation". International Journal of Molecular Sciences 22, nr 20 (16.10.2021): 11174. http://dx.doi.org/10.3390/ijms222011174.

Pełny tekst źródła

Streszczenie:

The selenoprotein family includes 25 members, many of which are antioxidant or redox regulating enzymes. A unique member of this family is Selenoprotein I (SELENOI), which does not catalyze redox reactions, but instead is an ethanolamine phosphotransferase (Ept). In fact, the characteristic selenocysteine residue that defines selenoproteins lies far outside of the catalytic domain of SELENOI. Furthermore, data using recombinant SELENOI lacking the selenocysteine residue have suggested that the selenocysteine amino acid is not directly involved in the Ept reaction. SELENOI is involved in two different pathways for the synthesis of phosphatidylethanolamine (PE) and plasmenyl PE, which are constituents of cellular membranes. Ethanolamine phospholipid synthesis has emerged as an important process for metabolic reprogramming that occurs in pluripotent stem cells and proliferating tumor cells, and this review discusses roles for upregulation of SELENOI during T cell activation, proliferation, and differentiation. SELENOI deficiency lowers but does not completely diminish de novo synthesis of PE and plasmenyl PE during T cell activation. Interestingly, metabolic reprogramming in activated SELENOI deficient T cells is impaired and this reduces proliferative capacity while favoring tolerogenic to pathogenic phenotypes that arise from differentiation. The implications of these findings are discussed related to vaccine responses, autoimmunity, and cell-based therapeutic approaches.

Style APA, Harvard, Vancouver, ISO itp.

26

Tupikina, Elena Yu, Valerii V. Karpov i Peter M. Tolstoy. "On the influence of water molecules on the outer electronic shells of R–SeH, R–Se(−) and R–SeOH fragments in the selenocysteine amino acid residue". Physical Chemistry Chemical Physics 23, nr 25 (2021): 13965–70. http://dx.doi.org/10.1039/d1cp01345a.

Pełny tekst źródła

Streszczenie:

The presence of water molecules near the selenocysteine residue in the active centre of the GPx enzyme promotes its antioxidant activity. The ⁷⁷Se NMR chemical shift is sensitive both to the oxidation and the hydration states of the selenium atom.

Style APA, Harvard, Vancouver, ISO itp.

27

Moustafa, Mohamed E., Bradley A. Carlson, Muhammad A. El-Saadani, Gregory V. Kryukov, Qi-An Sun, John W. Harney, Kristina E. Hill i in. "Selective Inhibition of Selenocysteine tRNA Maturation and Selenoprotein Synthesis in Transgenic Mice Expressing Isopentenyladenosine-Deficient Selenocysteine tRNA". Molecular and Cellular Biology 21, nr 11 (1.06.2001): 3840–52. http://dx.doi.org/10.1128/mcb.21.11.3840-3852.2001.

Pełny tekst źródła

Streszczenie:

ABSTRACT Selenocysteine (Sec) tRNA (tRNA[Ser]Sec) serves as both the site of Sec biosynthesis and the adapter molecule for donation of this amino acid to protein. The consequences on selenoprotein biosynthesis of overexpressing either the wild type or a mutant tRNA[Ser]Sec lacking the modified base, isopentenyladenosine, in its anticodon loop were examined by introducing multiple copies of the corresponding tRNA[Ser]Sec genes into the mouse genome. Overexpression of wild-type tRNA[Ser]Sec did not affect selenoprotein synthesis. In contrast, the levels of numerous selenoproteins decreased in mice expressing isopentenyladenosine-deficient (i6A−) tRNA[Ser]Sec in a protein- and tissue-specific manner. Cytosolic glutathione peroxidase and mitochondrial thioredoxin reductase 3 were the most and least affected selenoproteins, while selenoprotein expression was most and least affected in the liver and testes, respectively. The defect in selenoprotein expression occurred at translation, since selenoprotein mRNA levels were largely unaffected. Analysis of the tRNA[Ser]Sec population showed that expression of i6A− tRNA[Ser]Sec altered the distribution of the two major isoforms, whereby the maturation of tRNA[Ser]Sec by methylation of the nucleoside in the wobble position was repressed. The data suggest that the levels of i6A− tRNA[Ser]Sec and wild-type tRNA[Ser]Sec are regulated independently and that the amount of wild-type tRNA[Ser]Sec is determined, at least in part, by a feedback mechanism governed by the level of the tRNA[Ser]Sec population. This study marks the first example of transgenic mice engineered to contain functional tRNA transgenes and suggests that i6A−tRNA[Ser]Sec transgenic mice will be useful in assessing the biological roles of selenoproteins.

Style APA, Harvard, Vancouver, ISO itp.

28

Peng, Jing-Jing, Shi-Yang Yue, Yu-Hui Fang, Xiao-Ling Liu i Cheng-Hua Wang. "Mechanisms Affecting the Biosynthesis and Incorporation Rate of Selenocysteine". Molecules 26, nr 23 (25.11.2021): 7120. http://dx.doi.org/10.3390/molecules26237120.

Pełny tekst źródła

Streszczenie:

Selenocysteine (Sec) is the 21st non-standard proteinogenic amino acid. Due to the particularity of the codon encoding Sec, the selenoprotein synthesis needs to be completed by unique mechanisms in specific biological systems. In this paper, the underlying mechanisms for the biosynthesis and incorporation of Sec into selenoprotein were comprehensively reviewed on five aspects: (i) the specific biosynthesis mechanism of Sec and the role of its internal influencing factors (SelA, SelB, SelC, SelD, SPS2 and PSTK); (ii) the elements (SECIS, PSL, SPUR and RF) on mRNA and their functional mechanisms; (iii) the specificity (either translation termination or translation into Sec) of UGA; (iv) the structure–activity relationship and action mechanism of SelA, SelB, SelC and SelD; and (v) the operating mechanism of two key enzyme systems for inorganic selenium source flow before Sec synthesis. Lastly, the size of the translation initiation interval, other action modes of SECIS and effects of REPS (Repetitive Extragenic Palindromic Sequences) that affect the incorporation efficiency of Sec was also discussed to provide scientific basis for the large-scale industrial fermentation for the production of selenoprotein.

Style APA, Harvard, Vancouver, ISO itp.

29

Kremer, Penny M., Daniel J. Torres, Ann C. Hashimoto i Marla J. Berry. "Disruption of Selenium Handling During Puberty Causes Sex-Specific Neurological Impairments in Mice". Antioxidants 8, nr 4 (24.04.2019): 110. http://dx.doi.org/10.3390/antiox8040110.

Pełny tekst źródła

Streszczenie:

Selenium is an essential trace element linked to normal development and antioxidant defense mechanisms through its incorporation into selenoproteins via the amino acid, selenocysteine (Sec). Male mice lacking both the Se transporter, selenoprotein P (SELENOP), and selenocysteine lyase (Scly), which plays a role in intracellular Se utilization, require Se supplementation for viability and exhibit neuromotor deficits. Previously, we demonstrated that male SELENOP/Scly double knockout (DKO) mice suffer from loss of motor function and audiogenic seizures due to neurodegeneration, both of which are alleviated by prepubescent castration. The current study examined the neuromotor function of female DKO mice using the rotarod and open field test, as well as the effects of dietary Se restriction. Female DKO mice exhibited a milder form of neurological impairment than their male counterparts. This impairment is exacerbated by removal of Se supplementation during puberty. These results indicate there is a critical time frame in which Se supplementation is essential for neurodevelopment. These sex-specific differences may unveil new insights into dietary requirements for this essential nutrient in humans.

Style APA, Harvard, Vancouver, ISO itp.

30

Steegborn, Clemens, i Ulrich Schweizer. "Structure and Mechanism of Iodothyronine Deiodinases – What We Know, What We Don’t Know, and What Would Be Nice to Know". Experimental and Clinical Endocrinology & Diabetes 128, nr 06/07 (7.11.2019): 375–78. http://dx.doi.org/10.1055/a-1022-9916.

Pełny tekst źródła

Streszczenie:

AbstractDeiodinases catalyze the specific removal of iodine atoms from one of the two iodinated phenyl rings in iodothyronines. They thereby fine-regulate local thyroid hormone concentrations in organs or cells. The chemical reaction is unique in the sense that in metazoans the reductive elimination of iodide depends on the rare amino acid selenocysteine in the enzymes’ active centers. While there is no prokaryotic homologue of such deiodinases, the solution of the crystal structure of a catalytic domain of mouse deiodinase 3 has revealed that the ancient peroxiredoxin structure has been repurposed, and improved using selenocysteine, as a deiodinase during metazoan evolution. Likewise, many biochemical findings obtained over decades can now be interpreted in light of the molecular structure. Despite this leap in our understanding of deiodinase structure, there are still several open questions that need to be addressed in order to fully understand substrate binding, catalytic mechanism, and regulation of deiodinases. We surmise that these issues as well as differences between the three highly homologous isoenzymes must be understood in order to develop modulators of deiodinases that could be valuable in clinical use.

Style APA, Harvard, Vancouver, ISO itp.

31

Mundaganore, D. S., Y. D. Mundagnore i K. V. Ashokan. "In Silico Validation of Middle East Respiratory Syndrome (MERS) Virus Proteins for Better Drug Development". International Journal of Applied Sciences and Biotechnology 1, nr 4 (21.12.2013): 272–78. http://dx.doi.org/10.3126/ijasbt.v1i4.9184.

Pełny tekst źródła

Streszczenie:

MERS Co-virus protein sequence of N, M, E and S-protein was validated by bioinformatics servers and tools. The study revealed that S-protein shows highest percentage of amino acid and the least in M and E-protein. The bit score also shows the same trend but the E-value is maximum in E and M protein. The amino acid composition revealed that N-protein is rich in glycine and M-protein rich in leucin. Pyrrolysine, Selenocysteine and cystein (N-Protein) are absent in all the protein studied an indication of low thermo stability. The physico-chemical study showed that M, N, and E proteins are positively charged due to specific amino acids (Arginin and lysine) and S-protein is negatively charged due to aspartic acid and glutamic acid. EC is maximum in S-protein. Instability Index (II) shows that E and S-proteins are more stable in test tube than other proteins. Further all proteins are hydrophobic with GRAVY below ‘0’. To get clearer picture of the physical and chemical attribute of the protein we generated 3D model and the model was validated and observed that the 3D structure falls in the accepted limits. The practical implication of the study is that the result will assists the pharmacologist and other drug developers and Government bodies to better knowledge on these proteins and develop possible new vaccine against MERS Co-virus.DOI: http://dx.doi.org/10.3126/ijasbt.v1i4.9184 Int J Appl Sci Biotechnol, Vol. 1(4): 272-278

Style APA, Harvard, Vancouver, ISO itp.

32

Vank, Judith C., Carlos P. Sosa, Andras Perczel i Imre G. Csizmadia. "Peptide models XXVII. An exploratory ab initio study on the 21st amino acid side-chain conformations of N-formyl-L-selenocysteinamide (For-L-Sec-NH2) and N-acetyl-L-selenocysteine-N-methylamide (Ac-L-Sec-NHMe) in their γL backbone conformation". Canadian Journal of Chemistry 78, nr 3 (1.03.2000): 395–408. http://dx.doi.org/10.1139/v00-029.

Pełny tekst źródła

Streszczenie:

Selenocysteine is expected to have 9 × 9 = 81 conformations [3 × 3 = 9 backbone: ψ (g+,a,g-) × ϕ (g+,a,g-) and 3 × 3 = 9 side-chain: χ1 (g+,a,g-) × χ2 (g+,a,g-)]. In the present study, all the torsional modes of the side-chain (χ1: rotation about the Cα-Cβ and χ2: rotation about the Cβ-Se bonds) were investigated in the relaxed γL backbone [(ϕ,ψ); (g-,g+)] conformation. Seven out of the nine expected minima were found at the RHF/3-21G level of theory for N-formyl-L-selenocysteinamide (For-L-Sec-NH2) and N-acetyl-L-selenocysteine-N-methylamide (Ac-L-Sec-NHMe). The stabilization energy exerted by the -CH2-SeH side-chain has been compared with that of -CH2-SH and -CH2-OH. Relative energies of the various conformers were also obtained via single point calculations at the B3LYP/6-31G(d,p) level of theory. Topological analysis of the electron density has been performed by Bader's Atoms in Molecule (AIM) approach using the results. The structures were also optimized at the B3LYP/6-31+G(d,p) level of theory.Key words: selenocysteine side-chain conformations, ab initio MO study, Multidimensional Conformational Analysis (MDCA), Atoms in Molecules (AIM), Bader's electron density analysis.

Style APA, Harvard, Vancouver, ISO itp.

33

Peters, Franziska, Michael Rother i Matthias Boll. "Selenocysteine-Containing Proteins in Anaerobic Benzoate Metabolism of Desulfococcus multivorans". Journal of Bacteriology 186, nr 7 (1.04.2004): 2156–63. http://dx.doi.org/10.1128/jb.186.7.2156-2163.2004.

Pełny tekst źródła

Streszczenie:

ABSTRACT The sulfate-reducing bacterium Desulfococcus multivorans uses various aromatic compounds as sources of cell carbon and energy. In this work, we studied the initial steps in the aromatic metabolism of this strictly anaerobic model organism. An ATP-dependent benzoate coenzyme A (CoA) ligase (AMP plus PPi forming) composed of a single 59-kDa subunit was purified from extracts of cells grown on benzoate. Specific activity was highest with benzoate and some benzoate derivatives, whereas aliphatic carboxylic acids were virtually unconverted. The N-terminal amino acid sequence showed high similarities with benzoate CoA ligases from Thauera aromatica and Azoarcus evansii. When cultivated on benzoate, cells strictly required selenium and molybdenum, whereas growth on nonaromatic compounds, such as cyclohexanecarboxylate or lactate, did not depend on the presence of the two trace elements. The growth rate on benzoate was half maximal with 1 nM selenite present in the growth medium. In molybdenum- and/or selenium-depleted cultures, growth on benzoate could be induced by addition of the missing trace elements. In extracts of cells grown on benzoate in the presence of [75Se]selenite, three radioactively labeled proteins with molecular masses of ∼100, 30, and 27 kDa were detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis. The 100- and 30-kDa selenoproteins were 5- to 10-fold induced in cells grown on benzoate compared to cells grown on lactate. These results suggest that the dearomatization process in D. multivorans is not catalyzed by the ATP-dependent Fe-S enzyme benzoyl-CoA reductase as in facultative anaerobes but rather involves unknown molybdenum- and selenocysteine-containing proteins.

Style APA, Harvard, Vancouver, ISO itp.

34

Bellinger, Frederick P., Arjun V. Raman, Mariclair A. Reeves i Marla J. Berry. "Regulation and function of selenoproteins in human disease". Biochemical Journal 422, nr 1 (29.07.2009): 11–22. http://dx.doi.org/10.1042/bj20090219.

Pełny tekst źródła

Streszczenie:

Selenoproteins are proteins containing selenium in the form of the 21st amino acid, selenocysteine. Members of this protein family have many diverse functions, but their synthesis is dependent on a common set of cofactors and on dietary selenium. Although the functions of many selenoproteins are unknown, several disorders involving changes in selenoprotein structure, activity or expression have been reported. Selenium deficiency and mutations or polymorphisms in selenoprotein genes and synthesis cofactors are implicated in a variety of diseases, including muscle and cardiovascular disorders, immune dysfunction, cancer, neurological disorders and endocrine function. Members of this unusual family of proteins have roles in a variety of cell processes and diseases.

Style APA, Harvard, Vancouver, ISO itp.

35

Thanbichler, Martin, Bernhard Neuhierl i August Böck. "S-Methylmethionine Metabolism in Escherichia coli". Journal of Bacteriology 181, nr 2 (15.01.1999): 662–65. http://dx.doi.org/10.1128/jb.181.2.662-665.1999.

Pełny tekst źródła

Streszczenie:

ABSTRACT Selenium-accumulating Astragalus spp. contain an enzyme which specifically transfers a methyl group fromS-methylmethionine to the selenol of selenocysteine, thus converting it to a nontoxic, since nonproteinogenic, amino acid. Analysis of the amino acid sequence of this enzyme revealed thatEscherichia coli possesses a protein (YagD) which shares high sequence similarity with the enzyme. The properties and physiological role of YagD were investigated. YagD is anS-methylmethionine: homocysteine methyltransferase which also accepts selenohomocysteine as a substrate. Mutants inyagD which also possess defects in metE andmetH are unable to utilize S-methylmethionine for growth, whereas a metE metH double mutant still grows on S-methylmethionine. Upstream of yagD and overlapping with its reading frame is a gene (ykfD) which, when inactivated, also blocks growth on methylmethionine in ametE metH genetic background. Since it displays sequence similarities with amino acid permeases it appears to be the transporter for S-methylmethionine. Methionine but notS-methylmethionine in the medium reduces the amount ofyagD protein. This and the existence of four MET box motifs upstream of yfkD indicate that the two genes are members of the methionine regulon. The physiological roles of the ykfDand yagD products appear to reside in the acquisition ofS-methylmethionine, which is an abundant plant product, and its utilization for methionine biosynthesis.

Style APA, Harvard, Vancouver, ISO itp.

36

Schoenmakers, Erik, i Krishna Chatterjee. "Human Genetic Disorders Resulting in Systemic Selenoprotein Deficiency". International Journal of Molecular Sciences 22, nr 23 (29.11.2021): 12927. http://dx.doi.org/10.3390/ijms222312927.

Pełny tekst źródła

Streszczenie:

Selenium, a trace element fundamental to human health, is incorporated as the amino acid selenocysteine (Sec) into more than 25 proteins, referred to as selenoproteins. Human mutations in SECISBP2, SEPSECS and TRU-TCA1-1, three genes essential in the selenocysteine incorporation pathway, affect the expression of most if not all selenoproteins. Systemic selenoprotein deficiency results in a complex, multifactorial disorder, reflecting loss of selenoprotein function in specific tissues and/or long-term impaired selenoenzyme-mediated defence against oxidative and endoplasmic reticulum stress. SEPSECS mutations are associated with a predominantly neurological phenotype with progressive cerebello-cerebral atrophy. Selenoprotein deficiency due to SECISBP2 and TRU-TCA1-1 defects are characterized by abnormal circulating thyroid hormones due to lack of Sec-containing deiodinases, low serum selenium levels (low SELENOP, GPX3), with additional features (myopathy due to low SELENON; photosensitivity, hearing loss, increased adipose mass and function due to reduced antioxidant and endoplasmic reticulum stress defence) in SECISBP2 cases. Antioxidant therapy ameliorates oxidative damage in cells and tissues of patients, but its longer term benefits remain undefined. Ongoing surveillance of patients enables ascertainment of additional phenotypes which may provide further insights into the role of selenoproteins in human biological processes.

Style APA, Harvard, Vancouver, ISO itp.

37

Itoh, Yuzuru, Markus J. Bröcker, Shun-ichi Sekine, Gifty Hammond, Shiro Suetsugu, Dieter Söll i Shigeyuki Yokoyama. "Decameric SelA•tRNASec Ring Structure Reveals Mechanism of Bacterial Selenocysteine Formation". Science 340, nr 6128 (4.04.2013): 75–78. http://dx.doi.org/10.1126/science.1229521.

Pełny tekst źródła

Streszczenie:

The 21st amino acid, selenocysteine (Sec), is synthesized on its cognate transfer RNA (tRNASec). In bacteria, SelA synthesizes Sec from Ser-tRNASec, whereas in archaea and eukaryotes SepSecS forms Sec from phosphoserine (Sep) acylated to tRNASec. We determined the crystal structures of Aquifex aeolicus SelA complexes, which revealed a ring-shaped homodecamer that binds 10 tRNASec molecules, each interacting with four SelA subunits. The SelA N-terminal domain binds the tRNASec-specific D-arm structure, thereby discriminating Ser-tRNASec from Ser-tRNASer. A large cleft is created between two subunits and accommodates the 3′-terminal region of Ser-tRNASec. The SelA structures together with in vivo and in vitro enzyme assays show decamerization to be essential for SelA function. SelA catalyzes pyridoxal 5′-phosphate–dependent Sec formation involving Arg residues nonhomologous to those in SepSecS. Different protein architecture and substrate coordination of the bacterial enzyme provide structural evidence for independent evolution of the two Sec synthesis systems present in nature.

Style APA, Harvard, Vancouver, ISO itp.

38

Sonet, Jordan, Maurine Mosca, Katarzyna Bierla, Karolina Modzelewska, Anna Flis-Borsuk, Piotr Suchocki, Iza Ksiazek i in. "Selenized Plant Oil Is an Efficient Source of Selenium for Selenoprotein Biosynthesis in Human Cell Lines". Nutrients 11, nr 7 (4.07.2019): 1524. http://dx.doi.org/10.3390/nu11071524.

Pełny tekst źródła

Streszczenie:

Selenium is an essential trace element which is incorporated in the form of a rare amino acid, the selenocysteine, into an important group of proteins, the selenoproteins. Among the twenty-five selenoprotein genes identified to date, several have important cellular functions in antioxidant defense, cell signaling and redox homeostasis. Many selenoproteins are regulated by the availability of selenium which mostly occurs in the form of water-soluble molecules, either organic (selenomethionine, selenocysteine, and selenoproteins) or inorganic (selenate or selenite). Recently, a mixture of selenitriglycerides, obtained by the reaction of selenite with sunflower oil at high temperature, referred to as Selol, was proposed as a novel non-toxic, highly bioavailable and active antioxidant and antineoplastic agent. Free selenite is not present in the final product since the two phases (water soluble and oil) are separated and the residual water-soluble selenite discarded. Here we compare the assimilation of selenium as Selol, selenite and selenate by various cancerous (LNCaP) or immortalized (HEK293 and PNT1A) cell lines. An approach combining analytical chemistry, molecular biology and biochemistry demonstrated that selenium from Selol was efficiently incorporated in selenoproteins in human cell lines, and thus produced the first ever evidence of the bioavailability of selenium from selenized lipids.

Style APA, Harvard, Vancouver, ISO itp.

39

Perry, A. C. F., R. Jones, L. S. P. Niang, R. M. Jackson i L. Hall. "Genetic evidence for an androgen-regulated epididymal secretory glutathione peroxidase whose transcript does not contain a selenocysteine codon". Biochemical Journal 285, nr 3 (1.08.1992): 863–70. http://dx.doi.org/10.1042/bj2850863.

Pełny tekst źródła

Streszczenie:

Epididymal glutathione peroxidase (GPX) has been suggested as a major factor in combating loss of fertility of spermatozoa due to lipid peroxidation. We report here the isolation and sequence of putative GPX cDNAs from rat (Rattus rattus) and cynomolgus-monkey (Macaca fascicularis) epididymis, which exhibit marked sequence identity with known GPXs. In both species the cDNAs encode predicted preproteins containing 221 amino acid residues. Unlike other characterized GPX sequences, epididymal GPX mRNA does not contain a selenocysteine codon (UGA). However, sequence comparison and molecular-modelling studies suggest a high degree of structural conservation between epididymal and other GPXs. Transcripts corresponding to epididymal GPX are not detected in a variety of other tissues (liver, spleen, kidney and testis) and appear to be androgen-regulated in the epididymis.

Style APA, Harvard, Vancouver, ISO itp.

40

Ghuge, Sandip A., Ulhas Sopanrao Kadam i Jong Chan Hong. "Selenoprotein: Potential Player in Redox Regulation in Chlamydomonas reinhardtii". Antioxidants 11, nr 8 (22.08.2022): 1630. http://dx.doi.org/10.3390/antiox11081630.

Pełny tekst źródła

Streszczenie:

Selenium (Se) is an essential micro-element for many organisms, including Chlamydomonas reinhardtii, and is required in trace amounts. It is obtained from the 21st amino acid selenocysteine (Sec, U), genetically encoded by the UGA codon. Proteins containing Sec are known as selenoproteins. In eukaryotes, selenoproteins are present in animals and algae, whereas fungi and higher plants lack them. The human genome contains 25 selenoproteins, most of which are involved in antioxidant defense activity, redox regulation, and redox signaling. In algae, 42 selenoprotein families were identified using various bioinformatics approaches, out of which C. reinhardtii is known to have 10 selenoprotein genes. However, the role of selenoproteins in Chlamydomonas is yet to be reported. Chlamydomonas selenoproteins contain conserved domains such as CVNVGC and GCUG, in the case of thioredoxin reductase, and CXXU in other selenoproteins. Interestingly, Sec amino acid residue is present in a catalytically active domain in Chlamydomonas selenoproteins, similar to human selenoproteins. Based on catalytical active sites and conserved domains present in Chlamydomonas selenoproteins, we suggest that Chlamydomonas selenoproteins could have a role in redox regulation and defense by acting as antioxidants in various physiological conditions.

Style APA, Harvard, Vancouver, ISO itp.

41

Turanov, Anton A., Xue-Ming Xu, Bradley A. Carlson, Min-Hyuk Yoo, Vadim N. Gladyshev i Dolph L. Hatfield. "Biosynthesis of Selenocysteine, the 21st Amino Acid in the Genetic Code, and a Novel Pathway for Cysteine Biosynthesis". Advances in Nutrition 2, nr 2 (1.03.2011): 122–28. http://dx.doi.org/10.3945/an.110.000265.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

42

Watabe, Shoji, Yumiko Makino, Kazuo Ogawa, Tomoko Hiroi, Yoshimi Yamamoto i Susumu Y. Takahashi. "Mitochondrial thioredoxin reductase in bovine adrenal cortex. Its purification, properties, nucleotide/amino acid sequences, and identification of selenocysteine". European Journal of Biochemistry 264, nr 1 (15.08.1999): 74–84. http://dx.doi.org/10.1046/j.1432-1327.1999.00578.x.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

43

Sliwkowski, M. X., i T. C. Stadtman. "Selenoprotein A of the clostridial glycine reductase complex: purification and amino acid sequence of the selenocysteine-containing peptide." Proceedings of the National Academy of Sciences 85, nr 2 (1.01.1988): 368–71. http://dx.doi.org/10.1073/pnas.85.2.368.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

44

Premadasa, Lakmini, Gabrielle Dailey, Jan A. Ruzicka i Ethan Will Taylor. "Selenium-Dependent Read Through of the Conserved 3’-Terminal UGA Stop Codon of HIV-1 nef". American Journal of Biopharmacy and Pharmaceutical Sciences 1 (1.11.2021): 1. http://dx.doi.org/10.25259/ajbps_6_2021.

Pełny tekst źródła

Streszczenie:

Objectives: The HIV-1 nef gene terminates in a 3’-UGA stop codon, which is highly conserved in the main group of HIV-1 subtypes, along with a downstream potential coding region that could extend the nef protein by 33 amino acids, if readthrough of the stop codon occurs. It has been proposed that antisense tethering interactions (ATIs) between a viral mRNA and a host selenoprotein mRNA are a potential viral strategy for the capture of a host selenocysteine insertion sequence (SECIS) element. This mRNA hijacking mechanism could enable the expression of virally encoded selenoprotein modules, through translation of in-frame UGA stop codons as selenocysteine (Sec). Here, our aim was to assess whether readthrough of the 3’-terminal UGA codon of nef occurs during translation of HIV-1 nef expression constructs in transfected cells, and whether selenium-based mechanisms might be involved. Material and Methods: To assess UGA codon readthrough, we used fluorescence microscopy image analysis and flow cytometry of HEK 293 cells transfected with full length HIV-1 nef gene expression constructs including the 3’-UGA stop codon and a predicted thioredoxin reductase 1 (TXNRD1) antisense region spanning the UGA codon, engineered with a downstream in-frame green fluorescent protein (GFP) reporter gene. These were designed so that GFP can only be expressed by translational recoding of the UGA codon, that is, if the UGA codon is translated as an amino acid or bypassed by ribosomal hopping. To assess readthrough efficiency, appropriate mutant control constructs were used for 100% and 0% readthrough. We used anti-TXNRD1 siRNA to assess the possible role of the proposed antisense interaction in this event, by knockdown of TXNRD1 mRNA levels. Results: UGA stop codon readthrough efficiency for the wild-type nef construct was estimated by flow cytometry to be about 19% (P < 0.0001). siRNA knockdown of TXNRD1 mRNA resulted in a 67% decrease in GFP expression in this system relative to control cells (P < 0.0001), presumably due to reduced availability of the components involved in selenocysteine incorporation for the stop codon readthrough (i.e. the TXNRD1 SECIS element). Addition of 20 nM sodium selenite to the media enhanced stop codon readthrough in the pNefATI1 plasmid construct by >100% (P < 0.0001), that is, more than doubled the amount of readthrough product, supporting the hypothesis that selenium is involved in the UGA readthrough mechanism. Conclusion: Our results show that readthrough of the 3’-terminal UGA codon of nef occurs during translation of HIV-1 nef expression constructs in transfected cells, that this is dependent on selenium concentration, and the presence of TXNRD1 mRNA, supporting the proposed antisense tethering interaction.

Style APA, Harvard, Vancouver, ISO itp.

45

Haruna, Ken-ichi, Muhammad H. Alkazemi, Yuchen Liu, Dieter Söll i Markus Englert. "Engineering the elongation factor Tu for efficient selenoprotein synthesis". Nucleic Acids Research 42, nr 15 (26.07.2014): 9976–83. http://dx.doi.org/10.1093/nar/gku691.

Pełny tekst źródła

Streszczenie:

Abstract Selenocysteine (Sec) is naturally co-translationally incorporated into proteins by recoding the UGA opal codon with a specialized elongation factor (SelB in bacteria) and an RNA structural signal (SECIS element). We have recently developed a SECIS-free selenoprotein synthesis system that site-specifically—using the UAG amber codon—inserts Sec depending on the elongation factor Tu (EF-Tu). Here, we describe the engineering of EF-Tu for improved selenoprotein synthesis. A Sec-specific selection system was established by expression of human protein O6-alkylguanine-DNA alkyltransferase (hAGT), in which the active site cysteine codon has been replaced by the UAG amber codon. The formed hAGT selenoprotein repairs the DNA damage caused by the methylating agent N-methyl-N′-nitro-N-nitrosoguanidine, and thereby enables Escherichia coli to grow in the presence of this mutagen. An EF-Tu library was created in which codons specifying the amino acid binding pocket were randomized. Selection was carried out for enhanced Sec incorporation into hAGT; the resulting EF-Tu variants contained highly conserved amino acid changes within members of the library. The improved UTu-system with EF-Sel1 raises the efficiency of UAG-specific Sec incorporation to >90%, and also doubles the yield of selenoprotein production.

Style APA, Harvard, Vancouver, ISO itp.

46

Labunskyy, Vyacheslav M., Dolph L. Hatfield i Vadim N. Gladyshev. "Selenoproteins: Molecular Pathways and Physiological Roles". Physiological Reviews 94, nr 3 (lipiec 2014): 739–77. http://dx.doi.org/10.1152/physrev.00039.2013.

Pełny tekst źródła

Streszczenie:

Selenium is an essential micronutrient with important functions in human health and relevance to several pathophysiological conditions. The biological effects of selenium are largely mediated by selenium-containing proteins (selenoproteins) that are present in all three domains of life. Although selenoproteins represent diverse molecular pathways and biological functions, all these proteins contain at least one selenocysteine (Sec), a selenium-containing amino acid, and most serve oxidoreductase functions. Sec is cotranslationally inserted into nascent polypeptide chains in response to the UGA codon, whose normal function is to terminate translation. To decode UGA as Sec, organisms evolved the Sec insertion machinery that allows incorporation of this amino acid at specific UGA codons in a process requiring a cis-acting Sec insertion sequence (SECIS) element. Although the basic mechanisms of Sec synthesis and insertion into proteins in both prokaryotes and eukaryotes have been studied in great detail, the identity and functions of many selenoproteins remain largely unknown. In the last decade, there has been significant progress in characterizing selenoproteins and selenoproteomes and understanding their physiological functions. We discuss current knowledge about how these unique proteins perform their functions at the molecular level and highlight new insights into the roles that selenoproteins play in human health.

Style APA, Harvard, Vancouver, ISO itp.

47

Shimada, Briana K., Sydonie Swanson, Pamela Toh i Lucia A. Seale. "Metabolism of Selenium, Selenocysteine, and Selenoproteins in Ferroptosis in Solid Tumor Cancers". Biomolecules 12, nr 11 (28.10.2022): 1581. http://dx.doi.org/10.3390/biom12111581.

Pełny tekst źródła

Streszczenie:

A potential target of precision nutrition in cancer therapeutics is the micronutrient selenium (Se). Se is metabolized and incorporated as the amino acid selenocysteine (Sec) into 25 human selenoproteins, including glutathione peroxidases (GPXs) and thioredoxin reductases (TXNRDs), among others. Both the processes of Se and Sec metabolism for the production of selenoproteins and the action of selenoproteins are utilized by cancer cells from solid tumors as a protective mechanism against oxidative damage and to resist ferroptosis, an iron-dependent cell death mechanism. Protection against ferroptosis in cancer cells requires sustained production of the selenoprotein GPX4, which involves increasing the uptake of Se, potentially activating Se metabolic pathways such as the trans-selenation pathway and the TXNRD1-dependent decomposition of inorganic selenocompounds to sustain GPX4 synthesis. Additionally, endoplasmic reticulum-resident selenoproteins also affect apoptotic responses in the presence of selenocompounds. Selenoproteins may also help cancer cells adapting against increased oxidative damage and the challenges of a modified nutrient metabolism that result from the Warburg switch. Finally, cancer cells may also rewire the selenoprotein hierarchy and use Se-related machinery to prioritize selenoproteins that are essential to the adaptations against ferroptosis and oxidative damage. In this review, we discuss both the evidence and the gaps in knowledge on how cancer cells from solid tumors use Se, Sec, selenoproteins, and the Se-related machinery to promote their survival particularly via resistance to ferroptosis.

Style APA, Harvard, Vancouver, ISO itp.

48

Novoselov, Sergey V., Deame Hua, Alexey V. Lobanov i Vadim N. Gladyshev. "Identification and characterization of Fep15, a new selenocysteine-containing member of the Sep15 protein family". Biochemical Journal 394, nr 3 (24.02.2006): 575–79. http://dx.doi.org/10.1042/bj20051569.

Pełny tekst źródła

Streszczenie:

Sec (selenocysteine) is a rare amino acid in proteins. It is co-translationally inserted into proteins at UGA codons with the help of SECIS (Sec insertion sequence) elements. A full set of selenoproteins within a genome, known as the selenoproteome, is highly variable in different organisms. However, most of the known eukaryotic selenoproteins are represented in the mammalian selenoproteome. In addition, many of these selenoproteins have cysteine orthologues. Here, we describe a new selenoprotein, designated Fep15, which is distantly related to members of the 15 kDa selenoprotein (Sep15) family. Fep15 is absent in mammals, can be detected only in fish and is present in these organisms only in the selenoprotein form. In contrast with other members of the Sep15 family, which contain a putative active site composed of Sec and cysteine, Fep15 has only Sec. When transiently expressed in mammalian cells, Fep15 incorporated Sec in an SECIS- and SBP2 (SECIS-binding protein 2)-dependent manner and was targeted to the endoplasmic reticulum by its N-terminal signal peptide. Phylogenetic analyses of Sep15 family members suggest that Fep15 evolved by gene duplication.

Style APA, Harvard, Vancouver, ISO itp.

49

Kazi Tani, Latifa Sarra, Nouria Dennouni-Medjati, Benoit Toubhans i Laurent Charlet. "Selenium Deficiency—From Soil to Thyroid Cancer". Applied Sciences 10, nr 15 (4.08.2020): 5368. http://dx.doi.org/10.3390/app10155368.

Pełny tekst źródła

Streszczenie:

Selenium (Se) is an essential micronutrient present in human diet, entering in the composition of selenoproteins as selenocysteine (Se-Cys) amino acid. At the thyroid level, these proteins play an important role as antioxidant and in hormone metabolism. Selenoproteins are essential for the balance of redox homeostasis and antioxidant defense of mammalian organisms, while the corresponding imbalance is now recognized as the cause of many diseases including cancer. The food chain is the main source of Se in human body. Dietary intake is strongly correlated with Se content in soil and varies according to several factors such as geology and atmospheric input. Both Se deficiency and toxicity have been associated with adverse health effects. This review synthesizes recent data on the transfer of Se from soil to humans, Se U-shaped deficiency and toxicity uptake effects and particularly the impact of Se deficiency on thyroid cancer.

Style APA, Harvard, Vancouver, ISO itp.

50

Sengupta, Aniruddha, Bradley A. Carlson, Vyacheslav M. Labunskyy, Vadim N. Gladyshev i Dolph L. Hatfield. "Selenoprotein T deficiency alters cell adhesion and elevates selenoprotein W expression in murine fibroblast cells". Biochemistry and Cell Biology 87, nr 6 (grudzień 2009): 953–61. http://dx.doi.org/10.1139/o09-064.

Pełny tekst źródła

Streszczenie:

Mammalian selenoproteins have diverse functions, cellular locations, and evolutionary histories, but all use the amino acid selenocysteine (Sec), often present in the enzyme’s active site. Only about half of mammalian selenoproteins have been functionally characterized, with most being oxidoreductases. The cellular role of selenoprotein T (SelT), manifesting a CxxU motif in a thioredoxin-like fold and localized to Golgi and the endoplasmic reticulum, is not known. To examine its biological function, we knocked down SelT expression in mouse fibroblast cells and found that SelT deficiency alters cell adhesion and enhances the expression of several oxidoreductase genes, while decreasing the expression of genes involved in cell structure organization, suggesting the involvement of SelT in redox regulation and cell anchorage. Furthermore, we found that the loss of SelT elevates expression of another selenoprotein, selenoprotein W (SepW1). SelT and SepW1 belong to the same protein family, suggesting that SepW1 may functionally compensate for SelT.

Style APA, Harvard, Vancouver, ISO itp.

Artykuły w czasopismach na temat „Amino acid selenocysteine”

Utwórz poprawne odniesienie w stylach APA, MLA, Chicago, Harvard i wielu innych