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Crespo L, Sede Lucena B, Martínez FG, Mozzi F, Pescuma M. Selenium bioactive compounds produced by beneficial microbes. ADVANCES IN APPLIED MICROBIOLOGY 2024; 126:63-92. [PMID: 38637107 DOI: 10.1016/bs.aambs.2024.02.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/20/2024]
Abstract
Selenium (Se) is an essential trace element present as selenocysteine (SeCys) in selenoproteins, which have an important role in thyroid metabolism and the redox system in humans. Se deficiency affects between 500 and 1000 million people worldwide. Increasing Se intake can prevent from bacterial and viral infections. Se deficiency has been associated with cancer, Alzheimer, Parkinson, decreased thyroid function, and male infertility. Se intake depends on the food consumed which is directly related to the amount of Se in the soil as well as on its availability. Se is unevenly distributed on the earth's crust, being scarce in some regions and in excess in others. The easiest way to counteract the symptoms of Se deficiency is to enhance the Se status of the human diet. Se salts are the most toxic form of Se, while Se amino acids and Se-nanoparticles (SeNPs) are the least toxic and most bio-available forms. Some bacteria transform Se salts into these Se species. Generally accepted as safe selenized microorganisms can be directly used in the manufacture of selenized fermented and/or probiotic foods. On the other hand, plant growth-promoting bacteria and/or the SeNPs produced by them can be used to promote plant growth and produce crops enriched with Se. In this chapter we discuss bacterial Se metabolism, the effect of Se on human health, the applications of SeNPs and Se-enriched bacteria, as well as their effect on food fortification. Different strategies to counteract Se deficiency by enriching foods using sustainable strategies and their possible implications for improving human health are discussed.
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Affiliation(s)
- L Crespo
- Centro de Referencia para Lactobacilos (CERELA)-CONICET, San Miguel de Tucumán, Argentina
| | - B Sede Lucena
- Centro de Investigación y Extensión Forestal Andino Patagónico (CIEFAP), Esquel, Chubut, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - F G Martínez
- Centro de Referencia para Lactobacilos (CERELA)-CONICET, San Miguel de Tucumán, Argentina
| | - F Mozzi
- Centro de Referencia para Lactobacilos (CERELA)-CONICET, San Miguel de Tucumán, Argentina
| | - M Pescuma
- Centro de Investigación y Extensión Forestal Andino Patagónico (CIEFAP), Esquel, Chubut, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina.
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Shimizu A, Tobe R, Aono R, Inoue M, Hagita S, Kiriyama K, Toyotake Y, Ogawa T, Kurihara T, Goto K, Prakash NT, Mihara H. Initial Step of Selenite Reduction via Thioredoxin for Bacterial Selenoprotein Biosynthesis. Int J Mol Sci 2021; 22:ijms222010965. [PMID: 34681630 PMCID: PMC8538045 DOI: 10.3390/ijms222010965] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 10/05/2021] [Accepted: 10/08/2021] [Indexed: 12/11/2022] Open
Abstract
Many organisms reductively assimilate selenite to synthesize selenoprotein. Although the thioredoxin system, consisting of thioredoxin 1 (TrxA) and thioredoxin reductase with NADPH, can reduce selenite and is considered to facilitate selenite assimilation, the detailed mechanism remains obscure. Here, we show that selenite was reduced by the thioredoxin system from Pseudomonas stutzeri only in the presence of the TrxA (PsTrxA), and this system was specific to selenite among the oxyanions examined. Mutational analysis revealed that Cys33 and Cys36 residues in PsTrxA are important for selenite reduction. Free thiol-labeling assays suggested that Cys33 is more reactive than Cys36. Mass spectrometry analysis suggested that PsTrxA reduces selenite via PsTrxA-SeO intermediate formation. Furthermore, an in vivo formate dehydrogenase activity assay in Escherichia coli with a gene disruption suggested that TrxA is important for selenoprotein biosynthesis. The introduction of PsTrxA complemented the effects of TrxA disruption in E. coli cells, only when PsTrxA contained Cys33 and Cys36. Based on these results, we proposed the early steps of the link between selenite and selenoprotein biosynthesis via the formation of TrxA–selenium complexes.
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Affiliation(s)
- Atsuki Shimizu
- College of Life Sciences, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu 525-8577, Shiga, Japan; (A.S.); (R.T.); (R.A.); (M.I.); (S.H.); (K.K.)
| | - Ryuta Tobe
- College of Life Sciences, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu 525-8577, Shiga, Japan; (A.S.); (R.T.); (R.A.); (M.I.); (S.H.); (K.K.)
| | - Riku Aono
- College of Life Sciences, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu 525-8577, Shiga, Japan; (A.S.); (R.T.); (R.A.); (M.I.); (S.H.); (K.K.)
| | - Masao Inoue
- College of Life Sciences, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu 525-8577, Shiga, Japan; (A.S.); (R.T.); (R.A.); (M.I.); (S.H.); (K.K.)
- R-GIRO, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu 525-8577, Shiga, Japan
| | - Satoru Hagita
- College of Life Sciences, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu 525-8577, Shiga, Japan; (A.S.); (R.T.); (R.A.); (M.I.); (S.H.); (K.K.)
| | - Kaito Kiriyama
- College of Life Sciences, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu 525-8577, Shiga, Japan; (A.S.); (R.T.); (R.A.); (M.I.); (S.H.); (K.K.)
| | - Yosuke Toyotake
- Institute for Chemical Research, Kyoto University, Gokasho, Uji 611-0011, Kyoto, Japan; (Y.T.); (T.O.); (T.K.)
| | - Takuya Ogawa
- Institute for Chemical Research, Kyoto University, Gokasho, Uji 611-0011, Kyoto, Japan; (Y.T.); (T.O.); (T.K.)
| | - Tatsuo Kurihara
- Institute for Chemical Research, Kyoto University, Gokasho, Uji 611-0011, Kyoto, Japan; (Y.T.); (T.O.); (T.K.)
| | - Kei Goto
- Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551, Japan;
| | - N. Tejo Prakash
- School of Energy and Environment, Thapar Institute of Engineering and Technology, Patiala 147004, Punjab, India;
| | - Hisaaki Mihara
- College of Life Sciences, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu 525-8577, Shiga, Japan; (A.S.); (R.T.); (R.A.); (M.I.); (S.H.); (K.K.)
- Correspondence: ; Tel.: +81-(0)77-561-2732
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Wells M, Basu P, Stolz JF. The physiology and evolution of microbial selenium metabolism. Metallomics 2021; 13:6261189. [PMID: 33930157 DOI: 10.1093/mtomcs/mfab024] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 04/21/2021] [Accepted: 04/22/2021] [Indexed: 12/27/2022]
Abstract
Selenium is an essential trace element whose compounds are widely metabolized by organisms from all three domains of life. Moreover, phylogenetic evidence indicates that selenium species, along with iron, molybdenum, tungsten, and nickel, were metabolized by the last universal common ancestor of all cellular lineages, primarily for the synthesis of the 21st amino acid selenocysteine. Thus, selenium metabolism is both environmentally ubiquitous and a physiological adaptation of primordial life. Selenium metabolic reactions comprise reductive transformations both for assimilation into macromolecules and dissimilatory reduction of selenium oxyanions and elemental selenium during anaerobic respiration. This review offers a comprehensive overview of the physiology and evolution of both assimilatory and dissimilatory selenium metabolism in bacteria and archaea, highlighting mechanisms of selenium respiration. This includes a thorough discussion of our current knowledge of the physiology of selenocysteine synthesis and incorporation into proteins in bacteria obtained from structural biology. Additionally, this is the first comprehensive discussion in a review of the incorporation of selenium into the tRNA nucleoside 5-methylaminomethyl-2-selenouridine and as an inorganic cofactor in certain molybdenum hydroxylase enzymes. Throughout, conserved mechanisms and derived features of selenium metabolism in both domains are emphasized and discussed within the context of the global selenium biogeochemical cycle.
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Affiliation(s)
- Michael Wells
- Department of Biological Sciences, Duquesne University, Pittsburgh, PA 15282, USA
| | - Partha Basu
- Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, USA
| | - John F Stolz
- Department of Biological Sciences, Duquesne University, Pittsburgh, PA 15282, USA
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Tobe R, Mihara H. Delivery of selenium to selenophosphate synthetase for selenoprotein biosynthesis. Biochim Biophys Acta Gen Subj 2018; 1862:2433-2440. [PMID: 29859962 DOI: 10.1016/j.bbagen.2018.05.023] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Revised: 05/28/2018] [Accepted: 05/29/2018] [Indexed: 11/16/2022]
Abstract
BACKGROUND Selenophosphate, the key selenium donor for the synthesis of selenoprotein and selenium-modified tRNA, is produced by selenophosphate synthetase (SPS) from ATP, selenide, and H2O. Although free selenide can be used as the in vitro selenium substrate for selenophosphate synthesis, the precise physiological system that donates in vivo selenium substrate to SPS has not yet been characterized completely. SCOPE OF REVIEW In this review, we discuss selenium metabolism with respect to the delivery of selenium to SPS in selenoprotein biosynthesis. MAJOR CONCLUSIONS Glutathione, selenocysteine lyase, cysteine desulfurase, and selenium-binding proteins are the candidates of selenium delivery system to SPS. The thioredoxin system is also implicated in the selenium delivery to SPS in Escherichia coli. GENERAL SIGNIFICANCE Selenium delivered via a protein-bound selenopersulfide intermediate emerges as a central element not only in achieving specific selenoprotein biosynthesis but also in preventing the occurrence of toxic free selenide in the cell. This article is part of a Special Issue entitled "Selenium research in biochemistry and biophysics - 200 year anniversary".
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Affiliation(s)
- Ryuta Tobe
- Department of Biotechnology, College of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan
| | - Hisaaki Mihara
- Department of Biotechnology, College of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan.
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Xu D, Yang L, Wang Y, Wang G, Rensing C, Zheng S. Proteins enriched in charged amino acids control the formation and stabilization of selenium nanoparticles in Comamonas testosteroni S44. Sci Rep 2018; 8:4766. [PMID: 29555951 PMCID: PMC5859168 DOI: 10.1038/s41598-018-23295-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Accepted: 03/08/2018] [Indexed: 12/22/2022] Open
Abstract
Elemental selenium nanoparticles (SeNPs) are useful in medicine, environmental remediation and in material science. Biosynthesized SeNPs (BioSeNPs) by bacteria are cheap, eco-friendly and have a lower cytotoxicity in comparison with chemically synthesized ones. Organic matters were found to cap on the surface of BioSeNPs, but the functions were still not entirely clear. The purified BioSeNPs were coated in a thick layer of organic substrates observed by transmission electron microscopy (TEM). Fourier Transform Infrared (FT-IR) and quantitative detection of the coating agents showed that one gram of purified BioSeNPs bound 1069 mg proteins, 23 mg carbohydrates and only very limited amounts of lipids. Proteomics of BioSeNPs showed more than 800 proteins bound to BioSeNPs. Proteins enriched in charged amino acids are the major factor thought to govern the formation process and stabilization of BioSeNPs in bacteria. In view of the results reported here, a schematic model for the molecular mechanism of BioSeNPs formation in bacteria is proposed. These findings are helpful for the artificial green synthesis of stable SeNPs under specific condition and guiding the surface modification of SeNPs for medicine application.
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Affiliation(s)
- Ding Xu
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, P. R. China
| | - Lichen Yang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, P. R. China
| | - Yu Wang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, P. R. China
| | - Gejiao Wang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, P. R. China
| | - Christopher Rensing
- Institute of Environmental Microbiology, College of Resources and Environment, Fujian Agriculture & Forestry University, Fuzhou, Fujian, 350002, P. R. China
| | - Shixue Zheng
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, P. R. China.
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Silva IR, Serrão VHB, Manzine LR, Faim LM, da Silva MTA, Makki R, Saidemberg DM, Cornélio ML, Palma MS, Thiemann OH. Formation of a Ternary Complex for Selenocysteine Biosynthesis in Bacteria. J Biol Chem 2015; 290:29178-88. [PMID: 26378233 DOI: 10.1074/jbc.m114.613406] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Indexed: 11/06/2022] Open
Abstract
The synthesis of selenocysteine-containing proteins (selenoproteins) involves the interaction of selenocysteine synthase (SelA), tRNA (tRNA(Sec)), selenophosphate synthetase (SelD, SPS), a specific elongation factor (SelB), and a specific mRNA sequence known as selenocysteine insertion sequence (SECIS). Because selenium compounds are highly toxic in the cellular environment, the association of selenium with proteins throughout its metabolism is essential for cell survival. In this study, we demonstrate the interaction of SPS with the SelA-tRNA(Sec) complex, resulting in a 1.3-MDa ternary complex of 27.0 ± 0.5 nm in diameter and 4.02 ± 0.05 nm in height. To assemble the ternary complex, SPS undergoes a conformational change. We demonstrated that the glycine-rich N-terminal region of SPS is crucial for the SelA-tRNA(Sec)-SPS interaction and selenoprotein biosynthesis, as revealed by functional complementation experiments. Taken together, our results provide new insights into selenoprotein biosynthesis, demonstrating for the first time the formation of the functional ternary SelA-tRNA(Sec)-SPS complex. We propose that this complex is necessary for proper selenocysteine synthesis and may be involved in avoiding the cellular toxicity of selenium compounds.
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Affiliation(s)
- Ivan R Silva
- From the Physics and Informatics Department, Physics Institute of Sao Carlos, University of Sao Paulo - USP, CEP 13563-120 Sao Carlos, SP
| | - Vitor H B Serrão
- From the Physics and Informatics Department, Physics Institute of Sao Carlos, University of Sao Paulo - USP, CEP 13563-120 Sao Carlos, SP, the Physics Department, Federal University of Sao Carlos - UFSCar, 13565-905 Sao Carlos, SP, Brazil
| | - Livia R Manzine
- From the Physics and Informatics Department, Physics Institute of Sao Carlos, University of Sao Paulo - USP, CEP 13563-120 Sao Carlos, SP
| | - Lívia M Faim
- From the Physics and Informatics Department, Physics Institute of Sao Carlos, University of Sao Paulo - USP, CEP 13563-120 Sao Carlos, SP
| | - Marco T A da Silva
- From the Physics and Informatics Department, Physics Institute of Sao Carlos, University of Sao Paulo - USP, CEP 13563-120 Sao Carlos, SP
| | - Raphaela Makki
- From the Physics and Informatics Department, Physics Institute of Sao Carlos, University of Sao Paulo - USP, CEP 13563-120 Sao Carlos, SP
| | - Daniel M Saidemberg
- the Department of Biology/CEIS, Biosciences Institute of Rio Claro, Sao Paulo State University - UNESP, 13506-900 Rio Claro, SP, and
| | - Marinônio L Cornélio
- the Physics Department, Institute of Biosciences, Letters and Exact Sciences (IBILCE), Sao Paulo State University - UNESP, 15054-000 Sao Jose do Rio Preto, SP, Brazil
| | - Mário S Palma
- the Department of Biology/CEIS, Biosciences Institute of Rio Claro, Sao Paulo State University - UNESP, 13506-900 Rio Claro, SP, and
| | - Otavio H Thiemann
- From the Physics and Informatics Department, Physics Institute of Sao Carlos, University of Sao Paulo - USP, CEP 13563-120 Sao Carlos, SP,
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Fröhlich H. biRte: Bayesian inference of context-specific regulator activities and transcriptional networks. Bioinformatics 2015; 31:3290-8. [PMID: 26112290 DOI: 10.1093/bioinformatics/btv379] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Accepted: 06/15/2015] [Indexed: 11/14/2022] Open
Abstract
UNLABELLED In the last years there has been an increasing effort to computationally model and predict the influence of regulators (transcription factors, miRNAs) on gene expression. Here we introduce biRte as a computationally attractive approach combining Bayesian inference of regulator activities with network reverse engineering. biRte integrates target gene predictions with different omics data entities (e.g. miRNA and mRNA data) into a joint probabilistic framework. The utility of our method is tested in extensive simulation studies and demonstrated with applications from prostate cancer and Escherichia coli growth control. The resulting regulatory networks generally show a good agreement with the biological literature. AVAILABILITY AND IMPLEMENTATION biRte is available on Bioconductor (http://bioconductor.org). CONTACT frohlich@bit.uni-bonn.de SUPPLEMENTARY INFORMATION Supplementary data are available at Bioinformatics online.
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Affiliation(s)
- Holger Fröhlich
- University of Bonn, Institute for Computer Science, Römerstr. 164, 53117 Bonn, Germany
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9
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Metabolic engineering of Escherichia coli to enhance hydrogen production from glycerol. Appl Microbiol Biotechnol 2014; 98:4757-70. [PMID: 24615384 DOI: 10.1007/s00253-014-5600-3] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Revised: 02/05/2014] [Accepted: 02/06/2014] [Indexed: 12/20/2022]
Abstract
Glycerol is an attractive carbon source for biofuel production since it is cheap and abundant due to the increasing demand for renewable and clean energy sources, which includes production of biodiesel. This research aims to enhance hydrogen production by Escherichia coli from glycerol by manipulating its metabolic pathways via targeted deletions. Since our past strain, which had been engineered for producing hydrogen from glucose, was not suitable for producing hydrogen from glycerol, we rescreened 14 genes related to hydrogen production and glycerol metabolism. We found that 10 single knockouts are beneficial for enhanced hydrogen production from glycerol, namely, frdC (encoding for furmarate reductase), ldhA (lactate dehydrogenase), fdnG (formate dehydrogenase), ppc (phosphoenolpyruvate carboxylase), narG (nitrate reductase), focA (formate transporter), hyaB (the large subunit of hydrogenase 1), aceE (pyruvate dehydrogenase), mgsA (methylglyoxal synthase), and hycA (a regulator of the transcriptional regulator FhlA). On that basis, we created multiple knockout strains via successive P1 transductions. Simultaneous knockouts of frdC, ldhA, fdnG, ppc, narG, mgsA, and hycA created the best strain that produced 5-fold higher hydrogen and had a 5-fold higher hydrogen yield than the parent strain. The engineered strain also reached the theoretical maximum yield of 1 mol H2/mol glycerol after 48 h. Under low partial pressure fermentation, the strain grew over 2-fold faster, indicating faster utilization of glycerol and production of hydrogen. By combining metabolic engineering and low partial pressure fermentation, hydrogen production from glycerol was enhanced significantly.
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Wu Z, Wang Z, Wang G, Tan T. Improved 1,3-propanediol production by engineering the 2,3-butanediol and formic acid pathways in integrative recombinant Klebsiella pneumoniae. J Biotechnol 2013; 168:194-200. [PMID: 23665191 DOI: 10.1016/j.jbiotec.2013.04.022] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Revised: 04/03/2013] [Accepted: 04/26/2013] [Indexed: 11/16/2022]
Abstract
In the biotechnological process, insufficient cofactor NADH and multiple by-products restrain the final titer of 1,3-propanediol (1,3-PD). In this study, 1,3-PD production was improved by engineering the 2,3-butanediol (2,3-BD) and formic acid pathways in integrative recombinant Klebsiella pneumoniae. The formation of 2,3-BD is catalysed by acetoin reductase (AR). An inactivation mutation of the AR in K. pneumoniae CF was generated by insertion of a formate dehydrogenase gene. Inactivation of AR and expression of formate dehydrogenase reduced 2,3-BD formation and improved 1,3-PD production. Fermentation results revealed that intracellular metabolic flux was redistributed pronouncedly. The yield of 1,3-PD reached 0.74 mol/mol glycerol in flask fermentation, which is higher than the theoretical yield. In 5 L fed-batch fermentation, the final titer and 1,3-PD yield of the K. pneumoniae CF strain reached 72.2 g/L and 0.569 mol/mol, respectively, which were 15.9% and 21.7% higher than those of the wild-type strain. The titers of 2,3-BD and formic acid decreased by 52.2% and 73.4%, respectively. By decreasing the concentration of all nonvolatile by-products and by increasing the availability of NADH, this study demonstrates an important strategy in the metabolic engineering of 1,3-PD production by integrative recombinant hosts.
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Affiliation(s)
- Zhe Wu
- Key Laboratory of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, PR China
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Ishii TM, Kotlova N, Tapsoba F, Steinberg SV. The long D-stem of the selenocysteine tRNA provides resilience at the expense of maximal function. J Biol Chem 2013; 288:13337-44. [PMID: 23525102 DOI: 10.1074/jbc.m112.434704] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND The selenocysteine tRNA (tRNASec) has a uniquely long D-stem containing 6 base pairs. RESULTS The extended D-stem is not essential for function but is required for stability. CONCLUSION Enhanced secondary structure in selenocysteine tRNA compensates for the absence of canonical tertiary interactions. SIGNIFICANCE The flexibility due to the absence of tertiary interactions is required for tRNASec function, whereas the enhanced secondary structure compensates for the decreased stability. The D-stem of the selenocysteine tRNA (tRNA(Sec)) contains 2 additional base pairs, which replace tertiary interactions 8-14 and 15-48 universally present in all other cytosolic tRNAs. To study the role of these additional base pairs in the tRNA(Sec) function, we used the instant evolution approach. In vivo screening of six combinatorial gene libraries provided 158 functional variants of the Escherichia coli tRNA(Sec). Analysis of these variants showed that the additional base pairs in the D-stem were not required for the tRNA(Sec) function. Moreover, at lower temperatures, these base pairs notably harmed the tRNA(Sec) activity. However, at elevated temperatures, these base pairs became essential as they made the tRNA structure more stable. The alternative way to stabilize the structure through formation of the standard tertiary interactions was not an option for tRNA(Sec) variants, which suggests that the absence of these interactions and the resulting flexibility of the tertiary structure are essential for tRNA(Sec) function.
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Affiliation(s)
- Tetsu M Ishii
- Department of Biochemistry, Université de Montréal, Succursale Centre-ville, Montréal, Québec H3C 3J7, Canada
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Trchounian K, Poladyan A, Vassilian A, Trchounian A. Multiple and reversible hydrogenases for hydrogen production byEscherichia coli: dependence on fermentation substrate, pH and the F0F1-ATPase. Crit Rev Biochem Mol Biol 2012; 47:236-49. [DOI: 10.3109/10409238.2012.655375] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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13
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Selenite reduction by the thioredoxin system: kinetics and identification of protein-bound selenide. Biosci Biotechnol Biochem 2011; 75:1184-7. [PMID: 21670519 DOI: 10.1271/bbb.100847] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Selenite (SeO(3)(2-)) assimilation into a bacterial selenoprotein depends on thioredoxin (trx) reductase in Esherichia coli, but the molecular mechanism has not been elucidated. The mineral-oil overlay method made it possible to carry out anaerobic enzyme assay, which demonstrated an initial lag-phase followed by time-dependent steady NADPH consumption with a positive cooperativity toward selenite and trx. SDS-PAGE/autoradiography using (75)Se-labeled selenite as substrate revealed the formation of trx-bound selenium in the reaction mixture. The protein-bound selenium has metabolic significance in being stabilized in the divalent state, and it also produced the selenopersulfide (-S-SeH) form by the catalysis of E. coli trx reductase (TrxB).
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14
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Yoshizawa S, Böck A. The many levels of control on bacterial selenoprotein synthesis. Biochim Biophys Acta Gen Subj 2009; 1790:1404-14. [DOI: 10.1016/j.bbagen.2009.03.010] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2009] [Revised: 03/04/2009] [Accepted: 03/05/2009] [Indexed: 11/28/2022]
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Jasenec A, Barasa N, Kulkarni S, Shaik N, Moparthi S, Konda V, Caguiat J. Proteomic profiling of L-cysteine induced selenite resistance in Enterobacter sp. YSU. Proteome Sci 2009; 7:30. [PMID: 19715574 PMCID: PMC2744661 DOI: 10.1186/1477-5956-7-30] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2009] [Accepted: 08/28/2009] [Indexed: 11/10/2022] Open
Abstract
Background Enterobacter sp. YSU is resistant to several different heavy metal salts, including selenite. A previous study using M-9 minimal medium showed that when the selenite concentration was 100,000 times higher than the sulfate concentration, selenite entered Escherichia coli cells using two pathways: a specific and a non-specific pathway. In the specific pathway, selenite entered the cells through a yet to be characterized channel dedicated for selenite. In the non-specific pathway, selenite entered the cells through a sulfate permease channel. Addition of L-cystine, an L-cysteine dimer, appeared to indirectly decrease selenite import into the cell through the non-specific pathway. However, it did not affect the level of selenite transport into the cell through the specific pathway. Results Growth curves using M-9 minimal medium containing 40 mM selenite and 1 mM sulfate showed that Enterobacter sp. YSU grew when L-cysteine was present but died when it was absent. Differential protein expression analysis by two dimensional gel electrophoresis showed that CysK was present in cultures containing selenite and lacking L-cysteine but absent in cultures containing both selenite and L-cysteine. Additional RT-PCR studies demonstrated that transcripts for the sulfate permease genes, cysA, cysT and cysW, were down-regulated in the presence of L-cysteine. Conclusion L-cysteine appeared to confer selenite resistance upon Enterobacter sp. YSU by decreasing the level of selenite transport into the cell through the non-specific pathway.
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Affiliation(s)
- Ashley Jasenec
- Department of Biological Sciences, Youngstown State University, OH 44555, USA.
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Lu J, Berndt C, Holmgren A. Metabolism of selenium compounds catalyzed by the mammalian selenoprotein thioredoxin reductase. Biochim Biophys Acta Gen Subj 2009; 1790:1513-9. [PMID: 19406206 DOI: 10.1016/j.bbagen.2009.04.013] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2009] [Revised: 04/21/2009] [Accepted: 04/22/2009] [Indexed: 01/24/2023]
Abstract
The mammalian thioredoxin reductases (TrxR) are selenoproteins with a catalytic selenocysteine residue which in the oxidized enzyme forms a selenenylsulfide and in the reduced enzyme is present as a selenolthiol. Selenium compounds such as selenite, selenodiglutathione and selenocystine are substrates for the enzyme with low K(m)-values and the enzyme is implicated in reductive assimilation of selenium by generating selenide for selenoprotein synthesis. Redox cycling of reduced metabolites of these selenium compounds including selenide with oxygen via TrxR and reduced thioredoxin (Trx) will oxidize NADPH and produce reactive oxygen species inducing cell death at high concentrations explaining selenite toxicity. There is no free pool of selenocysteine since this would be toxic in an oxygen environment by redox cycling via thioredoxin systems. The importance of selenium compounds and TrxR in cancer and cardiovascular diseases both for prevention and treatment is discussed. A selenazol drug like ebselen is a direct substrate for mammalian TrxR and dithiol Trx and ebselen selenol is readily reoxidized by hydrogen peroxide and lipid hydroperoxides, acting as an anti-oxidant and anti-inflammatory drug.
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Affiliation(s)
- Jun Lu
- Division of Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE 171 77 Stockholm, Sweden
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Lu J, Zhong L, Lönn ME, Burk RF, Hill KE, Holmgren A. Penultimate selenocysteine residue replaced by cysteine in thioredoxin reductase from selenium-deficient rat liver. FASEB J 2009; 23:2394-402. [PMID: 19351701 DOI: 10.1096/fj.08-127662] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Selenium is an essential micronutrient for humans and animals, and its deficiency can predispose to the development of pathological conditions. This study evaluates the effect of selenium deficiency on the thioredoxin system, consisting of NADPH, selenoprotein thioredoxin reductase (TrxR), and thioredoxin (Trx); and the glutathione system, including NADPH, glutathione reductase, glutathione, and glutaredoxin coupled with selenoprotein glutathione peroxidase (GPx). We particularly investigate whether inactive truncated TrxR is present under selenium-starvation conditions due to reading of the UGA codon as stop. Feeding rats a selenium-deficient diet resulted in a large decrease in activity of TrxR and GPx in rat liver but not in the levels of Trx1 and Grx1. However, selenium deficiency induced mitochondrial Grx2 10-fold and markedly changed the expression of some flavoproteins that are involved in the cellular folate, glucose, and lipid metabolism. Liver TrxR mRNA was nearly unchanged, but no truncated enzyme was found. Instead, a low-activity form of TrxR with a cysteine substituted for the penultimate selenocysteine in the C-terminal active site was identified in selenium-deficient rat liver. These results show a novel mechanism for decoding the UGA stop codon, inserting cysteine to make a full-length enzyme that may be required for selenium assimilation.
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Affiliation(s)
- Jun Lu
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, SE-171 77 Stockholm, Sweden
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Vlamis-Gardikas A. The multiple functions of the thiol-based electron flow pathways of Escherichia coli: Eternal concepts revisited. Biochim Biophys Acta Gen Subj 2008; 1780:1170-200. [PMID: 18423382 DOI: 10.1016/j.bbagen.2008.03.013] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2007] [Revised: 03/18/2008] [Accepted: 03/22/2008] [Indexed: 10/22/2022]
Abstract
Electron flow via thiols is a theme with many variations in all kingdoms of life. The favourable physichochemical properties of the redox active couple of two cysteines placed in the optimised environment of the thioredoxin fold allow for two electron transfers in between top biological reductants and ultimate oxidants. The reduction of ribonucleotide reductases by thioredoxin and thioredoxin reductase of Escherichia coli (E. coli) was one of the first pathways to be elucidated. Diverse functions such as protein folding in the periplasm, maturation of respiratory enzymes, detoxification of hydrogen peroxide and prevention of oxidative damage may be based on two electron transfers via thiols. A growing field is the relation of thiol reducing pathways and the interaction of E. coli with different organisms. This concept combined with the sequencing of the genomes of different bacteria may allow for the identification of fine differences in the systems employing thiols for electron flow between pathogens and their corresponding mammalian hosts. The emerging possibility is the development of novel antibiotics.
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Affiliation(s)
- Alexios Vlamis-Gardikas
- Center of Basic Research I-Biochemistry Division, Biomedical Research Foundation (BRFAA), Academy of Athens, Soranou Efessiou 4, GR-11527 Athens, Greece.
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