1
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Seager S, Petkowski JJ, Huang J, Zhan Z, Ravela S, Bains W. Fully fluorinated non-carbon compounds NF 3 and SF 6 as ideal technosignature gases. Sci Rep 2023; 13:13576. [PMID: 37604949 PMCID: PMC10442443 DOI: 10.1038/s41598-023-39972-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Accepted: 08/02/2023] [Indexed: 08/23/2023] Open
Abstract
Waste gas products from technological civilizations may accumulate in an exoplanet atmosphere to detectable levels. We propose nitrogen trifluoride (NF3) and sulfur hexafluoride (SF6) as ideal technosignature gases. Earth life avoids producing or using any N-F or S-F bond-containing molecules and makes no fully fluorinated molecules with any element. NF3 and SF6 may be universal technosignatures owing to their special industrial properties, which unlike biosignature gases, are not species-dependent. Other key relevant qualities of NF3 and SF6 are: their extremely low water solubility, unique spectral features, and long atmospheric lifetimes. NF3 has no non-human sources and was absent from Earth's pre-industrial atmosphere. SF6 is released in only tiny amounts from fluorine-containing minerals, and is likely produced in only trivial amounts by volcanic eruptions. We propose a strategy to rule out SF6's abiotic source by simultaneous observations of SiF4, which is released by volcanoes in an order of magnitude higher abundance than SF6. Other fully fluorinated human-made molecules are of interest, but their chemical and spectral properties are unavailable. We summarize why life on Earth-and perhaps life elsewhere-avoids using F. We caution, however, that we cannot definitively disentangle an alien biochemistry byproduct from a technosignature gas.
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Affiliation(s)
- Sara Seager
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, 02139, USA.
- Department of Physics, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, 02139, USA.
- Department of Aeronautics and Astronautics, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, 02139, USA.
| | - Janusz J Petkowski
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, 02139, USA
- JJ Scientific, 02-792, Warsaw, Poland
| | - Jingcheng Huang
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, 02139, USA
| | - Zhuchang Zhan
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, 02139, USA
| | - Sai Ravela
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, 02139, USA
| | - William Bains
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, 02139, USA
- School of Physics and Astronomy, Cardiff University, 4 The Parade, Cardiff, CF24 3AA, UK
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2
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Kong Y, Cao T, Zhu S. TEMPO‐Regulated
Regio‐ and Stereoselective
Cross‐Dihalogenation
with Dual Electrophilic X
+
Reagents. CHINESE J CHEM 2021. [DOI: 10.1002/cjoc.202100472] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Yi Kong
- Key Laboratory of Functional Molecular Engineering of Guangdong Province, School of Chemistry and Chemical Engineering, South China University of Technology Guangzhou Guangdong 510640 China
| | - Tongxiang Cao
- Key Laboratory of Functional Molecular Engineering of Guangdong Province, School of Chemistry and Chemical Engineering, South China University of Technology Guangzhou Guangdong 510640 China
| | - Shifa Zhu
- Key Laboratory of Functional Molecular Engineering of Guangdong Province, School of Chemistry and Chemical Engineering, South China University of Technology Guangzhou Guangdong 510640 China
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3
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Matulja D, Wittine K, Malatesti N, Laclef S, Turks M, Markovic MK, Ambrožić G, Marković D. Marine Natural Products with High Anticancer Activities. Curr Med Chem 2020; 27:1243-1307. [PMID: 31931690 DOI: 10.2174/0929867327666200113154115] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 12/03/2019] [Accepted: 12/15/2019] [Indexed: 12/13/2022]
Abstract
This review covers recent literature from 2012-2019 concerning 170 marine natural products and their semisynthetic analogues with strong anticancer biological activities. Reports that shed light on cellular and molecular mechanisms and biological functions of these compounds, thus advancing the understanding in cancer biology are also included. Biosynthetic studies and total syntheses, which have provided access to derivatives and have contributed to the proper structure or stereochemistry elucidation or revision are mentioned. The natural compounds isolated from marine organisms are divided into nine groups, namely: alkaloids, sterols and steroids, glycosides, terpenes and terpenoids, macrolides, polypeptides, quinones, phenols and polyphenols, and miscellaneous products. An emphasis is placed on several drugs originating from marine natural products that have already been marketed or are currently in clinical trials.
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Affiliation(s)
- Dario Matulja
- Department of Biotechnology, University of Rijeka, Radmile Matejcic 2, 51000 Rijeka, Croatia
| | - Karlo Wittine
- Department of Biotechnology, University of Rijeka, Radmile Matejcic 2, 51000 Rijeka, Croatia
| | - Nela Malatesti
- Department of Biotechnology, University of Rijeka, Radmile Matejcic 2, 51000 Rijeka, Croatia
| | - Sylvain Laclef
- Laboratoire de Glycochimie, des Antimicrobiens et des Agro-ressources (LG2A), CNRS FRE 3517, 33 rue Saint-Leu, 80039 Amiens, France
| | - Maris Turks
- Faculty of Material Science and Applied Chemistry, Riga Technical University, P. Valdena Str. 3, Riga, LV-1007, Latvia
| | - Maria Kolympadi Markovic
- Department of Physics, and Center for Micro- and Nanosciences and Technologies, University of Rijeka, Radmile Matejcic 2, 51000 Rijeka, Croatia
| | - Gabriela Ambrožić
- Department of Physics, and Center for Micro- and Nanosciences and Technologies, University of Rijeka, Radmile Matejcic 2, 51000 Rijeka, Croatia
| | - Dean Marković
- Department of Biotechnology, University of Rijeka, Radmile Matejcic 2, 51000 Rijeka, Croatia
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4
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Poshala S, Thunga S, Golla S, Satheesh V, Kokatla HP. A Facile One‐Pot Synthesis of 2,2,2‐Trichloroacetates Through Acid‐Catalyzed Deimination and Its Applications. ChemistrySelect 2019. [DOI: 10.1002/slct.201902189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Soumya Poshala
- Department of Chemistry, National Institute of Technology Warangal Telangana 506004 India
| | - Sanjeeva Thunga
- Department of Chemistry, National Institute of Technology Warangal Telangana 506004 India
| | - Sivaparwathi Golla
- Department of Chemistry, National Institute of Technology Warangal Telangana 506004 India
| | - Vanaparthi Satheesh
- Department of Chemistry, National Institute of Technology Warangal Telangana 506004 India
| | - Hari Prasad Kokatla
- Department of Chemistry, National Institute of Technology Warangal Telangana 506004 India
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5
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Veldmann KH, Dachwitz S, Risse JM, Lee JH, Sewald N, Wendisch VF. Bromination of L-tryptophan in a Fermentative Process With Corynebacterium glutamicum. Front Bioeng Biotechnol 2019; 7:219. [PMID: 31620432 PMCID: PMC6759940 DOI: 10.3389/fbioe.2019.00219] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2019] [Accepted: 08/27/2019] [Indexed: 01/22/2023] Open
Abstract
Brominated compounds such as 7-bromo-l-tryptophan (7-Br-Trp) occur in Nature. Many synthetic and natural brominated compounds have applications in the agriculture, food, and pharmaceutical industries, for example, the 20S-proteasome inhibitor TMC-95A that may be derived from 7-Br-Trp. Mild halogenation by cross-linked enzyme aggregates containing FAD-dependent halogenase, NADH-dependent flavin reductase, and alcohol dehydrogenase as well as by fermentation with recombinant Corynebacterium glutamicum expressing the genes for the FAD-dependent halogenase RebH and the NADH-dependent flavin reductase RebF from Lechevalieria aerocolonigenes have recently been developed as green alternatives to more hazardous chemical routes. In this study, the fermentative production of 7-Br-Trp was established. The fermentative process employs an l-tryptophan producing C. glutamicum strain expressing rebH and rebF from L. aerocolonigenes for halogenation and is based on glucose, ammonium and sodium bromide. C. glutamicum tolerated high sodium bromide concentrations, but its growth rate was reduced to half-maximal at 0.09 g L−1 7-bromo-l-tryptophan. This may be, at least in part, due to inhibition of anthranilate phosphoribosyltransferase by 7-Br-Trp since anthranilate phosphoribosyltransferase activity in crude extracts was half-maximal at about 0.03 g L−1 7-Br-Trp. Fermentative production of 7-Br-Trp by recombinant C. glutamicum was scaled up to a working volume of 2 L and operated in batch and fed-batch mode. The titers were increased from batch fermentation in CGXII minimal medium with 0.3 g L−1 7-Br-Trp to fed-batch fermentation in HSG complex medium, where up to 1.2 g L−1 7-Br-Trp were obtained. The product isolated from the culture broth was characterized by NMR and LC-MS and shown to be 7-Br-Trp.
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Affiliation(s)
- Kareen H Veldmann
- Genetics of Prokaryotes, Faculty of Biology & Center for Biotechnology (CeBiTec), Bielefeld University, Bielefeld, Germany
| | - Steffen Dachwitz
- Organic and Bioorganic Chemistry, Faculty of Chemistry & Center for Biotechnology (CeBiTec), Bielefeld University, Bielefeld, Germany
| | - Joe Max Risse
- Fermentation Technology, Technical Faculty & Center for Biotechnology (CeBiTec), Bielefeld University, Bielefeld, Germany
| | - Jin-Ho Lee
- Major in Food Science and Biotechnology, School of Food Biotechnology and Nutrition, BB21+, Kyungsung University, Busan, South Korea
| | - Norbert Sewald
- Organic and Bioorganic Chemistry, Faculty of Chemistry & Center for Biotechnology (CeBiTec), Bielefeld University, Bielefeld, Germany
| | - Volker F Wendisch
- Genetics of Prokaryotes, Faculty of Biology & Center for Biotechnology (CeBiTec), Bielefeld University, Bielefeld, Germany
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6
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Denmark SE, Ryabchuk P, Burk MT, Gilbert BB. Toward Catalytic, Enantioselective Chlorolactonization of 1,2-Disubstituted Styrenyl Carboxylic Acids. J Org Chem 2016; 81:10411-10423. [PMID: 27555101 PMCID: PMC5100718 DOI: 10.1021/acs.joc.6b01455] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
An investigation into the use of Lewis base catalysis for the enantioselective chlorolactonization of 1,2-disubstituted alkenoic acids is described. Two mechanistically distinct reaction pathways for catalytic chlorolactonization have been identified. Mechanistic investigation revealed that tertiary amines predominately operate as Brønsted rather than Lewis bases. Two potential modes of activation have been identified that involve donation of electron density of the carboxylate to the C═C bond as well hydrogen bonding to the chlorinating agent. Sulfur- and selenium-based additives operate under Lewis base catalysis; however, due to the instability of the intermediate benzylic chloriranium ion, chlorolactonization suffers from low chemo-, diastereo-, and enantioselectivities. Independent generation of the benzylic chloriranium ion shows that it is in equilibrium with an open cation, which leads to low specificities in the nucleophilic capture of the intermediate.
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Affiliation(s)
- Scott E Denmark
- Department of Chemistry University of Illinois 600 South Mathews Avenue Urbana, Illinois 61801, United States
| | - Pavel Ryabchuk
- Department of Chemistry University of Illinois 600 South Mathews Avenue Urbana, Illinois 61801, United States
| | - Matthew T Burk
- Department of Chemistry University of Illinois 600 South Mathews Avenue Urbana, Illinois 61801, United States
| | - Bradley B Gilbert
- Department of Chemistry University of Illinois 600 South Mathews Avenue Urbana, Illinois 61801, United States
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7
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Cresswell AJ, Eey STC, Denmark SE. Catalytic, Stereoselective Dihalogenation of Alkenes: Challenges and Opportunities. Angew Chem Int Ed Engl 2015; 54:15642-82. [PMID: 26630449 PMCID: PMC5072131 DOI: 10.1002/anie.201507152] [Citation(s) in RCA: 140] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Indexed: 11/09/2022]
Abstract
Although recent years have witnessed significant advances in the development of catalytic, enantioselective halofunctionalizations of alkenes, the related dihalogenation of olefins to afford enantioenriched vicinal dihalide products remains comparatively underdeveloped. However, the growing number of complex natural products bearing halogen atoms at stereogenic centers has underscored this critical gap in the synthetic chemist's arsenal. This Review highlights the selectivity challenges inherent in the design of enantioselective dihalogenation processes, and formulates a mechanism-based classification of alkene dihalogenations, including those that may circumvent the "classical" haliranium (or alkene-dihalogen π-complex) intermediates. A variety of metal and main group halide reagents that have been used for the dichlorination or dibromination of alkenes are discussed, and the proposed mechanisms of these transformations are critically evaluated.
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Affiliation(s)
| | - Stanley T-C Eey
- Organic Chemistry, Institute of Chemical and Engineering Sciences, A*STAR, Singapore 138667 (Singapore)
| | - Scott E Denmark
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (USA) http://www.scs.illinois.edu/denmark.
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8
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Katalytische stereoselektive Dihalogenierung von Alkenen: Herausforderungen und Chancen. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201507152] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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9
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Gopi E, Namboothiri INN. Synthesis of α-tribromomethylamines via Mg-mediated addition of bromoform to imines. Org Biomol Chem 2014; 12:2769-77. [PMID: 24668340 DOI: 10.1039/c4ob00259h] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Mg-mediated addition of bromoform to electron deficient imines such as N-sulfonylimines affords α-tribromomethylated N-sulfonylamines in good to excellent yields. The procedure could be further simplified by transforming the imine precursors, α-sulfonyl-N-tosyl- and Boc-amines, in one pot to the corresponding α-tribromomethyl derivatives. Facile removal of the Boc protecting group in nearly quantitative yield and a silver carbonate mediated monodebromination have also been demonstrated.
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Affiliation(s)
- Elumalai Gopi
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400 076, India.
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10
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Harnessing the potential of halogenated natural product biosynthesis by mangrove-derived actinomycetes. Mar Drugs 2013; 11:3875-90. [PMID: 24129229 PMCID: PMC3826140 DOI: 10.3390/md11103875] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Revised: 09/26/2013] [Accepted: 09/27/2013] [Indexed: 12/30/2022] Open
Abstract
Mangrove-derived actinomycetes are promising sources of bioactive natural products. In this study, using homologous screening of the biosynthetic genes and anti-microorganism/tumor assaying, 163 strains of actinomycetes isolated from mangrove sediments were investigated for their potential to produce halogenated metabolites. The FADH2-dependent halogenase genes, identified in PCR-screening, were clustered in distinct clades in the phylogenetic analysis. The coexistence of either polyketide synthase (PKS) or nonribosomal peptide synthetase (NRPS) as the backbone synthetases in the strains harboring the halogenase indicated that these strains had the potential to produce structurally diversified antibiotics. As a validation, a new enduracidin producer, Streptomyces atrovirens MGR140, was identified and confirmed by gene disruption and HPLC analysis. Moreover, a putative ansamycin biosynthesis gene cluster was detected in Streptomyces albogriseolus MGR072. Our results highlight that combined genome mining is an efficient technique to tap promising sources of halogenated natural products synthesized by mangrove-derived actinomycetes.
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11
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Romanov‐Michailidis F, Guénée L, Alexakis A. Enantioselective Organocatalytic Fluorination‐Induced Wagner–Meerwein Rearrangement. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201303527] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Fedor Romanov‐Michailidis
- Department of Organic Chemistry, University of Geneva, Quai Ernest Ansermet 30, 1211 Geneva 4 (Switzerland)
| | - Laure Guénée
- Laboratory of Crystallography, University of Geneva, Quai Ernest Ansermet 24, 1211 Geneva 4 (Switzerland)
| | - Alexandre Alexakis
- Department of Organic Chemistry, University of Geneva, Quai Ernest Ansermet 30, 1211 Geneva 4 (Switzerland)
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12
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Wang BG, Gloer JB, Ji NY, Zhao JC. Halogenated Organic Molecules of Rhodomelaceae Origin: Chemistry and Biology. Chem Rev 2013; 113:3632-85. [DOI: 10.1021/cr9002215] [Citation(s) in RCA: 168] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Bin-Gui Wang
- Key Laboratory of Experimental
Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, P. R. China
| | - James B. Gloer
- Department of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
| | - Nai-Yun Ji
- Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences,
Yantai 264003, P. R. China
| | - Jian-Chun Zhao
- Key Laboratory of Experimental
Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, P. R. China
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13
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Nilewski C, Carreira EM. Recent Advances in the Total Synthesis of Chlorosulfolipids. European J Org Chem 2012. [DOI: 10.1002/ejoc.201101525] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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14
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Iyer LM, Abhiman S, de Souza RF, Aravind L. Origin and evolution of peptide-modifying dioxygenases and identification of the wybutosine hydroxylase/hydroperoxidase. Nucleic Acids Res 2010; 38:5261-79. [PMID: 20423905 PMCID: PMC2938197 DOI: 10.1093/nar/gkq265] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Unlike classical 2-oxoglutarate and iron-dependent dioxygenases, which include several nucleic acid modifiers, the structurally similar jumonji-related dioxygenase superfamily was only known to catalyze peptide modifications. Using comparative genomics methods, we predict that a family of jumonji-related enzymes catalyzes wybutosine hydroxylation/peroxidation at position 37 of eukaryotic tRNAPhe. Identification of this enzyme raised questions regarding the emergence of protein- and nucleic acid-modifying activities among jumonji-related domains. We addressed these with a natural classification of DSBH domains and reconstructed the precursor of the dioxygenases as a sugar-binding domain. This precursor gave rise to sugar epimerases and metal-binding sugar isomerases. The sugar isomerase active site was exapted for catalysis of oxygenation, with a radiation of these enzymes in bacteria, probably due to impetus from the primary oxygenation event in Earth’s history. 2-Oxoglutarate-dependent versions appear to have further expanded with rise of the tricarboxylic acid cycle. We identify previously under-appreciated aspects of their active site and multiple independent innovations of 2-oxoacid-binding basic residues among these superfamilies. We show that double-stranded β-helix dioxygenases diversified extensively in biosynthesis and modification of halogenated siderophores, antibiotics, peptide secondary metabolites and glycine-rich collagen-like proteins in bacteria. Jumonji-related domains diversified into three distinct lineages in bacterial secondary metabolism systems and these were precursors of the three major clades of eukaryotic enzymes. The specificity of wybutosine hydroxylase/peroxidase probably relates to the structural similarity of the modified moiety to the ancestral amino acid substrate of this superfamily.
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Affiliation(s)
- Lakshminarayan M Iyer
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA
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15
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Ferraroni M, Kolomytseva MP, Solyanikova IP, Scozzafava A, Golovleva LA, Briganti F. Crystal structure of 3-chlorocatechol 1,2-dioxygenase key enzyme of a new modified ortho-pathway from the Gram-positive Rhodococcus opacus 1CP grown on 2-chlorophenol. J Mol Biol 2006; 360:788-99. [PMID: 16793061 DOI: 10.1016/j.jmb.2006.05.046] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2006] [Revised: 05/15/2006] [Accepted: 05/18/2006] [Indexed: 11/18/2022]
Abstract
The crystal structure of the 3-chlorocatechol 1,2-dioxygenase from the Gram-positive bacterium Rhodococcus opacus (erythropolis) 1CP, a Fe(III) ion-containing enzyme specialized in the aerobic biodegradation of 3-chloro- and methyl-substituted catechols, has been solved by molecular replacement techniques using the coordinates of 4-chlorocatechol 1,2-dioxygenase from the same organism (PDB code 1S9A) as a starting model and refined at 1.9 A resolution (R(free) 21.9%; R-factor 17.4%). The analysis of the structure and of the kinetic parameters for a series of different substrates, and the comparison with the corresponding data for the 4-chlorocatechol 1,2-dioxygenase isolated from the same bacterial strain, provides evidence of which active site residues are responsible for the observed differences in substrate specificity. Among the amino acid residues expected to interact with substrates, only three are altered Val53(Ala53), Tyr78(Phe78) and Ala221(Cys224) (3-chlorocatechol 1,2-dioxygenase(4-chlorocatechol 1,2-dioxygenase)), clearly identifying the substitutions influencing substrate selectivity in these enzymes. The crystallographic asymmetric unit contains eight subunits (corresponding to four dimers) that show heterogeneity in the conformation of a co-crystallized molecule bound to the catalytic non-heme iron(III) ion resembling a benzohydroxamate moiety, probably a result of the breakdown of recently discovered siderophores synthesized by Gram-positive bacteria. Several different modes of binding benzohydroxamate into the active site induce distinct conformations of the interacting protein ligands Tyr167 and Arg188, illustrating the plasticity of the active site origin of the more promiscuous substrate preferences of the present enzyme.
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Affiliation(s)
- Marta Ferraroni
- Dipartimento di Chimica, Università di Firenze, Via della Lastruccia 3, I-50019 Sesto Fiorentino (FI), Italy
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16
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Cantón RF, Sanderson JT, Letcher RJ, Bergman A, van den Berg M. Inhibition and induction of aromatase (CYP19) activity by brominated flame retardants in H295R human adrenocortical carcinoma cells. Toxicol Sci 2005; 88:447-55. [PMID: 16177243 DOI: 10.1093/toxsci/kfi325] [Citation(s) in RCA: 121] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Brominated flame retardants (BFRs) are persistent and ubiquitous chemicals in the environment, and they are found at increasing levels in tissues of wildlife and humans. Previous in vitro studies with the BFR class of polybrominated diphenyl ethers (BDEs) have shown endocrine-disrupting properties. Our study assessed the potential effects of nineteen BDEs, five hydroxylated BDEs (OH-BDEs), one methoxylated BDE (CH(3)O-BDE), tetrabromobisphenol-A (TBBPA), its dibromopropane ether derivative (TBBPA-DBPE), and the brominated phenols/anisols 2,4,6-tribromophenol (TBP), 4-bromophenol (4BP) and 2,4,6-tribromoanisole (TBA) on the catalytic activity of the steroidogenic enzyme aromatase (CYP19) in H295R human adrenocortical carcinoma cells. Effects were studied in the concentration range from 0.5 to 7.5 microM; exposures were for 24 h. Both 6-OH-BDE47 and 6-OH-BDE99 showed an inhibitory effect on aromatase activity at concentrations >2.5 microM and >5 microM, respectively. However, 6-OH-BDE47 also caused a statistically significant increase in cytotoxicity (based on mitochondrial MTT reduction and lactate dehydrogenase-leakage [LDH]) at concentrations >2.5 microM that could explain in part the apparent inhibitory effect on aromatase activity. Compared to 6-OH-BDE47, the methoxy analog (6-CH(3)O-BDE47) did not elicit a cytotoxic effect, whereas significant inhibition of aromatase remained. TBP caused a concentration-dependent induction of aromatase activity between 0.5 and 7.5 microM (with a maximum of 3.8-fold induction at 7.5 microM). This induction was not observed when a OH- group replaced the CH(3)O- group or when bromine atoms adjacent to this OH- group were absent. These in vitro results provide a basis for studies of more detailed structure-activity relationships between these brominated compounds and the modulation of aromatase activity.
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Affiliation(s)
- Rocío F Cantón
- Institute for Risk Assessment Sciences, IRAS Utrecht University, The Netherlands.
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18
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Abstract
A large number of halogenated compounds is produced by chemical synthesis. Some of these compounds are very toxic and cause enormous problems to human health and to the environment. Investigations on the degradation of halocompounds by microorganisms have led to the detection of various dehalogenating enzymes catalyzing the removal of halogen atoms under aerobic and anaerobic conditions involving different mechanisms. On the other hand, more than 3500 halocompounds are known to be produced biologically, some of them in great amounts. Until 1997, only haloperoxidases were thought to be responsible for incorporation of halogen atoms into organic compounds. However, recent investigations into the biosynthesis of halogenated metabolites by bacteria have shown that a novel type of halogenating enzymes, FADH(2)-dependent halogenases, are involved in biosyntheses of halogenated metabolites. In every gene cluster coding for the biosynthesis of a halogenated metabolite, isolated so far, one or several genes for FADH(2)-dependent halogenases have been identified.
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Zhuang W, McKague B, Reeve D, Carey J. Identification and confirmation of traces of chlorinated fatty acids in fish downstream of bleached kraft pulp mills by gas chromatography with halogen-specific detection. J Chromatogr A 2003; 994:137-57. [PMID: 12779225 DOI: 10.1016/s0021-9673(03)00482-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Methyl esters of threo-9,10-dichlorooctadecanoic, threo-7,8-dichlorohexadecanoic, and threo-5,6-dichlorotetradecanoic acids, present in transesterified extracts of filets, gonad, intestinal fat and carcass of white sucker (Catostomus commersoni) sampled in receiving waters of bleached kraft pulp mill effluents, were identified by gas chromatography with halogen-specific detection (XSD). Identification was based on (1) a comparison of the retention times of a sample peak with a prospective reference standard on two stationary phases of very different polarities by spiking, and (2) elution behavior of configurational and positional isomers of dichloro fatty acid methyl esters.
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Affiliation(s)
- Wenshan Zhuang
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario M5S 3E5, Canada.
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Chloromethane production by wood-rotting fungi and an estimate of the global flux to the atmosphere. ACTA ACUST UNITED AC 1998. [DOI: 10.1017/s0953756298006157] [Citation(s) in RCA: 101] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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