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Li X, Lv JM, Hu D, Abe I. Biosynthesis of alkyne-containing natural products. RSC Chem Biol 2021; 2:166-180. [PMID: 34458779 PMCID: PMC8341276 DOI: 10.1039/d0cb00190b] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Accepted: 11/30/2020] [Indexed: 11/23/2022] Open
Abstract
Alkyne-containing natural products are important molecules that are widely distributed in microbes and plants. Inspired by the advantages of acetylenic products used in the fields of medicinal chemistry, organic synthesis and material science, great efforts have focused on discovering the biosynthetic enzymes and pathways for alkyne formation. Here, we summarize the biosyntheses of alkyne-containing natural products and introduce de novo biosynthetic strategies for alkyne-tagged compound production.
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Affiliation(s)
- Xinyang Li
- Graduate School of Pharmaceutical Sciences, The University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo 113-0033 Japan
| | - Jian-Ming Lv
- Institute of Traditional Chinese Medicine and Natural Products, College of Pharmacy, Jinan University Guangzhou 510632 People's Republic of China
| | - Dan Hu
- Institute of Traditional Chinese Medicine and Natural Products, College of Pharmacy, Jinan University Guangzhou 510632 People's Republic of China
| | - Ikuro Abe
- Graduate School of Pharmaceutical Sciences, The University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo 113-0033 Japan
- Collaborative Research Institute for Innovative Microbiology, The University of Tokyo Yayoi 1-1-1 Bunkyo-ku Tokyo 113-8657 Japan
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2
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TRPA1 Modulating C 14 Polyacetylenes from the Iranian Endemic Plant Echinophora platyloba. Molecules 2018; 23:molecules23071750. [PMID: 30018233 PMCID: PMC6099690 DOI: 10.3390/molecules23071750] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 07/13/2018] [Accepted: 07/15/2018] [Indexed: 11/17/2022] Open
Abstract
Phytochemical investigation of the apolar extract obtained from aerial parts of the Iranian endemic plant Echinophora platyloba DC (Apiaceae) resulted in the characterization of the polyacetylene fraction of this plant. This resulted to be composed of the known echinophorins A and B, embedding the very rare α-pyrone terminal, and of the new echinophorin D (3), including also three conjugated triple bonds. The chemical structures of these compounds were secured by detailed inspection of MS and 1D/2D NMR spectra. The isolated polyacteylenes were evaluated for their modulation of six thermo-TRP channels and they revealed a selective activity on TRPA1, an ion channel involved in the mediation of neuropathic and inflammatory pain. This is the first report on the activity of plant polyacetylenes on transient receptor potential (TRP) channels.
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3
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Butler MJ, White AJP, Crimmin MR. Heterobimetallic Rebound: A Mechanism for Diene-to-Alkyne Isomerization with M---Zr Hydride Complexes (M = Al, Zn, and Mg). Organometallics 2018. [DOI: 10.1021/acs.organomet.7b00908] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- M. J. Butler
- Department of Chemistry, Imperial College London, South Kensington, London SW7 2AZ, United Kingdom
| | - A. J. P. White
- Department of Chemistry, Imperial College London, South Kensington, London SW7 2AZ, United Kingdom
| | - M. R. Crimmin
- Department of Chemistry, Imperial College London, South Kensington, London SW7 2AZ, United Kingdom
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4
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Sun JY, Guo X, Smith MA. Identification of Crepenynic Acid in the Seed Oil of Atractylodes lancea and A. macrocephala. J AM OIL CHEM SOC 2017. [DOI: 10.1007/s11746-017-2974-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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5
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Butler MJ, White AJP, Crimmin MR. Isomerization of Cyclooctadiene to Cyclooctyne with a Zinc/Zirconium Heterobimetallic Complex. Angew Chem Int Ed Engl 2016; 55:6951-3. [PMID: 27071992 PMCID: PMC5074263 DOI: 10.1002/anie.201601758] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Indexed: 11/23/2022]
Abstract
Reaction of a zinc/zirconium heterobimetallic complex with 1,5-cyclooctadiene (1,5-COD) results in slow isomerization to 1,3-cyclooctadiene (1,3-COD), along with the formation of a new complex that includes a cyclooctyne ligand bridging two metal centers. While analogous magnesium/zirconium and aluminum/zirconium heterobimetallic complexes are competent for the catalytic isomerization of 1,5-COD to 1,3-COD, only in the case of the zinc species is the cyclooctyne adduct observed.
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Affiliation(s)
- Michael J Butler
- Department of Chemistry, Imperial College London, South Kensington, London, SW7 2AZ, UK
| | - Andrew J P White
- Department of Chemistry, Imperial College London, South Kensington, London, SW7 2AZ, UK
| | - Mark R Crimmin
- Department of Chemistry, Imperial College London, South Kensington, London, SW7 2AZ, UK.
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6
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Butler MJ, White AJP, Crimmin MR. Isomerization of Cyclooctadiene to Cyclooctyne with a Zinc/Zirconium Heterobimetallic Complex. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201601758] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Michael J. Butler
- Department of Chemistry; Imperial College London; South Kensington London SW7 2AZ UK
| | - Andrew J. P. White
- Department of Chemistry; Imperial College London; South Kensington London SW7 2AZ UK
| | - Mark R. Crimmin
- Department of Chemistry; Imperial College London; South Kensington London SW7 2AZ UK
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7
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Gervasio G, Sappa E, Secco A. Advances in the chemistry of alkyne-substituted homo- and heterometallic carbonyl clusters of the iron, cobalt and nickel triads. An update. J Organomet Chem 2014. [DOI: 10.1016/j.jorganchem.2013.08.046] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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8
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Zhao JQ, Lv JJ, Wang YM, Xu M, Zhu HT, Wang D, Yang CR, Wang YF, Zhang YJ. Phyllanflexoid C: first example of phenylacetylene-bearing 18-nor-diterpenoid glycoside from the roots of Phyllanthus flexuosus. Tetrahedron Lett 2013. [DOI: 10.1016/j.tetlet.2013.06.082] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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9
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Haritos VS, Horne I, Damcevski K, Glover K, Gibb N, Okada S, Hamberg M. The convergent evolution of defensive polyacetylenic fatty acid biosynthesis genes in soldier beetles. Nat Commun 2013; 3:1150. [PMID: 23093187 DOI: 10.1038/ncomms2147] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Accepted: 09/20/2012] [Indexed: 11/09/2022] Open
Abstract
The defensive and bioactive polyacetylenic fatty acid, 8Z-dihydromatricaria acid, is sequestered within a wide range of organisms, including plants, fungi and soldier beetles. The 8Z-dihydromatricaria acid is concentrated in the defence and accessory glands of soldier beetles to repel avian predators and protect eggs. In eukaryotes, acetylenic modifications of fatty acids are catalysed by acetylenases, which are desaturase-like enzymes that act on existing double bonds. Here we obtained acyl Coenzyme A-linked desaturases from soldier beetle RNA and functionally expressed them in yeast. We show that three genes were sufficient for the conversion of a common monounsaturated fatty acid, oleic acid, to the 18 carbon precursor of 8Z-dihydromatricaria acid, that is, 9Z,16Z-octadecadiene-12,14-diynoic acid. These are the first eukaryotic genes reported to produce conjugated polyacetylenic fatty acids. Phylogenetic analysis shows that the genes responsible for 8Z-dihydromatricaria acid synthesis in soldier beetles evolved de novo and independently of the acetylenases of plants and fungi.
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Affiliation(s)
- Victoria S Haritos
- CSIRO Ecosystem Sciences, GPO Box 1700, Canberra, Australian Capital Territory 2601, Australia.
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10
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Palko JW, Buist PH, Manthorpe JM. A flexible and modular stereoselective synthesis of (9R,10S)-dihydrosterculic acid. ACTA ACUST UNITED AC 2013. [DOI: 10.1016/j.tetasy.2013.01.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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11
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Bhar P, Reed DW, Covello PS, Buist PH. Topological Study of Mechanistic Diversity in Conjugated Fatty Acid Biosynthesis. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201202080] [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]
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12
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Bhar P, Reed DW, Covello PS, Buist PH. Topological study of mechanistic diversity in conjugated fatty acid biosynthesis. Angew Chem Int Ed Engl 2012; 51:6686-90. [PMID: 22623346 DOI: 10.1002/anie.201202080] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2012] [Indexed: 11/11/2022]
Affiliation(s)
- Palash Bhar
- Department of Chemistry, Carleton University, 1125 Colonel By Drive, Ottawa, ON K1S 5B6, Canada
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13
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Applications of stereospecifically-labeled Fatty acids in oxygenase and desaturase biochemistry. Lipids 2011; 47:101-16. [PMID: 21971646 DOI: 10.1007/s11745-011-3612-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Accepted: 08/30/2011] [Indexed: 10/17/2022]
Abstract
Oxygenation and desaturation reactions are inherently associated with the abstraction of a hydrogen from the fatty acid substrate. Since the first published application in 1965, stereospecific placement of a labeled hydrogen isotope (deuterium or tritium) at the reacting carbons has proven a highly effective strategy for investigating the chemical mechanisms catalyzed by lipoxygenases, hemoprotein fatty acid dioxygenases including cyclooxygenases, cytochromes P450, and also the desaturases and isomerases. This review presents a synopsis of all published studies through 2010 on the synthesis and use of stereospecifically labeled fatty acids (71 references), and highlights some of the mechanistic insights gained by application of stereospecifically labeled fatty acids.
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14
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Blacklock BJ, Scheffler BE, Shepard MR, Jayasuriya N, Minto RE. Functional diversity in fungal fatty acid synthesis: the first acetylenase from the Pacific golden chanterelle, Cantharellus formosus. J Biol Chem 2010; 285:28442-9. [PMID: 20606235 PMCID: PMC2937869 DOI: 10.1074/jbc.m110.151498] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2010] [Revised: 07/03/2010] [Indexed: 01/12/2023] Open
Abstract
Acetylenic specialized metabolites containing one or more carbon-carbon triple bonds are widespread, being found in fungi, vascular and lower plants, marine sponges and algae, and insects. Plants, moss, and most recently, insects, have been shown to employ an energetically difficult, sequential dehydrogenation mechanism for acetylenic bond formation. Here, we describe the cloning and heterologous expression in yeast of a linoleoyl 12-desaturase (acetylenase) and a bifunctional desaturase with Delta(12)-/Delta(14)-regiospecificity from the Pacific golden chanterelle. The acetylenase gene, which is the first identified from a fungus, is phylogenetically distinct from known plant and fungal desaturases. Together, the bifunctional desaturase and the acetylenase provide the enzymatic activities required to drive oleate through linoleate to crepenynate and the conjugated enyne (14Z)-dehydrocrepenynate, the branchpoint precursors to a major class of acetylenic natural products.
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Affiliation(s)
- Brenda J. Blacklock
- From the
Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana 46202 and
| | - Brian E. Scheffler
- the
Genomics and Bioinformatics Research Unit, Jamie Whitten Delta States Research Center, Stoneville, Mississippi 38776
| | - Michael R. Shepard
- From the
Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana 46202 and
| | - Naomi Jayasuriya
- From the
Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana 46202 and
| | - Robert E. Minto
- From the
Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana 46202 and
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15
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Gagné SJ, Reed DW, Gray GR, Covello PS. Structural control of chemoselectivity, stereoselectivity, and substrate specificity in membrane-bound fatty acid acetylenases and desaturases. Biochemistry 2010; 48:12298-304. [PMID: 19950909 DOI: 10.1021/bi901605d] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The FAD2-like desaturases comprise a group of membrane-bound oxygenases involved in the modification of fatty acyl groups in plants and fungi. This group includes typical oleate desaturases which introduce a Delta12 cis double bond and more unusual enzymes such as Crep1, an acetylenase from the plant Crepis alpina, which introduces a triple bond in linoleate at the Delta12 position. In this study, the structure-function relationship between FAD2-like acetylenases and desaturases was examined through site-directed mutagenesis and heterologous expression. Eleven amino acid positions were identified that show complete evolutionary conservation within acetylenases or desaturases but have different amino acids in the other class of enzyme. Point mutants in Crep1 were constructed and expressed in yeast to test the role in fatty acid modification of the amino acids at the 11 positions. Results indicate the importance of five amino acid positions within Crep1 with regard to desaturase and acetylenase chemoselectivity, stereoselectivity, and substrate recognition. For example, relative to wild-type Crep1, the Y150F, F259L, and H266Q mutations all favored desaturation over acetylenation. The data indicate that small changes in primary sequence, particularly in the vicinity of the active site, can have profound changes on chemoselectivity and other aspects of the function of membrane-bound desaturase-like enzymes.
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Affiliation(s)
- Steve J Gagné
- Plant Biotechnology Institute, National Research Council of Canada, 110 Gymnasium Place, Saskatoon SK S7N 0W9, Canada
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16
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Liang ZX. Complexity and simplicity in the biosynthesis of enediyne natural products. Nat Prod Rep 2010; 27:499-528. [DOI: 10.1039/b908165h] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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17
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Minto RE, Blacklock BJ. Biosynthesis and function of polyacetylenes and allied natural products. Prog Lipid Res 2008; 47:233-306. [PMID: 18387369 PMCID: PMC2515280 DOI: 10.1016/j.plipres.2008.02.002] [Citation(s) in RCA: 242] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2007] [Revised: 02/25/2008] [Accepted: 02/28/2008] [Indexed: 11/19/2022]
Abstract
Polyacetylenic natural products are a substantial class of often unstable compounds containing a unique carbon-carbon triple bond functionality, that are intriguing for their wide variety of biochemical and ecological functions, economic potential, and surprising mode of biosynthesis. Isotopic tracer experiments between 1960 and 1990 demonstrated that the majority of these compounds are derived from fatty acid and polyketide precursors. During the past decade, research into the metabolism of polyacetylenes has swiftly advanced, driven by the cloning of the first genes responsible for polyacetylene biosynthesis in plants, moss, fungi, and actinomycetes and the initial characterization of the gene products. The current state of knowledge of the biochemistry and molecular genetics of polyacetylenic secondary metabolic pathways will be presented together with an up-to-date survey of new terrestrial and marine natural products, their known biological activities, and a discussion of their likely metabolic origins.
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Affiliation(s)
- Robert E Minto
- Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis, 402 North Blackford Street, Indianapolis, IN 46202, United States.
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18
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Serra M, Piña B, Abad JL, Camps F, Fabriàs G. A multifunctional desaturase involved in the biosynthesis of the processionary moth sex pheromone. Proc Natl Acad Sci U S A 2007; 104:16444-9. [PMID: 17921252 PMCID: PMC2034215 DOI: 10.1073/pnas.0705385104] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2007] [Indexed: 11/18/2022] Open
Abstract
The sex pheromone of the female processionary moth, Thaumetopoea pityocampa, is a unique C16 enyne acetate that is biosynthesized from palmitic acid. Three consecutive desaturation reactions transform this saturated precursor into the triunsaturated fatty acyl intermediate: formation of (Z)-11-hexadecenoic acid, acetylenation to 11-hexadecynoic acid, and final Delta(13) desaturation to (Z)-13-hexadecen-11-ynoic acid. By using degenerate primers common to all reported insect desaturases, a single cDNA sequence was isolated from total RNA of T. pityocampa female pheromone glands. The full-length transcript of this putative desaturase was expressed in elo1Delta/ole1Delta yeast mutants (both elongase 1 and Delta(9) desaturase-deficient) for functional assays. The construct fully rescued the Deltaole1 yeast phenotype, confirming its desaturase activity. Analysis of the unsaturated products from transformed yeast extracts demonstrated that the cloned enzyme showed Delta(11) desaturase, Delta(11) acetylenase, and Delta(13) desaturase activities. Therefore, this single desaturase may account for the three desaturation steps involved in the sex pheromone biosynthetic pathway of the processionary moth.
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Affiliation(s)
- Montserrat Serra
- *Research Unit on BioActive Molecules (RUBAM), Departament de Química Orgànica Biològica, Institut d'Investigacions Químiques i Ambientals de Barcelona, and
| | - Benjamin Piña
- Departament de Biologia Molecular i Cellular, Institut de Biologia Molecular i Cellular de Barcelona, Consejo Superior de Investigaciones Científicas (CSIC), Jordi Girona 18, 08034 Barcelona, Spain
| | - José Luis Abad
- *Research Unit on BioActive Molecules (RUBAM), Departament de Química Orgànica Biològica, Institut d'Investigacions Químiques i Ambientals de Barcelona, and
| | - Francisco Camps
- *Research Unit on BioActive Molecules (RUBAM), Departament de Química Orgànica Biològica, Institut d'Investigacions Químiques i Ambientals de Barcelona, and
| | - Gemma Fabriàs
- *Research Unit on BioActive Molecules (RUBAM), Departament de Química Orgànica Biològica, Institut d'Investigacions Químiques i Ambientals de Barcelona, and
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19
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Abstract
Many biotransformations of mid- to long chain fatty acyl derivatives are intrinsically interesting because of their high selectivity and novel mechanisms. These include one carbon transfer, hydration, isomerization, hydrogenation, ladderane and hydrocarbon formation, thiolation and various oxidative transformations such as epoxidation, hydroxylation and desaturation. In addition, hydroperoxidation of polyunsaturated fatty acids leads to a diverse array of bioactive compounds. The bioorganic aspects of selected reactions will be highlighted in this review; 210 references are cited.
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Affiliation(s)
- Peter H Buist
- Department of Chemistry, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario, Canada K1S 5B6
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21
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Carlsson AS, Thomaeus S, Hamberg M, Stymne S. Properties of two multifunctional plant fatty acid acetylenase/desaturase enzymes. ACTA ACUST UNITED AC 2004; 271:2991-7. [PMID: 15233795 DOI: 10.1111/j.1432-1033.2004.04231.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The properties of the Delta6 desaturase/acetylenase from the moss Ceratodon purpureus and the Delta12 acetylenase from the dicot Crepis alpina were studied by expressing the encoding genes in Arabidopsis thaliana and Saccharomyces cerevisiae. The acetylenase from C. alpinaDelta12 desaturated both oleate and linoleate with about equal efficiency. The desaturation of oleate gave rise to 9(Z),12(E)- and 9(Z),12(Z)-octadecadienoates in a ratio of approximately 3 : 1. Experiments using stereospecifically deuterated oleates showed that the pro-R hydrogen atoms were removed from C-12 and C-13 in the introduction of the 12(Z) double bond, whereas the pro-R and pro-S hydrogen atoms were removed from these carbons during the formation of the 12(E) double bond. The results suggested that the Delta12 acetylenase could accommodate oleate having either a cisoid or transoid conformation of the C(12)-C(13) single bond, and that these conformers served as precursors of the 12(Z) and 12(E) double bonds, respectively. However, only the 9(Z),12(Z)-octadecadienoate isomer could be further desaturated to 9(Z)-octadecen-12-ynoate (crepenynate) by the enzyme. The evolutionarily closely related Delta12 epoxygenase from Crepis palaestina had only weak desaturase activity but could also produce 9(Z),12(E)-octadecadienoate from oleate. The Delta6 acetylenase/desaturase from C. purpureus, on the other hand, produced only the 6(Z) isomers using C16 and C18 acyl groups possessing a Delta9 double bond as substrates. The Delta6 double bond was efficiently further converted to an acetylenic bond by a second round of desaturation but only if the acyl substrate had a Delta12 double bond and that this was in the Z configuration.
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Affiliation(s)
- Anders S Carlsson
- Department of Crop Science, Swedish University of Agricultural Sciences, Alnarp, Sweden.
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22
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Sasata RJ, Reed DW, Loewen MC, Covello PS. Domain swapping localizes the structural determinants of regioselectivity in membrane-bound fatty acid desaturases of Caenorhabditis elegans. J Biol Chem 2004; 279:39296-302. [PMID: 15226312 DOI: 10.1074/jbc.m405712200] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Most fatty acid desaturases are members of a large superfamily of integral membrane, O(2)-dependent, iron-containing enzymes that catalyze a variety of oxidative modifications to lipids. Sharing a similar primary structure and membrane topology, these enzymes are broadly categorized according to their positional specificity or regioselectivity, which designates the preferred position for substrate modification. To investigate the structural basis of regioselectivity in membrane-bound desaturases, the Caenorhabditis elegans omega-3 (FAT-1) and "Delta12" (FAT-2) desaturases were used as a model system. With the use of unnatural substrates, the regioselectivity of C. elegans FAT-2 was clearly defined as nu+3, i.e. it "measures" three carbons from an existing double bond. The structural basis for nu+3 and omega-3 regioselectivities was examined through construction and expression of chimeric DNA sequences based on FAT-1 and FAT-2. Each sequence was divided into seven domains, and chimeras were constructed in which specific domains were replaced with sequence from the other desaturase. When tested by expression in yeast using exogenously supplied substrates, chimeric sequences were found in which domain swapping resulted in a change of regioselectivity from nu+3 to omega-3 and vice versa. In this way, the structural determinants of regioselectivity in FAT-1 and FAT-2 have been localized to two interdependent regions: a relatively hydrophobic region between the first two histidine boxes and the carboxyl-terminal region.
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Affiliation(s)
- Robert J Sasata
- Plant Biotechnology Institute, Saskatoon, Saskatchewan S7N OW9, Canada
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