1
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Harms V, Kirschning A, Dickschat JS. Nature-driven approaches to non-natural terpene analogues. Nat Prod Rep 2020; 37:1080-1097. [DOI: 10.1039/c9np00055k] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The reactions catalysed by terpene synthases belong to the most complex and fascinating cascade-type transformations in Nature.
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Affiliation(s)
- Vanessa Harms
- Institute of Organic Chemistry and Center of Biomolecular Drug Research (BMWZ)
- Leibniz Universität Hannover
- 30167 Hannover
- Germany
| | - Andreas Kirschning
- Institute of Organic Chemistry and Center of Biomolecular Drug Research (BMWZ)
- Leibniz Universität Hannover
- 30167 Hannover
- Germany
| | - Jeroen S. Dickschat
- Kekulé-Institute of Organic Chemistry and Biochemistry
- University of Bonn
- 53121 Bonn
- Germany
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2
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Fukuda Y, Watanabe T, Hoshino T. Mutated variants of squalene-hopene cyclase: enzymatic syntheses of triterpenes bearing oxygen-bridged monocycles and a new 6,6,6,6,6-fusded pentacyclic scaffold, named neogammacerane, from 2,3-oxidosqualene. Org Biomol Chem 2019; 16:8365-8378. [PMID: 30209480 DOI: 10.1039/c8ob02009d] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Squalene-hopene cyclase (SHC) catalyzes the conversion of acyclic squalene molecule into a 6,6,6,6,5-fused pentacyclic hopene and hopanol. SHC is also able to convert (3S)-2,3-oxidosqualene into 3β-hydroxyhopene and 3β-hydroxyhopanol and can generate 3α-hydroxyhopene and 3α-hydroxyhopanol from (3R)-2,3-oxidosqualene. Functional analyses of active site residues toward the squalene cyclization reaction have been extensively reported, but investigations of the cyclization reactions of (3R,S)-oxidosqualene by SHC have rarely been reported. The cyclization reactions of oxidosqualene with W169X, G600F/F601G and F601G/P602F were examined. The variants of the W169L generated new triterpene skeletons possessing a 7-oxabicyclo[2.2.1]heptane moiety (oxygen-bridged monocycle) with (1S,2S,4R)- and (1R,2S,4S)-stereochemistry, which were produced from (3R)- and (3S)-oxidosqualenes, respectively. The F601G/P602F double mutant also furnished a novel triterpene, named neogammacer-21(22)-en-3β-ol, consisting of a 6,6,6,6,6-fused pentacyclic system, in which Me-29 at C-22 of the gammacerane skeleton migrated to C-21. We propose to name this novel scaffold neogammacerane. The formation mechanisms of the enzymatic products from 2,3-oxidosqualene are discussed.
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Affiliation(s)
- Yoriyuki Fukuda
- Graduate School of Science and Technology and Department of Applied Biological Chemistry, Faculty of Agriculture, Niigata University, Ikarashi 2-8050, Nishi-ku, Niigata 950-2181, Japan.
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3
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Nakano C, Watanabe T, Minamino M, Hoshino T. Enzymatic syntheses of novel carbocyclic scaffolds with a 6,5 + 5,5 ring system by squalene-hopene cyclase. Org Biomol Chem 2019; 17:9375-9389. [DOI: 10.1039/c9ob01941c] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A novel scaffold with a 6,5 + 5, 5 ring system (allodammarane) was synthesized from 27-norsqualene (13a), 3R-(18) and 3S-27-noroxidosqualenes (19).
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Affiliation(s)
- Chiaki Nakano
- Department of Applied Biological Chemistry
- Faculty of Agriculture
- and Graduate School of Science and Technology
- Niigata University
- Niigata
| | - Takumi Watanabe
- Department of Applied Biological Chemistry
- Faculty of Agriculture
- and Graduate School of Science and Technology
- Niigata University
- Niigata
| | - Mai Minamino
- Department of Applied Biological Chemistry
- Faculty of Agriculture
- and Graduate School of Science and Technology
- Niigata University
- Niigata
| | - Tsutomu Hoshino
- Department of Applied Biological Chemistry
- Faculty of Agriculture
- and Graduate School of Science and Technology
- Niigata University
- Niigata
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4
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Ideno N, Umeyama S, Watanabe T, Nakajima M, Sato T, Hoshino T. Alicyclobacillus acidocaldarius
Squalene‐Hopene Cyclase: The Critical Role of Steric Bulk at Ala306 and the First Enzymatic Synthesis of Epoxydammarane from 2,3‐Oxidosqualene. Chembiochem 2018; 19:1873-1886. [DOI: 10.1002/cbic.201800281] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Indexed: 11/12/2022]
Affiliation(s)
- Natsumi Ideno
- Graduate School of Science and Technology andDepartment of Applied Biological ChemistryFaculty of AgricultureNiigata University Ikarashi 2–8050, Nishi-ku Niigata 950–2181 Japan
| | - Shikou Umeyama
- Graduate School of Science and Technology andDepartment of Applied Biological ChemistryFaculty of AgricultureNiigata University Ikarashi 2–8050, Nishi-ku Niigata 950–2181 Japan
| | - Takashi Watanabe
- Graduate School of Science and Technology andDepartment of Applied Biological ChemistryFaculty of AgricultureNiigata University Ikarashi 2–8050, Nishi-ku Niigata 950–2181 Japan
| | - Mami Nakajima
- Graduate School of Science and Technology andDepartment of Applied Biological ChemistryFaculty of AgricultureNiigata University Ikarashi 2–8050, Nishi-ku Niigata 950–2181 Japan
| | - Tsutomu Sato
- Graduate School of Science and Technology andDepartment of Applied Biological ChemistryFaculty of AgricultureNiigata University Ikarashi 2–8050, Nishi-ku Niigata 950–2181 Japan
| | - Tsutomu Hoshino
- Graduate School of Science and Technology andDepartment of Applied Biological ChemistryFaculty of AgricultureNiigata University Ikarashi 2–8050, Nishi-ku Niigata 950–2181 Japan
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5
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Kaneko I, Terasawa Y, Hoshino T. Squalene-Hopene Cyclase: Mechanistic Insights into the Polycyclization Cascades of Squalene Analogs Bearing Ethyl and Hydroxymethyl Groups at the C-2 and C-23 Positions. Chemistry 2018; 24:11139-11157. [DOI: 10.1002/chem.201801668] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Indexed: 12/17/2022]
Affiliation(s)
- Ikki Kaneko
- Graduate School of Science and Technology and Department of Applied Biological Chemistry, Faculty of Agriculture; Niigata University; Ikarashi 2-8050 Nishi-ku Niigata 950-2181 Japan
| | - Yuri Terasawa
- Graduate School of Science and Technology and Department of Applied Biological Chemistry, Faculty of Agriculture; Niigata University; Ikarashi 2-8050 Nishi-ku Niigata 950-2181 Japan
| | - Tsutomu Hoshino
- Graduate School of Science and Technology and Department of Applied Biological Chemistry, Faculty of Agriculture; Niigata University; Ikarashi 2-8050 Nishi-ku Niigata 950-2181 Japan
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6
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Takahashi K, Sasaki Y, Hoshino T. Squalene-Hopene Cyclase: On the Polycyclization Reactions of Squalene Analogues Bearing Ethyl Groups at Positions C-6, C-10, C-15, and C-19. European J Org Chem 2018. [DOI: 10.1002/ejoc.201800010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Kazunari Takahashi
- Graduate School of Science and Technology and Department of Applied Biological Chemistry; Faculty of Agriculture; Niigata University; Ikarashi 2-8050 950-2181 Nishi-ku, Niigata Japan
| | - Yusuke Sasaki
- Graduate School of Science and Technology and Department of Applied Biological Chemistry; Faculty of Agriculture; Niigata University; Ikarashi 2-8050 950-2181 Nishi-ku, Niigata Japan
| | - Tsutomu Hoshino
- Graduate School of Science and Technology and Department of Applied Biological Chemistry; Faculty of Agriculture; Niigata University; Ikarashi 2-8050 950-2181 Nishi-ku, Niigata Japan
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7
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Bastian SA, Hammer SC, Kreß N, Nestl BM, Hauer B. Selectivity in the Cyclization of Citronellal Introduced by Squalene Hopene Cyclase Variants. ChemCatChem 2017. [DOI: 10.1002/cctc.201700734] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Silke A. Bastian
- Institute of Biochemistry and Technical Biochemistry, Chair of Technical Biochemistry; Universitaet Stuttgart; Allmandring 31 70569 Stuttgart Germany
| | - Stephan C. Hammer
- Institute of Biochemistry and Technical Biochemistry, Chair of Technical Biochemistry; Universitaet Stuttgart; Allmandring 31 70569 Stuttgart Germany
| | - Nico Kreß
- Institute of Biochemistry and Technical Biochemistry, Chair of Technical Biochemistry; Universitaet Stuttgart; Allmandring 31 70569 Stuttgart Germany
| | - Bettina M. Nestl
- Institute of Biochemistry and Technical Biochemistry, Chair of Technical Biochemistry; Universitaet Stuttgart; Allmandring 31 70569 Stuttgart Germany
| | - Bernhard Hauer
- Institute of Biochemistry and Technical Biochemistry, Chair of Technical Biochemistry; Universitaet Stuttgart; Allmandring 31 70569 Stuttgart Germany
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8
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Hoshino T. β-Amyrin biosynthesis: catalytic mechanism and substrate recognition. Org Biomol Chem 2017; 15:2869-2891. [DOI: 10.1039/c7ob00238f] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
In the past five years, there have been remarkable advances in the study of β-amyrin synthase. This review outlines the catalytic mechanism and substrate recognition in β-amyrin biosynthesis, which have been attained by the site-directed mutagenesis and substrate analog experiments.
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Affiliation(s)
- Tsutomu Hoshino
- Graduate School of Science and Technology and Department of Applied Biological Chemistry
- Faculty of Agriculture
- Niigata University
- Niigata 950-2181
- Japan
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9
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Terasawa Y, Sasaki Y, Yamaguchi Y, Takahashi K, Hoshino T. β-Amyrin Biosynthesis: Effect of Steric Bulk at the 6-, 10- and 15-Positions in the 2,3-Oxidosqualene Backbone on Polycyclisation Cascades. European J Org Chem 2016. [DOI: 10.1002/ejoc.201601306] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Yuri Terasawa
- Department of Applied Biological Chemistry; Faculty of Agriculture and Graduate School of Science and Technology; Niigata University; Ikarashi 2-8050 950-2181 Nishi-ku, Niigata Japan
| | - Yusuke Sasaki
- Department of Applied Biological Chemistry; Faculty of Agriculture and Graduate School of Science and Technology; Niigata University; Ikarashi 2-8050 950-2181 Nishi-ku, Niigata Japan
| | - Yuki Yamaguchi
- Department of Applied Biological Chemistry; Faculty of Agriculture and Graduate School of Science and Technology; Niigata University; Ikarashi 2-8050 950-2181 Nishi-ku, Niigata Japan
| | - Kazunari Takahashi
- Department of Applied Biological Chemistry; Faculty of Agriculture and Graduate School of Science and Technology; Niigata University; Ikarashi 2-8050 950-2181 Nishi-ku, Niigata Japan
| | - Tsutomu Hoshino
- Department of Applied Biological Chemistry; Faculty of Agriculture and Graduate School of Science and Technology; Niigata University; Ikarashi 2-8050 950-2181 Nishi-ku, Niigata Japan
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10
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Hoshino T, Miyahara Y, Hanaoka M, Takahashi K, Kaneko I. β-Amyrin Biosynthesis: The Methyl-30 Group of (3S)-2,3-Oxidosqualene Is More Critical to Its Correct Folding To Generate the Pentacyclic Scaffold than the Methyl-24 Group. Chemistry 2015; 21:15769-84. [DOI: 10.1002/chem.201502389] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2015] [Indexed: 11/11/2022]
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11
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Photochemical reactions of 1,2-diketones with silyl enol ethers. RESEARCH ON CHEMICAL INTERMEDIATES 2015. [DOI: 10.1007/s11164-013-1203-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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12
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Hoshino T, Yamaguchi Y, Takahashi K, Ito R. β-Amyrin Biosynthesis: The Critical Role of Steric Volume at C-19 of 2,3-Oxidosqualene for Its Correct Folding To Generate the Pentacyclic Scaffold. Org Lett 2014; 16:3548-51. [DOI: 10.1021/ol501498q] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Tsutomu Hoshino
- Graduate School of Science
and Technology, and Department of Applied Biological Chemistry, Faculty
of Agriculture, Niigata University, Ikarashi 2-8050, Nishi-ku, Niigata 950-2181, Japan
| | - Yuki Yamaguchi
- Graduate School of Science
and Technology, and Department of Applied Biological Chemistry, Faculty
of Agriculture, Niigata University, Ikarashi 2-8050, Nishi-ku, Niigata 950-2181, Japan
| | - Kazunari Takahashi
- Graduate School of Science
and Technology, and Department of Applied Biological Chemistry, Faculty
of Agriculture, Niigata University, Ikarashi 2-8050, Nishi-ku, Niigata 950-2181, Japan
| | - Ryousuke Ito
- Graduate School of Science
and Technology, and Department of Applied Biological Chemistry, Faculty
of Agriculture, Niigata University, Ikarashi 2-8050, Nishi-ku, Niigata 950-2181, Japan
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13
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Ito R, Masukawa Y, Nakada C, Amari K, Nakano C, Hoshino T. β-Amyrin synthase from Euphorbia tirucalli. Steric bulk, not the π-electrons of Phe, at position 474 has a key role in affording the correct folding of the substrate to complete the normal polycyclization cascade. Org Biomol Chem 2014; 12:3836-46. [DOI: 10.1039/c4ob00064a] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The importance of the steric bulk at 474 residue is described for completion of the cyclization cascade, but not the π-electrons of the Phe residue.
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Affiliation(s)
- Ryousuke Ito
- Graduate School of Science and Technology
- and Department of Applied Biological Chemistry
- Faculty of Agriculture
- Niigata University
- Niigata 950-2181, Japan
| | - Yukari Masukawa
- Graduate School of Science and Technology
- and Department of Applied Biological Chemistry
- Faculty of Agriculture
- Niigata University
- Niigata 950-2181, Japan
| | - Chika Nakada
- Graduate School of Science and Technology
- and Department of Applied Biological Chemistry
- Faculty of Agriculture
- Niigata University
- Niigata 950-2181, Japan
| | - Kanako Amari
- Graduate School of Science and Technology
- and Department of Applied Biological Chemistry
- Faculty of Agriculture
- Niigata University
- Niigata 950-2181, Japan
| | - Chiaki Nakano
- Graduate School of Science and Technology
- and Department of Applied Biological Chemistry
- Faculty of Agriculture
- Niigata University
- Niigata 950-2181, Japan
| | - Tsutomu Hoshino
- Graduate School of Science and Technology
- and Department of Applied Biological Chemistry
- Faculty of Agriculture
- Niigata University
- Niigata 950-2181, Japan
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14
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Ito R, Hashimoto I, Masukawa Y, Hoshino T. Effect of Cation-π Interactions and Steric Bulk on the Catalytic Action of Oxidosqualene Cyclase: A Case Study of Phe728 of β-Amyrin Synthase fromEuphorbia tirucalli L. Chemistry 2013; 19:17150-8. [DOI: 10.1002/chem.201301917] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2013] [Revised: 08/31/2013] [Indexed: 11/06/2022]
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15
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Seitz M, Syrén PO, Steiner L, Klebensberger J, Nestl BM, Hauer B. Synthesis of heterocyclic terpenoids by promiscuous squalene-hopene cyclases. Chembiochem 2013; 14:436-9. [PMID: 23418022 DOI: 10.1002/cbic.201300018] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2013] [Indexed: 11/07/2022]
Abstract
PROMISCUOUS ENZYMES: The substrate promiscuity of squalene-hopene cyclases has been explored and applied in the enzyme-catalyzed synthesis of heterocyclic terpenoids. Features of this work include cyclization reactions without pyrophosphate activation, and stereospecific ring closure of substrates of varying chain length and terminal nucleophile. This provides a biocatalytic alternative to traditional chemical catalysts.
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Affiliation(s)
- Miriam Seitz
- Institute of Technical Biochemistry, Universität Stuttgart, Allmandring 31, 70569 Stuttgart, Germany
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16
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Abstract
Hopanoids and sterols are members of a large group of cyclic triterpenoic compounds that have important functions in many prokaryotic and eukaryotic organisms. They are biochemically synthesized from linear precursors (squalene, 2,3-oxidosqualene) in only one enzymatic step that is catalyzed by squalene-hopene cyclase (SHC) or oxidosqualene cyclase (OSC). SHCs and OSCs are related in amino acid sequences and probably are derived from a common ancestor. The SHC reaction requires the formation of five ring structures, 13 covalent bonds, and nine stereo centers and therefore is one of the most complex one-step enzymatic reactions. We summarize the knowledge of the properties of triterpene cyclases and details of the reaction mechanism of Alicyclobacillus acidocaldarius SHC. Properties of other SHCs are included.
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Affiliation(s)
| | - Dieter Jendrossek
- Institute for Microbiology, University of Stuttgart, Stuttgart, Germany
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17
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Hoshino T, Kumai Y, Sato T. Reviewing the polyolefin cyclization reaction of the c(35) polyprene catalyzed by squalene-hopene cyclase. Chemistry 2009; 15:2091-100. [PMID: 19142932 DOI: 10.1002/chem.200802142] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
A review of the polycyclization reaction of the C(35) polyprenoid by squalene-hopene cyclase: Surprisingly, our results completely disagree with a previous publication in which it was reported that a hexacyclic skeleton was constructed as the single product. In our work many tri- and tetracyclic scaffolds were isolated, but no penta- or hexacycles. The reasons for the different results and the mechanism of the polycyclization reaction are discussed (see figure).Squalene-hopene cyclase (SHC) catalyzes the polycyclization of squalene (C(30)) to the pentacyclic hopene with regio- and stereochemical specificity. In this study, we reviewed the polycyclization reaction of the C(35) polyprenoid catalyzed by SHC. Surprisingly, our results completely disagreed with a previous publication in which it was reported that a hexacyclic skeleton was constructed as the single product in 10 % yield (I. Abe, H. Tanaka, H. Noguchi, J. Am. Chem. Soc. 2002, 124, 14514-14515). Our experimental results showed that many tri- and tetracyclic products, up to 12, including novel carbocyclic cores, were generated in a high conversion ratio (97 %), but no detectable amounts of the penta- and hexacycle were produced. The mechanisms for the formation of the C(35) polyprene products isolated by us are discussed in this paper. The following four conformations were generated during the polycyclization cascade: chair-chair-boat, chair-chair-chair, chair-chair-chair-boat, and chair-chair-chair-chair. Larger amounts of the false intermediates with 13alpha-H (tricycle) and 17alpha-H (tetracycle) were produced compared with the true intermediates (13beta-H and 17beta-H), which indicates that the C(35) polyprene cannot fold correctly in the enzyme cavity due to the extra C(5) unit appended to squalene. This would have promoted the formation of the aborted cyclization products with tri- and tetracycles. In addition, the fact that no penta- or hexacyclic products were formed further indicates that SHC does not have sufficient space to accommodate the entire carbon framework of C(35).
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Affiliation(s)
- Tsutomu Hoshino
- Department of Applied Biological Chemistry, Faculty of Agriculture and Graduate School of Science and Technology, Niigata University, Ikarashi 2-8050, Nishi-ku, Niigata 950-2181, Japan.
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18
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Cheng J, Hoshino T. Cyclization cascade of the C33-bisnorheptaprenoid catalyzed by recombinant squalene cyclase. Org Biomol Chem 2009; 7:1689-99. [PMID: 19343258 DOI: 10.1039/b823167b] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The enzymatic cyclization reaction of polyprenoid C(33) by squalene-hopene cyclase (SHC) was investigated with the intention of creating an unnatural hexacyclic compound. The enzymatic products consisted of mono-, bi-, tri-, tetra- and pentacyclic skeletons; however, hexacyclic products were not generated, contrary to our expectations. The absence of a hexacyclic skeleton indicated that the entire carbon chain of C(33) polyprene could not be included in the reaction cavity. Formation mechanisms of the products having mono- to pentacycles were discussed. Both chair/chair/boat conformation and chair/chair/chair conformations were formed for a tricycle, and both chair/chair/chair/boat conformation and chair/chair/chair/chair structures were constructed for a tetracycle. The pentacyclic product was created from the chair/chair/chair/chair/boat conformation. Squalene was folded in an all pre-chair conformation inside the reaction cavity to form the hopene skeleton. Therefore, the formation of a boat structure during the polycyclization reaction indicated that the molecule of polyprene C(33) was folded improperly due to incorrect arrangement/positioning in the reaction cavity. The creation of the hexacyclic core failed; however, it should be noted that SHC possessed great potential to tolerate the elongated squalene analog C(33), thus leading to the creation of novel compounds with C(33).
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Affiliation(s)
- Jun Cheng
- Department of Applied Biological Chemistry, Faculty of Agriculture and Graduate School of Science and Technology, Niigata University, Ikarashi 2, Nishi-ku, Niigata 950-2181, Japan
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19
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Hoshino T, Yonemura Y, Abe T, Sugino Y. Production of epoxydammaranes by the enzymatic reactions of (3R)- and (3S)-2,3-squalene diols and those of 2,3:22,23-dioxidosqualenes with recombinant squalene cyclase and the mechanistic insight into the polycyclization reactions. Org Biomol Chem 2007; 5:792-801. [PMID: 17315066 DOI: 10.1039/b615897h] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The enzymatic cyclizations of (3R)- and (3S)-2,3-squalene diols by squalene cyclase afforded bicyclic compounds and epoxydamamranes in a ca. 3 : 2 ratio. Formation of the epoxydammarane scaffold indicates that a 6/6/6/5-fused tetracyclic cation is involved as the intermediate in the polycyclization reaction. 2,3:22,23-Dioxidosqualenes also afforded an epoxydammarane skeleton, i.e., 3alpha- or 3beta-hydroxyepoxydammaranes, but the amount of bicyclic compounds produced was markedly lower than that of the squalene diols, indicating that the larger steric bulk of the diols had a more significant influence on the polycyclization pathway than the smaller bulk of the expoxide. All the epoxydammaranes had 17R,20R stereochemistry except for one product, demonstrating that these analogs were folded into an all-chair conformation in the reaction cavity. The mechanistic insight into the observed stereochemical specificities indicated that the organized all-chair conformation is rigidly constricted by squalene cyclase and, thus, free conformational change is not allowed inside the reaction cavity; a small rotation of the hydroxyl group or the epoxide toward the intermediary cation gave a high yield of the enzymatic products, while a large rotation led to a low yield of the product. The stereochemistries of the generated epoxydammaranes are opposite to those from natural sources, and thus almost all of the enzymatic products described here are novel.
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Affiliation(s)
- Tsutomu Hoshino
- Department of Applied Biological Chemistry, Faculty of Agriculture, and Graduate School of Science and Technology, Niigata University, Ikarashi, Niigata 950-2181, Japan.
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20
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21
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Tanaka H, Noma H, Noguchi H, Abe I. Enzymatic formation of pyrrole-containing novel cyclic polyprenoids by bacterial squalene:hopene cyclase. Tetrahedron Lett 2006. [DOI: 10.1016/j.tetlet.2006.02.151] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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22
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Xiong Q, Rocco F, Wilson WK, Xu R, Ceruti M, Matsuda SPT. Structure and reactivity of the dammarenyl cation: configurational transmission in triterpene synthesis. J Org Chem 2005; 70:5362-75. [PMID: 15989315 DOI: 10.1021/jo050147e] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
[reaction: see text] The dammarenyl cation (13) is the last common intermediate in the cyclization of oxidosqualene to a diverse array of secondary triterpene metabolites in plants. We studied the structure and reactivity of 13 to understand the factors governing the regio- and stereospecificity of triterpene synthesis. First, we demonstrated that 13 has a 17beta side chain in Arabidopsis thaliana lupeol synthase (LUP1) by incubating the substrate analogue (18E)-22,23-dihydro-20-oxaoxidosqualene (21) with LUP1 from a recombinant yeast strain devoid of other cyclases and showing that the sole product of 21 was 3beta-hydroxy-22,23,24,25,26,27-hexanor-17beta-dammaran-20-one. Quantum mechanical calculations were carried out on gas-phase models to show that the 20-oxa substitution has negligible effect on substrate binding and on the activation energies of reactions leading to either C17 epimer of 13. Further molecular modeling indicated that, because of limited rotational freedom in the cyclase active site cavity, the C17 configuration of the tetracyclic intermediate 13 can be deduced from the angular methyl configuration of the pentacyclic or 6-6-6-6 tetracyclic product. This rule of configurational transmission aided in elucidating the mechanistic pathway accessed by individual cyclases. Grouping of cyclases according to mechanistic and taxonomic criteria suggested that the transition between pathways involving 17alpha and 17beta intermediates occurred rarely in evolutionary history. Two other mechanistic changes were also rare, whereas variations on cation rearrangements evolved readily. This perspective furnished insights into the phylogenetic relationships of triterpene synthases.
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Affiliation(s)
- Quanbo Xiong
- Department of Biochemistry and Cell Biology, Rice University, 6100 Main Street, Houston, Texas 77005, USA
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23
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Abe T, Hoshino T. Enzymatic cyclizations of squalene analogs with threo- and erythro-diols at the 6,7- or 10,11-positions by recombinant squalene cyclase. Trapping of carbocation intermediates and mechanistic insights into the product and substrate specificities. Org Biomol Chem 2005; 3:3127-39. [PMID: 16106294 DOI: 10.1039/b506590a] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In order to trap the carbocation intermediates formed during the squalene cyclization cascade, squalene analogs with threo- and erythro-diols at the 6,7- and 10,11-positions were incubated with the recombinant squalene cyclase from Alicyclobacillus acidocaldarius, leading to the construction of the triterpenes with tetrahydropyran, octahydrochromene, decahydronaphthalene with a carbonyl group, dodecahydrobenzo[f]chromene, tetradecahydronaphtho[2,1-b]oxepine and malabaricane skeletons, almost of which are novel compounds. These products indicate that 6-membered monocyclic, 6/6-fused bicyclic and 6/6/5-fused tricyclic cations were involved in the cyclization reaction in addition to acyclic cation. All the trapped cations were the stable tertiary cation, but not the secondary one, indicating that the polycyclization reaction proceeds with a Markovnikov closure. The product profiles revealed that the cyclization reactions proceeded with the product and substrate specificities in addition to enantioselectivity. Mechanistic insight into the observed stereochemical specificities indicated that the pre-organized chair-conformation of squalene-diols is tightly constricted by the cyclase and a free motion or a conformational change is not allowed in the reaction cavity, thus, the substrate and product specificities are dominantly directed by the least motion of the nucleophilic hydroxyl group toward the intermediary carbocation; a small rotation of the hydroxyl group afforded the cyclization products in a good yield, but a large rotation of the hydroxyl group gave a marginal or no detectable amount of products.
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Affiliation(s)
- Takamasa Abe
- Department of Applied Biological Chemistry, Faculty of Agriculture, and Graduate School of Science and Technology, Niigata University, Ikarashi, Niigata 950-2181, Japan
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24
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Enzymatic cyclization of 26- and 27-methylidenesqualene to novel unnatural C31 polyprenoids by squalene:hopene cyclase. Tetrahedron Lett 2004. [DOI: 10.1016/j.tetlet.2004.02.090] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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25
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Hoshino T, Kumai Y, Kudo I, Nakano SI, Ohashi S. Enzymatic cyclization reactions of geraniol, farnesol and geranylgeraniol, and those of truncated squalene analogs having C20and C25by recombinant squalene cyclase. Org Biomol Chem 2004; 2:2650-7. [PMID: 15351829 DOI: 10.1039/b407001a] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The substrate specificity of squalene-hopene cyclase was investigated using the C10-C25 analogs including naturally occurring substances, e.g. geraniol (C10), farnesol (C15) and geranylgeraniol (C20). No cyclization occurred for geraniol, but a significantly high conversion ratio (64%) was observed for farnesol, yielding the cyclic sesquiterpenes consisting of 6/6-fused bicyclic ring systems. Among them, an attractive compound having C30 was produced, in the structure of which acyclic the farnesol unit is linked to the bicyclic skeleton through ether linkage. Conversion of geranylgeraniol was low (ca. 12%). The squalene analogs having C20 and C25 also were cyclized in yields of ca. 33-36%, but the analogs having the methyl group at C7 and/or at C11 underwent no cyclization; the large steric bulk size of C7-Me and/or C11-Me, which is arranged in [small alpha]-disposition for all the pre-chair conformation, would have interacted repulsively with the cyclase recognition site near to the C7 and/or C11, resulting in no construction of the all-chair conformation inside the reaction cavity. A relatively low yield of geranylgeraniol indicated that a less bulky hydrogen atom must be located at C14 for the efficient polycyclization reaction. The squalene cyclase shows remarkably broad substrate specificity to accept the truncated analogs having carbon-chain lengths of C(15)-C25 in addition to C30.
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Affiliation(s)
- Tsutomu Hoshino
- Department of Applied Biological Chemistry, Faculty of Agriculture, and Graduate School of Science and Technology, Niigata University, Ikarashi, Niigata, Japan 950-2181.
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26
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Nakano SI, Ohashi S, Hoshino T. Squalene–hopene cyclase: insight into the role of the methyl group on the squalene backbone upon the polycyclization cascade. Enzymatic cyclization products of squalene analogs lacking a 26-methyl group and possessing a methyl group at C(7) or C(11). Org Biomol Chem 2004; 2:2012-22. [PMID: 15254628 DOI: 10.1039/b404287e] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
To provide deep insight into the polycyclization reaction of squalene, some analogs were synthesized and incubated with the cell-free homogenates of the recombinant Escherichia coli encoding the wild-type squalene cyclase. The presence of C6-Me leads to an efficient polycyclization cascade. Substitution of the C14-H and the C18-H with a methyl group halted the polycylization reaction at the tricyclic ring stage having a 6/6/6-fused ring system and the tetracycle with a 6/6/6/6-fused ring, respectively, both of which were produced according to a Markovnikov closure. Replacement of the C7-H and the C11-H with a methyl group led to no cyclization. These results, in conjunction with our previous reports, indicated that the methyl positions are important for bringing to completion of the normal polycylization reaction and further demonstrated that the precise steric bulk size at the methyl positions of squalene is critical to the correct folding and the strong binding of the substrate to the squalene cyclase.
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Affiliation(s)
- Shin-Ichi Nakano
- Department of Applied Biological Chemistry, Faculty of Agriculture, and Graduate School of Science and Technology, Niigata University, Ikarashi, Niigata 950-2181, Japan
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27
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Hoshino T, Nakano SI, Kondo T, Sato T, Miyoshi A. Squalene–hopene cyclase: final deprotonation reaction, conformational analysis for the cyclization of (3R,S)-2,3-oxidosqualene and further evidence for the requirement of an isopropylidene moiety both for initiation of the polycyclization cascade and for the formation of the 5-membered E-ring. Org Biomol Chem 2004; 2:1456-70. [PMID: 15136801 DOI: 10.1039/b401172d] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
To provide insight into the polycyclization mechanism of squalene by squalene-hopene cyclase (SHC) from Alicyclobacilus acidocaldarius, some analogs of nor- and bisnorsqualenes were synthesized including the deuterium-labeled squalenes and incubated with the wild-type SHC, leading to the following inferences. (1) The deprotonation reaction for the introduction of the double bond of the hopene skeleton occurs exclusively from the Z-methyl group on the terminal double bond of squalene. (2) 3R-Oxidosqualene was folded in a boat conformation for the A-ring construction, while the 3S-form was in a chair structure. (3) The terminal two methyl groups are indispensable both for the formation of the 5-membered E-ring of the hopene skeleton and for the initiation of the polycyclization cascade, but the terminal Z-methyl group has a more crucial role for the construction of the 5-membered E-ring than the E-methyl group. (4) Some of the novel terpene skeletons, 36, 37, 39 and 40, were created from the analogs employed in this investigation.
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Affiliation(s)
- Tsutomu Hoshino
- Department of Applied Biological Chemistry, Faculty of Agriculture, and Graduate School of Science and Technology, Niigata University, Ikarashi, Niigata 950-2181, Japan.
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28
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Rajamani R, Gao J. Balancing kinetic and thermodynamic control: the mechanism of carbocation cyclization by squalene cyclase. J Am Chem Soc 2003; 125:12768-81. [PMID: 14558824 DOI: 10.1021/ja0371799] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Molecular dynamics simulations with a combined quantum mechanical and molecular mechanical (QM/MM) potential have been carried out to investigate the squalene-to-hopene carbocation cyclization mechanism in squalene-hopene cyclase (SHC). The present study is based on free energy simulations by constructing the free energy surface for the cyclization steps along the reaction pathway. The picture that emerges for the carbocation cyclization cascade is a delicate balance of thermodynamic and kinetic control that ultimately favors the formation of the final hopanoids carbon skeleton. A key finding is that the five- to six-membered ring expansion process is not a viable reaction pathway for either C- or D-ring formation in the cyclization reaction. The only significant intermediate is the A/B-bicyclic cyclohexyl cation (III), from which two asynchronous concerted reaction pathways lead to, respectively, the 6,6,6,5-tetracyclic carbon skeleton and the 6,6,6,6,5-pentacyclic hopanoids. Experimentally, these two products are observed to have 1% and 99% yields, respectively, in the wild-type enzyme. We conclude that the product distribution in the wild-type enzyme is dictated by kinetic control of these two reaction pathways.
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Affiliation(s)
- Ramkumar Rajamani
- Department of Chemistry and Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455, USA
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29
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Bunte JO, Rinne S, Schäfer C, Neumann B, Stammler HG, Mattay J. Synthesis and PET oxidative cyclization of silyl enol ethers: build-up of quasi-steroidal carbocycles. Tetrahedron Lett 2003. [DOI: 10.1016/s0040-4039(02)02491-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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