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Hou X, Feng J, Franklin JL, Russo R, Guo Z, Zhou J, Gao JM, Liu HW, Wang B. Mechanistic Insights from the Crystal Structure and Computational Analysis of the Radical SAM Deaminase DesII. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024:e2403494. [PMID: 38943270 DOI: 10.1002/advs.202403494] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2024] [Revised: 05/06/2024] [Indexed: 07/01/2024]
Abstract
Radical S-adenosyl-L-methionine (SAM) enzymes couple the reductive cleavage of SAM to radical-mediated transformations that have proven to be quite broad in scope. DesII is one such enzyme from the biosynthetic pathway of TDP-desosamine where it catalyzes a radical-mediated deamination. Previous studies have suggested that this reaction proceeds via direct elimination of ammonia from an α-hydroxyalkyl radical or its conjugate base (i.e., a ketyl radical) rather than 1,2-migration of the amino group to form a carbinolamine radical intermediate. However, without a crystal structure, the active site features responsible for this chemistry have remained largely unknown. The crystallographic studies described herein help to fill this gap by providing a structural description of the DesII active site. Computational analyses based on the solved crystal structure are consistent with direct elimination and indicate that an active site glutamate residue likely serves as a general base to promote deprotonation of the α-hydroxyalkyl radical intermediate and elimination of the ammonia group.
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Affiliation(s)
- Xueli Hou
- Shaanxi Key Laboratory of Natural Products & Chemical Biology, College of Chemistry & Pharmacy, Northwest A&F University, Yangling, Shaanxi, 712100, China
- Key Laboratory of Quantitative Synthetic Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
| | - Jianqiang Feng
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering and Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province (IKKEM), Xiamen University, Xiamen, 361005, China
| | - Joseph Livy Franklin
- Division of Chemical Biology & Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, Austin, TX, 78712, USA
| | - Ryan Russo
- Division of Chemical Biology & Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, Austin, TX, 78712, USA
| | - Zhiyong Guo
- State Key Laboratory of Biocatalysis and Enzyme Engineering, Hubei Key Laboratory of Industrial Biotechnology, School of Life Sciences, Hubei University, Wuhan, 430062, China
| | - Jiahai Zhou
- Key Laboratory of Quantitative Synthetic Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing, 210023, China
| | - Jin-Ming Gao
- Shaanxi Key Laboratory of Natural Products & Chemical Biology, College of Chemistry & Pharmacy, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Hung-Wen Liu
- Division of Chemical Biology & Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, Austin, TX, 78712, USA
- Department of Chemistry, University of Texas at Austin, Austin, TX, 78712, USA
| | - Binju Wang
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering and Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province (IKKEM), Xiamen University, Xiamen, 361005, China
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2
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Zhang M, Shuang B, Arakawa K. Accumulation of lankamycin derivative with a branched-chain sugar from a blocked mutant of chalcose biosynthesis in Streptomyces rochei 7434AN4. Bioorg Med Chem Lett 2023; 80:129125. [PMID: 36621553 DOI: 10.1016/j.bmcl.2023.129125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 12/28/2022] [Accepted: 01/03/2023] [Indexed: 01/07/2023]
Abstract
Lankamycin, a macrolide antibiotic produced by Streptomyces rochei 7434AN4, exhibits a moderate antimicrobial activity and acts as a synergistic pair with carbocyclic antibiotic lankacidin C by binding to the ribosome exit tunnel. Its biosynthetic gene (lkm) cluster (orf24-orf53) is located on the largest plasmid pSLA2-L (210,614 bp). Our group possesses a variety of lankamycin derivatives and macrolide-modification enzymes including P450 enzymes and glycosyltransferases, which may lead to expand the chemical library of bioactive macrolides. Here we constructed a mutant of a 3-ketoreductase gene lkmCVI (orf42) involved in d-chalcose biosynthesis, and its metabolite was isolated and structure-elucidated. Accumulation of novel lankamycin derivative harboring a branched-chain deoxysugar, 5-O-(4',6'-dideoxy-3'-C-acetyl-d-ribo-hexopyranosyl)-3-O-(4″-O-acetyl-l-arcanosyl)-lankanolide, indicated that LkmCVI acts as a gate keeper enzyme for d-chalcose synthesis in lankamycin biosynthesis.
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Affiliation(s)
- Mingge Zhang
- Graduate School of Integrated Sciences for Life, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan; Hiroshima Research Center for Healthy Aging (HiHA), Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan
| | - Bao Shuang
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan; School of Life Sciences, Northeast Agricultural University, 600 Changjiang Road, Xiangfang District, Harbin, Heilongjiang 150030, China
| | - Kenji Arakawa
- Graduate School of Integrated Sciences for Life, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan; Hiroshima Research Center for Healthy Aging (HiHA), Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan; Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan.
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3
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Zhang FL, Li B, Houk KN, Wang YF. Application of the Spin-Center Shift in Organic Synthesis. JACS AU 2022; 2:1032-1042. [PMID: 35647602 PMCID: PMC9131482 DOI: 10.1021/jacsau.2c00051] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 03/24/2022] [Accepted: 03/25/2022] [Indexed: 05/09/2023]
Abstract
Spin-center shift (SCS) is a radical process involving 1,2-radical translocation along with a two-electron ionic movement, such as elimination of an adjacent leaving group. Such a process was initially observed in some important biochemical transformations, and the unique property has also attracted considerable interest in synthetic chemistry. Experimental, kinetic, as well as computational studies have been performed, and a series of useful radical transformations have been developed and applied in organic synthesis based on SCS processes in the last 20 years. This Perspective is an overview of radical transformations involving the SCS mechanism.
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Affiliation(s)
- Feng-Lian Zhang
- Department
of Chemistry, University of Science and
Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026, China
| | - Bin Li
- Department
of Chemistry, University of Science and
Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026, China
| | - K. N. Houk
- Department
of Chemistry and Biochemistry, University
of California, Los Angeles, California 90095, United States
| | - Yi-Feng Wang
- Department
of Chemistry, University of Science and
Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026, China
- State
Key Laboratory of Elemento-Organic Chemistry, Nankai University, Tianjin 300071, China
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4
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Wohlgemuth R. Selective Biocatalytic Defunctionalization of Raw Materials. CHEMSUSCHEM 2022; 15:e202200402. [PMID: 35388636 DOI: 10.1002/cssc.202200402] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 04/05/2022] [Indexed: 06/14/2023]
Abstract
Biobased raw materials, such as carbohydrates, amino acids, nucleotides, or lipids contain valuable functional groups with oxygen and nitrogen atoms. An abundance of many functional groups of the same type, such as primary or secondary hydroxy groups in carbohydrates, however, limits the synthetic usefulness if similar reactivities cannot be differentiated. Therefore, selective defunctionalization of highly functionalized biobased starting materials to differentially functionalized compounds can provide a sustainable access to chiral synthons, even in case of products with fewer functional groups. Selective defunctionalization reactions, without affecting other functional groups of the same type, are of fundamental interest for biocatalytic reactions. Controlled biocatalytic defunctionalizations of biobased raw materials are attractive for obtaining valuable platform chemicals and building blocks. The biocatalytic removal of functional groups, an important feature of natural metabolic pathways, can also be utilized in a systemic strategy for sustainable metabolite synthesis.
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Affiliation(s)
- Roland Wohlgemuth
- Institute of Molecular and Industrial Biotechnology, Lodz University of Technology Łódź, 90-537, Lodz, Poland
- Swiss Coordination Committee Biotechnology (SKB), 8002, Zurich, Switzerland
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5
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Lee YH, Hou X, Chen R, Feng J, Liu X, Ruszczycky MW, Gao JM, Wang B, Zhou J, Liu HW. Radical S-Adenosyl Methionine Enzyme BlsE Catalyzes a Radical-Mediated 1,2-Diol Dehydration during the Biosynthesis of Blasticidin S. J Am Chem Soc 2022; 144:4478-4486. [PMID: 35238201 DOI: 10.1021/jacs.1c12010] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The biosynthesis of blasticidin S has drawn attention due to the participation of the radical S-adenosyl methionine (SAM) enzyme BlsE. The original assignment of BlsE as a radical-mediated, redox-neutral decarboxylase is unusual because this reaction appears to serve no biosynthetic purpose and would need to be reversed by a subsequent carboxylation step. Furthermore, with the exception of BlsE, all other radical SAM decarboxylases reported to date are oxidative in nature. Careful analysis of the BlsE reaction, however, demonstrates that BlsE is not a decarboxylase but instead a lyase that catalyzes the dehydration of cytosylglucuronic acid (CGA) to form cytosyl-4'-keto-3'-deoxy-d-glucuronic acid, which can rapidly decarboxylate nonenzymatically in vitro. Analysis of substrate isotopologs, fluorinated analogues, as well as computational models based on X-ray crystal structures of the BlsE·SAM (2.09 Å) and BlsE·SAM·CGA (2.62 Å) complexes suggests that BlsE catalysis likely proceeds via direct elimination of water from the CGA C4' α-hydroxyalkyl radical as opposed to 1,2-migration of the C3'-hydroxyl prior to dehydration. Biosynthetic and mechanistic implications of the revised assignment of BlsE are discussed.
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Affiliation(s)
- Yu-Hsuan Lee
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
| | - Xueli Hou
- Shaanxi Key Laboratory of Natural Products & Chemical Biology, College of Chemistry & Pharmacy, Northwest A&F University, Yangling 712100, Shaanxi China.,State Key Laboratory of Bioorganic and Natural Products Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China
| | - Ridao Chen
- Division of Chemical Biology & Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, Austin, Texas 78712, United States.,State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, China
| | - Jianqiang Feng
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Xiao Liu
- Division of Chemical Biology & Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, Austin, Texas 78712, United States.,School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing 100029, China
| | - Mark W Ruszczycky
- Division of Chemical Biology & Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, Austin, Texas 78712, United States
| | - Jin-Ming Gao
- Shaanxi Key Laboratory of Natural Products & Chemical Biology, College of Chemistry & Pharmacy, Northwest A&F University, Yangling 712100, Shaanxi China
| | - Binju Wang
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Jiahai Zhou
- State Key Laboratory of Bioorganic and Natural Products Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China.,CAS Key Laboratory of Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Hung-Wen Liu
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States.,Division of Chemical Biology & Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, Austin, Texas 78712, United States
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6
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Suh CE, Carder HM, Wendlandt AE. Selective Transformations of Carbohydrates Inspired by Radical-Based Enzymatic Mechanisms. ACS Chem Biol 2021; 16:1814-1828. [PMID: 33988380 DOI: 10.1021/acschembio.1c00190] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Enzymes are a longstanding source of inspiration for synthetic reaction development. However, enzymatic reactivity and selectivity are frequently untenable in a synthetic context, as the principles that govern control in an enzymatic setting often do not translate to small molecule catalysis. Recent synthetic methods have revealed the viability of using small molecule catalysts to promote highly selective radical-mediated transformations of minimally protected sugar substrates. These transformations share conceptual similarities with radical SAM enzymes found in microbial carbohydrate biosynthesis and present opportunities for synthetic chemists to access microbial and unnatural carbohydrate building blocks without the need for protecting groups or lengthy synthetic sequences. Here, we highlight strategies through which radical reaction pathways can enable the site-, regio-, and diastereoselective transformation of minimally protected carbohydrates in both synthetic and enzymatic systems.
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Affiliation(s)
- Carolyn E. Suh
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Hayden M. Carder
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Alison E. Wendlandt
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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7
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Carder HM, Suh CE, Wendlandt AE. A Unified Strategy to Access 2- and 4-Deoxygenated Sugars Enabled by Manganese-Promoted 1,2-Radical Migration. J Am Chem Soc 2021; 143:13798-13805. [PMID: 34406756 DOI: 10.1021/jacs.1c05993] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The selective manipulation of carbohydrate scaffolds is challenging due to the presence of multiple, nearly chemically indistinguishable O-H and C-H bonds. As a result, protecting-group-based synthetic strategies are typically necessary for carbohydrate modification. Here we report a concise semisynthetic strategy to access diverse 2- and 4-deoxygenated carbohydrates without relying on the exhaustive use of protecting groups to achieve site-selective reaction outcomes. Our approach leverages a Mn2+-promoted redox isomerization step, which proceeds via sugar radical intermediates accessed by neutral hydrogen atom abstraction under visible light-mediated photoredox conditions. The resulting deoxyketopyranosides feature chemically distinguishable functional groups and are readily transformed into diverse carbohydrate structures. To showcase the versatility of this method, we report expedient syntheses of the rare sugars l-ristosamine, l-olivose, l-mycarose, and l-digitoxose from commercial l-rhamnose. The findings presented here validate the potential for radical intermediates to facilitate the selective transformation of carbohydrates and showcase the step and efficiency advantages attendant to synthetic strategies that minimize a reliance upon protecting groups.
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Affiliation(s)
- Hayden M Carder
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Carolyn E Suh
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Alison E Wendlandt
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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8
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Atanasoff-Kardjalieff AK, Lünne F, Kalinina S, Strauss J, Humpf HU, Studt L. Biosynthesis of Fusapyrone Depends on the H3K9 Methyltransferase, FmKmt1, in Fusarium mangiferae. FRONTIERS IN FUNGAL BIOLOGY 2021; 2:671796. [PMID: 37744112 PMCID: PMC10512364 DOI: 10.3389/ffunb.2021.671796] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Accepted: 06/09/2021] [Indexed: 09/26/2023]
Abstract
The phytopathogenic fungus Fusarium mangiferae belongs to the Fusarium fujikuroi species complex (FFSC). Members of this group cause a wide spectrum of devastating diseases on diverse agricultural crops. F. mangiferae is the causal agent of the mango malformation disease (MMD) and as such detrimental for agriculture in the southern hemisphere. During plant infection, the fungus produces a plethora of bioactive secondary metabolites (SMs), which most often lead to severe adverse defects on plants health. Changes in chromatin structure achieved by posttranslational modifications (PTM) of histones play a key role in regulation of fungal SM biosynthesis. Posttranslational tri-methylation of histone 3 lysine 9 (H3K9me3) is considered a hallmark of heterochromatin and established by the SET-domain protein Kmt1. Here, we show that FmKmt1 is involved in H3K9me3 in F. mangiferae. Loss of FmKmt1 only slightly though significantly affected fungal hyphal growth and stress response and is required for wild type-like conidiation. While FmKmt1 is largely dispensable for the biosynthesis of most known SMs, removal of FmKMT1 resulted in an almost complete loss of fusapyrone and deoxyfusapyrone, γ-pyrones previously only known from Fusarium semitectum. Here, we identified the polyketide synthase (PKS) FmPKS40 to be involved in fusapyrone biosynthesis, delineate putative cluster borders by co-expression studies and provide insights into its regulation.
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Affiliation(s)
- Anna K. Atanasoff-Kardjalieff
- Department of Applied Genetics and Cell Biology, Institute of Microbial Genetics, University of Natural Resources and Life Sciences, Vienna (BOKU), Tulln an der Donau, Austria
| | - Friederike Lünne
- Institute of Food Chemistry, Westfälische Wilhelms-Universität, Münster, Germany
| | - Svetlana Kalinina
- Institute of Food Chemistry, Westfälische Wilhelms-Universität, Münster, Germany
| | - Joseph Strauss
- Department of Applied Genetics and Cell Biology, Institute of Microbial Genetics, University of Natural Resources and Life Sciences, Vienna (BOKU), Tulln an der Donau, Austria
| | - Hans-Ulrich Humpf
- Institute of Food Chemistry, Westfälische Wilhelms-Universität, Münster, Germany
| | - Lena Studt
- Department of Applied Genetics and Cell Biology, Institute of Microbial Genetics, University of Natural Resources and Life Sciences, Vienna (BOKU), Tulln an der Donau, Austria
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9
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Prasertanan T, Palmer DRJ, Sanders DAR. Snapshots along the catalytic path of KabA, a PLP-dependent aminotransferase required for kanosamine biosynthesis in Bacillus cereus UW85. J Struct Biol 2021; 213:107744. [PMID: 33984505 DOI: 10.1016/j.jsb.2021.107744] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2021] [Revised: 05/05/2021] [Accepted: 05/06/2021] [Indexed: 10/21/2022]
Abstract
Kanosamine is an antibiotic and antifungal monosaccharide. The kanosamine biosynthetic pathway from glucose 6-phosphate in Bacillus cereus UW85 was recently reported, and the functions of each of the three enzymes in the pathway, KabA, KabB and KabC, were demonstrated. KabA, a member of a subclass of the VIβ family of PLP-dependent aminotransferases, catalyzes the second step in the pathway, generating kanosamine 6-phosphate (K6P) using l-glutamate as the amino-donor. KabA catalysis was shown to be extremely efficient, with a second-order rate constant with respect to K6P transamination of over 107 M-1s-1. Here we report the high-resolution structure of KabA in both the PLP- and PMP-bound forms. In addition, co-crystallization with K6P allowed the structure of KabA in complex with the covalent PLP-K6P adduct to be solved. Co-crystallization or soaking with glutamate or 2-oxoglutarate did not result in crystals with either substrate/product. Reduction of the PLP-KabA complex with sodium cyanoborohydride gave an inactivated enzyme, and crystals of the reduced KabA were soaked with the l-glutamate analog glutarate to mimic the KabA-PLP-l-glutamate complex. Together these four structures give a complete picture of how the active site of KabA recognizes substrates for each half-reaction. The KabA structure is discussed in the context of homologous aminotransferases.
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Affiliation(s)
| | - David R J Palmer
- Department of Chemistry, University of Saskatchewan, Saskatoon, SK S7N 5C9, Canada.
| | - David A R Sanders
- Department of Chemistry, University of Saskatchewan, Saskatoon, SK S7N 5C9, Canada.
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10
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11
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Tang XL, Dai P, Gao H, Wang CX, Chen GD, Hong K, Hu D, Yao XS. A Single Gene Cluster for Chalcomycins and Aldgamycins: Genetic Basis for Bifurcation of Their Biosynthesis. Chembiochem 2016; 17:1241-9. [PMID: 27191535 DOI: 10.1002/cbic.201600118] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2016] [Indexed: 01/27/2023]
Abstract
Aldgamycins are 16-membered macrolide antibiotics with a rare branched-chain sugar d-aldgarose or decarboxylated d-aldgarose at C-5. In our efforts to clone the gene cluster for aldgamycins from a marine-derived Streptomyces sp. HK-2006-1 capable of producing both aldgamycins and chalcomycins, we found that both are biosynthesized from a single gene cluster. Whole-genome sequencing combined with gene disruption established the entire gene cluster of aldgamycins: nine new genes are incorporated with the previously identified chalcomycin gene cluster. Functional analysis of these genes revealed that almDI/almDII, (encoding α/β subunits of pyruvate dehydrogenase) triggers the biosynthesis of aldgamycins, whereas almCI (encoding an oxidoreductase) initiates chalcomycins biosynthesis. This is the first report that aldgamycins and chalcomycins are derived from a single gene cluster and of the genetic basis for bifurcation in their biosynthesis.
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Affiliation(s)
- Xiao-Long Tang
- College of Traditional Chinese Materia Medica, Shenyang Pharmaceutical University, No. 103 Wenhua Road, Shenyang, 110016, China
| | - Ping Dai
- Institute of Traditional Chinese Medicine and Natural Products, College of Pharmacy, Jinan University, No. 601 Huangpu Avenue, Guangzhou, 510632, China
| | - Hao Gao
- Institute of Traditional Chinese Medicine and Natural Products, College of Pharmacy, Jinan University, No. 601 Huangpu Avenue, Guangzhou, 510632, China
| | - Chuan-Xi Wang
- Institute of Traditional Chinese Medicine and Natural Products, College of Pharmacy, Jinan University, No. 601 Huangpu Avenue, Guangzhou, 510632, China
| | - Guo-Dong Chen
- Institute of Traditional Chinese Medicine and Natural Products, College of Pharmacy, Jinan University, No. 601 Huangpu Avenue, Guangzhou, 510632, China
| | - Kui Hong
- Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, School of Pharmaceutical Sciences, Wuhan University, No. 185 Donghu Road, Wuhan, 430071, China
| | - Dan Hu
- Institute of Traditional Chinese Medicine and Natural Products, College of Pharmacy, Jinan University, No. 601 Huangpu Avenue, Guangzhou, 510632, China.
| | - Xin-Sheng Yao
- College of Traditional Chinese Materia Medica, Shenyang Pharmaceutical University, No. 103 Wenhua Road, Shenyang, 110016, China. .,Institute of Traditional Chinese Medicine and Natural Products, College of Pharmacy, Jinan University, No. 601 Huangpu Avenue, Guangzhou, 510632, China.
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12
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Lin GM, Choi SH, Ruszczycky MW, Liu HW. Mechanistic Investigation of the Radical S-Adenosyl-L-methionine Enzyme DesII Using Fluorinated Analogues. J Am Chem Soc 2015; 137:4964-7. [PMID: 25826575 PMCID: PMC4862307 DOI: 10.1021/jacs.5b02545] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
DesII is a radical S-adenosyl-l-methionine (SAM) enzyme that can act as a deaminase or a dehydrogenase depending on the nature of its TDP-sugar substrate. Previous work has implicated a substrate-derived, C3-centered α-hydroxyalkyl radical as a key intermediate during catalysis. Although deprotonation of the α-hydroxyalkyl radical has been shown to be important for dehydrogenation, much less is known regarding the course of the deamination reaction. To investigate the role played by the C3 hydroxyl during deamination, 3-deutero-3-fluoro analogues of both substrates were prepared and characterized with DesII. In neither case was deamination or oxidation observed; however, in both cases deuterium was efficiently exchanged between the substrate analogues and SAM. These results imply that the C3 hydroxyl plays a key role in both reactions—thereby arguing against a 1,2-migration mechanism of deamination—and that homolysis of SAM concomitant with H atom abstraction from the substrate is readily reversible when forward partitioning is inhibited.
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Affiliation(s)
- Geng-Min Lin
- Department of Chemistry, University of Texas at Austin, Austin, TX 78712, USA
| | - Sei-Hyun Choi
- Department of Chemistry, University of Texas at Austin, Austin, TX 78712, USA
| | - Mark W. Ruszczycky
- Division of Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, Austin, TX 78712, USA
| | - Hung-wen Liu
- Department of Chemistry, University of Texas at Austin, Austin, TX 78712, USA
- Division of Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, Austin, TX 78712, USA
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13
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Abstract
DesII is a member of the radical SAM family of enzymes that catalyzes radical-mediated transformations of TDP-4-amino-4,6-didexoy-D-glucose as well as other sugar nucleotide diphosphates. Like nearly all radical SAM enzymes, the reactions begin with the reductive homolysis of SAM to produce a 5'-deoxyadenosyl radical which is followed by regiospecific hydrogen atom abstraction from the substrate. What happens next, however, depends on the nature of the substrate radical so produced. In the case of the biosynthetically relevant substrate, a radical-mediated deamination ensues; however, when this amino group is replaced with a hydroxyl, one instead observes dehydrogenation. The factors that govern the fate of the initially generated substrate radical as well as the mechanistic details underlying these transformations have been a key focus of research into the chemistry of DesII. This review will discuss recent discoveries pertaining to the enzymology of DesII, how it may relate to understanding other radical-mediated lyases and dehydrogenases and the working hypotheses currently being investigated regarding the mechanism of DesII catalysis.
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Affiliation(s)
- Mark W. Ruszczycky
- Division of Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, Austin, Texas 78712, United States
| | - Hung-wen Liu
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
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14
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Ko Y, Ruszczycky MW, Choi SH, Liu HW. Mechanistic studies of the radical S-adenosylmethionine enzyme DesII with TDP-D-fucose. Angew Chem Int Ed Engl 2015; 54:860-3. [PMID: 25418063 PMCID: PMC4293265 DOI: 10.1002/anie.201409540] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Indexed: 11/06/2022]
Abstract
DesII is a radical S-adenosylmethionine (SAM) enzyme that catalyzes the C4-deamination of TDP-4-amino-4,6-dideoxyglucose through a C3 radical intermediate. However, if the C4 amino group is replaced with a hydroxy group (to give TDP-quinovose), the hydroxy group at C3 is oxidized to a ketone with no C4-dehydration. It is hypothesized that hyperconjugation between the C4 C-N/O bond and the partially filled p orbital at C3 of the radical intermediate modulates the degree to which elimination competes with dehydrogenation. To investigate this hypothesis, the reaction of DesII with the C4-epimer of TDP-quinovose (TDP-fucose) was examined. The reaction primarily results in the formation of TDP-6-deoxygulose and likely regeneration of TDP-fucose. The remainder of the substrate radical partitions roughly equally between C3-dehydrogenation and C4-dehydration. Thus, changing the stereochemistry at C4 permits a more balanced competition between elimination and dehydrogenation.
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Affiliation(s)
- Yeonjin Ko
- Division of Medicinal Chemistry, College of Pharmacy, and Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
| | - Mark W. Ruszczycky
- Division of Medicinal Chemistry, College of Pharmacy, and Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
| | - Sei-Hyun Choi
- Division of Medicinal Chemistry, College of Pharmacy, and Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
| | - Hung-wen Liu
- Division of Medicinal Chemistry, College of Pharmacy, and Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
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15
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Ko Y, Ruszczycky MW, Choi SH, Liu HW. Mechanistic Studies of the RadicalS-Adenosylmethionine Enzyme DesII with TDP-D-Fucose. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201409540] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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16
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Broderick JB, Duffus B, Duschene KS, Shepard EM. Radical S-adenosylmethionine enzymes. Chem Rev 2014; 114:4229-317. [PMID: 24476342 PMCID: PMC4002137 DOI: 10.1021/cr4004709] [Citation(s) in RCA: 584] [Impact Index Per Article: 58.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2013] [Indexed: 12/22/2022]
Affiliation(s)
- Joan B. Broderick
- Department of Chemistry and
Biochemistry, Montana State University, Bozeman, Montana 59717, United States
| | - Benjamin
R. Duffus
- Department of Chemistry and
Biochemistry, Montana State University, Bozeman, Montana 59717, United States
| | - Kaitlin S. Duschene
- Department of Chemistry and
Biochemistry, Montana State University, Bozeman, Montana 59717, United States
| | - Eric M. Shepard
- Department of Chemistry and
Biochemistry, Montana State University, Bozeman, Montana 59717, United States
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17
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Lamichhane J, Jha AK, Singh B, Pandey RP, Sohng JK. Heterologous production of spectinomycin in Streptomyces venezuelae by exploiting the dTDP-d-desosamine pathway. J Biotechnol 2014; 174:57-63. [DOI: 10.1016/j.jbiotec.2014.01.028] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Revised: 01/22/2014] [Accepted: 01/27/2014] [Indexed: 11/30/2022]
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18
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Deoxysugar pathway interchange for erythromycin analogues heterologously produced through Escherichia coli. Metab Eng 2013; 20:92-100. [PMID: 24060454 DOI: 10.1016/j.ymben.2013.09.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Revised: 08/30/2013] [Accepted: 09/11/2013] [Indexed: 01/16/2023]
Abstract
The overall erythromycin biosynthetic pathway can be sub-divided into macrocyclic polyketide formation and polyketide tailoring to produce the final bioactive molecule. In this study, the native deoxysugar tailoring reactions were exchanged for the purpose of demonstrating the production of alternative final erythromycin compounds. Both the d-desosamine and l-mycarose deoxysugar pathways were replaced with the alternative d-mycaminose and d-olivose pathways to produce new erythromycin analogues through the Escherichia coli heterologous system. Both analogues exhibited bioactivity against multiple antibiotic-resistant Bacillus subtilis strains. Besides demonstrating an intrinsic flexibility for the biosynthetic system to accommodate alternative tailoring pathways, the results offer an initial attempt to leverage the E. coli platform for erythromycin analogue production.
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19
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X-ray analysis of butirosin biosynthetic enzyme BtrN redefines structural motifs for AdoMet radical chemistry. Proc Natl Acad Sci U S A 2013; 110:15949-54. [PMID: 24048029 DOI: 10.1073/pnas.1312228110] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The 2-deoxy-scyllo-inosamine (DOIA) dehydrogenases are key enzymes in the biosynthesis of 2-deoxystreptamine-containing aminoglycoside antibiotics. In contrast to most DOIA dehydrogenases, which are NAD-dependent, the DOIA dehydrogenase from Bacillus circulans (BtrN) is an S-adenosyl-l-methionine (AdoMet) radical enzyme. To examine how BtrN employs AdoMet radical chemistry, we have determined its structure with AdoMet and substrate to 1.56 Å resolution. We find a previously undescribed modification to the core AdoMet radical fold: instead of the canonical (β/α)6 architecture, BtrN displays a (β5/α4) motif. We further find that an auxiliary [4Fe-4S] cluster in BtrN, thought to bind substrate, is instead implicated in substrate-radical oxidation. High structural homology in the auxiliary cluster binding region between BtrN, fellow AdoMet radical dehydrogenase anSME, and molybdenum cofactor biosynthetic enzyme MoaA provides support for the establishment of an AdoMet radical structural motif that is likely common to ~6,400 uncharacterized AdoMet radical enzymes.
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20
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Dahy AA, Koga N, Nakazawa H. Catalytic Cycle for N–CN Bond Cleavage by Molybdenum Silyl Catalyst: A DFT Study. Organometallics 2013. [DOI: 10.1021/om400179y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- AbdelRahman A. Dahy
- Department
of Chemistry, Faculty
of Science, Assiut University, Assiut 71516,
Egypt
- Graduate School of
Information
Science, Nagoya University, Nagoya 464-8601,
Japan
| | - Nobuaki Koga
- Graduate School of
Information
Science, Nagoya University, Nagoya 464-8601,
Japan
| | - Hiroshi Nakazawa
- Department of Chemistry,
Graduate
School of Science, Osaka City University, Sumiyoshi-ku, Osaka 558-8585, Japan
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21
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EPR-kinetic isotope effect study of the mechanism of radical-mediated dehydrogenation of an alcohol by the radical SAM enzyme DesII. Proc Natl Acad Sci U S A 2013; 110:2088-93. [PMID: 23329328 DOI: 10.1073/pnas.1209446110] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The radical S-adenosyl-L-methionine enzyme DesII from Streptomyces venezuelae is able to oxidize the C3 hydroxyl group of TDP-D-quinovose to the corresponding ketone via an α-hydroxyalkyl radical intermediate. It is unknown whether electron transfer from the radical intermediate precedes or follows its deprotonation, and answering this question would offer considerable insight into the mechanism by which the small but important class of radical-mediated alcohol dehydrogenases operate. This question can be addressed by measuring steady-state kinetic isotope effects (KIEs); however, their interpretation is obfuscated by the degree to which the steps of interest limit catalysis. To circumvent this problem, we measured the solvent deuterium KIE on the saturating steady-state concentration of the radical intermediate using electron paramagnetic resonance spectroscopy. The resulting value, 0.22 ± 0.03, when combined with the solvent deuterium KIE on the maximum rate of turnover (V) of 1.8 ± 0.2, yielded a KIE of 8 ± 2 on the net rate constant specifically associated with the α-hydroxyalkyl radical intermediate. This result implies that electron transfer from the radical intermediate does not precede deprotonation. Further analysis of these isotope effects, along with the pH dependence of the steady-state kinetic parameters, likewise suggests that DesII must be in the correct protonation state for initial generation of the α-hydroxyalkyl radical. In addition to providing unique mechanistic insights, this work introduces a unique approach to investigating enzymatic reactions using KIEs.
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22
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Ruszczycky MW, Ogasawara Y, Liu HW. Radical SAM enzymes in the biosynthesis of sugar-containing natural products. BIOCHIMICA ET BIOPHYSICA ACTA 2012; 1824:1231-44. [PMID: 22172915 PMCID: PMC3438383 DOI: 10.1016/j.bbapap.2011.11.006] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2011] [Accepted: 11/28/2011] [Indexed: 11/24/2022]
Abstract
Carbohydrates play a key role in the biological activity of numerous natural products. In many instances their biosynthesis requires radical mediated rearrangements, some of which are catalyzed by radical SAM enzymes. BtrN is one such enzyme responsible for the dehydrogenation of a secondary alcohol in the biosynthesis of 2-deoxystreptamine. DesII is another example that catalyzes a deamination reaction necessary for the net C4 deoxygenation of a glucose derivative en route to desosamine formation. BtrN and DesII represent the two most extensively characterized radical SAM enzymes involved in carbohydrate biosynthesis. In this review, we summarize the biosynthetic roles of these two enzymes, their mechanisms of catalysis, the questions that have arisen during these investigations and the insight they can offer for furthering our understanding of radical SAM enzymology. This article is part of a Special Issue entitled: Radical SAM enzymes and Radical Enzymology.
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Affiliation(s)
- Mark W. Ruszczycky
- Division of Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, Austin, TX 78712, USA Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, TX 78712, USA
| | - Yasushi Ogasawara
- Division of Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, Austin, TX 78712, USA Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, TX 78712, USA
| | - Hung-wen Liu
- Division of Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, Austin, TX 78712, USA Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, TX 78712, USA
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23
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Dahy AA, Koga N, Nakazawa H. Density Functional Theory Study of N–CN and O–CN Bond Cleavage by an Iron Silyl Complex. Organometallics 2012. [DOI: 10.1021/om300232h] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- AbdelRahman A. Dahy
- Department of Chemistry, Faculty
of Science, Assiut University, Assiut 71516,
Egypt
- Graduate School of
Information
Science, Nagoya University, Nagoya 464-8601,
Japan
| | - Nobuaki Koga
- Graduate School of
Information
Science, Nagoya University, Nagoya 464-8601,
Japan
| | - Hiroshi Nakazawa
- Department of Chemistry, Graduate School of
Science, Osaka City University, Sumiyoshi-ku,
Osaka 558-8585,
Japan
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24
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Romo AJ, Liu HW. Mechanisms and structures of vitamin B(6)-dependent enzymes involved in deoxy sugar biosynthesis. BIOCHIMICA ET BIOPHYSICA ACTA 2011; 1814:1534-47. [PMID: 21315852 PMCID: PMC3115481 DOI: 10.1016/j.bbapap.2011.02.003] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2010] [Revised: 01/08/2011] [Accepted: 02/01/2011] [Indexed: 10/18/2022]
Abstract
PLP is well-regarded for its role as a coenzyme in a number of diverse enzymatic reactions. Transamination, deoxygenation, and aldol reactions mediated by PLP-dependent enzymes enliven and enrich deoxy sugar biosynthesis, endowing these compounds with unique structures and contributing to their roles as determinants of biological activity in many natural products. The importance of deoxy aminosugars in natural product biosynthesis has spurred several recent structural investigations of sugar aminotransferases. The structure of a PMP-dependent enzyme catalyzing the C-3 deoxygenation reaction in the biosynthesis of ascarylose was also determined. These studies, and the crystal structures they have provided, offer a wealth of new insights regarding the enzymology of PLP/PMP-dependent enzymes in deoxy sugar biosynthesis. In this review, we consider these recent achievements in the structural biology of deoxy sugar biosynthetic enzymes and the important implications they hold for understanding enzyme catalysis and natural product biosynthesis in general. This article is part of a Special Issue entitled: Pyridoxal Phosphate Enzymology.
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Affiliation(s)
- Anthony J. Romo
- Division of Medicinal Chemistry, College of Pharmacy, and Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712
| | - Hung-wen Liu
- Division of Medicinal Chemistry, College of Pharmacy, and Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712
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25
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Engineered biosynthesis of glycosylated derivatives of narbomycin and evaluation of their antibacterial activities. Appl Microbiol Biotechnol 2011; 93:1147-56. [DOI: 10.1007/s00253-011-3592-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2011] [Revised: 08/24/2011] [Accepted: 09/17/2011] [Indexed: 10/17/2022]
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26
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Zhang Q, Liu W. Complex biotransformations catalyzed by radical S-adenosylmethionine enzymes. J Biol Chem 2011; 286:30245-30252. [PMID: 21771780 DOI: 10.1074/jbc.r111.272690] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The radical S-adenosylmethionine (AdoMet) superfamily currently comprises thousands of proteins that participate in numerous biochemical processes across all kingdoms of life. These proteins share a common mechanism to generate a powerful 5'-deoxyadenosyl radical, which initiates a highly diverse array of biotransformations. Recent studies are beginning to reveal the role of radical AdoMet proteins in the catalysis of highly complex and chemically unusual transformations, e.g. the ThiC-catalyzed complex rearrangement reaction. The unique features and intriguing chemistries of these proteins thus demonstrate the remarkable versatility and sophistication of radical enzymology.
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Affiliation(s)
- Qi Zhang
- State Key Laboratory of Bioorganic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China.
| | - Wen Liu
- State Key Laboratory of Bioorganic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China.
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27
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Ruszczycky MW, Choi SH, Mansoorabadi SO, Liu HW. Mechanistic studies of the radical S-adenosyl-L-methionine enzyme DesII: EPR characterization of a radical intermediate generated during its catalyzed dehydrogenation of TDP-D-quinovose. J Am Chem Soc 2011; 133:7292-5. [PMID: 21513273 DOI: 10.1021/ja201212f] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
DesII, a radical S-adenosyl-l-methionine (SAM) enzyme from Streptomyces venezuelae, catalyzes the deamination of TDP-4-amino-4,6-dideoxy-D-glucose to TDP-3-keto-4,6-dideoxy-D-glucose in the desosamine biosynthetic pathway. DesII can also catalyze the dehydrogenation of TDP-D-quinovose to the corresponding 3-keto sugar. Similar to other radical SAM enzymes, DesII catalysis has been proposed to proceed via a radical mechanism. This hypothesis is now confirmed by EPR spectroscopy with the detection of a TDP-D-quinovose radical intermediate having a g-value of 2.0025 with hyperfine coupling to two spin 1/2 nuclei, each with a splitting constant of 33.6 G. A significant decrease in the EPR line width is observed when the radical is generated in reactions conducted in D(2)O versus H(2)O. These results are consistent with a C3 α-hydroxyalkyl radical in which the p-orbital harboring the unpaired electron spin at C3 is periplanar with the C-H bonds at both C2 and C4.
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Affiliation(s)
- Mark W Ruszczycky
- Division of Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, Austin, Texas 78712, USA
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28
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Chen Y, Yang Z, Guo CX, Ni CY, Li HX, Ren ZG, Lang JP. Using alcohols as alkylation reagents for 4-cyanopyridinium and N,N′-dialkyl-4,4′-bipyridinium and their one-dimensional iodoplumbates. CrystEngComm 2011. [DOI: 10.1039/c0ce00309c] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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29
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Ruszczycky MW, Choi SH, Liu HW. Stoichiometry of the redox neutral deamination and oxidative dehydrogenation reactions catalyzed by the radical SAM enzyme DesII. J Am Chem Soc 2010; 132:2359-69. [PMID: 20121093 DOI: 10.1021/ja909451a] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
DesII from Streptomyces venezuelae is a radical SAM (S-adenosyl-l-methionine) enzyme that catalyzes the deamination of TDP-4-amino-4,6-dideoxy-d-glucose to form TDP-3-keto-4,6-dideoxy-d-glucose in the biosynthesis of TDP-d-desosamine. DesII also catalyzes the dehydrogenation of the nonphysiological substrate TDP-D-quinovose to TDP-3-keto-6-deoxy-d-glucose. These properties prompted an investigation of how DesII handles SAM in the redox neutral deamination versus the oxidative dehydrogenation reactions. This work was facilitated by the development of an enzymatic synthesis of TDP-4-amino-4,6-dideoxy-d-glucose that couples a transamination equilibrium to the thermodynamically favorable oxidation of formate. In this study, DesII is found to consume SAM versus TDP-sugar with stoichiometries of 0.96 +/- 0.05 and 1.01 +/- 0.05 in the deamination and dehydrogenation reactions, respectively, using Na(2)S(2)O(4) as the reductant. Importantly, no significant change in stoichiometry is observed when the flavodoxin/flavodoxin NADP(+) oxidoreductase/NADPH reducing system is used in place of Na(2)S(2)O(4). Moreover, there is no evidence of an uncoupled or abortive process in the deamination reaction, as indicated by the observation that dehydrogenation can take place in the absence of an external source of reductant whereas deamination cannot. Mechanistic and biochemical implications of these results are discussed.
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Affiliation(s)
- Mark W Ruszczycky
- Division of Medicinal Chemistry, College of Pharmacy, and Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712, USA
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30
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Marsh ENG, Patterson DP, Li L. Adenosyl radical: reagent and catalyst in enzyme reactions. Chembiochem 2010; 11:604-21. [PMID: 20191656 PMCID: PMC3011887 DOI: 10.1002/cbic.200900777] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2009] [Indexed: 12/17/2022]
Abstract
Adenosine is undoubtedly an ancient biological molecule that is a component of many enzyme cofactors: ATP, FADH, NAD(P)H, and coenzyme A, to name but a few, and, of course, of RNA. Here we present an overview of the role of adenosine in its most reactive form: as an organic radical formed either by homolytic cleavage of adenosylcobalamin (coenzyme B(12), AdoCbl) or by single-electron reduction of S-adenosylmethionine (AdoMet) complexed to an iron-sulfur cluster. Although many of the enzymes we discuss are newly discovered, adenosine's role as a radical cofactor most likely arose very early in evolution, before the advent of photosynthesis and the production of molecular oxygen, which rapidly inactivates many radical enzymes. AdoCbl-dependent enzymes appear to be confined to a rather narrow repertoire of rearrangement reactions involving 1,2-hydrogen atom migrations; nevertheless, mechanistic insights gained from studying these enzymes have proved extremely valuable in understanding how enzymes generate and control highly reactive free radical intermediates. In contrast, there has been a recent explosion in the number of radical-AdoMet enzymes discovered that catalyze a remarkably wide range of chemically challenging reactions; here there is much still to learn about their mechanisms. Although all the radical-AdoMet enzymes so far characterized come from anaerobically growing microbes and are very oxygen sensitive, there is tantalizing evidence that some of these enzymes might be active in aerobic organisms including humans.
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Affiliation(s)
- E. Neil G. Marsh
- Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA
| | - Dustin P. Patterson
- Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA
| | - Lei Li
- Department of Chemistry and Chemical Biology, Indiana University – Purdue University Indianapolis, Indianapolis, IN 46202, USA
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31
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Chen Y, Wang ZO, Yang Z, Ren ZG, Li HX, Lang JP. Unique assembly of low-dimensional viologen iodoplumbates and their improved semiconducting properties. Dalton Trans 2010; 39:9476-9. [DOI: 10.1039/c0dt00757a] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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32
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Szu PH, Ruszczycky MW, Choi SH, Yan F, Liu HW. Characterization and mechanistic studies of DesII: a radical S-adenosyl-L-methionine enzyme involved in the biosynthesis of TDP-D-desosamine. J Am Chem Soc 2009; 131:14030-42. [PMID: 19746907 PMCID: PMC2780582 DOI: 10.1021/ja903354k] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
D-desosamine (1) is a 3-(N,N-dimethylamino)-3,4,6-trideoxyhexose found in a number of macrolide antibiotics including methymycin (2), neomethymycin (3), pikromycin (4), and narbomycin (5) produced by Streptomyces venezuelae . It plays an essential role in conferring biological activities to its parent aglycones. Previous genetic and biochemical studies of the biosynthesis of desosamine in S. venezuelae showed that the conversion of TDP-4-amino-4,6-dideoxy-D-glucose (8) to TDP-3-keto-4,6-dideoxy-D-glucose (9) is catalyzed by DesII, which is a member of the radical S-adenosyl-L-methionine (SAM) enzyme superfamily. Here, we report the purification and reconstitution of His(6)-tagged DesII, characterization of its [4Fe-4S] cluster using UV-vis and EPR spectroscopies, and the capability of flavodoxin, flavodoxin reductase, and NADPH to reduce the [4Fe-4S](2+) cluster. Also included are a steady-state kinetic analysis of DesII-catalyzed reaction and an investigation of the substrate flexibility of DesII. Studies of deuterium incorporation into SAM using TDP-[3-(2)H]-4-amino-4,6-dideoxy-D-glucose as the substrate provides strong evidence for direct hydrogen atom transfer to a 5'-deoxyadenosyl radical in the catalytic cycle. The fact that hydrogen atom abstraction occurs at C-3 also sheds light on the mechanism of this intriguing deamination reaction.
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Affiliation(s)
- Ping-Hui Szu
- Division of Medicinal Chemistry, College of Pharmacy, and Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712, USA
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33
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Abstract
Many bioactive compounds contain as part of their molecules one or more deoxysugar units. Their presence in the final compound is generally necessary for biological activity. These sugars derive from common monosaccharides, like d-glucose, which have lost one or more hydroxyl groups (monodeoxysugars, dideoxysugars, trideoxysugars) during their biosynthesis. These deoxysugars are transferred to the final molecule by the action of a glycosyltransferase. Here, we first summarize the different biosynthetic steps required for the generation of the different families of deoxysugars, including those containing extra methyl or amino groups, or tailoring modifications of the glycosylated compounds. We then give examples of several strategies for modification of the glycosylation pattern of a given bioactive compound: inactivation of genes involved in the biosynthesis of deoxysugars; heterologous expression of genes for the biosynthesis or transfer of a specific deoxysugar; and combinatorial biosynthesis (including the use of gene cassette plasmids). Finally, we report techniques for the isolation and detection of the new glycosylated derivatives generated using these strategies.
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Affiliation(s)
- Felipe Lombó
- Departamento de Biología Funcional and Instituto Universitario de Oncología del Principado de Asturias (I.U.O.P.A), Universidad de Oviedo, Oviedo, Spain
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34
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Thoden JB, Schäffer C, Messner P, Holden HM. Structural analysis of QdtB, an aminotransferase required for the biosynthesis of dTDP-3-acetamido-3,6-dideoxy-alpha-D-glucose. Biochemistry 2009; 48:1553-61. [PMID: 19178182 DOI: 10.1021/bi8022015] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
3-Acetamido-3,6-dideoxy-alpha-d-glucose or Quip3NAc is an unusual deoxyamino sugar found in the O-antigens of some Gram-negative bacteria and in the S-layers of Gram-positive bacteria. It is synthesized in these organisms as a dTDP-linked sugar via the action of five enzymes. The focus of this investigation is on QdtB from Thermoanaerobacterium thermosaccharolyticum E207-71, a PLP-dependent aminotransferase that catalyzes the penultimate step in the production of dTDP-Quip3NAc. For this analysis, the enzyme was crystallized in the presence of its product, dTDP-Quip3N, and the structure was solved and refined to 2.15 A resolution. QdtB is a dimer, and its overall fold places it into the well-characterized aspartate aminotransferase superfamily. Electron density corresponding to the bound product reveals the presence of a Schiff base between C-4' of the PLP cofactor and the amino nitrogen of the sugar. Those amino acid side chains involved in binding the dTDP-sugar into the active site include Tyr 183, His 309, and Tyr 310 from subunit 1 and Lys 219 from subunit 2. Notably there is a decided lack of interactions between the pyranosyl C-4' hydroxyl of the dTDP-sugar and the protein. In keeping with this observation, we show that QdtB can also turn over dTDP-3-acetamido-3,6-dideoxy-alpha-d-galactose. This investigation represents the first structural analysis of a sugar-modifying aminotransferase with a bound product in its active site that functions at the C-3' rather than the C-4' position of the hexose.
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Affiliation(s)
- James B Thoden
- Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706, USA
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35
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Abstract
Many biologically active bacterial natural products contain highly modified deoxysugar residues that are often critical for the activity of the parent compounds. Most of these deoxysugars are secondary metabolites that are biosynthesized in the form of nucleotide diphosphate (NDP) sugars prior to their transfer to natural product aglycones by glycosyltransferases. Over the past decade, many biosynthetic pathways that lead to the formation of these unusual sugars have been unraveled, and the mechanisms of many key enzymatic transformations involved in these pathways have been elucidated. However, obtaining workable quantities of NDP-deoxysugars for in vitro studies is often a difficult task. This limitation has hindered an in-depth investigation of the substrate specificity of deoxysugar biosynthetic enzymes, many of which are promiscuous with respect to their NDP-sugar substrates and are, thus, potentially useful catalysts for natural product glycoengineering. Presented in this review are procedures for the enzymatic synthesis and purification of a variety of NDP-deoxysugars, including some early intermediates in NDP-deoxysugar biosynthetic pathways, and highly modified NDP-deoxysugars that are late intermediates in their respective biosynthetic pathways. The procedures described herein could be used as general guidelines for the development of specific protocols for the synthesis of other NDP-deoxysugars.
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36
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Fukumoto K, Oya T, Itazaki M, Nakazawa H. N−CN Bond Cleavage of Cyanamides by a Transition-Metal Complex. J Am Chem Soc 2008; 131:38-9. [DOI: 10.1021/ja807896b] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Kozo Fukumoto
- Department of Chemistry, Graduate School of Science, Osaka City University, Sumiyoshi-ku, Osaka 558-8585, Japan
| | - Tsukuru Oya
- Department of Chemistry, Graduate School of Science, Osaka City University, Sumiyoshi-ku, Osaka 558-8585, Japan
| | - Masumi Itazaki
- Department of Chemistry, Graduate School of Science, Osaka City University, Sumiyoshi-ku, Osaka 558-8585, Japan
| | - Hiroshi Nakazawa
- Department of Chemistry, Graduate School of Science, Osaka City University, Sumiyoshi-ku, Osaka 558-8585, Japan
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37
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Thibodeaux C, Melançon C, Liu HW. Biosynthese von Naturstoffzuckern und enzymatische Glycodiversifizierung. Angew Chem Int Ed Engl 2008. [DOI: 10.1002/ange.200801204] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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38
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Timmons SC, Thorson JS. Increasing carbohydrate diversity via amine oxidation: aminosugar, hydroxyaminosugar, nitrososugar, and nitrosugar biosynthesis in bacteria. Curr Opin Chem Biol 2008; 12:297-305. [PMID: 18424273 PMCID: PMC2517148 DOI: 10.1016/j.cbpa.2008.03.017] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2008] [Revised: 03/19/2008] [Accepted: 03/19/2008] [Indexed: 12/14/2022]
Abstract
Bacterial secondary metabolites often contain carbohydrate attachments that play a significant role in conferring biological activity. A small proportion of these bioactive sugars are derived from aminosugar oxidation to ultimately provide hydroxyaminosugars, nitrososugars, and nitrosugars. Recent advances in the elucidation of hydroxyaminosugar-, nitrososugar-, and nitrosugar-containing natural product gene clusters have enabled the proposal of biosynthetic pathways, the in vitro characterization of aminosugar oxidases, and the structure determination of key enzymes. This article focuses upon the key enzymatic transformations in aminosugar, hydroxyaminosugar, nitrososugar, and nitrosugar biosynthesis, as well as the unique chemical reactivity of alkoxyaminosugars, with a particular focus upon developments within the past two years.
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Affiliation(s)
- Shannon C. Timmons
- Laboratory for Biosynthetic Chemistry, Pharmaceutical Sciences Division, School of Pharmacy, University of Wisconsin-Madison, 777 Highland Avenue, Madison, Wisconsin 53705; University of Wisconsin National Cooperative Drug Discovery Group Program
| | - Jon S. Thorson
- Laboratory for Biosynthetic Chemistry, Pharmaceutical Sciences Division, School of Pharmacy, University of Wisconsin-Madison, 777 Highland Avenue, Madison, Wisconsin 53705; University of Wisconsin National Cooperative Drug Discovery Group Program
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39
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Abstract
The radical S-adenosylmethionine (SAM) superfamily currently comprises more than 2800 proteins with the amino acid sequence motif CxxxCxxC unaccompanied by a fourth conserved cysteine. The charcteristic three-cysteine motif nucleates a [4Fe-4S] cluster, which binds SAM as a ligand to the unique Fe not ligated to a cysteine residue. The members participate in more than 40 distinct biochemical transformations, and most members have not been biochemically characterized. A handful of the members of this superfamily have been purified and at least partially characterized. Significant mechanistic and structural information is available for lysine 2,3-aminomutase, pyruvate formate-lyase, coproporphyrinogen III oxidase, and MoaA required for molybdopterin biosynthesis. Biochemical information is available for spore photoproduct lyase, anaerobic ribonucleotide reductase activation subunit, lipoyl synthase, and MiaB involved in methylthiolation of isopentenyladenine-37 in tRNA. The radical SAM enzymes biochemically characterized to date have in common the cleavage of the [4Fe-4S](1 +) -SAM complex to [4Fe-4S](2 +)-Met and the 5' -deoxyadenosyl radical, which abstracts a hydrogen atom from the substrate to initiate a radical mechanism.
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Affiliation(s)
- Perry A Frey
- Department of Biochemistry, University of Madison, Wisconin-Madison, Wisconsin 53726, USA.
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40
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Hong L, Zhao Z, Melançon CE, Zhang H, Liu HW. In vitro characterization of the enzymes involved in TDP-D-forosamine biosynthesis in the spinosyn pathway of Saccharopolyspora spinosa. J Am Chem Soc 2008; 130:4954-67. [PMID: 18345667 DOI: 10.1021/ja0771383] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Forosamine (4-dimethylamino)-2,3,4,6-tetradeoxy-beta-D-threo-hexopyranose) is a highly deoxygenated sugar component of several important natural products, including the potent yet environmentally benign insecticide spinosyns. To study D-forosamine biosynthesis, the five genes (spnO, N, Q, R, and S) from the spinosyn gene cluster thought to be involved in the conversion of TDP-4-keto-6-deoxy-D-glucose to TDP-D-forosamine were cloned and heterologously expressed, and the corresponding proteins were purified and their activities examined in vitro. Previous work demonstrated that SpnQ functions as a pyridoxamine 5'-monophosphate (PMP)-dependent 3-dehydrase which, in the presence of the cellular reductase pairs ferredoxin/ferredoxin reductase or flavodoxin/flavodoxin reductase, catalyzes C-3 deoxygenation of TDP-4-keto-2,6-dideoxy-D-glucose. It was also established that SpnR functions as a transaminase which converts the SpnQ product, TDP-4-keto-2,3,6-trideoxy-D-glucose, to TDP-4-amino-2,3,4,6-tetradeoxy-D-glucose. The results presented here provide a full account of the characterization of SpnR and SpnQ and reveal that SpnO and SpnN functions as a 2,3-dehydrase and a 3-ketoreductase, respectively. These two enzymes act sequentially to catalyze C-2 deoxygenation of TDP-4-keto-6-deoxy-D-glucose to form the SpnQ substrate, TDP-4-keto-2,6-dideoxy-D-glucose. Evidence has also been obtained to show that SpnS functions as the 4-dimethyltransferase that converts the SpnR product to TDP-D-forosamine. Thus, the biochemical functions of the five enzymes involved in TDP-D-forosamine formation have now been fully elucidated. The steady-state kinetic parameters for the SpnQ-catalyzed reaction have been determined, and the substrate specificities of SpnQ and SpnR have been explored. The implications of this work for natural product glycodiversification and comparative mechanistic analysis of SpnQ and related NDP-sugar 3-dehydrases E1 and ColD are discussed.
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Affiliation(s)
- Lin Hong
- Division of Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, Austin, Texas 78712, USA
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41
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Thibodeaux CJ, Melançon CE, Liu HW. Natural-product sugar biosynthesis and enzymatic glycodiversification. Angew Chem Int Ed Engl 2008; 47:9814-59. [PMID: 19058170 PMCID: PMC2796923 DOI: 10.1002/anie.200801204] [Citation(s) in RCA: 320] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Many biologically active small-molecule natural products produced by microorganisms derive their activities from sugar substituents. Changing the structures of these sugars can have a profound impact on the biological properties of the parent compounds. This realization has inspired attempts to derivatize the sugar moieties of these natural products through exploitation of the sugar biosynthetic machinery. This approach requires an understanding of the biosynthetic pathway of each target sugar and detailed mechanistic knowledge of the key enzymes. Scientists have begun to unravel the biosynthetic logic behind the assembly of many glycosylated natural products and have found that a core set of enzyme activities is mixed and matched to synthesize the diverse sugar structures observed in nature. Remarkably, many of these sugar biosynthetic enzymes and glycosyltransferases also exhibit relaxed substrate specificity. The promiscuity of these enzymes has prompted efforts to modify the sugar structures and alter the glycosylation patterns of natural products through metabolic pathway engineering and enzymatic glycodiversification. In applied biomedical research, these studies will enable the development of new glycosylation tools and generate novel glycoforms of secondary metabolites with useful biological activity.
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Affiliation(s)
- Christopher J. Thibodeaux
- Division of Medicinal Chemistry, College of Pharmacy, and Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, TX. (USA), 78712
| | - Charles E. Melançon
- Division of Medicinal Chemistry, College of Pharmacy, and Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, TX. (USA), 78712
| | - Hung-wen Liu
- Division of Medicinal Chemistry, College of Pharmacy, and Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, TX. (USA), 78712
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42
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Schell U, Haydock SF, Kaja AL, Carletti I, Lill RE, Read E, Sheehan LS, Low L, Fernandez MJ, Grolle F, McArthur HAI, Sheridan RM, Leadlay PF, Wilkinson B, Gaisser S. Engineered biosynthesis of hybrid macrolide polyketides containing d-angolosamine and d-mycaminose moieties. Org Biomol Chem 2008; 6:3315-27. [DOI: 10.1039/b807914e] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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43
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Buckel W, Kratky C, Golding BT. Stabilisation of methylene radicals by cob(II)alamin in coenzyme B12 dependent mutases. Chemistry 2007; 12:352-62. [PMID: 16304645 DOI: 10.1002/chem.200501074] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Coenzyme B12 initiates radical chemistry in two types of enzymatic reactions, the irreversible eliminases (e.g., diol dehydratases) and the reversible mutases (e.g., methylmalonyl-CoA mutase). Whereas eliminases that use radical generators other than coenzyme B12 are known, no alternative coenzyme B12 independent mutases have been detected for substrates in which a methyl group is reversibly converted to a methylene radical. We predict that such mutases do not exist. However, coenzyme B12 independent pathways have been detected that circumvent the need for glutamate, beta-lysine or methylmalonyl-CoA mutases by proceeding via different intermediates. In humans the methylcitrate cycle, which is ostensibly an alternative to the coenzyme B12 dependent methylmalonyl-CoA pathway for propionate oxidation, is not used because it would interfere with the Krebs cycle and thereby compromise the high-energy requirement of the nervous system. In the diol dehydratases the 5'-deoxyadenosyl radical generated by homolysis of the carbon-cobalt bond of coenzyme B12 moves about 10 A away from the cobalt atom in cob(II)alamin. The substrate and product radicals are generated at a similar distance from cob(II)alamin, which acts solely as spectator of the catalysis. In glutamate and methylmalonyl-CoA mutases the 5'-deoxyadenosyl radical remains within 3-4 A of the cobalt atom, with the substrate and product radicals approximately 3 A further away. It is suggested that cob(II)alamin acts as a conductor by stabilising both the 5'-deoxyadenosyl radical and the product-related methylene radicals.
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Affiliation(s)
- Wolfgang Buckel
- Fachbereich Biologie, Philipps-Universität, 35032 Marburg, Germany.
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44
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Burgie ES, Thoden JB, Holden HM. Molecular architecture of DesV from Streptomyces venezuelae: a PLP-dependent transaminase involved in the biosynthesis of the unusual sugar desosamine. Protein Sci 2007; 16:887-96. [PMID: 17456741 PMCID: PMC2206644 DOI: 10.1110/ps.062711007] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Desosamine is a 3-(dimethylamino)-3,4,6-trideoxyhexose found in certain macrolide antibiotics such as the commonly prescribed erythromycin. Six enzymes are required for its biosynthesis in Streptomyces venezuelae. The focus of this article is DesV, which catalyzes the PLP-dependent replacement of a 3-keto group with an amino functionality in the fifth step of the pathway. For this study the three-dimensional structures of both the internal aldimine and the ketimine intermediate with glutamate were determined to 2.05 A resolution. DesV is a homodimer with each subunit containing 12 alpha-helical regions and 12 beta-strands that together form three layers of sheet. The structure of the internal aldimine demonstrates that the PLP-cofactor is held in place by residues contributed from both subunits (Asp 164 and Gln 167 from Subunit I and Tyr 221 and Asn 235 from Subunit II). When the ketimine intermediate is present in the active site, the loop defined by Gln 225 to Ser 228 from Subunit II closes down upon the active site. The structure of DesV is similar to another sugar-modifying enzyme referred to as PseC. This enzyme is involved in the biosynthesis of pseudaminic acid, which is a sialic acid-like nonulosonate found in the flagellin of Helicobacter pylori. In the case of PseC, however, the amino group is transferred to the C-4 rather than the C-3 position. Details concerning the structural analysis of DesV and a comparison of its molecular architecture to that of PseC are presented.
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Affiliation(s)
- E Sethe Burgie
- Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706, USA
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45
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Thibodeaux CJ, Melançon CE, Liu HW. Unusual sugar biosynthesis and natural product glycodiversification. Nature 2007; 446:1008-16. [PMID: 17460661 DOI: 10.1038/nature05814] [Citation(s) in RCA: 250] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The enzymes involved in the biosynthesis of carbohydrates and the attachment of sugar units to biological acceptor molecules catalyse an array of chemical transformations and coupling reactions. In prokaryotes, both common sugar precursors and their enzymatically modified derivatives often become substituents of biologically active natural products through the action of glycosyltransferases. Recently, researchers have begun to harness the power of these biological catalysts to alter the sugar structures and glycosylation patterns of natural products both in vivo and in vitro. Biochemical and structural studies of sugar biosynthetic enzymes and glycosyltransferases, coupled with advances in bioengineering methodology, have ushered in a new era of drug development.
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Affiliation(s)
- Christopher J Thibodeaux
- Institute for Cellular and Molecular Biology, 1 University Station A4810, University of Texas at Austin, Austin, Texas 78712, USA
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46
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Chung YS, Kim DH, Seo WM, Lee HC, Liou K, Oh TJ, Sohng JK. Enzymatic synthesis of dTDP-4-amino-4,6-dideoxy-D-glucose using GerB (dTDP-4-keto-6-deoxy-D-glucose aminotransferase). Carbohydr Res 2007; 342:1412-8. [PMID: 17532307 DOI: 10.1016/j.carres.2007.04.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2007] [Accepted: 04/11/2007] [Indexed: 11/27/2022]
Abstract
Over-expressed GerB (dTDP-4-keto-6-deoxy-d-glucose aminotransferase) of Streptomyces sp. GERI-155 was used in the enzymatic synthesis of dTDP-4-amino-4,6-dideoxy-D-glucose (2) from dTDP-4-keto-6-deoxy-D-glucose (1). [Carbohydrate structure: see text]. Five enzymes including dTMP kinase (TMK), acetate kinase (ACK), dTDP-glucose synthase (TGS), dTDP-glucose 4,6-dehydratase (DH), and dTDP-4-keto-6-deoxy-d-glucose aminotransferase (GerB) were used to synthesize 2 on a large scale from glucose-1-phosphate and TMP. A conversion yield of up to 57% was obtained by HPLC peak integration given a reaction time of 270min. After purification by two successive preparative HPLC systems, the final product was identified by HPLC and then analyzed by (1)H, (13)C, (1)H-(1)H COSY NMR spectrometry.
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Affiliation(s)
- Young Soo Chung
- Genechem Inc., 59-5 Jang-dong, Yuseong-gu, Daejeon 305-343, South Korea
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47
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Lee HY, Khosla C. Bioassay-guided evolution of glycosylated macrolide antibiotics in Escherichia coli. PLoS Biol 2007; 5:e45. [PMID: 17298179 PMCID: PMC1790958 DOI: 10.1371/journal.pbio.0050045] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2006] [Accepted: 12/13/2006] [Indexed: 11/19/2022] Open
Abstract
Macrolide antibiotics such as erythromycin are clinically important polyketide natural products. We have engineered a recombinant strain of Escherichia coli that produces small but measurable quantities of the bioactive macrolide 6-deoxyerythromycin D. Bioassay-guided evolution of this strain led to the identification of an antibiotic-overproducing mutation in the mycarose biosynthesis and transfer pathway that was detectable via a colony-based screening assay. This high-throughput assay was then used to evolve second-generation mutants capable of enhanced precursor-directed biosynthesis of macrolide antibiotics. The availability of a screen for macrolide biosynthesis in E. coli offers a fundamentally new approach in dissecting modular megasynthase mechanisms as well as engineering antibiotics with novel pharmacological properties.
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Affiliation(s)
- Ho Young Lee
- Department of Chemistry, Stanford University, Stanford, California, United States of America
| | - Chaitan Khosla
- Department of Chemistry, Stanford University, Stanford, California, United States of America
- Department of Chemical Engineering, Stanford University, Stanford, California, United States of America
- * To whom correspondence should be addressed. E-mail:
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48
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Melançon CE, Hong L, White JA, Liu YN, Liu HW. Characterization of TDP-4-keto-6-deoxy-D-glucose-3,4-ketoisomerase from the D-mycaminose biosynthetic pathway of Streptomyces fradiae: in vitro activity and substrate specificity studies. Biochemistry 2007; 46:577-90. [PMID: 17209568 PMCID: PMC2515277 DOI: 10.1021/bi061907y] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Deoxysugars are critical structural elements for the bioactivity of many natural products. Ongoing work on elucidating a variety of deoxysugar biosynthetic pathways has paved the way for manipulation of these pathways for the generation of structurally diverse glycosylated natural products. In the course of this work, the biosynthesis of d-mycaminose in the tylosin pathway of Streptomyces fradiae was investigated. Attempts to reconstitute the entire mycaminose biosynthetic machinery in a heterologous host led to the discovery of a previously overlooked gene, tyl1a, encoding an enzyme thought to convert TDP-4-keto-6-deoxy-d-glucose to TDP-3-keto-6-deoxy-d-glucose, a 3,4-ketoisomerization reaction in the pathway. Tyl1a has now been overexpressed, purified, and assayed, and its activity has been verified by product analysis. Incubation of Tyl1a and the C-3 aminotransferase TylB, the next enzyme in the pathway, produced TDP-3-amino-3,6-dideoxy-d-glucose, confirming that these two enzymes act sequentially. Steady state kinetic parameters of the Tyl1a-catalyzed reaction were determined, and the ability of Tyl1a and TylB to process a C-2 deoxygenated substrate and a CDP-linked substrate was also demonstrated. Enzymes catalyzing 3,4-ketoisomerization of hexoses represent a new class of enzymes involved in unusual sugar biosynthesis. The fact that Tyl1a exhibits a relaxed substrate specificity holds potential for future deoxysugar biosynthetic engineering endeavors.
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Affiliation(s)
- Charles E. Melançon
- Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712
| | - Lin Hong
- Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712
| | - Jessica A. White
- Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, Texas 78712
| | - Yung-nan Liu
- Division of Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, Austin, Texas 78712
| | - Hung-wen Liu
- Division of Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, Austin, Texas 78712
- Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712
- Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, Texas 78712
- To whom correspondence and reprint requests should be addressed. Phone: 512-232-7811, Fax: 512-471-2746. E-mail:
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49
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Rodríguez E, Peirú S, Carney JR, Gramajo H. In vivo characterization of the dTDP-D-desosamine pathway of the megalomicin gene cluster from Micromonospora megalomicea. MICROBIOLOGY-SGM 2006; 152:667-673. [PMID: 16514147 DOI: 10.1099/mic.0.28680-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In vivo reconstitution of the dTDP-D-desosamine pathway of the megalomicin gene cluster from Micromonospora megalomicea was achieved by expression of the genes in Escherichia coli. LC/MS/MS analysis of the dTDP-sugar intermediates produced by operons containing different sets of genes showed that production of dTDP-D-desosamine from dtdp-4-keto-6-deoxy-D-glucose requires only four biosynthetic steps, catalysed by MegCIV, MegCV, MegDII and MegDIII, and that MegCII is not involved. Instead, bioconversion studies demonstrated that MegCII is needed together with MegCIII to catalyse transfer of D-desosamine to 3-alpha-mycarosylerythronolide B.
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Affiliation(s)
- Eduardo Rodríguez
- Kosan Biosciences, Inc., 3832 Bay Center Place, Hayward, CA 94545, USA
- Microbiology Division, IBR (Instituto de Biología Molecular y Celular de Rosario), Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias, Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, (S2002LRK) Rosario, Argentina
| | - Salvador Peirú
- Microbiology Division, IBR (Instituto de Biología Molecular y Celular de Rosario), Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias, Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, (S2002LRK) Rosario, Argentina
| | - John R Carney
- Kosan Biosciences, Inc., 3832 Bay Center Place, Hayward, CA 94545, USA
| | - Hugo Gramajo
- Kosan Biosciences, Inc., 3832 Bay Center Place, Hayward, CA 94545, USA
- Microbiology Division, IBR (Instituto de Biología Molecular y Celular de Rosario), Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias, Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, (S2002LRK) Rosario, Argentina
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