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Bogart JW, Kramer NJ, Turlik A, Bleich RM, Catlin DS, Schroeder FC, Nair SK, Williamson RT, Houk KN, Bowers AA. Interception of the Bycroft-Gowland Intermediate in the Enzymatic Macrocyclization of Thiopeptides. J Am Chem Soc 2020; 142:13170-13179. [PMID: 32609512 DOI: 10.1021/jacs.0c05639] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Thiopeptides are a broad class of macrocyclic, heavily modified peptide natural products that are unified by the presence of a substituted, nitrogen-containing heterocycle core. Early work indicated that this core might be fashioned from two dehydroalanines by an enzyme-catalyzed aza-[4 + 2] cycloaddition to give a cyclic-hemiaminal intermediate. This common intermediate could then follow a reductive path toward a dehydropiperidine, as in the thiopeptide thiostrepton, or an aromatization path to yield the pyridine groups observed in many other thiopeptides. Although several of the enzymes proposed to perform this cycloaddition have been reconstituted, only pyridine products have been isolated and any hemiaminal intermediates have yet to be observed. Here, we identify the conditions and substrates that decouple the cycloaddition from subsequent steps and allow interception and characterization of this long hypothesized intermediate. Transition state modeling indicates that the key amide-iminol tautomerization is the major hurdle in an otherwise energetically favorable cycloaddition. An anionic model suggests that deprotonation and polarization of this amide bond by TbtD removes this barrier and provides a sufficient driving force for facile (stepwise) cycloaddition. This work provides evidence for a mechanistic link between disparate cyclases in thiopeptide biosynthesis.
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Affiliation(s)
- Jonathan W Bogart
- Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Nicholas J Kramer
- Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Aneta Turlik
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
| | - Rachel M Bleich
- Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Daniel S Catlin
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Frank C Schroeder
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Ithaca, New York 14853, United States
| | - Satish K Nair
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - R Thomas Williamson
- Department of Chemistry and Biochemistry, University of North Carolina Wilmington, Wilmington, North Carolina 28403, United States
| | - K N Houk
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
| | - Albert A Bowers
- Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States.,Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
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Burkhart BJ, Schwalen CJ, Mann G, Naismith JH, Mitchell DA. YcaO-Dependent Posttranslational Amide Activation: Biosynthesis, Structure, and Function. Chem Rev 2017; 117:5389-5456. [PMID: 28256131 DOI: 10.1021/acs.chemrev.6b00623] [Citation(s) in RCA: 134] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
With advances in sequencing technology, uncharacterized proteins and domains of unknown function (DUFs) are rapidly accumulating in sequence databases and offer an opportunity to discover new protein chemistry and reaction mechanisms. The focus of this review, the formerly enigmatic YcaO superfamily (DUF181), has been found to catalyze a unique phosphorylation of a ribosomal peptide backbone amide upon attack by different nucleophiles. Established nucleophiles are the side chains of Cys, Ser, and Thr which gives rise to azoline/azole biosynthesis in ribosomally synthesized and posttranslationally modified peptide (RiPP) natural products. However, much remains unknown about the potential for YcaO proteins to collaborate with other nucleophiles. Recent work suggests potential in forming thioamides, macroamidines, and possibly additional post-translational modifications. This review covers all knowledge through mid-2016 regarding the biosynthetic gene clusters (BGCs), natural products, functions, mechanisms, and applications of YcaO proteins and outlines likely future research directions for this protein superfamily.
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Affiliation(s)
| | | | - Greg Mann
- Biomedical Science Research Complex, University of St Andrews , BSRC North Haugh, St Andrews KY16 9ST, United Kingdom
| | - James H Naismith
- Biomedical Science Research Complex, University of St Andrews , BSRC North Haugh, St Andrews KY16 9ST, United Kingdom.,State Key Laboratory of Biotherapy, Sichuan University , Sichuan, China
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Abstract
Thiopeptides, or thiazolylpeptides, are a family of highly modified peptide antibiotics first discovered several decades ago. Dozens of thiopeptides have since been identified, but, until recently, the biosynthetic genes responsible for their production remained elusive. The biosynthetic systems for a handful of thiopeptide metabolites were identified in the first portion of 2009. The surprising finding that these metabolites arise from the enzymatic tailoring of a simple, linear, ribosomally-synthesized precursor peptide led to a renewed appreciation of the architectural complexity accessible by posttranslational modification. This recent progress toward understanding thiopeptide antibiotic biosynthesis benefits the discovery of novel thiopeptides by either directed screening techniques or by mining available microbial genome sequences. Furthermore, access to the biosynthetic machinery now opens an avenue to the biosynthetic engineering of thiopeptide analogs. This Highlight discusses the genetic and biochemical insights revealed by these initial reports of the biosynthetic gene clusters for thiopeptide metabolites.
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Affiliation(s)
- Chaoxuan Li
- School of Chemistry and Biochemistry and the Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
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4
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Latajka R, Jewginski M, Makowski M, Krezel A. Conformational studies of hexapeptides containing two dehydroamino acid residues in positions 3 and 5 in peptide chain. J Mol Struct 2008. [DOI: 10.1016/j.molstruc.2008.06.023] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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5
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Latajka R, Jewginski M, Makowski M, Krezel A, Paluch S. Conformational studies of hexapeptides containing two dehydroamino acid residues in positions 2 and 5 in peptide chain. Biopolymers 2008; 89:691-9. [DOI: 10.1002/bip.20994] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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6
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Affiliation(s)
- Mark C Bagley
- School of Chemistry, Main Building, Cardiff University, Park Place, Cardiff, CF10 3AT, Wales, United Kingdom.
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Dey S, Vijayaraghavan R, Goel V, Kumar S, Kumar P, Singh T. Design rules for peptides with α, β-dehydro-residues: synthesis of a model peptide Boc-Ile-ΔAla-OCH3 and its crystal structures obtained from two different solvents. J Mol Struct 2005. [DOI: 10.1016/j.molstruc.2004.10.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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8
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Okeley NM, Zhu Y, van Der Donk WA. Facile chemoselective synthesis of dehydroalanine-containing peptides. Org Lett 2000; 2:3603-6. [PMID: 11073655 DOI: 10.1021/ol006485d] [Citation(s) in RCA: 133] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Useful methodology is described for the synthesis of dehydroalanine residues (II) within peptides. The unnatural amino acid (Se)-phenylselenocysteine (I) can be incorporated into growing peptide chains via standard peptide synthesis procedures. Subsequent oxidative elimination affords a dehydroalanine at the desired position. The oxidation conditions are mild and tolerate functionalities commonly found in peptides, including variously protected cysteine residues. To illustrate its utility, cyclic lanthionines have been synthesized by this method.
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Affiliation(s)
- N M Okeley
- Department of Chemistry, University of Illinois, Urbana, Illinois 61801, USA
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9
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Berg M, Chasse G, Deretey E, Füzéry A, Fung B, Fung D, Henry-Riyad H, Lin A, Mak M, Mantas A, Patel M, Repyakh I, Staikova M, Salpietro S, Tang TH, Vank J, Perczel A, Csonka G, Farkas Ö, Torday L, Székely Z, Csizmadia I. Prospects in computational molecular medicine: a millennial mega-project on peptide folding. ACTA ACUST UNITED AC 2000. [DOI: 10.1016/s0166-1280(00)00448-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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10
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Sheppeck JE, Gauss CM, Chamberlin AR. Inhibition of the Ser-Thr phosphatases PP1 and PP2A by naturally occurring toxins. Bioorg Med Chem 1997; 5:1739-50. [PMID: 9354230 DOI: 10.1016/s0968-0896(97)00146-6] [Citation(s) in RCA: 133] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The okadaic acid class of naturally occurring toxins is a structurally diverse group of molecules that inhibit the protein phosphatases PP1 and PP2A. Studies providing information about the mode of binding between the toxins and the phosphatases contribute to an overall understanding of the signal transduction pathways in which the phosphatases are involved.
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Affiliation(s)
- J E Sheppeck
- Department of Chemistry, University of California at Irvine 92697, USA
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Abstract
Dimethyl sulfomycinamate (1), a methanolysis product from the natural antibiotic sulfomycin I, is synthesized in 11 steps (Scheme 19). The chemistry of various pyridine, thiazole, and oxazole heterocycles and their coupling reactions under palladium catalysis are examined. The key transformations in the synthesis are the selective palladium-catalyzed coupling reactions on doubly activated pyridine 62 and the condensation reaction between bromo ketone 69 and amide 28 to form the oxazole moiety 76. The first preparation of oxazole triflates is described, as are some of their chemical properties.
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Affiliation(s)
- T. Ross Kelly
- Department of Chemistry, E. F. Merkert Chemistry Center, Boston College, Chestnut Hill, Massachusetts 02167
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12
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Blettner C, Bradley M. Asparagine as a masked dehydroalanine residue in solid phase peptide synthesis. Tetrahedron Lett 1994. [DOI: 10.1016/0040-4039(94)85082-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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13
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Luukkainen R, Sivonen K, Namikoshi M, Färdig M, Rinehart KL, Niemelä SI. Isolation and identification of eight microcystins from thirteen Oscillatoria agardhii strains and structure of a new microcystin. Appl Environ Microbiol 1993; 59:2204-9. [PMID: 8357254 PMCID: PMC182258 DOI: 10.1128/aem.59.7.2204-2209.1993] [Citation(s) in RCA: 90] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Microcystins (cyclic heptapeptide hepatotoxins), isolated from 13 freshwater Oscillatoria agardhii strains from eight different Finnish lakes by high-performance liquid chromatography, were characterized by amino acid analysis, fast atom bombardment mass spectrometry (FABMS), and tandem FABMS (FABMS/collisionary-induced dissociation/MS). All strains produced two to five different microcystins. In total, eight different compounds, of which five were known microcystins, were isolated. The known compounds identified were [D-Asp3]MCYST (microcystin)-LR, [Dha7]MCYST-LR, [D-Asp3]MCYST-RR, [Dha7]MCYST-RR, and [D-Asp3,Dha7]MCYST-RR. This is the first time that isolation of these toxins from Oscillatoria spp., with the exception of [D-Asp3]MCYST-RR, has been reported. Three of the strains produced a new microcystin, and the structure was assigned as [D-Asp3,Mser7]MCYST-RR. The structures of two new microcystins, produced as minor components by one Oscillatoria strain, could not be determined because of the small amounts isolated from the cells. Four strains produced [Dha7]MCYST-RR as the main toxin, but [D-Asp3]MCYST-RR was clearly the most abundant and most frequently occurring toxin among these isolates of O. agardhii.
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Affiliation(s)
- R Luukkainen
- Department of Applied Chemistry and Microbiology, University of Helsinki, Finland
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Stotts RR, Namikoshi M, Haschek WM, Rinehart KL, Carmichael WW, Dahlem AM, Beasley VR. Structural modifications imparting reduced toxicity in microcystins from Microcystis spp. Toxicon 1993; 31:783-9. [PMID: 8342176 DOI: 10.1016/0041-0101(93)90384-u] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
A cyanobacterial (blue-green algal) bloom containing Microcystis aeruginosa (dominant), M. viridis, and M. wesenbergii, was collected from Homer Lake (Illinois, U.S.A.) in the summer of 1988 and microcystins were isolated. One microcystin of substantially reduced toxicity was isolated, together with ten hepatotoxic microcystins. The compound with reduced toxicity was nonlethal at 1 mg/kg (i.p. mouse) and was determined to have a (C3H7O2) mono-ester of the alpha-carboxyl on the Glu unit of microcystin-LR. The other nine microcystins apart from MCLR had approximate LD50S ranging from 97 micrograms/kg to 750 micrograms/kg.
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Affiliation(s)
- R R Stotts
- Department of Veterinary Biosciences, University of Illinois, Urbana 61801
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Namikoshi M, Sivonen K, Evans WR, Carmichael WW, Sun F, Rouhiainen L, Luukkainen R, Rinehart KL. Two new L-serine variants of microcystins-LR and -RR from Anabaena sp. strains 202 A1 and 202 A2. Toxicon 1992; 30:1457-64. [PMID: 1485340 DOI: 10.1016/0041-0101(92)90521-6] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Two new microcystins, [L-Ser7]microcystin-LR (1) and [L-Ser7]microcystin-RR (2), were isolated from a filamentous fresh water cyanobacterium (blue-green alga), Anabaena sp. strain 202 A1, along with the two major toxins, [Dha7]microcystin-LR (3) and [Dha7]microcystin-RR (4) and their minor components the D-Asp variants [D-Asp3,Dha7]microcystin-LR (5) and [D-Asp3,Dha7]microcystin-RR (6). Anabaena sp. strain 202 A1 also produced another new toxin, whose structure is tentatively proposed as [D-Asp3,L-Ser7]microcystin-XR (7), where X is a leucine homologue. Anabaena sp. strain 202 A2 produced one new microcystin, 1, and three known microcystins, 3, 4, and 5. The structures of the toxins were assigned based on their amino acid analyses, and fast atom bombardment mass spectrometry data.
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Affiliation(s)
- M Namikoshi
- Roger Adams Laboratory, University of Illinois, Urbana 61801
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Gavaret J, Nunez J, Cahnmann H. Formation of dehydroalanine residues during thyroid hormone synthesis in thyroglobulin. J Biol Chem 1980. [DOI: 10.1016/s0021-9258(19)70782-0] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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