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Dang TT, Harvey PJ, Chan LY, Huang Y, Kaas Q, Craik DJ. Mutagenesis of cyclotide Cter 27 exemplifies a robust folding strategy for bracelet cyclotides. Pept Sci (Hoboken) 2022. [DOI: 10.1002/pep2.24284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Tien T. Dang
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science The University of Queensland Brisbane Queensland
- Institute of Applied Materials Science Vietnam Academy of Science and Technology Ho Chi Minh City Australia
| | - Peta J. Harvey
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science The University of Queensland Brisbane Queensland
| | - Lai Yue Chan
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science The University of Queensland Brisbane Queensland
| | - Yen‐Hua Huang
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science The University of Queensland Brisbane Queensland
| | - Quentin Kaas
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science The University of Queensland Brisbane Queensland
| | - David J. Craik
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science The University of Queensland Brisbane Queensland
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Dang TT, Chan LY, Tombling BJ, Harvey PJ, Gilding EK, Craik DJ. In Planta Discovery and Chemical Synthesis of Bracelet Cystine Knot Peptides from Rinorea bengalensis. JOURNAL OF NATURAL PRODUCTS 2021; 84:395-407. [PMID: 33570395 DOI: 10.1021/acs.jnatprod.0c01065] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Cyclotides are plant-derived peptides that have attracted interest as biocides and scaffolds for the development of stable peptide therapeutics. Cyclotides are characterized by their cyclic backbone and cystine knot framework, which engenders them with remarkably high stability. This study reports the cystine knot-related peptidome of Rinorea bengalensis, a small rainforest tree in the Violaceae family that is distributed from Australia westward to India. Surprisingly, many more acyclic knotted peptides (acyclotides) were discovered than cyclic counterparts (cyclotides), with 32 acyclotides and 1 cyclotide sequenced using combined transcriptome and proteomic analyses. Nine acyclotides were isolated and screened against a panel of mammalian cell lines, showing they had the cytotoxic properties normally associated with cyclotide-like peptides. NMR analysis of the acyclotide ribes 21 and 22 and the cyclotide ribe 33 confirmed that these peptides contained the cystine knot structural motif. The bracelet-subfamily cyclotide ribe 33 was amenable to chemical synthesis in reasonable yield, an achievement that has long eluded previous attempts to synthetically produce bracelet cyclotides. Accordingly, ribe 33 represents an exciting new bracelet cyclotide scaffold that can be subject to chemical modification for future molecular engineering applications.
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Affiliation(s)
- Tien T Dang
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Lai Y Chan
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Benjamin J Tombling
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Peta J Harvey
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Edward K Gilding
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, QLD 4072, Australia
| | - David J Craik
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, QLD 4072, Australia
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Abstract
This Review explores the class of plant-derived macrocyclic peptides called cyclotides. We include an account of their discovery, characterization, and distribution in the plant kingdom as well as a detailed analysis of their sequences and structures, biosynthesis and chemical synthesis, biological functions, and applications. These macrocyclic peptides are around 30 amino acids in size and are characterized by their head-to-tail cyclic backbone and cystine knot motif, which render them to be exceptionally stable, with resistance to thermal or enzymatic degradation. Routes to their chemical synthesis have been developed over the past two decades, and this capability has facilitated a wide range of mutagenesis and structure-activity relationship studies. In turn, these studies have both led to an increased understanding of their mechanisms of action as well as facilitated a range of applications in agriculture and medicine, as ecofriendly crop protection agents, and as drug leads or scaffolds for pharmaceutical design. Our overall objective in this Review is to provide readers with a comprehensive overview of cyclotides that we hope will stimulate further work on this fascinating family of peptides.
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Affiliation(s)
- Simon J de Veer
- Institute for Molecular Bioscience , The University of Queensland , Brisbane , Queensland 4072 , Australia
| | - Meng-Wei Kan
- Institute for Molecular Bioscience , The University of Queensland , Brisbane , Queensland 4072 , Australia
| | - David J Craik
- Institute for Molecular Bioscience , The University of Queensland , Brisbane , Queensland 4072 , Australia
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Synthetic Cystine-Knot Miniproteins - Valuable Scaffolds for Polypeptide Engineering. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 917:121-44. [PMID: 27236555 DOI: 10.1007/978-3-319-32805-8_7] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Peptides with the cystine-knot architecture, often termed knottins, are promising scaffolds for biomolecular engineering. These unique molecules combine diverse bioactivities with excellent structural, thermal, and proteolytical stability. Being different in the composition and structure of their amino acid backbone, knottins share the same core element, namely cystine knot, which is built by six cysteine residues forming three disulfides upon oxidative folding. This motif ensures a notably rigid framework that highly tolerates both rational and combinatorial changes in the primary structure. Being accessible through recombinant production and total chemical synthesis, cystine-knot miniproteins can be endowed with novel bioactivities by variation of surface-exposed loops and incorporation of non-natural elements within their non-conserved regions towards the generation of tailor-made peptidic compounds. In this chapter the topology of cystine-knot peptides, their synthesis and applications for diagnostics and therapy is discussed.
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Cheneval O, Schroeder CI, Durek T, Walsh P, Huang YH, Liras S, Price DA, Craik DJ. Fmoc-based synthesis of disulfide-rich cyclic peptides. J Org Chem 2014; 79:5538-44. [PMID: 24918986 DOI: 10.1021/jo500699m] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Disulfide-rich cyclic peptides have exciting potential as leads or frameworks in drug discovery; however, their use is faced with some synthetic challenges, mainly associated with construction of the circular backbone and formation of the correct disulfides. Here we describe a simple and efficient Fmoc solid-phase peptide synthesis (SPPS)-based method for synthesizing disulfide-rich cyclic peptides. This approach involves SPPS on 2-chlorotrityl resin, cyclization of the partially protected peptide in solution, cleavage of the side-chain protecting groups, and oxidization of cysteines to yield the desired product. We illustrate this method with the synthesis of peptides from three different classes of cyclic cystine knot motif-containing cyclotides: Möbius (M), trypsin inhibitor (T), and bracelet (B). We show that the method is broadly applicable to peptide engineering, illustrated by the synthesis of two mutants and three grafted analogues of kalata B1. The method reduces the use of highly caustic and toxic reagents and is better suited for high-throughput synthesis than previously reported methods for producing disulfide-rich cyclic peptides, thus offering great potential to facilitate pharmaceutical optimization of these scaffolds.
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Affiliation(s)
- Olivier Cheneval
- Institute for Molecular Bioscience, The University of Queensland , Brisbane, 4072, QLD Australia
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Burman R, Gunasekera S, Strömstedt AA, Göransson U. Chemistry and biology of cyclotides: circular plant peptides outside the box. JOURNAL OF NATURAL PRODUCTS 2014; 77:724-36. [PMID: 24527877 DOI: 10.1021/np401055j] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Cyclotides stand out as the largest family of circular proteins of plant origin hitherto known, with more than 280 sequences isolated at peptide level and many more predicted from gene sequences. Their unusual stability resulting from the signature cyclic cystine knot (CCK) motif has triggered a broad interest in these molecules for potential therapeutic and agricultural applications. Since the time of the first cyclotide discovery, our laboratory in Uppsala has been engaged in cyclotide discovery as well as the development of protocols to isolate and characterize these seamless peptides. We have also developed methods to chemically synthesize cyclotides by Fmoc-SPPS, which are useful in protein grafting applications. In this review, experience in cyclotide research over two decades and the recent literature related to their structures, synthesis, and folding as well the recent proof-of-concept findings on their use as "epitope" stabilizing scaffolds are summarized.
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Affiliation(s)
- Robert Burman
- Division of Pharmacognosy, Department of Medicinal Chemistry, Uppsala University , Biomedical Centre, Box 574, SE-751 23 Uppsala, Sweden
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Cowper B, Craik DJ, Macmillan D. Making ends meet: chemically mediated circularization of recombinant proteins. Chembiochem 2013; 14:809-12. [PMID: 23559418 PMCID: PMC4016753 DOI: 10.1002/cbic.201300105] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Indexed: 01/16/2023]
Abstract
A selective N→S acyl transfer reaction facilitates semi-synthesis of the plant cyclotide kalata B1 from a linear precursor peptide of bacterial origin, through simple appendage of N-terminal cysteine and a thiol-labile C-terminal Gly-Cys motif. This constitutes the first synthesis of a ribosomally derived circular miniprotein, without recourse to protein splicing elements.
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Affiliation(s)
- Ben Cowper
- Department of Chemistry, University College London, Christopher Ingold Building20 Gordon Street, London, WC1H 0AJ (UK) E-mail:
| | - David J Craik
- Institute for Molecular Bioscience, University of QueenslandBrisbane, Queensland, 4072 (Australia)
| | - Derek Macmillan
- Department of Chemistry, University College London, Christopher Ingold Building20 Gordon Street, London, WC1H 0AJ (UK) E-mail:
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Avrutina O, Fittler H, Glotzbach B, Kolmar H, Empting M. Between two worlds: a comparative study on in vitro and in silico inhibition of trypsin and matriptase by redox-stable SFTI-1 variants at near physiological pH. Org Biomol Chem 2013; 10:7753-62. [PMID: 22903577 DOI: 10.1039/c2ob26162f] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
A comparative study on in vitro and in silico inhibition of trypsin and matriptase by derivatives of the sunflower trypsin inhibitor-1 at near physiological pH is reported. Besides wild-type bicyclic SFTI-1, monocyclic variants possessing native cystine as well as redox-stable triazolyl side-chain macrocyclization motifs were studied for the first time in matriptase inhibition assays. Interestingly, monocyclic SFTI-1[1,14] demonstrated higher potency against this pharmacologically relevant protease compared to its bicyclic counterpart. Structural analysis of binding/inhibition of investigated SFTI-1 derivatives was performed using a combination of molecular dynamics simulations and docking experiments. In silico data were in good accordance with in vitro results, indicating the importance of the terminal inhibitor regions for the affinity towards matriptase. Presented work gives new perspectives for the optimization of the SFTI-1 framework towards in vivo applications.
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Affiliation(s)
- Olga Avrutina
- Clemens-Schöpf Institute of Organic Chemistry and Biochemistry, Technische Universität Darmstadt, Petersenstr. 22, 64287 Darmstadt, Germany
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Chemical synthesis, backbone cyclization and oxidative folding of cystine-knot peptides: promising scaffolds for applications in drug design. Molecules 2012; 17:12533-52. [PMID: 23095896 PMCID: PMC6268209 DOI: 10.3390/molecules171112533] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2012] [Revised: 09/19/2012] [Accepted: 10/22/2012] [Indexed: 02/03/2023] Open
Abstract
Cystine-knot peptides display exceptional structural, thermal, and biological stability. Their eponymous motif consists of six cysteine residues that form three disulfide bonds, resulting in a notably rigid structural core. Since they highly tolerate either rational or combinatorial changes in their primary structure, cystine knots are considered to be promising frameworks for the development of peptide-based pharmaceuticals. Despite their relatively small size (two to three dozens amino acid residues), the chemical synthesis route is challenging since it involves critical steps such as head-to-tail cyclization and oxidative folding towards the respective bioactive isomer. Herein we describe the topology of cystine-knot peptides, their synthetic availability and briefly discuss potential applications of engineered variants in diagnostics and therapy.
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Making Ends Meet: Microwave-Accelerated Synthesis of Cyclic and Disulfide Rich Proteins Via In Situ Thioesterification and Native Chemical Ligation. Int J Pept Res Ther 2012; 19:43-54. [PMID: 23504256 PMCID: PMC3597280 DOI: 10.1007/s10989-012-9331-y] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/29/2012] [Indexed: 12/21/2022]
Abstract
The development of synthetic methodologies for cyclic peptides is driven by the discovery of cyclic peptide drug scaffolds such as the plant-derived cyclotides, sunflower trypsin inhibitor 1 (SFTI-1) and the development of cyclized conotoxins. Currently, the native chemical ligation reaction between an N-terminal cysteine and C-terminal thioester group remains the most robust method to obtain a head-to-tail cyclized peptide. Peptidyl thioesters are effectively generated by Boc SPPS. However, their generation is challenging using Fmoc SPPS because thioester linkers are not stable to repeated piperidine exposure during deprotection. Herein we describe a Fmoc-based protocol for synthesizing cyclic peptides adapted for microwave assisted solid phase peptide synthesis. The protocol relies on the linker Di-Fmoc-3,4-diaminobenzoic acid, and we demonstrate the use of Gly, Ser, Arg and Ile as C-terminal amino acids (using HBTU and HATU as coupling reagents). Following synthesis, an N-acylurea moiety is generated at the C-terminal of the peptide; the resin bound acylurea peptide is then deprotected and cleaved from the resin. The fully deprotected peptide undergoes thiolysis in aqueous buffer, generating the thioester in situ. Ultimately, the head-to-tail cyclized peptide is obtained via native chemical ligation. Two naturally occurring cyclic peptides, the prototypical Möbius cyclotide kalata B1 and SFTI-1 were synthesized efficiently, avoiding potential branching at the diamino linker, using the optimized protocol. In addition, we demonstrate the possibility to use the approach for the synthesis of long and synthetically challenging linear sequences, by the ligation of two truncated fragments of a 50-residue long plant defensin.
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Machado A, Fázio MA, Miranda A, Daffre S, Machini MT. Synthesis and properties of cyclic gomesin and analogues. J Pept Sci 2012; 18:588-98. [PMID: 22865764 DOI: 10.1002/psc.2439] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2011] [Revised: 07/06/2012] [Accepted: 07/09/2012] [Indexed: 11/11/2022]
Abstract
Gomesin (Gm) was the first antimicrobial peptide (AMP) isolated from the hemocytes of a spider, the Brazilian mygalomorph Acanthoscurria gomesiana. We have been studying the properties of this interesting AMP, which also displays anticancer, antimalarial, anticryptococcal and anti-Leishmania activities. In the present study, the total syntheses of backbone-cyclized analogues of Gm (two disulfide bonds), [Cys(Acm)(2,15)]-Gm (one disulfide bond) and [Thr(2,6,11,15),(D)-Pro(9)]-Gm (no disulfide bonds) were accomplished, and the impact of cyclization on their properties was examined. The consequence of simultaneous deletion of pGlu(1) and Arg(16) -Glu-Arg(18) -NH(2) on Gm antimicrobial activity and structure was also analyzed. The results obtained showed that the synthetic route that includes peptide backbone cyclization on resin was advantageous and that a combination of 20% DMSO/NMP, EDC/HOBt, 60 °C and conventional heating appears to be particularly suitable for backbone cyclization of bioactive peptides. The biological properties of the Gm analogues clearly revealed that the N-terminal amino acid pGlu(1) and the amidated C-terminal tripeptide Arg(16) -Glu-Arg(18) -NH(2) play a major role in the interaction of Gm with the target membranes. Moreover, backbone cyclization practically did not affect the stability of the peptides in human serum; it also did not affect or enhanced hemolytic activity, but induced selectivity and, in some cases, discrete enhancements of antimicrobial activity and salt tolerance. Because of its high therapeutic index, easy synthesis and lower cost, the [Thr(2,6,11,15),(D)-Pro(9)]-Gm analogue remains the best active Gm-derived AMP developed so far; nevertheless, its elevated instability in human serum may limit its therapeutic potential.
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Affiliation(s)
- Alessandra Machado
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, Brazil
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Zheng JS, Tang S, Guo Y, Chang HN, Liu L. Synthesis of Cyclic Peptides and Cyclic Proteins via Ligation of Peptide Hydrazides. Chembiochem 2012; 13:542-6. [DOI: 10.1002/cbic.201100580] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2011] [Indexed: 02/01/2023]
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Thorstholm L, Craik D. Discovery and applications of naturally occurring cyclic peptides. DRUG DISCOVERY TODAY. TECHNOLOGIES 2012; 9:e1-e70. [PMID: 24064240 DOI: 10.1016/j.ddtec.2011.07.005] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
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Pedersen SL, Tofteng AP, Malik L, Jensen KJ. Microwave heating in solid-phase peptide synthesis. Chem Soc Rev 2012; 41:1826-44. [DOI: 10.1039/c1cs15214a] [Citation(s) in RCA: 214] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Zheng JS, Chang HN, Shi J, Liu L. Chemical synthesis of a cyclotide via intramolecular cyclization of peptide O-esters. Sci China Chem 2011. [DOI: 10.1007/s11426-011-4434-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
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