1
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Huang YH, Jiang Z, Du Q, Yap K, Bigot A, Kaas Q, Wang CK, Craik DJ. Scanning mutagenesis identifies residues that improve the long-term stability and insecticidal activity of cyclotide kalata B1. J Biol Chem 2024; 300:105682. [PMID: 38272233 PMCID: PMC10877628 DOI: 10.1016/j.jbc.2024.105682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2023] [Revised: 01/13/2024] [Accepted: 01/17/2024] [Indexed: 01/27/2024] Open
Abstract
Cyclotides are plant-derived disulfide-rich cyclic peptides that have a natural function in plant defense and potential for use as agricultural pesticides. Because of their highly constrained topology, they are highly resistant to thermal, chemical, or enzymatic degradation. However, the stability of cyclotides at alkaline pH for incubation times of longer than a few days is poorly studied but important since these conditions could be encountered in the environment, during storage or field application as insecticides. In this study, kalata B1 (kB1), the prototypical cyclotide, was engineered to improve its long-term stability and retain its insecticidal activity via point mutations. We found that substituting either Asn29 or Gly1 to lysine or leucine increased the stability of kB1 by twofold when incubated in an alkaline buffer (pH = 9.0) for 7 days, while retaining its insecticidal activity. In addition, when Gly1 was replaced with lysine or leucine, the mutants could be cyclized using an asparaginyl endopeptidase, in vitro with a yield of ∼90% within 5 min. These results demonstrate the potential to manufacture kB1 mutants with increased stability and insecticidal activity recombinantly or in planta. Overall, the discovery of mutants of kB1 that have enhanced stability could be useful in leading to longer term activity in the field as bioinsecticides.
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Affiliation(s)
- 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, Australia
| | - Zhihao Jiang
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Queensland, Australia
| | - Qingdan Du
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Queensland, Australia
| | - Kuok Yap
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Queensland, Australia
| | | | - 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, Australia
| | - Conan K Wang
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Queensland, 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, Queensland, Australia.
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2
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Dang TT, Tran TTT, Tran GH, Pham SH, Nguyen THN. Cyclotides derived from Viola dalatensis Gagnep: A novel approach for enrichment and evaluation of antimicrobial activity. Toxicon 2024; 239:107606. [PMID: 38181837 DOI: 10.1016/j.toxicon.2024.107606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Revised: 12/25/2023] [Accepted: 01/03/2024] [Indexed: 01/07/2024]
Abstract
Cyclotides, plant-derived cysteine-rich peptides, exhibit a wide range of beneficial biological activities and possess exceptional structural stability. Cyclotides are commonly distributed throughout the Violaceae family. Viola dalatensis Gagnep, a Vietnamese species, has not been well studied, especially for cyclotides. This pioneering research explores cyclotides from V. dalatensis as antimicrobials. This study used a novel approach to enhance cyclotides after extraction. The approach combined 30% ammonium sulfate salt precipitation and RP-HPLC. A comprehensive analysis was performed to ascertain the overall protein content, flavonoids content, polyphenol content, and free radical scavenging capacity of compounds derived from V. dalatensis. Six known cyclotides were sequenced utilizing MS tandem. Semi-purified cyclotide mixtures (M1, M2, and M3) exhibited antibacterial efficacy against Bacillus subtilis (inhibitory diameters: 19.67-23.50 mm), Pseudomonas aeruginosa (22.17-23.50 mm), and Aspergillus flavus (14.67-21.33 mm). The enriched cyclotide precipitate from the stem extract demonstrated a minimum inhibitory concentration (MIC) of 0.08 mg/mL against P. aeruginosa, showcasing significant antibacterial effectiveness compared to the stem extract (MIC: 12.50 mg/mL). Considerable advancements have been achieved in the realm of cyclotides, specifically in their application as antimicrobial agents.
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Affiliation(s)
- Tien T Dang
- Institute of Applied Materials Science, Vietnam Academy of Science and Technology, 1B TL29, District 12, Ho Chi Minh City, Viet Nam.
| | - Tam T T Tran
- Institute of Applied Materials Science, Vietnam Academy of Science and Technology, 1B TL29, District 12, Ho Chi Minh City, Viet Nam
| | - Gia-Hoa Tran
- Institute of Applied Materials Science, Vietnam Academy of Science and Technology, 1B TL29, District 12, Ho Chi Minh City, Viet Nam
| | - Son H Pham
- Institute of Applied Materials Science, Vietnam Academy of Science and Technology, 1B TL29, District 12, Ho Chi Minh City, Viet Nam
| | - Tuan H N Nguyen
- Biomedical Research Center, Pham Ngoc Thach University of Medicine, Viet Nam; Department of Medical Biochemistry & Molecular Biology, Pham Ngoc Thach University of Medicine, Viet Nam
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3
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Eteme ON, Zondegoumba EN, Tadayozzi YS, Serafim JA, Leite WQ, de Freitas Genari Severino M, Vicente EF. Methods for extraction, isolation and sequencing of cyclotides and others cyclic peptides with anti-helminthic activities: An overview. Parasitol Int 2024; 98:102808. [PMID: 37717651 DOI: 10.1016/j.parint.2023.102808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Revised: 08/21/2023] [Accepted: 09/07/2023] [Indexed: 09/19/2023]
Abstract
The mortality rate caused by parasitic worms on their hosts is of great concern and studies have been carried out to find molecules to reduce the prevalence, host-parasite interaction, and resistance of parasites to treatments. Existing drugs on the market are very often toxic and have many side effects, hence the need to find new, more active molecules. It has been demonstrated in several works that medicinal plants constitute a wide range of new molecules that can solve this problem. Several works have already been able to demonstrate that cyclic peptides of plant origin have shown good activity in the fight against different types of helminths. Therefore, this review aims to provide a general overview of the methods and techniques of extraction, isolation, activities and mechanisms of action of cyclotides and other cyclic peptides for application in the treatment of helminthic infections.
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Affiliation(s)
- Olivier Ndogo Eteme
- São Paulo State University (UNESP), School of Sciences and Engineering, Tupã, São Paulo 17602-496, Brazil; University of Yaounde I, Faculty of Science, Department of Organic Chemistry, PO. BOX 812, Cameroon.
| | | | - Yasmin Saegusa Tadayozzi
- São Paulo State University (UNESP), School of Sciences and Engineering, Tupã, São Paulo 17602-496, Brazil
| | - Jessica Aparecida Serafim
- São Paulo State University (UNESP), School of Sciences and Engineering, Tupã, São Paulo 17602-496, Brazil
| | - Wendell Queiroz Leite
- São Paulo State University (UNESP), School of Agricultural and Veterinarian Sciences, Jaboticabal 14884-900, Brazil
| | | | - Eduardo Festozo Vicente
- São Paulo State University (UNESP), School of Sciences and Engineering, Tupã, São Paulo 17602-496, Brazil.
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4
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Philippe GJB, Huang YH, Mittermeier A, Brown CJ, Kaas Q, Ramlan SR, Wang CK, Lane D, Loewer A, Troeira Henriques S, Craik DJ. Delivery to, and Reactivation of, the p53 Pathway in Cancer Cells Using a Grafted Cyclotide Conjugated with a Cell-Penetrating Peptide. J Med Chem 2024; 67:1197-1208. [PMID: 38174919 DOI: 10.1021/acs.jmedchem.3c01682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Peptides are promising drug modalities that can modulate protein-protein interactions, but their application is hampered by their limited ability to reach intracellular targets. Here, we improved the cytosolic delivery of a peptide blocking p53:MDM2/X interactions using a cyclotide as a stabilizing scaffold. We applied several design strategies to improve intracellular delivery and found that the conjugation of the lead cyclotide to the cyclic cell-penetrating peptide cR10 was the most effective. Conjugation allowed cell internalization at micromolar concentration and led to elevated intracellular p53 levels in A549, MCF7, and MCF10A cells, as well as inducing apoptosis in A549 cells without causing membrane disruption. The lead peptide had >35-fold improvement in inhibitory activity and increased cellular uptake compared to a previously reported cyclotide p53 activator. In summary, we demonstrated the delivery of a large polar cyclic peptide in the cytosol and confirmed its ability to modulate intracellular protein-protein interactions involved in cancer.
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Affiliation(s)
- Grégoire Jean-Baptiste Philippe
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Queensland 4072, Australia
- School of Biomedical Sciences, Queensland University of Technology, Translational Research Institute, Brisbane, Queensland 4102, Australia
| | - 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 4072, Australia
| | - Anna Mittermeier
- Department of Biology, Technical University Darmstadt, 64287 Darmstadt, Germany
| | - Christopher J Brown
- Institute of Molecular and Cell Biology (IMCB), Agency for Science, Technology and Research (A*STAR), 61 Biopolis Drive, Proteos, Singapore 138673, Singapore
| | - 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 4072, Australia
| | - Siti Radhiah Ramlan
- Institute of Molecular and Cell Biology (IMCB), Agency for Science, Technology and Research (A*STAR), 61 Biopolis Drive, Proteos, Singapore 138673, Singapore
| | - Conan K Wang
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - David Lane
- Institute of Molecular and Cell Biology (IMCB), Agency for Science, Technology and Research (A*STAR), 61 Biopolis Drive, Proteos, Singapore 138673, Singapore
| | - Alexander Loewer
- Department of Biology, Technical University Darmstadt, 64287 Darmstadt, Germany
| | - Sónia Troeira Henriques
- School of Biomedical Sciences, Queensland University of Technology, Translational Research Institute, Brisbane, Queensland 4102, 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, Queensland 4072, Australia
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5
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Chaudhuri D, Lu T, Jacob B, Abraham S, Shankar P, Poss MA, Neamati N, Camarero JA. Lipidation of a bioactive cyclotide-based CXCR4 antagonist greatly improves its pharmacokinetic profile in vivo. J Control Release 2023; 359:26-32. [PMID: 37236320 PMCID: PMC10527528 DOI: 10.1016/j.jconrel.2023.05.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 04/28/2023] [Accepted: 05/18/2023] [Indexed: 05/28/2023]
Abstract
The CXCR4 chemokine is a key molecular regulator of many biological functions controlling leukocyte functions during inflammation and immunity, and during embryonic development. Overexpression of CXCR4 is also associated with many types of cancer where its activation promotes angiogenesis, tumor growth/survival, and metastasis. In addition, CXCR4 is involved in HIV replication, working as a co-receptor for viral entry, making CXCR4 a very attractive target for developing novel therapeutic agents. Here we report the pharmacokinetic profile in rats of a potent CXCR4 antagonist cyclotide, MCo-CVX-5c, previously developed in our group that displayed a remarkable in vivo resistance to biological degradation in serum. This bioactive cyclotide, however, was rapidly eliminated through renal clearance. Several lipidated versions of cyclotide MCo-CVX-5c showed a significant increase in the half-life when compared to the unlipidated form. The palmitoylated version of cyclotide MCo-CVX-5c displayed similar CXCR4 antagonistic activity as the unlipidated cyclotide, while the cyclotide modified with octadecanedioic (18-oxo-octadecanoic) acid exhibited a remarkable decrease in its ability to antagonize CXCR4. Similar results were also obtained when tested for its ability to inhibit growth in two cancer cell lines and HIV infection in cells. These results show that the half-life of cyclotides can be improved by lipidation although it can also affect their biological activity depending on the lipid employed.
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Affiliation(s)
- Dipankar Chaudhuri
- Department of Pharmacology and Pharmaceutical Sciences, Alfred E. Mann School of Pharmacy and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Tiangong Lu
- Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, Ann Arbor, MI 48109-2800, USA
| | - Binu Jacob
- Department of Pharmacology and Pharmaceutical Sciences, Alfred E. Mann School of Pharmacy and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Sojan Abraham
- Department of Biomedical Sciences, Center of Excellence in Infectious Disease, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center, El Paso, TX 79430, USA
| | - Premlata Shankar
- Department of Biomedical Sciences, Center of Excellence in Infectious Disease, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center, El Paso, TX 79430, USA
| | - Michael A Poss
- Bristol Myers Squibb Research and Development, P.O. Box 4000, Princeton, NJ 08543, USA
| | - Nouri Neamati
- Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, Ann Arbor, MI 48109-2800, USA
| | - Julio A Camarero
- Department of Pharmacology and Pharmaceutical Sciences, Alfred E. Mann School of Pharmacy and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90089, USA; Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, CA9033, USA.
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6
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Bajpai A, Jackson MA, Huang YH, Yap K, Du Q, Chau TCY, Craik DJ, Gilding EK. Nematicidal Activity of Cyclotides: Toxicity Against Caenorhabditis elegans. J Nat Prod 2023; 86:1222-1229. [PMID: 37099442 DOI: 10.1021/acs.jnatprod.2c01124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Cyclotides are a unique family of stable and cyclic mini-proteins found in plants that have nematicidal and anthelmintic activities. They are distributed across the Rubiaceae, Violaceae, Fabaceae, Cucurbitaceae, and Solanaceae plant families, where they are posited to act as protective agents against pests. In this study, we tested the nematicidal properties of extracts from four major cyclotide-producing plants, Oldenlandia affinis, Clitoria ternatea, Viola odorata, and Hybanthus enneaspermus, against the free-living model nematode Caenorhabditis elegans. We evaluated the nematicidal activity of the cyclotides kalata B1, cycloviolacin O2, and hyen D present in these extracts and found them to be active against the larvae of C. elegans. Both the plant extracts and isolated cyclotides exerted dose-dependent toxicity on the first-stage larvae of C. elegans. Isolated cyclotides caused death or damage upon interacting with the worms' mouth, pharynx, and midgut or membrane. Cycloviolacin O2 and hyen D produced bubble-like structures around the C. elegans membrane, termed blebs, implicating membrane disruption causing toxicity and death. All tested cyclotides lost their toxicity when the hydrophobic patches present on them were disrupted via a single-point mutation. The present results provide a facile assay design to measure and explore the nematicidal activities of plant extracts and purified cyclotides on C. elegans.
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Affiliation(s)
- Abhishek Bajpai
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Mark A Jackson
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - 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 4072, Australia
| | - Kuok Yap
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Qingdan Du
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Tevin Chui-Ying Chau
- ACRF Cancer Biology Imaging Facility, Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland 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, Queensland 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, Queensland 4072, Australia
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7
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Fernández-Bobey A, Pinto MEF, de Almeida LC, de Souza BM, Dias NB, de Paula-Souza J, Cilli EM, Lopes NP, Costa-Lotufo LV, Palma MS, da Silva Bolzani V. Cytotoxic Cyclotides from Anchietea pyrifolia, a South American Plant Species. J Nat Prod 2022; 85:2127-2134. [PMID: 36044031 DOI: 10.1021/acs.jnatprod.1c01129] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Cyclotides are mini-proteins with potent bioactivities and outstanding potential for agricultural and pharmaceutical applications. More than 450 different plant cyclotides have been isolated from six angiosperm families. In Brazil, studies involving this class of natural products are still scarce, despite its rich floristic diversity. Herein were investigated the cyclotides from Anchietea pyrifolia roots, a South American medicinal plant from the family Violaceae. Fourteen putative cyclotides were annotated by LC-MS. Among these, three new bracelet cyclotides, anpy A-C, and the known cycloviolacins O4 (cyO4) and O17 (cyO17) were sequenced through a combination of chemical and enzymatic reactions followed by MALDI-MS/MS analysis. Their cytotoxic activity was evaluated by a cytotoxicity assay against three human cancer cell lines (colorectal carcinoma cells: HCT 116 and HCT 116 TP53-/- and breast adenocarcinoma, MCF 7). For all assays, the IC50 values of isolated compounds ranged between 0.8 and 7.3 μM. CyO17 was the most potent cyclotide for the colorectal cancer cell lines (IC50, 0.8 and 1.2 μM). Furthermore, the hemolytic activity of anpy A and B, cyO4, and cyO17 was assessed, and the cycloviolacins were the least hemolytic (HD50 > 156 μM). This work sheds light on the cytotoxic effects of the anpy cyclotides against cancer cells. Moreover, this study expands the number of cyclotides obtained to date from Brazilian plant biodiversity and adds one more genus containing these molecules to the list of the Violaceae family.
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Affiliation(s)
- Antonio Fernández-Bobey
- Nucleus of Bioassays, Biosynthesis, and Ecophysiology of Natural Products (NuBBE), Institute of Chemistry, Sao Paulo State University (UNESP), 14800-060, Araraquara, Sao Paulo, Brazil
- Department of Basic and Applied Biology, Laboratory of Structural Biology and Zoochemistry, Institute of Biosciences, Sao Paulo State University (UNESP), 13506-900, Rio Claro, Sao Paulo, Brazil
| | - Meri Emili Ferreira Pinto
- Nucleus of Bioassays, Biosynthesis, and Ecophysiology of Natural Products (NuBBE), Institute of Chemistry, Sao Paulo State University (UNESP), 14800-060, Araraquara, Sao Paulo, Brazil
| | - Larissa Costa de Almeida
- Department of Pharmacology, Institute of Biomedical Science, University of Sao Paulo (USP), 05508-900, Sao Paulo, Brazil
| | - Bibiana Monson de Souza
- Department of Basic and Applied Biology, Laboratory of Structural Biology and Zoochemistry, Institute of Biosciences, Sao Paulo State University (UNESP), 13506-900, Rio Claro, Sao Paulo, Brazil
| | - Nathalia Baptista Dias
- Scientific and Technological Bioresource Nucleus (BIOREN), University of The Frontier (UFRO), 4881-176, Temuco, Chile
| | - Juliana de Paula-Souza
- Department of Botany, Federal University of Santa Catarina (UFSC), 88040-535, Florianopolis, Santa Catarina, Brazil
| | - Eduardo Maffud Cilli
- Nucleus of Bioassays, Biosynthesis, and Ecophysiology of Natural Products (NuBBE), Institute of Chemistry, Sao Paulo State University (UNESP), 14800-060, Araraquara, Sao Paulo, Brazil
| | - Norberto Peporine Lopes
- Nucleus Research in Natural and Synthetic Products (NPPNS), Faculty of Pharmaceutical Sciences of Ribeirao Preto, University of Sao Paulo (USP), 14040-903, Ribeirao Preto, Sao Paulo, Brazil
| | - Leticia Veras Costa-Lotufo
- Department of Pharmacology, Institute of Biomedical Science, University of Sao Paulo (USP), 05508-900, Sao Paulo, Brazil
| | - Mario Sergio Palma
- Department of Basic and Applied Biology, Laboratory of Structural Biology and Zoochemistry, Institute of Biosciences, Sao Paulo State University (UNESP), 13506-900, Rio Claro, Sao Paulo, Brazil
| | - Vanderlan da Silva Bolzani
- Nucleus of Bioassays, Biosynthesis, and Ecophysiology of Natural Products (NuBBE), Institute of Chemistry, Sao Paulo State University (UNESP), 14800-060, Araraquara, Sao Paulo, Brazil
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Abstract
Glioblastoma multiforme (GBM) is the most aggressive cancer originating in the brain, with a median survival of 12 months. Most patients do not respond to or develop resistance to the only effective chemotherapeutic drug, temozolomide (TMZ), used to treat gliomas. Novel treatment methods are critically needed. Cyclotides are plant peptides that may be promising adjuvants to TMZ chemotherapy. They exhibit antitumor activity and chemosensitize cells to doxorubicin in breast cancer studies. During this research, we optimized cyclotide isolation techniques, and several cyclotides (CyO2, CyO13, kalata B1, and varv peptide A) exhibited dose-dependent cytotoxicity in MTT assays with IC50 values of 2.15-7.92 μM against human brain astrocytoma cells (U-87 MG) and human bone marrow derived neuroblastoma cells (SH-SY5Y). CyO2 and varv peptide A increased TMZ-induced cell death in U-87 MG cultures alone and when coexposed with CyO2 or varv peptide A plus TMZ. Phase contrast microscopy of glioblastoma cells exposed to cyclotides alone and coexposed to TMZ indicated shrunken, granular cells with blebbing, and the most pronounced effects were observed with coexposure treatments of cyclotides and TMZ. Cumulative results provide the proof-of-concept that cyclotides may enhance TMZ chemotherapy, and in vivo pharmacokinetic investigations of cyclotides are warranted with respect to GBM.
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Affiliation(s)
- Samantha L Gerlach
- Department of Biology, Dillard University, New Orleans, Louisiana 70122, United States
| | - Rachael A Dunlop
- Institute for Ethnomedicine, Brain Chemistry Laboratories, Box 3464, Jackson, Wyoming 83001, United States
| | - James S Metcalf
- Institute for Ethnomedicine, Brain Chemistry Laboratories, Box 3464, Jackson, Wyoming 83001, United States
| | - Sandra A Banack
- Institute for Ethnomedicine, Brain Chemistry Laboratories, Box 3464, Jackson, Wyoming 83001, United States
| | - Paul Alan Cox
- Institute for Ethnomedicine, Brain Chemistry Laboratories, Box 3464, Jackson, Wyoming 83001, United States
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9
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Ganesan R, Dughbaj MA, Ramirez L, Beringer S, Aboye TL, Shekhtman A, Beringer PM, Camarero JA. Engineered Cyclotides with Potent Broad in Vitro and in Vivo Antimicrobial Activity. Chemistry 2021; 27:12702-12708. [PMID: 34159664 PMCID: PMC8410672 DOI: 10.1002/chem.202101438] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Indexed: 12/18/2022]
Abstract
The search for novel antimicrobial agents to combat microbial pathogens is intensifying in response to the rapid development of drug resistance to current antibiotic therapeutics. Respiratory failure and septicemia are the leading causes of mortality among hospitalized patients. Here, the development of a novel engineered cyclotide with effective broad-spectrum antibacterial activity against several ESKAPE bacterial strains and clinical isolates is reported. The most active antibacterial cyclotide was extremely stable in serum, showed little hemolytic activity, and provided protection in vivo in a murine model of P. aeruginosa peritonitis. These results highlight the potential of the cyclotide scaffold for the development of novel antimicrobial therapeutic leads for the treatment of bacteremia.
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Affiliation(s)
- Rajasekaran Ganesan
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, CA 90033, USA
| | - Mansour A. Dughbaj
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, CA 90033, USA
- Department of Clinical Pharmacy, School of Pharmacy, University of Southern California, Los Angeles, CA 90033, USA
| | - Lisa Ramirez
- Department of Chemistry, State University of New York, Albany, NY 12222, USA
| | - Steven Beringer
- Department of Clinical Pharmacy, School of Pharmacy, University of Southern California, Los Angeles, CA 90033, USA
| | - Teshome L. Aboye
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, CA 90033, USA
| | - Alexander Shekhtman
- Department of Chemistry, State University of New York, Albany, NY 12222, USA
| | - Paul M. Beringer
- Department of Clinical Pharmacy, School of Pharmacy, University of Southern California, Los Angeles, CA 90033, USA
| | - Julio A. Camarero
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, CA 90033, USA
- Department of Clinical Pharmacy, School of Pharmacy, University of Southern California, Los Angeles, CA 90033, USA
- Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA90033, USA
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10
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Muratspahić E, Tomašević N, Nasrollahi-Shirazi S, Gattringer J, Emser FS, Freissmuth M, Gruber CW. Plant-Derived Cyclotides Modulate κ-Opioid Receptor Signaling. J Nat Prod 2021; 84:2238-2248. [PMID: 34308635 PMCID: PMC8406418 DOI: 10.1021/acs.jnatprod.1c00301] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Cyclotides are plant-derived disulfide-rich peptides comprising a cyclic cystine knot, which confers remarkable stability against thermal, proteolytic, and chemical degradation. They represent an emerging class of G protein-coupled receptor (GPCR) ligands. In this study, utilizing a screening approach of plant extracts and pharmacological analysis we identified cyclotides from Carapichea ipecacuanha to be ligands of the κ-opioid receptor (KOR), an attractive target for developing analgesics with reduced side effects and therapeutics for multiple sclerosis (MS). This prompted us to verify whether [T20K]kalata B1, a cyclotide in clinical development for the treatment of MS, is able to modulate KOR signaling. T20K bound to and fully activated KOR in the low μM range. We then explored the ability of T20K to allosterically modulate KOR. Co-incubation of T20K with KOR ligands resulted in positive allosteric modulation in functional cAMP assays by altering either the efficacy of dynorphin A1-13 or the potency and efficacy of U50,488 (a selective KOR agonist), respectively. In addition, T20K increased the basal response upon cotreatment with U50,488. In the bioluminescence resonance energy transfer assay T20K negatively modulated the efficacy of U50,488. This study identifies cyclotides capable of modulating KOR and highlights the potential of plant-derived peptides as an opportunity to develop cyclotide-based KOR modulators.
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Affiliation(s)
- Edin Muratspahić
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, 1090 Vienna, Austria
| | - Nataša Tomašević
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, 1090 Vienna, Austria
| | - Shahrooz Nasrollahi-Shirazi
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, 1090 Vienna, Austria
- Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center for Physiology and Pharmacology, Medical University of Vienna, 1090 Vienna, Austria
| | - Jasmin Gattringer
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, 1090 Vienna, Austria
| | - Fabiola Susanna Emser
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, 1090 Vienna, Austria
| | - Michael Freissmuth
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, 1090 Vienna, Austria
- Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center for Physiology and Pharmacology, Medical University of Vienna, 1090 Vienna, Austria
| | - Christian W Gruber
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, 1090 Vienna, Austria
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11
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Dang TT, Chan LY, Huang YH, Nguyen LTT, Kaas Q, Huynh T, Craik DJ. Exploring the Sequence Diversity of Cyclotides from Vietnamese Viola Species. J Nat Prod 2020; 83:1817-1828. [PMID: 32437150 DOI: 10.1021/acs.jnatprod.9b01218] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Viola is the largest genus in the Violaceae plant family and is known for its ubiquitous natural production of cyclotides. Many Viola species are used as medicinal herbs across Asia and are often consumed by humans in teas for the treatment of diseases, including ulcers and asthma. Previous studies reported the isolation of cyclotides from Viola species in many countries in the hope of discovering novel compounds with anti-cancer activities; however, Viola species from Vietnam have not been investigated to date. Here, the discovery of cyclotides from three Viola species (V. arcuata, V. tonkinensis, and V. austrosinensis) collected in the northern mountainous region of Vietnam is reported. Ten cyclotides were isolated from these three Viola species: four are novel and six were previously reported to be expressed in other plants. The structures of three of the new bracelet cyclotides are similar to that of cycloviolacin O2. Because cycloviolacin O2 has previously been shown to have potent activity against a wide range of cancer cell lines including HeLa (human cervical cancer cells) and PC-3 (human prostate cancer cells), the cancer cytotoxicity of the cyclotides isolated from V. arcuata was assessed. All tested cyclotides were cytotoxic against cancer cells, albeit to varying degrees. The sequences discovered in this study significantly expand the understanding of cyclotide diversity, especially in comparison with other cyclotides found in plants from the Asian region.
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Affiliation(s)
- Tien T Dang
- The Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Lai Y Chan
- The Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Yen-Hua Huang
- The Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Linh T T Nguyen
- The Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Quentin Kaas
- The Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Tien Huynh
- Department of Biosciences and Food Technology, RMIT University, Victoria 3001, Australia
| | - David J Craik
- The Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
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12
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Dancewicz K, Slazak B, Kiełkiewicz M, Kapusta M, Bohdanowicz J, Gabryś B. Behavioral and physiological effects of Viola spp. cyclotides on Myzus persicae (Sulz.). J Insect Physiol 2020; 122:104025. [PMID: 32059835 DOI: 10.1016/j.jinsphys.2020.104025] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 01/27/2020] [Accepted: 02/10/2020] [Indexed: 05/22/2023]
Abstract
Cyclotides are defense peptides produced by several plant families. Viola spp. (Violaceae) produce an array of cyclotides with varying biological activities. The peach potato aphid Myzus persicae (Sulz.) (Hemiptera: Aphididae) is a generalist that feeds on the secondary hosts of over 40 plant families, including Violaceae. The present work aimed to evaluate the activities of cycloviolacins from Viola odorata L. and V. ulignosa Besser (cyO2, cyO3, cyO13, cyO19) against M. persicae. To investigate the peptides' influence on aphid feeding behavior, we used 20% sucrose diets supplemented with cyclotides and measured the effects with electrical penetration graph (EPG) technique. We also applied anti-cyclotide antibodies and immunohistochemistry to track the peptides in the digestive systems of the aphids. Our study shows that cyclotides affect aphid probing and feeding behavior and limit their diet sap uptake. The cycloviolacin cyclotides: cyO13 (100 µM) and cyO19 (50 µM) most strongly impeded aphid ingestion activities when applied in sucrose diet. Sustained ingestion of the diet was blocked by 100 µM cyO13, and no aphid showed ingestion of the diet for longer than 10 min. Cyclotides were detected in the pharynx, in contact with the epipharyngeal gustatory organ, in the stomach (midgut) and upper intestine. The present study shows the deterrent activity of cycloviolacins on M. persicae. This activity may be related to the peptides' effects on epithelial cells and gustatory organs along the aphid digestive system. We demonstrate that cyclotides may play an important role in plant-aphid interactions.
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Affiliation(s)
- Katarzyna Dancewicz
- Department of Botany and Ecology, University of Zielona Góra, Szafrana 1, 65-516 Zielona Góra, Poland
| | - Blazej Slazak
- W. Szafer Institute of Botany, Polish Academy of Sciences, 46 Lubicz St., 31-512 Cracow, Poland; Pharmacognosy, Department of Medicinal Chemistry, Uppsala University, Biomedical Centre (BMC), Box 574, 751 23 Uppsala, Sweden.
| | - Małgorzata Kiełkiewicz
- Section of Applied Entomology, Institute of Horticultural Sciences, Warsaw University of Life Sciences-SGGW (WULS-SGGW), 159 Nowoursynowska, 02-776 Warsaw, Poland
| | - Małgorzata Kapusta
- Department of Plant Cytology and Embryology, Faculty of Biology, University of Gdańsk, 59 Wita Stwosza St., 80-308 Gdańsk, Poland
| | - Jerzy Bohdanowicz
- Department of Plant Cytology and Embryology, Faculty of Biology, University of Gdańsk, 59 Wita Stwosza St., 80-308 Gdańsk, Poland
| | - Beata Gabryś
- Department of Botany and Ecology, University of Zielona Góra, Szafrana 1, 65-516 Zielona Góra, Poland
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13
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Tammineni R, Gulati P, Kumar S, Mohanty A. An overview of acyclotides: Past, present and future. Phytochemistry 2020; 170:112215. [PMID: 31812106 DOI: 10.1016/j.phytochem.2019.112215] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2019] [Revised: 11/19/2019] [Accepted: 11/20/2019] [Indexed: 06/10/2023]
Abstract
Acyclotides are plant-based, acyclic miniproteins with cystine knot motif formed by three conserved disulfide linkages and lack head to tail ligation. Acyclotides may not necessarily be less stable, even though they lack cyclic backbone, as the conserved cystine knot feature provides the required stability. Violacin A was the first acyclotide, isolated from Viola odorata in 2006. Until now, acyclotides have been reported from five dicot families (Violaceae, Rubiaceae, Cucurbitaceae, Solanaceae, Fabaceae) and one monocot family (Poaceae). In Poaceae, only acyclotides have been found whereas in dicot families both cyclotides and acyclotides have been isolated. In last 15 years, several acyclotides with antimicrobial, cytotoxic and hemolytic bioactivities have been discovered. Thus, although many naturally expressed acyclotides do exhibit bioactivities, the linearization of the cyclic peptides may result in loss of bioactivities. Although, bioactivities of acyclotides are comparable to their cyclic counterparts, the numbers of isolated acyclotides are still few. Further, those discovered, have the scope to be screened for agriculturally important activities (insecticidal, anti-helminthic, molluscicidal) and pharmaceutical properties (anticancer, anti-HIV, immuno-stimulant). The feasibility of application of acyclotides is because of their relatively less complex biological synthesis compared to cyclotides, as the cyclization step is not needed. This attribute facilitates the production of transgenic crops and/or its expression in heterologous organisms, lacking cyclization machinery. Keeping in view the bioactivities and the wide array of emerging potential applications of acyclotides, the present review discusses their distribution in plants, gene and protein structure, biosynthesis, bioactivities and mechanism of action. Further, their potential applications and future perspectives to exploit them in agriculture and pharmaceutical industries have been highlighted.
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Affiliation(s)
- Ramya Tammineni
- Bioinformatics Infrastructure Facility, Gargi College, University of Delhi, India
| | - Pooja Gulati
- Department of Microbiology, Maharshi Dayanand University, Rohtak, Haryana, India
| | - Sanjay Kumar
- Department of Microbiology, Maharshi Dayanand University, Rohtak, Haryana, India
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14
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Labudda M, Różańska E, Prabucka B, Muszyńska E, Marecka D, Kozak M, Dababat AA, Sobczak M. Activity profiling of barley vacuolar processing enzymes provides new insights into the plant and cyst nematode interaction. Mol Plant Pathol 2020; 21:38-52. [PMID: 31605455 PMCID: PMC6913211 DOI: 10.1111/mpp.12878] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Vacuolar processing enzymes (VPEs) play an important role during regular growth and development and defence responses. Despite substantial attempts to understand the molecular basis of plant-cyst nematode interaction, the mechanism of VPEs functioning during this interaction remains unknown. The second-stage Heterodera filipjevi juvenile penetrates host roots and induces the formation of a permanent feeding site called a syncytium. To investigate whether infection with H. filipjevi alters plant host VPEs, the studies were performed in Hordeum vulgare roots and leaves on the day of inoculation and at 7, 14 and 21 days post-inoculation (dpi). Implementing molecular, biochemical and microscopic methods we identified reasons for modulation of barley VPE activity during interaction with H. filipjevi. Heterodera filipjevi parasitism caused a general decrease of VPE activity in infected roots, but live imaging of VPEs showed that their activity is up-regulated in syncytia at 7 and 14 dpi and down-regulated at 21 dpi. These findings were accompanied by tissue-specific VPE gene expression patterns. Expression of the barley cystatin HvCPI-4 gene was stimulated in leaves but diminished in roots upon infestation. External application of cyclotides that can be produced naturally by VPEs elicits in pre-parasitic juveniles vesiculation of their body, enhanced formation of granules, induction of exploratory behaviour (stylet thrusts and head movements), production of reactive oxygen species (ROS) and final death by methuosis. Taken together, down-regulation of VPE activity through nematode effectors promotes the nematode invasion rates and leads to avoidance of the induction of the plant proteolytic response and death of the invading juveniles.
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Affiliation(s)
- Mateusz Labudda
- Department of Biochemistry and Microbiology, Institute of BiologyWarsaw University of Life Sciences‐SGGWWarsawPoland
| | - Elżbieta Różańska
- Department of Botany, Institute of BiologyWarsaw University of Life Sciences‐SGGWWarsawPoland
| | - Beata Prabucka
- Department of Biochemistry and Microbiology, Institute of BiologyWarsaw University of Life Sciences‐SGGWWarsawPoland
| | - Ewa Muszyńska
- Department of Botany, Institute of BiologyWarsaw University of Life Sciences‐SGGWWarsawPoland
| | - Dorota Marecka
- Department of Biochemistry and Microbiology, Institute of BiologyWarsaw University of Life Sciences‐SGGWWarsawPoland
| | - Marcin Kozak
- Department of Botany, Institute of BiologyWarsaw University of Life Sciences‐SGGWWarsawPoland
| | - Abdelfattah A. Dababat
- International Maize and Wheat Improvement Center (CIMMYT)Soil Borne Pathogens ProgramP.K. 39 Emek06511AnkaraTurkey
| | - Mirosław Sobczak
- Department of Botany, Institute of BiologyWarsaw University of Life Sciences‐SGGWWarsawPoland
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15
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Abstract
The emergence of rapidly evolving multidrug-resistant pathogens and a deficit of new compounds entering the clinical pipeline necessitate the exploration of alternative sources of antimicrobial therapeutics. Cyclotides revealed in Viola spp. are a class of highly stable, cyclic, and disulfide-bound peptides with diverse intrinsic bioactivities. Herein we have identified a novel complement of 42 putative cyclotide masses in the plant species Viola inconspicua. Cyclotide-containing fractions of a V. inconspicua peptide library revealed potent bioactivities against the Gram-negative bacteria Escherichia coli ATCC 25922 and the highly virulent and multidrug-resistant Klebsiella pneumoniae VK148. As such, six previously uncharacterized cyclotides, cycloviolacins I1-6 (cyI1-cyI6), were prioritized for molecular characterization. Cyclotides cyI3-cyI6 contain a novel "TLNGNPGA" motif in the highly variable loop six region, expanding the already substantial sequence diversity of this peptide class. Library fractions comprised of cyclotides cyI3-cyI6 exhibited MIC values of 18 and 35 μM against E. coli and K. pneumoniae, respectively, whereas isolated cyI3 killed ∼50% of E. coli at 60 μM and isolated cyI4 demonstrated no killing at concentrations >60 μM against both pathogens. This work expands the repertoire of bioactive cyclotides found in Viola spp. and highlights the potential of these antibacterial cyclic peptides.
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Affiliation(s)
- Nicole C. Parsley
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Patric W. Sadecki
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Conrad J. Hartmann
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Leslie M. Hicks
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
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16
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Abstract
Macrocyclic peptides are a unique class of molecules that display a relatively constrained peptidic backbone as compared to their linear counterparts leading to the defined 3-D orientation of the constituent amino acids (pharmacophore). Although they are attractive candidates for lead discovery owing to the unique conformational features, their peptidic backbone is susceptible to proteolytic cleavage in various biological fluids that compromise their efficacy. In this chapter we review the various classical and contemporary chemical and biological approaches that have been utilized to combat the metabolic instability of macrocyclic peptides. We note that any chemical modification that helps in providing either local or global conformational rigidity to these macrocyclic peptides aids in improving their metabolic stability typically by slowing the cleavage kinetics by the proteases.
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Affiliation(s)
- Bhavesh Khatri
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, India
| | | | - Jayanta Chatterjee
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, India.
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17
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Narayani M, Sai Varsha MKN, Potunuru UR, Sofi Beaula W, Rayala SK, Dixit M, Chadha A, Srivastava S. Production of bioactive cyclotides in somatic embryos of Viola odorata. Phytochemistry 2018; 156:135-141. [PMID: 30292877 DOI: 10.1016/j.phytochem.2018.09.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Revised: 09/16/2018] [Accepted: 09/25/2018] [Indexed: 05/21/2023]
Abstract
Viola odorata L. (Violaceae), an Indian medicinal plant, contains a plethora of cyclotides, which are a class of cyclic peptides derived from plants, possessing several applications. Somatic embryo culture of V. odorata was developed, via indirect somatic embryogenesis, to serve as an alternative to natural plant biomass for sustainable and continuous production of its bioactive ingredients, such as cyclotides. Among the various combinations of phytohormones tested, Murashige and Skoog medium supplemented with 1 mg/l thidiazuron gave rise to the maximum frequency of induction (86.7%) and a high number of somatic embryos (3) from an embryogenic callus. Identification and characterization of cyclotides in the somatic embryos were carried out using a Fourier transform mass spectrometer coupled with liquid chromatography (LC-FTMS). Among the cyclotides identified in the study, few were found to be exclusively present in the somatic embryo culture. Furthermore, the relative abundance of the cyclotides was higher in somatic embryo extract than in the natural plant extract. The biological activities (cytotoxic, haemolytic and antimicrobial) of the somatic embryos and the parent plant were compared. Unlike the natural plants, the somatic embryo extracts demonstrated specificity i.e. they were found to be potent against cancerous cells but not against non-cancerous cell line or red blood cells. In contrast to the plant extract, the somatic embryos extracts were found to be potent against Escherichia coli and Staphylococcus aureus. These results suggest that somatic embryos of V. odorata (rich in cyclotides) can be used as an alternative to plant biomass for its therapeutic applications and germplasm conservation.
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Affiliation(s)
- M Narayani
- Department of Biotechnology, Bhupat & Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai-600 036, India
| | - M K N Sai Varsha
- Department of Biotechnology, Bhupat & Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai-600 036, India
| | - Uma Rani Potunuru
- Department of Biotechnology, Bhupat & Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai-600 036, India
| | - W Sofi Beaula
- Department of Biotechnology, Bhupat & Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai-600 036, India
| | - Suresh Kumar Rayala
- Department of Biotechnology, Bhupat & Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai-600 036, India
| | - Madhulika Dixit
- Department of Biotechnology, Bhupat & Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai-600 036, India
| | - Anju Chadha
- Department of Biotechnology, Bhupat & Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai-600 036, India
| | - Smita Srivastava
- Department of Biotechnology, Bhupat & Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai-600 036, India.
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18
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Parsley NC, Kirkpatrick CL, Crittenden CM, Rad JG, Hoskin DW, Brodbelt JS, Hicks LM. PepSAVI-MS reveals anticancer and antifungal cycloviolacins in Viola odorata. Phytochemistry 2018; 152:61-70. [PMID: 29734037 PMCID: PMC6003877 DOI: 10.1016/j.phytochem.2018.04.014] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Revised: 04/12/2018] [Accepted: 04/24/2018] [Indexed: 05/07/2023]
Abstract
Widespread resistance to antimicrobial and cancer therapeutics is evolving in every country worldwide and has a direct impact on global health, agriculture and the economy. The specificity and selectivity of bioactive peptide natural products present a possible stopgap measure to address the ongoing deficit of new therapeutic compounds. PepSAVI-MS (Statistically-guided bioActive Peptides prioritized VIa Mass Spectrometry) is an adaptable method for the analysis of natural product libraries to rapidly identify bioactive peptides. This pipeline was validated via screening of the cyclotide-rich botanical species Viola odorata and identification of the known antimicrobial and anticancer cyclotide cycloviolacin O2. Herein we present and validate novel bioactivities of the anthelmintic V. odorata cyclotide, cycloviolacin O8 (cyO8), including micromolar anticancer activity against PC-3 prostate, MDA-MB-231 breast, and OVCAR-3 ovarian cancer cell lines and antifungal activity against the agricultural pathogen Fusarium graminearum. A reduction/alkylation strategy in tandem with PepSAVI-MS analysis also revealed several previously uncharacterized putatively bioactive cyclotides. Downstream implementation of ultraviolet photodissociation (UVPD) tandem mass spectrometry is demonstrated for cyO8 as a method to address traditionally difficult-to-sequence cyclotide species. This work emphasizes the therapeutic and agricultural potential of natural product bioactive peptides and the necessity of developing robust analytical tools to deconvolute nature's complexity.
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Affiliation(s)
- Nicole C Parsley
- Department of Chemistry, University of North Carolina at Chapel Hill, NC, USA
| | | | | | | | - David W Hoskin
- Department of Pathology, Dalhousie University, Nova Scotia, Canada; Department of Microbiology and Immunology, Dalhousie University, Nova Scotia, Canada; Department of Surgery, Dalhousie University, Nova Scotia, Canada
| | | | - Leslie M Hicks
- Department of Chemistry, University of North Carolina at Chapel Hill, NC, USA.
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19
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Pinto MEF, Najas JZG, Magalhães LG, Bobey AF, Mendonça JN, Lopes NP, Leme FM, Teixeira SP, Trovó M, Andricopulo AD, Koehbach J, Gruber CW, Cilli EM, Bolzani VS. Inhibition of Breast Cancer Cell Migration by Cyclotides Isolated from Pombalia calceolaria. J Nat Prod 2018; 81:1203-1208. [PMID: 29757646 PMCID: PMC5974699 DOI: 10.1021/acs.jnatprod.7b00969] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Two new bracelet cyclotides from roots of Pombalia calceolaria with potential anticancer activity have been characterized in this work. The cyclotides Poca A and B (1 and 2) and the previously known CyO4 (3) were de novo sequenced by MALDI-TOF/TOF mass spectrometry (MS). The MS2 spectra were examined and the amino acid sequences were determined. The purified peptides were tested for their cytotoxicity and effects on cell migration of MDA-MB-231, a triple-negative breast cancer cell line. The isolated cyclotides reduced the number of cancer cells by more than 80% at 20 μM, and the concentration-related cytotoxic responses were observed with IC50 values of 1.8, 2.7, and 9.8 μM for Poca A (1), Poca B (2), and CyO4 (3), respectively. Additionally, the inhibition of cell migration (wound-healing assay) exhibited that CyO4 (3) presents an interesting activity profile, in being able to inhibit cell migration (50%) at a subtoxic concentration (2 μM). The distribution of these cyclotides in the roots was analyzed by MALDI imaging, demonstrating that all three compounds are present in the phloem and cortical parenchyma regions.
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Affiliation(s)
- Meri Emili F. Pinto
- Institute
of Chemistry, São Paulo State University−UNESP, 14800-060, Araraquara, SP, Brazil
- Tel: 55-16-33019510. Fax: 55-16-33222308. E-mail:
| | - Jhenny Z. G. Najas
- Institute
of Chemistry, Federal University of Rio
de Janeiro−UFRJ, 21940-910, Rio de Janeiro, RJ, Brazil
| | - Luma G. Magalhães
- Computational
and Medicinal Chemistry Laboratory, Physics Institute of São
Carlos, The University of São Paulo−USP, 13563-120, São
Carlos, SP, Brazil
| | - Antonio F. Bobey
- Institute
of Chemistry, São Paulo State University−UNESP, 14800-060, Araraquara, SP, Brazil
| | - Jacqueline N. Mendonça
- Faculty
of Pharmaceutical Sciences of Ribeirão Preto, The University of São Paulo−USP, 14040-903, Ribeirão Preto, SP, Brazil
| | - Norberto P. Lopes
- Faculty
of Pharmaceutical Sciences of Ribeirão Preto, The University of São Paulo−USP, 14040-903, Ribeirão Preto, SP, Brazil
| | - Flávia M. Leme
- Faculty
of Pharmaceutical Sciences of Ribeirão Preto, The University of São Paulo−USP, 14040-903, Ribeirão Preto, SP, Brazil
| | - Simone P. Teixeira
- Faculty
of Pharmaceutical Sciences of Ribeirão Preto, The University of São Paulo−USP, 14040-903, Ribeirão Preto, SP, Brazil
| | - Marcelo Trovó
- Institute
of Chemistry, Federal University of Rio
de Janeiro−UFRJ, 21940-910, Rio de Janeiro, RJ, Brazil
| | - Adriano D. Andricopulo
- Computational
and Medicinal Chemistry Laboratory, Physics Institute of São
Carlos, The University of São Paulo−USP, 13563-120, São
Carlos, SP, Brazil
| | - Johannes Koehbach
- Center
for Physiology and Pharmacology, Medical
University of Vienna, 1090, Vienna, Austria
- Institute
for Molecular Bioscience, The University
of Queensland, 4072, St. Lucia, Queensland, Australia
| | - Christian W. Gruber
- Center
for Physiology and Pharmacology, Medical
University of Vienna, 1090, Vienna, Austria
| | - Eduardo Maffud Cilli
- Institute
of Chemistry, São Paulo State University−UNESP, 14800-060, Araraquara, SP, Brazil
| | - Vanderlan S. Bolzani
- Institute
of Chemistry, São Paulo State University−UNESP, 14800-060, Araraquara, SP, Brazil
- Tel: 55-16-33019660. Fax: 55-16-33222308. E-mail:
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20
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Nworu CS, Ejikeme TI, Ezike AC, Ndu O, Akunne TC, Onyeto CA, Okpalanduka P, Akah PA. Anti-plasmodial and anti-inflammatory activities of cyclotide-rich extract and fraction of Oldenlandia affinis (R. & S.) D.C. ( Rubiaceae). Afr Health Sci 2017; 17:827-843. [PMID: 29085411 PMCID: PMC5656185 DOI: 10.4314/ahs.v17i3.26] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND Oldenlandia affinis, commonly called 'kalata-kalata', a versatile plant used locally to treat malaria fever in some parts of sub-Saharan Africa was investigated for anti-plasmodial and anti-inflammatory activities. OBJECTIVE The study was designed to evaluate the antiplasmodial as well as anti-inflammatory activities of whole extract and cyclotide-rich fraction of Oldenlandia affinis. METHOD The dichloromethane-methanol extract (ODE) of the plant, O. affinis was investigated for suppressive and curative antiplasmodial activities against Plasmodium berghei in mice. ODE and the cyclotide-rich fraction (CRF) was investigated for chronic and acute anti-inflammatory activities in rat models of inflammation. Inhibition of pro-inflammatory mediators was studied in RAW264.7 macrophages. RESULTS ODE exhibited significant (p<0.05) reduction in mean parasitaemia in both the suppressive and curative models of Plasmodium berghei infection in mice.Administration of ODE(100, 200, or 400 mg/kg) and CRF (100, 200, or 400 mg/kg) produced significant inhibition of rodent models of acute and chronic inflammation . This observation is supported by the significant (P<0.05) inhibition of pro-inflammatory mediators, inducible nitric oxide (iNO) and tumour necrosis factor-alpha (TNF-α), and the reactive radical scavenging activities in RAW264.7 macrophages. CONCLUSION These findings could explain, at least in part, the successes reported in the use of the herb, Oldenlandia affinis in the traditional treatment of malaria fever.
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Affiliation(s)
- Chukwuemeka Sylvester Nworu
- Department of Pharmacology & Toxicology, Faculty of Pharmaceutical Sciences, University of Nigeria, Nsukka, 410001, Enugu State, Nigeria
| | - Tochukwu Ifenyinwa Ejikeme
- Department of Pharmacology & Toxicology, Faculty of Pharmaceutical Sciences, University of Nigeria, Nsukka, 410001, Enugu State, Nigeria
| | - Adaobi Chioma Ezike
- Department of Pharmacology & Toxicology, Faculty of Pharmaceutical Sciences, University of Nigeria, Nsukka, 410001, Enugu State, Nigeria
| | - Okechukwu Ndu
- Department of Pharmacology & Toxicology, Faculty of Pharmaceutical Sciences, University of Nigeria, Nsukka, 410001, Enugu State, Nigeria
| | - Theophine Chinwuba Akunne
- Department of Pharmacology & Toxicology, Faculty of Pharmaceutical Sciences, University of Nigeria, Nsukka, 410001, Enugu State, Nigeria
| | - Collins Azubuike Onyeto
- Department of Pharmacology & Toxicology, Faculty of Pharmaceutical Sciences, University of Nigeria, Nsukka, 410001, Enugu State, Nigeria
| | - Paul Okpalanduka
- Department of Pharmacology & Toxicology, Faculty of Pharmaceutical Sciences, University of Nigeria, Nsukka, 410001, Enugu State, Nigeria
| | - Peter Achunike Akah
- Department of Pharmacology & Toxicology, Faculty of Pharmaceutical Sciences, University of Nigeria, Nsukka, 410001, Enugu State, Nigeria
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21
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Abstract
Cyclotides are globular microproteins with a unique head-to-tail cyclized backbone, stabilized by three disulfide bonds forming a cystine knot. This unique circular backbone topology and knotted arrangement of three disulfide bonds makes them exceptionally stable to chemical, thermal, and biological degradation compared to other peptides of similar size. In addition, cyclotides have been shown to be highly tolerant to sequence variability, aside from the conserved residues forming the cystine knot. Cyclotides can also cross cellular membranes and are able to modulate intracellular protein-protein interactions, both in vitro and in vivo. All of these features make cyclotides highly promising as leads or frameworks for the design of peptide-based diagnostic and therapeutic tools. This article provides an overview on cyclotides and their applications as molecular imaging agents and peptide-based therapeutics.
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Affiliation(s)
- Andrew Gould
- Department of Pharmacology and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90089-9121, USA
| | - Julio A. Camarero
- Department of Pharmacology and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90089-9121, USA
- Department of Chemistry, University of Southern California, Los Angeles, CA 90089-9121, USA
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22
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Kirkpatrick CL, Broberg CA, McCool EN, Lee WJ, Chao A, McConnell EW, Pritchard DA, Hebert M, Fleeman R, Adams J, Jamil A, Madera L, Strömstedt AA, Göransson U, Liu Y, Hoskin DW, Shaw LN, Hicks LM. The "PepSAVI-MS" Pipeline for Natural Product Bioactive Peptide Discovery. Anal Chem 2017; 89:1194-1201. [PMID: 27991763 PMCID: PMC8609470 DOI: 10.1021/acs.analchem.6b03625] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The recent increase in extensively drug-resistant bacterial pathogens and the associated increase of morbidity and mortality demonstrate the immediate need for new antibiotic backbones with novel mechanisms of action. Here, we report the development of the PepSAVI-MS pipeline for bioactive peptide discovery. This highly versatile platform employs mass spectrometry and statistics to identify bioactive peptide targets from complex biological samples. We validate the use of this platform through the successful identification of known bioactive peptides from a botanical species, Viola odorata. Using this pipeline, we have widened the known antimicrobial spectrum for V. odorata cyclotides, including antibacterial activity of cycloviolacin O2 against A. baumannii. We further demonstrate the broad applicability of the platform through the identification of novel anticancer activities for cycloviolacins by their cytotoxicity against ovarian, breast, and prostate cancer cell lines.
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Affiliation(s)
| | | | - Elijah N. McCool
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC
| | - Woo Jean Lee
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC
| | - Alex Chao
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC
| | - Evan W. McConnell
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC
| | - David A. Pritchard
- Department of Biostatistics, University of North Carolina at Chapel Hill, Chapel Hill, NC
| | - Michael Hebert
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC
| | - Renee Fleeman
- Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, Tampa, FL
| | - Jessie Adams
- Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, Tampa, FL
| | - Amer Jamil
- Department of Biochemistry, University of Agriculture Faisalabad, Faisalabad, Pakistan
| | - Laurence Madera
- Department of Pathology, Dalhousie University, Halifax, Nova Scotia
| | - Adam A. Strömstedt
- Division of Pharmacognosy, Department of Medicinal Chemistry, Uppsala University, Uppsala, Sweden
| | - Ulf Göransson
- Division of Pharmacognosy, Department of Medicinal Chemistry, Uppsala University, Uppsala, Sweden
| | - Yufeng Liu
- Department of Statistics and Operations Research, Department of Genetics, Department of Biostatistics, and Carolina Center for Genome Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC
| | - David W. Hoskin
- Department of Pathology, Dalhousie University, Halifax, Nova Scotia
| | - Lindsey N. Shaw
- Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, Tampa, FL
| | - Leslie M. Hicks
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC
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23
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Matsuura HN, Poth AG, Yendo ACA, Fett-Neto AG, Craik DJ. Isolation and Characterization of Cyclotides from Brazilian Psychotria: Significance in Plant Defense and Co-occurrence with Antioxidant Alkaloids. J Nat Prod 2016; 79:3006-3013. [PMID: 28006906 DOI: 10.1021/acs.jnatprod.6b00492] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Plants from the genus Psychotria include species bearing cyclotides and/or alkaloids. The elucidation of factors affecting the metabolism of these molecules as well as their activities may help to understand their ecological function. In the present study, high concentrations of antioxidant indole alkaloids were found to co-occur with cyclotides in Psychotria leiocarpa and P. brachyceras. The concentrations of the major cyclotides and alkaloids in P. leiocarpa and P. brachyceras were monitored following herbivore- and pathogen-associated challenges, revealing a constitutive, phytoanticipin-like accumulation pattern. Psyleio A, the most abundant cyclotide found in the leaves of P. leiocarpa, and also found in P. brachyceras leaves, exhibited insecticidal activity against Helicoverpa armigera larvae. Addition of ethanol in the vehicle for peptide solubilization in larval feeding trials proved deleterious to insecticidal activity and resulted in increased rates of larval survival in treatments containing indole alkaloids. This suggests that plant alkaloids ingested by larvae might contribute to herbivore oxidative stress detoxification, corroborating, in a heterologous system with artificial oxidative stress stimulation, the antioxidant efficiency of Psychotria alkaloids previously observed in planta. Overall, the present study reports data for eight novel cyclotides, the identification of P. leiocarpa as a cyclotide-bearing species, and the absence of these peptides in P. umbellata.
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Affiliation(s)
- Hélio N Matsuura
- Center for Biotechnology and Department of Botany, Federal University of Rio Grande do Sul , Porto Alegre, RS, Brazil
| | - Aaron G Poth
- Institute for Molecular Bioscience, The University of Queensland , Brisbane, QLD, Australia
| | - Anna C A Yendo
- Center for Biotechnology and Department of Botany, Federal University of Rio Grande do Sul , Porto Alegre, RS, Brazil
| | - Arthur G Fett-Neto
- Center for Biotechnology and Department of Botany, Federal University of Rio Grande do Sul , Porto Alegre, RS, Brazil
| | - David J Craik
- Institute for Molecular Bioscience, The University of Queensland , Brisbane, QLD, Australia
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24
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Jagadish K, Gould A, Borra R, Majumder S, Mushtaq Z, Shekhtman A, Camarero JA. Recombinant Expression and Phenotypic Screening of a Bioactive Cyclotide Against α-Synuclein-Induced Cytotoxicity in Baker's Yeast. Angew Chem Int Ed Engl 2015; 54:8390-4. [PMID: 26096948 PMCID: PMC4545262 DOI: 10.1002/anie.201501186] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Revised: 04/03/2015] [Indexed: 11/08/2022]
Abstract
We report for the first time the recombinant expression of fully folded bioactive cyclotides inside live yeast cells by using intracellular protein trans-splicing in combination with a highly efficient split-intein. This approach was successfully used to produce the naturally occurring cyclotide MCoTI-I and the engineered bioactive cyclotide MCoCP4. Cyclotide MCoCP4 was shown to reduce the toxicity of human α-synuclein in live yeast cells. Cyclotide MCoCP4 was selected by phenotypic screening from cells transformed with a mixture of plasmids encoding MCoCP4 and inactive cyclotide MCoTI-I in a ratio of 1:5×10(4). This demonstrates the potential for using yeast to perform phenotypic screening of genetically encoded cyclotide-based libraries in eukaryotic cells.
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Affiliation(s)
- Krishnappa Jagadish
- Department of Pharmacology and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90033 (USA)
| | - Andrew Gould
- Department of Pharmacology and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90033 (USA)
| | - Radhika Borra
- Department of Pharmacology and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90033 (USA)
| | - Subhabrata Majumder
- Department of Chemistry, State University of New York, Albany, NY 12222 (USA)
| | - Zahid Mushtaq
- Department of Pharmacology and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90033 (USA)
| | - Alexander Shekhtman
- Department of Chemistry, State University of New York, Albany, NY 12222 (USA)
| | - Julio A Camarero
- Department of Pharmacology and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90033 (USA).
- Department of Chemistry, University of Southern California, Los Angeles, CA 90033 (USA).
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25
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Hellinger R, Koehbach J, Puigpinós A, Clark RJ, Tarragó T, Giralt E, Gruber CW. Inhibition of Human Prolyl Oligopeptidase Activity by the Cyclotide Psysol 2 Isolated from Psychotria solitudinum. J Nat Prod 2015; 78:1073-82. [PMID: 25894999 PMCID: PMC4444998 DOI: 10.1021/np501061t] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Indexed: 05/21/2023]
Abstract
Cyclotides are head-to-tail cyclized peptides comprising a stabilizing cystine-knot motif. To date, they are well known for their diverse bioactivities such as anti-HIV and immunosuppressive properties. Yet little is known about specific molecular mechanisms, in particular the interaction of cyclotides with cellular protein targets. Native and synthetic cyclotide-like peptides from Momordica plants are potent and selective inhibitors of different serine-type proteinases such as trypsin, chymotrypsin, matriptase, and tryptase-beta. This study describes the bioactivity-guided isolation of a cyclotide from Psychotria solitudinum as an inhibitor of another serine-type protease, namely, the human prolyl oligopeptidase (POP). Analysis of the inhibitory potency of Psychotria extracts and subsequent fractionation by liquid chromatography yielded the isolated peptide psysol 2 (1), which exhibited an IC50 of 25 μM. In addition the prototypical cyclotide kalata B1 inhibited POP activity with an IC50 of 5.6 μM. The inhibitory activity appeared to be selective for POP, since neither psysol 2 nor kalata B1 were able to inhibit the proteolytic activity of trypsin or chymotrypsin. The enzyme POP is well known for its role in memory and learning processes, and it is currently being considered as a promising therapeutic target for the cognitive deficits associated with several psychiatric and neurodegenerative diseases, such as schizophrenia and Parkinson's disease. In the context of discovery and development of POP inhibitors with beneficial ADME properties, cyclotides may be suitable starting points considering their stability in biological fluids and possible oral bioavailability.
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Affiliation(s)
- Roland Hellinger
- Center
for Physiology and Pharmacology, Medical
University of Vienna, Schwarzspanierstrasse 17, 1090 Vienna, Austria
| | - Johannes Koehbach
- Center
for Physiology and Pharmacology, Medical
University of Vienna, Schwarzspanierstrasse 17, 1090 Vienna, Austria
| | - Albert Puigpinós
- Institute
for Research in Biomedicine (IRB Barcelona), 08028 Barcelona, Spain
| | - Richard J. Clark
- School
of Biomedical Sciences, The University of
Queensland, Brisbane, QLD 4072, Australia
| | - Teresa Tarragó
- Institute
for Research in Biomedicine (IRB Barcelona), 08028 Barcelona, Spain
| | - Ernest Giralt
- Institute
for Research in Biomedicine (IRB Barcelona), 08028 Barcelona, Spain
- Department
of Organic Chemistry, University of Barcelona
(UB), 08028 Barcelona, Spain
| | - Christian W. Gruber
- Center
for Physiology and Pharmacology, Medical
University of Vienna, Schwarzspanierstrasse 17, 1090 Vienna, Austria
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26
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Liu MZ, Yang Y, Zhang SX, Tang L, Wang HM, Chen CJ, Shen ZF, Cheng KD, Kong JQ, Wang W. [A cyclotide against influenza A H1N1 virus from Viola yedoensis]. Yao Xue Xue Bao 2014; 49:905-912. [PMID: 25212039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Three cyclotides were isolated from the whole plant of Viola yedoensis in this study. The two, vary peptide E and cycloviolacin Y5, were previously reported, and a novel cycloviolacin VY1 was characterized according to the interpretation of MS/MS fragmentation of peptides which were produced from the reduced and alkylated parent peptide with the digestion of Endo Lys-C, trypsin and chymotrypsin, separately. The stability of remarkable resistance to proteolytic degradation by trypsin and chymotrypsin, and that of thermal denaturation was confirmed again. Besides, the IC50 value of cycloviolacin VY1 against influenza A H1N1 virus was (2.27 +/- 0.20) microg x mL(-1). It is the first cyclotide reported with anti-influenza A H1N1 virus activity in vitro assay.
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27
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Kinghorn AD. Changes for Volume 77. J Nat Prod 2014; 77:1. [PMID: 24409819 DOI: 10.1021/np401066x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
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28
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Gründemann C, Thell K, Lengen K, Garcia-Käufer M, Huang YH, Huber R, Craik DJ, Schabbauer G, Gruber CW. Cyclotides Suppress Human T-Lymphocyte Proliferation by an Interleukin 2-Dependent Mechanism. PLoS One 2013; 8:e68016. [PMID: 23840803 PMCID: PMC3694003 DOI: 10.1371/journal.pone.0068016] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Accepted: 05/24/2013] [Indexed: 02/07/2023] Open
Abstract
Cyclotides are a diverse and abundant group of ribosomally synthesized plant peptides containing a unique cyclic cystine-knotted topology that confers them with remarkable stability. Kalata B1, a representative member of this family of mini-proteins, has been found to inhibit the proliferation of human peripheral blood mononuclear cells. Analysis of T-cell proliferation upon treatment with chemically synthesized kalata B1 mutants revealed a region comprising inter-cysteine loops 1 and 2 of the cyclotide framework to be important for biological activity. Cytokine signaling analysis using an 'active' kalata B1 mutant [T20K], and the reference drug cyclosporin A (CsA) demonstrated that treatment of activated T-lymphocytes with these compounds decreased the expression of the interleukin-2 (IL-2) surface receptor as well as IL-2 cytokine secretion and IL-2 gene expression, whereas the 'inactive' kalata B1 mutant [V10K] did not cause any effects. The anti-proliferative activity of [T20K] kalata B1 was antagonized by addition of exogenous IL-2. Furthermore, treatment with [T20K] kalata B1 led to an initial reduction of the effector function, as indicated by the reduced IFN-γ and TNF-α production, but the levels of both cytokines stabilized over time and returned to their normal levels. On the other hand, the degranulation activity remained reduced. This indicated that cyclotides interfere with T-cell polyfunctionality and arrest the proliferation of immune-competent cells through inhibiting IL-2 biology at more than one site. The results open new avenues to utilize native and synthetically-optimized cyclotides for applications in immune-related disorders and as immunosuppressant peptides.
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Affiliation(s)
- Carsten Gründemann
- Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
- Center for Complementary Medicine, Department of Environmental Health Sciences, University Medical Center Freiburg, Freiburg, Germany
| | - Kathrin Thell
- Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Karin Lengen
- Center for Complementary Medicine, Department of Environmental Health Sciences, University Medical Center Freiburg, Freiburg, Germany
| | - Manuel Garcia-Käufer
- Center for Complementary Medicine, Department of Environmental Health Sciences, University Medical Center Freiburg, Freiburg, Germany
| | - Yen-Hua Huang
- Institute for Molecular Bioscience, the University of Queensland, Brisbane, Queensland, Australia
| | - Roman Huber
- Center for Complementary Medicine, Department of Environmental Health Sciences, University Medical Center Freiburg, Freiburg, Germany
| | - David J. Craik
- Institute for Molecular Bioscience, the University of Queensland, Brisbane, Queensland, Australia
| | - Gernot Schabbauer
- Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Christian W. Gruber
- Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
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29
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Abstract
Cyclotides are an abundant and diverse group of ribosomally synthesized plant peptides containing a cyclic cystine-knotted structure that confers them with remarkable stability. They are explored for their distribution in plants, although little is known about the individual peptide content of a single species. Therefore, we chemically analyzed the crude extract of the coffee-family plant Oldenlandia affinis using a rapid peptidomics workflow utilizing nano-LC-MS, peptide reconstruct with database identification, and MS/MS automated sequence analysis to determine its cyclotide content. Biologically, cyclotides are mainly explored for applications in agriculture and drug design; here we report their growth-inhibiting effects on primary cells of the human immune system using biological and immunological end points in cell-based test systems. LC-MS quantification of the active O. affinis plant extract triggered the characterization of the antiproliferative activity of kalata B1, one of the most abundant cyclotides in this extract, on primary activated human lymphocytes. The effect has a defined concentration range and was not due to cytotoxicity, thus opening a new avenue to utilize native and synthetically optimized plant cyclotides for applications in immune-related disorders and as immunosuppressant peptides.
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Affiliation(s)
- Carsten Gründemann
- Center for Complementary Medicine, Department of Environmental Health Sciences, University Medical Center Freiburg, Breisacher Straße 115B, D-79111 Freiburg, Germany
| | - Johannes Koehbach
- Center for Physiology and Pharmacology, Medical University of Vienna, Schwarzspanierstraße 17, A-1090 Vienna, Austria
| | - Roman Huber
- Center for Complementary Medicine, Department of Environmental Health Sciences, University Medical Center Freiburg, Breisacher Straße 115B, D-79111 Freiburg, Germany
| | - Christian W Gruber
- Center for Physiology and Pharmacology, Medical University of Vienna, Schwarzspanierstraße 17, A-1090 Vienna, Austria
- Corresponding Author: Tel: +43-(0)1-4277-62511. Fax: +43-(0)1-4277-9623.
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30
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Abstract
Cyclotides are plant mini-proteins whose natural function is thought to be to protect plants from pest or pathogens, particularly insect pests. They are approximately 30 amino acids in size and are characterized by a cyclic peptide backbone and a cystine knot arrangement of three conserved disulfide bonds. This article provides an overview of the reported pesticidal or toxic activities of cyclotides, discusses a possible common mechanism of action involving disruption of biological membranes in pest species, and describes methods that can be used to produce cyclotides for potential applications as novel pesticidal agents.
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Affiliation(s)
- David J Craik
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia.
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31
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Abstract
Peptides within the knottin family have been shown to possess inherent stability, making them attractive scaffolds for the development of therapeutic and diagnostic agents. Given its remarkable stability to proteases, the cyclic peptide kalata B1 was employed as a scaffold to create a large knottin library displayed on the surface of E. coli. A library exceeding 10(9) variants was constructed by randomizing seven amino acids within a loop of the kalata B1 scaffold and screened using fluorescence-activated cell sorting to identify peptide ligands specific for the active site of human thrombin. Refolded thrombin binders exhibited high nanomolar affinities in solution and slow dissociation rates and were able to inhibit thrombin's enzymatic activity. Importantly, 80% of a knottin-based thrombin inhibitor remained intact after a 2 h incubation both with trypsin and with chymotrypsin, demonstrating that modifying the kalata B1 sequence did not compromise its stability properties. In addition, the knottin variant mediated 20-fold enhanced affinity for thrombin, when compared to the same seven residue binding epitope constrained by a single disulfide bond. Our results indicate that peptide libraries derived from the kalata B1 scaffold can yield high-affinity protein ligands that retain the remarkable protease resistance associated with the parent scaffold. More generally, this strategy may prove useful in the development of stable peptide ligands suitable for in vivo applications.
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Affiliation(s)
- Jennifer A. Getz
- Department of Chemical Engineering, University of California, Santa Barbara, CA 93106
- Institute for Collaborative Biotechnologies, University of California, Santa Barbara, CA 93106
| | - Jeffrey J. Rice
- Department of Chemical Engineering, University of California, Santa Barbara, CA 93106
- Institute for Collaborative Biotechnologies, University of California, Santa Barbara, CA 93106
| | - Patrick S. Daugherty
- Department of Chemical Engineering, University of California, Santa Barbara, CA 93106
- Institute for Collaborative Biotechnologies, University of California, Santa Barbara, CA 93106
- Biomolecular Science and Engineering, University of California, Santa Barbara, CA 93106
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32
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He W, Chan LY, Zeng G, Daly NL, Craik DJ, Tan N. Isolation and characterization of cytotoxic cyclotides from Viola philippica. Peptides 2011; 32:1719-23. [PMID: 21723349 DOI: 10.1016/j.peptides.2011.06.016] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2011] [Revised: 06/16/2011] [Accepted: 06/16/2011] [Indexed: 11/24/2022]
Abstract
Cyclotides are a large family of plant peptides characterized by a macrocyclic backbone and knotted arrangement of three disulfide bonds. This unique structure renders cyclotides exceptionally stable to thermal, chemical and enzymatic treatments. They exhibit a variety of bioactivities, including uterotonic, anti-HIV, cytotoxic and hemolytic activity and it is these properties that make cyclotides an interesting peptide scaffold for drug design. In this study, eight new cyclotides (Viphi A-H), along with eight known cyclotides, were isolated from Viola philippica, a plant from the Violaceae family. In addition, Viba 17 and Mram 8 were isolated for the first time as peptides. The sequences of these cyclotides were elucidated primarily by using a strategy involving reduction, enzymatic digestion and tandem mass spectroscopy sequencing. Several of the cyclotides showed cytotoxic activities against the cancer cell lines MM96L, HeLa and BGC-823. The novel cyclotides reported here: (1) enhance the known sequence variation observed for cyclotides; (2) extend the number of species known to contain cyclotides; (3) provide interesting structure-activity relationships that delineate residues important for cytotoxic activity. In addition, this study provides insights into the potential active ingredients of traditional Chinese medicines.
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Affiliation(s)
- Wenjun He
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, 132# Lanhei Road, Heilongtan, Kunming 650204, Yunnan, PR China
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33
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Yeshak MY, Burman R, Asres K, Göransson U. Cyclotides from an extreme habitat: characterization of cyclic peptides from Viola abyssinica of the Ethiopian highlands. J Nat Prod 2011; 74:727-31. [PMID: 21434649 DOI: 10.1021/np100790f] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
As part of ongoing explorations of the structural diversity of cyclotides, the cyclotide content of a native violet of the East African highlands, Viola abyssinica (which grows at altitudes up to 3400 m), was studied. Six new cyclotides, vaby A-E (1-5) and varv E (6), were isolated and characterized by employing HPLC and MS techniques and quantitative amino acid analysis. Cyclotides 1-5 were found to have new sequences, and 1-3 have a further novel feature in their sequences, an alanine moiety in loop 2. Two of the cyclotides (1 and 4) also exhibited cytotoxic properties in a flourometric microculture cytotoxicity assay. The findings corroborate the hypothesis that investigating the cyclotide contents of violets growing in diverse environments is a promising approach for extending our knowledge of both the structural and biological diversity of cyclotides.
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Affiliation(s)
- Mariamawit Y Yeshak
- Division of Pharmacognosy, Department of Medicinal Chemistry, Uppsala University, Biomedical Centre, Box 574, SE-751 23 Uppsala, Sweden
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34
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Abstract
Abnormalities in the process of uterine muscle contractility during pregnancy and birth can have major clinical implications, including preterm labour, which is the single largest cause of maternal and prenatal mortality in the Western world and a major contributor to childhood developmental problems. In contrast, induction of labour may be necessary in certain conditions. Currently used interventional therapies to suppress (tocolytic agents) or to induce (uterotonic agents) uterine contractions lack potency and/or selectivity and can have harmful side effects for mother and baby. Nature's diversity has always been, and still is, one of the biggest resources of therapeutic lead compounds. Many natural products exhibit biological activity against unrelated targets, thus providing researchers with starting points for drug development. In this review we will provide an overview of uterine muscle physiology, describe currently available biological screening procedures for testing of uterotonic plant compounds and will summarise traditionally-used uterotonic plants, their active components and their mechanisms, primarily focusing on uterotonic active circular plant peptides called cyclotides. Finally we will comment on the discovery of novel cyclotide-producing plant species and the possibility for the development of novel plant-derived uterotonic and tocolytic drugs.
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35
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Tang J, Wang CK, Pan X, Yan H, Zeng G, Xu W, He W, Daly NL, Craik DJ, Tan N. Isolation and characterization of cytotoxic cyclotides from Viola tricolor. Peptides 2010; 31:1434-40. [PMID: 20580652 DOI: 10.1016/j.peptides.2010.05.004] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2010] [Revised: 05/10/2010] [Accepted: 05/10/2010] [Indexed: 11/27/2022]
Abstract
Many plants of the Violaceae plant family have been used in traditional remedies, and these plants often contain cyclotides, a particular type of plant cyclopeptide that is distinguished by a cyclic cystine knot motif. In general, bioactive plant cyclopeptides are interesting candidates for drug development. In the current study, a suite of 14 cyclotides, which includes seven novel cyclotides [vitri B, C, D, E, F, varv Hm, and He], together with seven known cyclotides [varv A, D, E, F, H, vitri A, and cycloviolacin O2], was isolated from Viola tricolor, a common flower. A chromatography-based method was used to isolate the cyclotides, which were characterized using tandem mass spectrometry and NMR spectroscopy. Several of the cyclotides showed cytotoxic activities against five cancer cell lines, U251, MDA-MB-231, A549, DU145, and BEL-7402. Three cyclotides, vitri A, vitri F, and cycloviolacin O2, were the most cytotoxic. The cytotoxic activity of the cyclotides did not correlate well with their hemolytic activity, indicating that different interactions, most likely with membranes, are involved for cytotoxic and hemolytic activities. Homology modeling of the structures was used in deriving structure-activity relationships.
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Affiliation(s)
- Jun Tang
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, 132# Lanhei Road, Heilongtan, Kunming 650204, Yunnan, PR China
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36
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Gerlach SL, Burman R, Bohlin L, Mondal D, Göransson U. Isolation, characterization, and bioactivity of cyclotides from the Micronesian plant Psychotria leptothyrsa. J Nat Prod 2010; 73:1207-1213. [PMID: 20575512 DOI: 10.1021/np9007365] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Cyclotides, the largest known family of head-to-tail cyclic peptides, have approximately 30 amino acid residues with a complex structure containing a circular peptide backbone and a cystine knot. They are found in plants from the Violaceae and Rubiaceae families and are speculated to function in plant protection. In addition to their insecticidal properties, cyclotides display cytotoxic, anti-HIV, antimicrobial, and inhibition of neurotensin binding activities. Although cyclotides are present in all violaceous species hitherto screened, their distribution and expression in Rubiaceae are not fully understood. In this study, we show that Psychotria leptothyrsa var. longicarpa (Rubiaceae) contains a suite of different cyclotides. The cyclotide fractions were isolated by RP-HPLC, and sequences of six new peptides, named psyles A-F, were determined by MS/MS sequencing. One of these, psyle C, is the first rubiaceous linear variant known. Psyles A, C, and E were analyzed in a fluorometric microculture assay to determine cytotoxicity toward the human lymphoma cell line U937-GTB. The IC(50) values of psyles A, C, and E were 26, 3.50, and 0.76 muM, respectively. This study expands the number of known rubiaceous cyclotides and shows that the linear cyclotide maintains cytotoxicity.
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Affiliation(s)
- Samantha L Gerlach
- Department of Ecology and Evolutionary Biology, Tulane University, 6823 St. Charles Avenue, New Orleans, LA 70118, USA.
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Colgrave ML, Kotze AC, Kopp S, McCarthy JS, Coleman GT, Craik DJ. Anthelmintic activity of cyclotides: In vitro studies with canine and human hookworms. Acta Trop 2009; 109:163-6. [PMID: 19059189 DOI: 10.1016/j.actatropica.2008.11.003] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2008] [Revised: 11/09/2008] [Accepted: 11/11/2008] [Indexed: 11/19/2022]
Abstract
Hookworm infection is a leading cause of maternal and child morbidity in countries of the tropics and subtropics, as well as being an important parasite in companion-animal medicine. The cyclotides are a novel family of cyclic cystine knot containing peptides from plants that have been shown to possess anthelmintic activity against Haemonchus contortus and Trichostrongylus colubriformis, two important gastrointestinal nematodes of sheep. In the current study we demonstrated the in vitro effects of three representative cyclotides, kalata B1, kalata B6 and cycloviolacin O14, on the viability of larval and adult life stages of the dog hookworm Ancylostoma caninum, and larvae of the human hookworm Necator americanus. The cyclotides showed significant anthelmintic activity towards both hookworm species. The different cyclotides showed similar patterns of relative activity as that seen previously with the livestock nematode species. This study demonstrates that cyclotides have promising activity in vitro against important parasites of companion animals and humans.
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Affiliation(s)
- Michelle L Colgrave
- Institute for Molecular Bioscience, University of Queensland, Brisbane, Australia
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38
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Abstract
Cyclotides are disulfide rich macrocyclic plant peptides that are defined by their unique topology in which a head-to-tail cyclized backbone is knotted by the interlocking arrangement of three disulfide bonds. This cyclic cystine knot motif gives the cyclotides exceptional resistance to thermal, chemical, or enzymatic degradation. Over 100 cyclotides have been reported and display a variety of biological activities, including a cytoprotective effect against HIV infected cells. It has been hypothesized that cyclotides from one subfamily, the Möbius subfamily, may be more appropriate than bracelet cyclotides as drug candidates given their lower toxicity to uninfected cells. Here, we report the anti-HIV and cytotoxic effects of three cyclotides, including two from the Möbius subfamily. We show that Möbius cyclotides have comparable inhibitory activity against HIV infection to bracelet cyclotides and that they are generally less cytotoxic to the target cells. To explore the structure activity relationships (SARs) of the 29 cyclotides tested so far for anti-HIV activity, we modeled the structures of the 21 cyclotides whose structures have not been previously solved. We show that within cyclotide subfamilies there is a correlation between hydrophobicity of certain loop regions and HIV inhibition. We also show that charged residues in these loops impact on the activity of the cyclotides, presumably by modulating membrane binding. In addition to providing new SAR data, this report is a mini-review that collates all cyclotide anti-HIV information reported so far and provides a resource for future studies on the therapeutic potential of cyclotides as natural anti-HIV agents.
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Affiliation(s)
- David C. Ireland
- Institute for Molecular Bioscience and Australian Research Council Special Research Centre for Functional and Applied Genomics, University of Queensland, Brisbane, QLD 4072, Australia
- UQ Business School. University of Queensland, Brisbane, QLD 4072, Australia
| | - Conan K. L. Wang
- Institute for Molecular Bioscience and Australian Research Council Special Research Centre for Functional and Applied Genomics, University of Queensland, Brisbane, QLD 4072, Australia
| | - Kirk R. Gustafson
- Molecular Targets Development Program, Center for Cancer Research, National Cancer Institute, Building 562, Room 201, Frederick, Maryland 21702-1201
| | - David J. Craik
- Institute for Molecular Bioscience and Australian Research Council Special Research Centre for Functional and Applied Genomics, University of Queensland, Brisbane, QLD 4072, Australia
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Wang CKL, Colgrave ML, Gustafson KR, Ireland DC, Goransson U, Craik DJ. Anti-HIV cyclotides from the Chinese medicinal herb Viola yedoensis. J Nat Prod 2008; 71:47-52. [PMID: 18081258 PMCID: PMC6327322 DOI: 10.1021/np070393g] [Citation(s) in RCA: 117] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Cyclotides are macrocyclic plant peptides characterized by a knotted arrangement of three disulfide bonds. They display a range of interesting bioactivities, including anti-HIV and insecticidal activities. More than 100 different cyclotides have been isolated from two phylogenetically distant plant families, the Rubiaceae and Violaceae. In this study we have characterized the cyclotides from Viola yedoensis, an important Chinese herb from the Violaceae family that has been reported to contain potential anti-HIV agents. From V. yedoensis five new and three known cyclotides were identified and shown to have anti-HIV activity. The most active of these is cycloviolacin Y5, which is one of the most potent of all cyclotides tested so far using in vitro XTT-based anti-HIV assays. Cycloviolacin Y5 is the most hydrophobic of the cyclotides from V. yedoensis. We show that there is a positive correlation between the hydrophobicity and the anti-HIV activity of the new cyclotides and that this trend tracks with their ability to disrupt membranes, as judged from hemolytic assays on human erythrocytes.
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Affiliation(s)
| | | | | | | | | | - David J. Craik
- To whom correspondence should be addressed. Tel: 61-7-3346-2019. Fax: 61-7-3346-2029.
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Greenwood KP, Daly NL, Brown DL, Stow JL, Craik DJ. The cyclic cystine knot miniprotein MCoTI-II is internalized into cells by macropinocytosis. Int J Biochem Cell Biol 2007; 39:2252-64. [PMID: 17693122 DOI: 10.1016/j.biocel.2007.06.016] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2007] [Revised: 06/14/2007] [Accepted: 06/18/2007] [Indexed: 10/23/2022]
Abstract
The cyclotides are macrocyclic knotted proteins characterized by a compact topology and exceptional stability. Accordingly it has been hypothesized that they may be useful as protein engineering frameworks for the stabilization and delivery of bioactive peptide sequences. This study examined the internalization of cyclotides into mammalian cells, a vital step for the delivery of bioactive peptide sequences to intracellular targets. Although the entry of various linear peptides into cells has been reported previously, this is the first report of internalization of a macrocyclic peptide. Cell uptake was examined for representatives of two cyclotide subfamilies; the first was MCoTI-II, a member of the trypsin inhibitor subfamily, which was internalized by a macrophage and breast cancer cell line and the second, the prototypic cyclotide kalata B1 from the Möbius subfamily, which remained extracellular. Biotin labeled MCoTI-II entered macrophages by macropinocytosis, resulting in vesicular encapsulation without trafficking to lysosomes for degradation. The ready uptake, coupled with low cytotoxicity, indicates that MCoTI-II has the potential to transport grafted bioactivities to intracellular targets, making it a potentially valuable framework in drug design applications.
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Affiliation(s)
- Kathryn P Greenwood
- Institute for Molecular Bioscience and Australian Research Council Special Research Centre for Functional and Applied Genomics, The University of Queensland, Brisbane, Queensland 4072, Australia
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Abstract
Plant cyclotides are unusual peptides with low molecular masses and a three-dimensional structure characterized by the presence of a cyclic fold. Synthetic peptides can adopt this circular conformation, but it is not a common feature for most members of other peptide groups. Cyclotides present a wide range of functions, such as the ability to induce stronger contractions during childbirth and anti-tumor activity. Additionally, some cyclotides present anti-viral, insecticidal or proteinase inhibitory activity. In this paper, we describe the structural and functional characteristics of plant cyclotides, their most conserved features and the development of these peptides for human health and biotechnological applications.
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Affiliation(s)
- Patrícia B Pelegrini
- Centro de Análises Proteômicas e Bioquímicas, Programa de Pós-Graduação em Ciências Genômicas e Biotecnologia, Universidade Católica de Brasília, Brasília, Brazil
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Abstract
Cyclotides are naturally occurring mini-proteins that have a cyclic peptide backbone and a knotted arrangement of three disulfide bonds. They are remarkably stable and have a diverse range of therapeutically useful biological activities, including antimicrobial and anti-HIV activity, although their natural function appears to be as plant defence agents. Cyclotides are amenable to chemical synthesis and the potential exists to graft new bioactivities onto their cyclic cystine knot framework as a way of stabilising peptide drugs. Over the last few years, proof-of-concept that bioactive peptide epitopes can be grafted onto cyclotides and related cystine knot mini-proteins has been obtained. The cystine knot framework is tolerant to a wide range of residue substitutions and is showing great promise as a scaffold in drug design and protein engineering.
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Affiliation(s)
- David J Craik
- University of Queensland, Institute for Molecular Bioscience, Australian Research Council Special Research Centre for Functional and Applied Genomics, Brisbane QLD 4072, Australia.
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Svangård E, Burman R, Gunasekera S, Lövborg H, Gullbo J, Göransson U. Mechanism of action of cytotoxic cyclotides: cycloviolacin O2 disrupts lipid membranes. J Nat Prod 2007; 70:643-7. [PMID: 17378610 DOI: 10.1021/np070007v] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
In recent years, the cyclotides have emerged as the largest family of naturally cyclized proteins. Cyclotides display potent cytotoxic activity that varies with the structure of the proteins, and combined with their unique structure, they represent novel cytotoxic agents. However, their mechanism of action is yet unknown. In this work we show that disruption of cell membranes plays a crucial role in the cytotoxic effect of the cyclotide cycloviolacin O2 (1), which has been isolated from Viola odorata. Cell viability and morphology studies on the human lymphoma cell line U-937 GTB showed that cells exposed to 1 displayed disintegrated cell membranes within 5 min. Functional studies on calcein-loaded HeLa cells and on liposomes showed rapid concentration-dependent release of their respective internal contents. The present results show that cyclotides have specific membrane-disrupting activity.
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Affiliation(s)
- Erika Svangård
- Division of Pharmacognosy, Department of Medicinal Chemistry, Biomedical Centre, Uppsala University, Uppsala, Sweden
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44
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Craik DJ, Cemazar M, Daly NL. The chemistry and biology of cyclotides. Curr Opin Drug Discov Devel 2007; 10:176-84. [PMID: 17436553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Cyclotides are mini-proteins with a macrocyclic peptide backbone and cystine-knot arrangement of disulfide bonds that makes them exceptionally stable to chemical, thermal or enzymatic degradation. They have a diverse range of bioactivities and are amenable to chemical synthesis, making them accessible as molecular templates for protein engineering and drug design applications. In the last two years, methods have been developed for the production of cyclotides using inteins in bacterial expression systems and using plant cell cultures, adding to established methods based on solid-phase peptide synthesis. The availability of an enhanced armory of synthetic methods promises to expand the potential range of cyclotide-based applications.
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Affiliation(s)
- David J Craik
- University of Queensland, Institute for Molecular Bioscience, Australian Research Council Special Research Center for Functional and Applied Genomics, Brisbane, QLD 4072, Australia.
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Ireland D, Colgrave M, Craik D. A novel suite of cyclotides from Viola odorata: sequence variation and the implications for structure, function and stability. Biochem J 2006; 400:1-12. [PMID: 16872274 PMCID: PMC1635437 DOI: 10.1042/bj20060627] [Citation(s) in RCA: 135] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Cyclotides are a fascinating family of plant-derived peptides characterized by their head-to-tail cyclized backbone and knotted arrangement of three disulfide bonds. This conserved structural architecture, termed the CCK (cyclic cystine knot), is responsible for their exceptional resistance to thermal, chemical and enzymatic degradation. Cyclotides have a variety of biological activities, but their insecticidal activities suggest that their primary function is in plant defence. In the present study, we determined the cyclotide content of the sweet violet Viola odorata, a member of the Violaceae family. We identified 30 cyclotides from the aerial parts and roots of this plant, 13 of which are novel sequences. The new sequences provide information about the natural diversity of cyclotides and the role of particular residues in defining structure and function. As many of the biological activities of cyclotides appear to be associated with membrane interactions, we used haemolytic activity as a marker of bioactivity for a selection of the new cyclotides. The new cyclotides were tested for their ability to resist proteolysis by a range of enzymes and, in common with other cyclotides, were completely resistant to trypsin, pepsin and thermolysin. The results show that while biological activity varies with the sequence, the proteolytic stability of the framework does not, and appears to be an inherent feature of the cyclotide framework. The structure of one of the new cyclotides, cycloviolacin O14, was determined and shown to contain the CCK motif. This study confirms that cyclotides may be regarded as a natural combinatorial template that displays a variety of peptide epitopes most likely targeted to a range of plant pests and pathogens.
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Affiliation(s)
- David C. Ireland
- *Institute for Molecular Bioscience and Australian Research Council Special Research Centre for Functional and Applied Genomics, The University of Queensland, Brisbane QLD 4072, Australia
- †School of Business, University of Queensland, Brisbane, QLD 4072, Australia
| | - Michelle L. Colgrave
- *Institute for Molecular Bioscience and Australian Research Council Special Research Centre for Functional and Applied Genomics, The University of Queensland, Brisbane QLD 4072, Australia
| | - David J. Craik
- *Institute for Molecular Bioscience and Australian Research Council Special Research Centre for Functional and Applied Genomics, The University of Queensland, Brisbane QLD 4072, Australia
- To whom correspondence should be addressed (email )
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Affiliation(s)
- David J Craik
- Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland 4072, Australia.
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Herrmann A, Svangård E, Claeson P, Gullbo J, Bohlin L, Göransson U. Key role of glutamic acid for the cytotoxic activity of the cyclotide cycloviolacin O2. Cell Mol Life Sci 2006; 63:235-45. [PMID: 16389447 DOI: 10.1007/s00018-005-5486-4] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Cyclotides are cyclic plant proteins with potent cytotoxic effects. Here we systematically probed the importance of surface-exposed charged amino acid residues of the cyclotide cycloviolacin O2, using a strategy involving chemical modifications. We show that the single glutamic acid plays a key role for the cytotoxicity: methylation of this residue produced a 48-fold decrease in potency. Virtually no change in potency was observed when masking the single arginine residue using 1,2-cyclohexanedione, while acetylation of the two lysine residues reduced the potency 3-fold. The derivative with modifications at both arginine and lysine residues showed a 7-fold loss of potency. In addition, we show that the activity is dependent on an intact disulfide network and that the short sequences between the six cysteine residues, that is, the backbone loops, are devoid of cytotoxic activity.
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Affiliation(s)
- A Herrmann
- Division of Pharmacognosy, Department of Medicinal Chemistry, Uppsala University, BMC, Box 574, 751 23 Uppsala, Sweden
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Craik DJ, Cemazar M, Daly NL. The cyclotides and related macrocyclic peptides as scaffolds in drug design. Curr Opin Drug Discov Devel 2006; 9:251-60. [PMID: 16566295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The applicability of linear peptides as drugs is potentially limited by their susceptibility to proteolytic cleavage and poor bioavailability. Cyclotides are macrocyclic cystine-knotted mini-proteins that have a broad range of bioactivities and are exceptionally stable, being resistant to chemical, thermal and enzymatic degradation. The general limitations of peptides as drugs can potentially be overcome by using the cyclotide framework as a scaffold onto which new activities may be engineered. The potential use of cyclotides and related peptide scaffolds for drug design is evaluated herein, with reference to increasing knowledge of the structures and sequence diversity of natural cyclotides and the emergence of new approaches in protein engineering.
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Affiliation(s)
- David J Craik
- University of Queensland, Institute for Molecular Bioscience, Australian Research Council Special Research Center for Functional and Applied Genomics, Brisbane.
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Abstract
Cycloviolacin H4, a new macrocyclic miniprotein comprising 30 amino acid residues, was isolated from the underground parts of the Australian native violet Viola hederaceae. Its sequence, cyclo-(CAESCVWIPCTVTALLGCSCSNNVCYNGIP), was determined by nanospray tandem mass spectrometry and quantitative amino acid analysis. A knotted disulfide arrangement, which was designated as a cyclic cystine knot motif and characteristic to all known cyclotides, is proposed for stabilizing the molecular structure and folding. The cyclotide is classified in the bracelet subfamily of cyclotides due to the absence of a cis-Pro peptide bond in the circular peptide backbone. A model of its three-dimensional structure was derived based on the template of the homologous cyclotide vhr1 (Trabi et al. Plant Cell 2004, 16, 2204-2216). Cycloviolacin H4 exhibits the most potent hemolytic activity in cyclotides reported so far, and this activity correlates with the size of a surface-exposed hydrophobic patch. This work has thus provided insight into the factors that modulate the cytotoxic properties of cyclotides.
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Affiliation(s)
- Bin Chen
- Institute for Molecular Bioscience, Australian Research Council Special Research Centre for Functional and Applied Genomics, University of Queensland, Brisbane, QLD 4072, Australia
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Chen B, Colgrave ML, Daly NL, Rosengren KJ, Gustafson KR, Craik DJ. Isolation and Characterization of Novel Cyclotides from Viola hederaceae. J Biol Chem 2005; 280:22395-405. [PMID: 15824119 DOI: 10.1074/jbc.m501737200] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Based on a newly established sequencing strategy featured by its efficiency, simplicity, and easy manipulation, the sequences of four novel cyclotides (macrocyclic knotted proteins) isolated from an Australian plant Viola hederaceae were determined. The three-dimensional solution structure of V. hederaceae leaf cyclotide-1 (vhl-1), a leaf-specific expressed 31-residue cyclotide, has been determined using two-dimensional (1)H NMR spectroscopy. vhl-1 adopts a compact and well defined structure including a distorted triple-stranded beta-sheet, a short 3(10) helical segment and several turns. It is stabilized by three disulfide bonds, which, together with backbone segments, form a cyclic cystine knot motif. The three-disulfide bonds are almost completely buried into the protein core, and the six cysteines contribute only 3.8% to the molecular surface. A pH titration experiment revealed that the folding of vhl-1 shows little pH dependence and allowed the pK(a) of 3.0 for Glu(3) and approximately 5.0 for Glu(14) to be determined. Met(7) was found to be oxidized in the native form, consistent with the fact that its side chain protrudes into the solvent, occupying 7.5% of the molecular surface. vhl-1 shows anti-HIV activity with an EC(50) value of 0.87 microm.
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Affiliation(s)
- Bin Chen
- Institute for Molecular Bioscience, University of Queensland, Brisbane, QLD 4072, Australia
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