1
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Lian Y, Tang X, Hu G, Miao C, Cui Y, Zhangsun D, Wu Y, Luo S. Characterization and evaluation of cytotoxic and antimicrobial activities of cyclotides from Viola japonica. Sci Rep 2024; 14:9733. [PMID: 38679643 PMCID: PMC11056381 DOI: 10.1038/s41598-024-60246-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Accepted: 04/19/2024] [Indexed: 05/01/2024] Open
Abstract
Cyclotides are a type of defense peptide most commonly found in the Violaceae family of plants, exhibiting various biological activities. In this study, we focused on the Viola japonica as our research subject and conducted transcriptome sequencing and analysis using high-throughput transcriptomics techniques. During this process, we identified 61 cyclotides, among which 25 were previously documented, while the remaining 36 were designated as vija 1 to vija 36. Mass spectrometry detection showed that 21 putative cyclotides were found in the extract of V. japonica. Through isolation, purification and tandem mass spectrometry, we characterized and investigated the activities of five cyclotides. Our results demonstrated inhibitory effects of these cyclotides on the growth of Acinetobacter baumannii and Bacillus subtilis, with minimum inhibitory concentrations (MICs) of 4.2 μM and 2.1 μM, respectively. Furthermore, time killing kinetic assays revealed that cyclotides at concentration of 4 MICs achieved completely bactericidal effects within 2 h. Additionally, fluorescence staining experiments confirmed that cyclotides disrupt microbial membranes. Moreover, cytotoxicity studies showed that cyclotides possess cytotoxic effects, with IC50 values ranging from 0.1 to 3.5 μM. In summary, the discovery of new cyclotide sequences enhances our understanding of peptide diversity and the exploration of their activity lays the foundation for a deeper investigation into the mechanisms of action of cyclotides.
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Affiliation(s)
- Yuanyuan Lian
- Guangxi Key Laboratory of Special Biomedicine, School of Medicine, Guangxi University, Nanning, China
| | - Xue Tang
- Guangxi Key Laboratory of Special Biomedicine, School of Medicine, Guangxi University, Nanning, China
| | - Gehui Hu
- Guangxi Key Laboratory of Special Biomedicine, School of Medicine, Guangxi University, Nanning, China
| | - Chenfang Miao
- Department of Pharmacy, The 900Th Hospital of Joint Logistics Team of the PLA, Fuzhou General Clinical Medical College of Fujian Medical University, Fuzhou, China
| | - Yunfei Cui
- Guangxi Key Laboratory of Special Biomedicine, School of Medicine, Guangxi University, Nanning, China
| | - Dongting Zhangsun
- Guangxi Key Laboratory of Special Biomedicine, School of Medicine, Guangxi University, Nanning, China
- Key Laboratory of Tropical Biological Resources of Ministry of Education, Hainan University, Haikou, China
| | - Yong Wu
- Guangxi Key Laboratory of Special Biomedicine, School of Medicine, Guangxi University, Nanning, China.
| | - Sulan Luo
- Guangxi Key Laboratory of Special Biomedicine, School of Medicine, Guangxi University, Nanning, China.
- Key Laboratory of Tropical Biological Resources of Ministry of Education, Hainan University, Haikou, China.
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2
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Tian S, de Veer SJ, Durek T, Wang CK, Craik DJ. Nucleation of a key beta-turn promotes cyclotide oxidative folding. J Biol Chem 2024; 300:107125. [PMID: 38432638 PMCID: PMC10999817 DOI: 10.1016/j.jbc.2024.107125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Revised: 02/05/2024] [Accepted: 02/19/2024] [Indexed: 03/05/2024] Open
Abstract
Cyclotides are plant-derived peptides characterized by a head-to-tail cyclic backbone and a cystine knot motif comprised of three disulfide bonds. Formation of this motif via in vitro oxidative folding can be challenging and can result in misfolded isomers with nonnative disulfide connectivities. Here, we investigated the effect of β-turn nucleation on cyclotide oxidative folding. Two types of β-turn mimics were grafted into kalata B1, individually replacing each of the four β-turns in the folded cyclotide. Insertion of d-Pro-Gly into loop 5 was beneficial to the folding of both cyclic kB1 and a linear form of the peptide. The linear grafted analog folded four-times faster in aqueous conditions than cyclic kB1 in optimized conditions. Additionally, the cyclic analogue folded without the need for redox agents by transitioning through a native-like intermediate that was on-pathway to product formation. Kalata B1 is from the Möbius subfamily of cyclotides. Grafting d-Pro-Gly into loop 5 of cyclotides from two other subfamilies also had a beneficial effect on folding. Our findings demonstrate the importance of a β-turn nucleation site for cyclotide oxidative folding, which could be adopted as a chemical strategy to improve the in vitro folding of diverse cystine-rich peptides.
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Affiliation(s)
- Sixin Tian
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Queensland, Australia
| | - Simon J de Veer
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Queensland, Australia
| | - Thomas Durek
- 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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3
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Chekan JR, Mydy LS, Pasquale MA, Kersten RD. Plant peptides - redefining an area of ribosomally synthesized and post-translationally modified peptides. Nat Prod Rep 2024. [PMID: 38411572 DOI: 10.1039/d3np00042g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/28/2024]
Abstract
Covering 1965 to February 2024Plants are prolific peptide chemists and are known to make thousands of different peptidic molecules. These peptides vary dramatically in their size, chemistry, and bioactivity. Despite their differences, all plant peptides to date are biosynthesized as ribosomally synthesized and post-translationally modified peptides (RiPPs). Decades of research in plant RiPP biosynthesis have extended the definition and scope of RiPPs from microbial sources, establishing paradigms and discovering new families of biosynthetic enzymes. The discovery and elucidation of plant peptide pathways is challenging due to repurposing and evolution of housekeeping genes as both precursor peptides and biosynthetic enzymes and due to the low rates of gene clustering in plants. In this review, we highlight the chemistry, biosynthesis, and function of the known RiPP classes from plants and recommend a nomenclature for the recent addition of BURP-domain-derived RiPPs termed burpitides. Burpitides are an emerging family of cyclic plant RiPPs characterized by macrocyclic crosslinks between tyrosine or tryptophan side chains and other amino acid side chains or their peptide backbone that are formed by copper-dependent BURP-domain-containing proteins termed burpitide cyclases. Finally, we review the discovery of plant RiPPs through bioactivity-guided, structure-guided, and gene-guided approaches.
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Affiliation(s)
- Jonathan R Chekan
- Department of Chemistry and Biochemistry, University of North Carolina at Greensboro, Greensboro, NC, USA.
| | - Lisa S Mydy
- Department of Medicinal Chemistry, University of Michigan, Ann Arbor, MI, USA.
| | - Michael A Pasquale
- Department of Chemistry and Biochemistry, University of North Carolina at Greensboro, Greensboro, NC, USA.
| | - Roland D Kersten
- Department of Medicinal Chemistry, University of Michigan, Ann Arbor, MI, USA.
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4
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Batiha GES, Lukman HY, Shaheen HM, Wasef L, Hafiz AA, Conte-Junior CA, Al-Farga A, Chamba MVM, Lawal B. A Systematic Review of Phytochemistry, Nutritional Composition, and Pharmacologic Application of Species of the Genus Viola in Noncommunicable Diseases (NCDs). EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE : ECAM 2023; 2023:5406039. [PMID: 37941895 PMCID: PMC10630019 DOI: 10.1155/2023/5406039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 06/03/2023] [Accepted: 10/11/2023] [Indexed: 11/10/2023]
Abstract
Viola L. is the largest genus of the Violaceae family with more than 500 species across the globe. The present extensive literature survey revealed Viola species to be a group of important nutritional and medicinal plants used for the ethnomedicinal treatment of noncommunicable diseases (NCDs) such as diabetes, asthma, lung diseases, and fatigue. Many plant species of this genus have also received scientific validation of their pharmacological activities including neuroprotective, immunomodulatory, anticancer, antihypertensive, antidyslipidemic, analgesic, antipyretic, diuretic, anti-inflammatory, anthelmintic, and antioxidant. Viola is highly rich in different natural products some of which have been isolated and identified in the past few decades; these include flavonoids terpenoids and phenylpropanoids of different pharmacological activities. The pharmacokinetics and clinical studies on this genus are lacking, and the present review is aimed at summarizing the current understanding of the ethnopharmacology, phytochemistry, nutritional composition, and pharmacological profile of medicinal plants from the Viola genus to reveal its therapeutic potentials, gaps, and subsequently open a new window for future pharmacological research.
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Affiliation(s)
- Gaber El-Saber Batiha
- Department of Pharmacology and Therapeutics, Faculty of Veterinary Medicine, Damanhour University, Damanhour 22511, AlBeheira, Egypt
| | - Halimat Yusuf Lukman
- Department of Chemical Sciences, Biochemistry Unit, College of Natural and Applied Sciences, Summit University Offa, Offa PMB 4412, Nigeria
| | - Hazem M. Shaheen
- Department of Pharmacology and Therapeutics, Faculty of Veterinary Medicine, Damanhour University, Damanhour 22511, AlBeheira, Egypt
| | - Lamiaa Wasef
- Department of Pharmacology and Therapeutics, Faculty of Veterinary Medicine, Damanhour University, Damanhour 22511, AlBeheira, Egypt
| | - Amin A. Hafiz
- Department of Clinical Nutrition, Faculty of Applied Medical Sciences, Umm Al-Qura University, Mecca, Saudi Arabia
| | - Carlos Adam Conte-Junior
- Laboratory of Advanced Analysis in Biochemistry and Molecular Biology (LAABBM), Department of Biochemistry, Federal University of Rio de Janeiro (UFRJ), Rio de Janeiro RJ 21941-909, Brazil
| | - Ammar Al-Farga
- Biochemistry Department, Faculty of Science, University of Jeddah, Jeddah 21577, Saudi Arabia
| | - Moses V. M. Chamba
- Department of Physics and Biochemical Sciences, Malawi University of Business and Applied Sciences, Private Bag 303, Chichiri, Blantyre 3, Malawi
| | - Bashir Lawal
- Faculty of Medical Science, New Gate University, Minna, Nigeria
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5
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Ho TNT, Pham SH, Nguyen LTT, Nguyen HT, Nguyen LT, Dang TT. Insights into the synthesis strategies of plant-derived cyclotides. Amino Acids 2023:10.1007/s00726-023-03271-8. [PMID: 37142771 DOI: 10.1007/s00726-023-03271-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Accepted: 04/18/2023] [Indexed: 05/06/2023]
Abstract
Cyclotides are plant peptides characterized with a head-to-tail cyclized backbone and three interlocking disulfide bonds, known as a cyclic cysteine knot. Despite the variations in cyclotides peptide sequences, this core structure is conserved, underlying their most useful feature: stability against thermal and chemical breakdown. Cyclotides are the only natural peptides known to date that are orally bioavailable and able to cross cell membranes. Cyclotides also display bioactivities that have been exploited and expanded to develop as potential therapeutic reagents for a wide range of conditions (e.g., HIV, inflammatory conditions, multiple sclerosis, etc.). As such, in vitro production of cyclotides is of the utmost importance since it could assist further research on this peptide class, specifically the structure-activity relationship and its mechanism of action. The information obtained could be utilized to assist drug development and optimization. Here, we discuss several strategies for the synthesis of cyclotides using both chemical and biological routes.
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Affiliation(s)
- Thao N T Ho
- 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
| | - Linh T T Nguyen
- Department of Chemistry, Ho Chi Minh City University of Education, 280 An Duong Vuong Street, District 5, Ho Chi Minh City, Viet Nam
| | - Ha T Nguyen
- National Key Laboratory of Polymer and Composite Materials, Department of Energy Materials, Faculty of Materials Technology, Ho Chi Minh City University of Technology (HCMUT), 268 Ly Thuong Kiet Street, District 10, Ho Chi Minh City, Viet Nam
- Vietnam National University Ho Chi Minh City, Linh Trung Ward, Thu Duc District, Ho Chi Minh City, Viet Nam
| | - Luan T Nguyen
- National Key Laboratory of Polymer and Composite Materials, Department of Energy Materials, Faculty of Materials Technology, Ho Chi Minh City University of Technology (HCMUT), 268 Ly Thuong Kiet Street, District 10, Ho Chi Minh City, Viet Nam
- Vietnam National University Ho Chi Minh City, Linh Trung Ward, Thu Duc District, Ho Chi Minh City, Viet Nam
| | - Tien T Dang
- Institute of Applied Materials Science, Vietnam Academy of Science and Technology, 1B TL29, District 12, Ho Chi Minh City, Viet Nam.
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6
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Rajendran S, Slazak B, Mohotti S, Muhammad T, Strömstedt AA, Kapusta M, Wilmowicz E, Göransson U, Hettiarachchi CM, Gunasekera S. Screening for Cyclotides in Sri Lankan Medicinal Plants: Discovery, Characterization, and Bioactivity Screening of Cyclotides from Geophila repens. JOURNAL OF NATURAL PRODUCTS 2023; 86:52-65. [PMID: 36525646 PMCID: PMC9887600 DOI: 10.1021/acs.jnatprod.2c00674] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Indexed: 06/17/2023]
Abstract
Cyclotides are an intriguing class of structurally stable circular miniproteins of plant origin with numerous potential pharmaceutical and agricultural applications. To investigate the occurrence of cyclotides in Sri Lankan flora, 50 medicinal plants were screened, leading to the identification of a suite of new cyclotides from Geophila repens of the family Rubiaceae. Cycloviolacin O2-like (cyO2-like) gere 1 and the known cyclotide kalata B7 (kB7) were among the cyclotides characterized at the peptide and/or transcript level together with several putative enzymes, likely involved in cyclotide biosynthesis. Five of the most abundant cyclotides were isolated, sequenced, structurally characterized, and screened in antimicrobial and cytotoxicity assays. All gere cyclotides showed cytotoxicity (IC50 of 2.0-10.2 μM), but only gere 1 inhibited standard microbial strains at a minimum inhibitory concentration of 4-16 μM. As shown by immunohistochemistry, large quantities of the cyclotides were localized in the epidermis of the leaves and petioles of G. repens. Taken together with the cytotoxicity and membrane permeabilizing activities, this implicates gere cyclotides as potential plant defense molecules. The presence of cyO2-like gere 1 in a plant in the Rubiaceae supports the notion that phylogenetically distant plants may have coevolved to express similar cytotoxic cyclotides for a specific functional role, most likely involving host defense.
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Affiliation(s)
- Sanjeevan Rajendran
- Phamacognosy,
Department of Pharmaceutical Biosciences, Uppsala University, Biomedical Centre, SE 75124 Uppsala, Sweden
- Department
of Chemistry, Faculty of Science, University
of Colombo, Thurstan Road, Colombo 00300, Sri Lanka
| | - Blazej Slazak
- Phamacognosy,
Department of Pharmaceutical Biosciences, Uppsala University, Biomedical Centre, SE 75124 Uppsala, Sweden
- W.
Szafer Institute of Botany of the Polish Academy of Sciences, 46 Lubicz, 31-512 Cracow, Poland
| | - Supun Mohotti
- Department
of Chemistry, Faculty of Science, University
of Colombo, Thurstan Road, Colombo 00300, Sri Lanka
| | - Taj Muhammad
- Phamacognosy,
Department of Pharmaceutical Biosciences, Uppsala University, Biomedical Centre, SE 75124 Uppsala, Sweden
| | - Adam A. Strömstedt
- Phamacognosy,
Department of Pharmaceutical Biosciences, Uppsala University, Biomedical Centre, SE 75124 Uppsala, Sweden
| | - Małgorzata Kapusta
- Department
of Plant Cytology and Embryology, Faculty of Biology, University of Gdańsk, 59 Wita Stwosza, 80-308 Gdańsk, Poland
| | - Emilia Wilmowicz
- Faculty
of Biological and Veterinary Sciences, Nicolaus
Copernicus University, 1 Lwowska Street, 87-100 Toruń, Poland
| | - Ulf Göransson
- Phamacognosy,
Department of Pharmaceutical Biosciences, Uppsala University, Biomedical Centre, SE 75124 Uppsala, Sweden
| | - Chamari M. Hettiarachchi
- Department
of Chemistry, Faculty of Science, University
of Colombo, Thurstan Road, Colombo 00300, Sri Lanka
| | - Sunithi Gunasekera
- Phamacognosy,
Department of Pharmaceutical Biosciences, Uppsala University, Biomedical Centre, SE 75124 Uppsala, Sweden
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7
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Jacob B, Vogelaar A, Cadenas E, Camarero JA. Using the Cyclotide Scaffold for Targeting Biomolecular Interactions in Drug Development. Molecules 2022; 27:molecules27196430. [PMID: 36234971 PMCID: PMC9570680 DOI: 10.3390/molecules27196430] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Revised: 09/21/2022] [Accepted: 09/24/2022] [Indexed: 11/28/2022] Open
Abstract
This review provides an overview of the properties of cyclotides and their potential for developing novel peptide-based therapeutics. The selective disruption of protein–protein interactions remains challenging, as the interacting surfaces are relatively large and flat. However, highly constrained polypeptide-based molecular frameworks with cell-permeability properties, such as the cyclotide scaffold, have shown great promise for targeting those biomolecular interactions. The use of molecular techniques, such as epitope grafting and molecular evolution employing the cyclotide scaffold, has shown to be highly effective for selecting bioactive cyclotides.
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Affiliation(s)
- Binu Jacob
- Department of Pharmacology and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 9033, USA
| | - Alicia Vogelaar
- Department of Pharmacology and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 9033, USA
| | - Enrique Cadenas
- Department of Pharmacology and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 9033, USA
| | - Julio A. Camarero
- Department of Pharmacology and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 9033, USA
- Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, CA 9033, USA
- Correspondence:
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8
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Aslam L, Kaur R, Hussain S, Kapoor N, Mahajan R. LC-MS/MS identification and structural characterization of isolated cyclotides from precursor sequences of Viola odorata L. petiole tissue using computational approach. J Biosci 2022. [DOI: 10.1007/s12038-022-00283-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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9
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Unusual Post-Translational Modifications in the Biosynthesis of Lasso Peptides. Int J Mol Sci 2022; 23:ijms23137231. [PMID: 35806232 PMCID: PMC9266682 DOI: 10.3390/ijms23137231] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 06/27/2022] [Accepted: 06/27/2022] [Indexed: 11/16/2022] Open
Abstract
Lasso peptides are a subclass of ribosomally synthesized and post-translationally modified peptides (RiPPs) and feature the threaded, lariat knot-like topology. The basic post-translational modifications (PTMs) of lasso peptide contain two steps, including the leader peptide removal of the ribosome-derived linear precursor peptide by an ATP-dependent cysteine protease, and the macrolactam cyclization by an ATP-dependent macrolactam synthetase. Recently, advanced bioinformatic tools combined with genome mining have paved the way to uncover a rapidly growing number of lasso peptides as well as a series of PTMs other than the general class-defining processes. Despite abundant reviews focusing on lasso peptide discoveries, structures, properties, and physiological functionalities, few summaries concerned their unique PTMs. In this review, we summarized all the unique PTMs of lasso peptides uncovered to date, shedding light on the related investigations in the future.
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10
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Hellinger R, Muratspahić E, Devi S, Koehbach J, Vasileva M, Harvey PJ, Craik DJ, Gründemann C, Gruber CW. Importance of the Cyclic Cystine Knot Structural Motif for Immunosuppressive Effects of Cyclotides. ACS Chem Biol 2021; 16:2373-2386. [PMID: 34592097 PMCID: PMC9286316 DOI: 10.1021/acschembio.1c00524] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The cyclotide T20K inhibits the proliferation of human immune cells and is currently in clinical trials for multiple sclerosis. Here, we provide novel functional data and mechanistic insights into structure-activity relationships of T20K. Analogs with partial or complete reduction of the cystine knot had loss of function in proliferation experiments. Similarly, an acyclic analog of T20K was inactive in lymphocyte bioassays. The lack of activity of non-native peptide analogs appears to be associated with the ability of cyclotides to interact with and penetrate cell membranes, since cellular uptake studies demonstrated fast fractional transfer only of the native peptide into the cytosol of human immune cells. Therefore, structural differences between cyclic and linear native folded peptides were investigated by NMR to elucidate structure-activity relationships. Acyclic T20K had a less rigid backbone and considerable structural changes in loops 1 and 6 compared to the native cyclic T20K, supporting the idea that the cyclic cystine knot motif is a unique bioactive scaffold. This study provides evidence that this structural motif in cyclotides governs bioactivity, interactions with and transport across biological membranes, and the structural integrity of these peptides. These observations could be useful to understand the structure-activity of other cystine knot proteins due to the structural conservation of the cystine knot motif across evolution and to provide guidance for the design of novel cyclic cysteine-stabilized molecules.
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Affiliation(s)
- Roland Hellinger
- Center for
Physiology and Pharmacology, Medical University
of Vienna, Schwarzspanierstr. 17, Vienna 1090, Austria
| | - Edin Muratspahić
- Center for
Physiology and Pharmacology, Medical University
of Vienna, Schwarzspanierstr. 17, Vienna 1090, Austria
| | - Seema Devi
- Institute
for Infection Prevention and Hospital Epidemiology, Center for Complementary
Medicine, Faculty of Medicine, University
of Freiburg, Breisacher Str. 115B, Freiburg 79106, Germany
| | - Johannes Koehbach
- 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
| | - Mina Vasileva
- Center for
Physiology and Pharmacology, Medical University
of Vienna, Schwarzspanierstr. 17, Vienna 1090, Austria
| | - Peta J. Harvey
- Institute
for Molecular Bioscience, Australian Research Council Centre of Excellence
for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Queensland 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
| | - Carsten Gründemann
- Translational
Complementary Medicine, Department of Pharmaceutical Sciences, University of Basel, Klingelbergstr. 80, Basel 4056, Switzerland
| | - Christian W. Gruber
- Center for
Physiology and Pharmacology, Medical University
of Vienna, Schwarzspanierstr. 17, Vienna 1090, Austria
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11
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Rajendran S, Slazak B, Mohotti S, Strömstedt AA, Göransson U, Hettiarachchi CM, Gunasekera S. Tropical vibes from Sri Lanka - cyclotides from Viola betonicifolia by transcriptome and mass spectrometry analysis. PHYTOCHEMISTRY 2021; 187:112749. [PMID: 33932786 DOI: 10.1016/j.phytochem.2021.112749] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2021] [Revised: 03/19/2021] [Accepted: 03/20/2021] [Indexed: 06/12/2023]
Abstract
Cyclotides are an extremely stable class of peptides, ubiquitously distributed in Violaceae. The aim of the present study was to investigate the presence of cyclotides in Sri Lankan Violaceae plants, using combined tools of transcriptomics and mass spectrometry. New cyclotides were discovered for the first time in the wild flora of Sri Lanka, within Viola betonicifolia, a plant used in traditional medicine as an antimicrobial. Plant extracts prepared in small scale from Viola betonicifolia were first subjected to LC-MS analysis. Subsequent transcriptome de novo sequencing of Viola betonicifolia uncovered 25 new (vibe 1-25) and three known (varv A/kalata S, viba 17, viba 11) peptide sequences from Möbius and bracelet cyclotide subfamilies as well as hybrid cyclotides. Among the transcripts, putative linear acyclotide sequences (vibe 4, vibe 10, vibe 11 and vibe 22) that lack a conserved asparagine or aspartic acid vital for cyclisation were also present. Four asparagine endopeptidases (AEPs), VbAEP1-4 were found within the Viola betonicifolia transcriptome, including a peptide asparaginyl ligase (PAL), potentially involved in cyclotide backbone cyclisation, showing >93% sequence homology to Viola yedoensis peptide asparaginyl ligases, VyPALs. In addition, we identified two protein disulfide isomerases (PDIs), VbPDI1-2, likely involved in cyclotide oxidative folding, having high sequence homology (>74%) with previously reported Rubiaceae and Violaceae PDIs. The current study highlights the ubiquity of cyclotides in Violaceae as well as the utility of transcriptomic analysis for cyclotides and their putative processing enzyme discovery. The high variability of cyclotide sequences in terms of loop sizes and residues in V. betonicifolia showcase the cyclotide structure as an adaptable scaffold as well as their importance as a combinatorial library, implicated in plant defense.
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Affiliation(s)
- Sanjeevan Rajendran
- Pharmacognosy, Department of Pharmaceutical Biosciences, Uppsala University, 751 23, Uppsala, Sweden; Department of Chemistry, Faculty of Science, University of Colombo, Thurston Rd, Colombo 03, Sri Lanka
| | - Blazej Slazak
- Pharmacognosy, Department of Pharmaceutical Biosciences, Uppsala University, 751 23, Uppsala, Sweden; W. Szafer Institute of Botany, Polish Academy of Science, 46 Lubicz St., 31-512, Cracow, Poland
| | - Supun Mohotti
- Department of Chemistry, Faculty of Science, University of Colombo, Thurston Rd, Colombo 03, Sri Lanka
| | - Adam A Strömstedt
- Pharmacognosy, Department of Pharmaceutical Biosciences, Uppsala University, 751 23, Uppsala, Sweden
| | - Ulf Göransson
- Pharmacognosy, Department of Pharmaceutical Biosciences, Uppsala University, 751 23, Uppsala, Sweden
| | - Chamari M Hettiarachchi
- Department of Chemistry, Faculty of Science, University of Colombo, Thurston Rd, Colombo 03, Sri Lanka
| | - Sunithi Gunasekera
- Pharmacognosy, Department of Pharmaceutical Biosciences, Uppsala University, 751 23, Uppsala, Sweden.
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12
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PDI-Regulated Disulfide Bond Formation in Protein Folding and Biomolecular Assembly. Molecules 2020; 26:molecules26010171. [PMID: 33396541 PMCID: PMC7794689 DOI: 10.3390/molecules26010171] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Revised: 12/25/2020] [Accepted: 12/28/2020] [Indexed: 02/06/2023] Open
Abstract
Disulfide bonds play a pivotal role in maintaining the natural structures of proteins to ensure their performance of normal biological functions. Moreover, biological molecular assembly, such as the gluten network, is also largely dependent on the intermolecular crosslinking via disulfide bonds. In eukaryotes, the formation and rearrangement of most intra- and intermolecular disulfide bonds in the endoplasmic reticulum (ER) are mediated by protein disulfide isomerases (PDIs), which consist of multiple thioredoxin-like domains. These domains assist correct folding of proteins, as well as effectively prevent the aggregation of misfolded ones. Protein misfolding often leads to the formation of pathological protein aggregations that cause many diseases. On the other hand, glutenin aggregation and subsequent crosslinking are required for the formation of a rheologically dominating gluten network. Herein, the mechanism of PDI-regulated disulfide bond formation is important for understanding not only protein folding and associated diseases, but also the formation of functional biomolecular assembly. This review systematically illustrated the process of human protein disulfide isomerase (hPDI) mediated disulfide bond formation and complemented this with the current mechanism of wheat protein disulfide isomerase (wPDI) catalyzed formation of gluten networks.
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13
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Okuda A, Matsusaki M, Masuda T, Morishima K, Sato N, Inoue R, Sugiyama M, Urade R. A novel soybean protein disulphide isomerase family protein possesses dithiol oxidation activity: identification and characterization of GmPDIL6. J Biochem 2020; 168:393-405. [PMID: 32458972 DOI: 10.1093/jb/mvaa058] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Accepted: 05/02/2020] [Indexed: 01/04/2023] Open
Abstract
Secretory and membrane proteins synthesized in the endoplasmic reticulum (ER) are folded with intramolecular disulphide bonds, viz. oxidative folding, catalysed by the protein disulphide isomerase (PDI) family proteins. Here, we identified a novel soybean PDI family protein, GmPDIL6. GmPDIL6 has a single thioredoxin-domain with a putative N-terminal signal peptide and an active centre (CKHC). Recombinant GmPDIL6 forms various oligomers binding iron. Oligomers with or without iron binding and monomers exhibited a dithiol oxidase activity level comparable to those of other soybean PDI family proteins. However, they displayed no disulphide reductase and extremely low oxidative refolding activity. Interestingly, GmPDIL6 was mainly expressed in the cotyledon during synthesis of seed storage proteins and GmPDIL6 mRNA was up-regulated under ER stress. GmPDIL6 may play a role in the formation of disulphide bonds in nascent proteins for oxidative folding in the ER.
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Affiliation(s)
- Aya Okuda
- Division of Agronomy and Horticultural Science, Graduate School of Agriculture, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Motonori Matsusaki
- Division of Agronomy and Horticultural Science, Graduate School of Agriculture, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Taro Masuda
- Division of Agronomy and Horticultural Science, Graduate School of Agriculture, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Ken Morishima
- Institute for Integrated Radiation and Nuclear Science, Kyoto University, Kumatori, Sennan-gun, Osaka 590-0494, Japan
| | - Nobuhiro Sato
- Institute for Integrated Radiation and Nuclear Science, Kyoto University, Kumatori, Sennan-gun, Osaka 590-0494, Japan
| | - Rintaro Inoue
- Institute for Integrated Radiation and Nuclear Science, Kyoto University, Kumatori, Sennan-gun, Osaka 590-0494, Japan
| | - Masaaki Sugiyama
- Institute for Integrated Radiation and Nuclear Science, Kyoto University, Kumatori, Sennan-gun, Osaka 590-0494, Japan
| | - Reiko Urade
- Division of Agronomy and Horticultural Science, Graduate School of Agriculture, Kyoto University, Uji, Kyoto 611-0011, Japan
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14
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Muratspahić E, Koehbach J, Gruber CW, Craik DJ. Harnessing cyclotides to design and develop novel peptide GPCR ligands. RSC Chem Biol 2020; 1:177-191. [PMID: 34458757 PMCID: PMC8341132 DOI: 10.1039/d0cb00062k] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 07/10/2020] [Indexed: 12/13/2022] Open
Abstract
Cyclotides are plant-derived cyclic, disulfide-rich peptides with a unique cyclic cystine knot topology that confers them with remarkable structural stability and resistance to proteolytic degradation. Recently, cyclotides have emerged as promising scaffold molecules for designing peptide-based therapeutics. Here, we provide examples of how engineering cyclotides using molecular grafting may lead to the development of novel peptide ligands of G protein-coupled receptors (GPCRs), today's most exploited drug targets. Integrating bioactive epitopes into stable cyclotide scaffolds can lead to improved pharmacokinetics and oral activity as well as selectivity and high enzymatic stability. We also discuss and highlight the importance of engineered cyclotides as novel tools to study GPCR signaling.
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Affiliation(s)
- Edin Muratspahić
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna Austria
- 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
| | - Johannes Koehbach
- 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
| | - Christian W Gruber
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna Austria
| | - 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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15
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Kalmankar NV, Venkatesan R, Balaram P, Sowdhamini R. Transcriptomic profiling of the medicinal plant Clitoria ternatea: identification of potential genes in cyclotide biosynthesis. Sci Rep 2020; 10:12658. [PMID: 32728092 PMCID: PMC7391643 DOI: 10.1038/s41598-020-69452-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Accepted: 07/10/2020] [Indexed: 01/20/2023] Open
Abstract
Clitoria ternatea a perennial climber of the Fabaceae family, is well known for its agricultural and medical applications. It is also currently the only known member of the Fabaceae family that produces abundant amounts of the ultra-stable macrocyclic peptides, cyclotides, across all tissues. Cyclotides are a class of gene-encoded, disulphide-rich, macrocyclic peptides (26–37 residues) acting as defensive metabolites in several plant species. Previous transcriptomic studies have demonstrated the genetic origin of cyclotides from the Fabaceae plant family to be embedded in the albumin-1 genes, unlike its counterparts in other plant families. However, the complete mechanism of its biosynthesis and the repertoire of enzymes involved in cyclotide folding and processing remains to be understood. In this study, using RNA-Seq data and de novo transcriptome assembly of Clitoria ternatea, we have identified 71 precursor genes of cyclotides. Out of 71 unique cyclotide precursor genes obtained, 51 sequences display unique cyclotide domains, of which 26 are novel cyclotide sequences, arising from four individual tissues. MALDI-TOF mass spectrometry analysis of fractions from different tissue extracts, coupled with precursor protein sequences obtained from transcriptomic data, established the cyclotide diversity in this plant species. Special focus in this study has also been on identifying possible enzymes responsible for proper folding and processing of cyclotides in the cell. Transcriptomic mining for oxidative folding enzymes such as protein-disulphide isomerases (PDI), ER oxidoreductin-1 (ERO1) and peptidylprolyl cis-trans isomerases (PPIases)/cyclophilins, and their levels of expression are also reported. In particular, it was observed that the CtPDI genes formed plant-specific clusters among PDI genes as compared to those from other plant species. Collectively, this work provides insights into the biogenesis of the medicinally important cyclotides and establishes the expression of certain key enzymes participating in peptide biosynthesis. Also, several novel cyclotide sequences are reported and precursor sequences are analysed in detail. In the absence of a published reference genome, a comprehensive transcriptomics approach was adopted to provide an overview of diverse properties and constituents of C. ternatea.
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Affiliation(s)
- Neha V Kalmankar
- National Centre for Biological Sciences (TIFR), GKVK Campus, Bangalore, Karnataka, 560065, India.,The University of Trans-Disciplinary Health Sciences and Technology (TDU), #74/2, Jarakabande Kaval, Post Attur, Via Yelahanka, Bangalore, Karnataka, 560064, India
| | - Radhika Venkatesan
- National Centre for Biological Sciences (TIFR), GKVK Campus, Bangalore, Karnataka, 560065, India.,Department of Biological Sciences, Indian Institute of Science, Education and Research, Kolkata, Mohanpur, West Bengal, 741246, India
| | - Padmanabhan Balaram
- National Centre for Biological Sciences (TIFR), GKVK Campus, Bangalore, Karnataka, 560065, India.,Molecular Biophysics Unit, Indian Institute of Science, Bangalore, Karnataka, 560012, India
| | - Ramanathan Sowdhamini
- National Centre for Biological Sciences (TIFR), GKVK Campus, Bangalore, Karnataka, 560065, India.
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16
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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] [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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17
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Abstract
This Review explores the class of plant-derived macrocyclic peptides called cyclotides. We include an account of their discovery, characterization, and distribution in the plant kingdom as well as a detailed analysis of their sequences and structures, biosynthesis and chemical synthesis, biological functions, and applications. These macrocyclic peptides are around 30 amino acids in size and are characterized by their head-to-tail cyclic backbone and cystine knot motif, which render them to be exceptionally stable, with resistance to thermal or enzymatic degradation. Routes to their chemical synthesis have been developed over the past two decades, and this capability has facilitated a wide range of mutagenesis and structure-activity relationship studies. In turn, these studies have both led to an increased understanding of their mechanisms of action as well as facilitated a range of applications in agriculture and medicine, as ecofriendly crop protection agents, and as drug leads or scaffolds for pharmaceutical design. Our overall objective in this Review is to provide readers with a comprehensive overview of cyclotides that we hope will stimulate further work on this fascinating family of peptides.
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Affiliation(s)
- Simon J de Veer
- Institute for Molecular Bioscience , The University of Queensland , Brisbane , Queensland 4072 , Australia
| | - Meng-Wei Kan
- Institute for Molecular Bioscience , The University of Queensland , Brisbane , Queensland 4072 , Australia
| | - David J Craik
- Institute for Molecular Bioscience , The University of Queensland , Brisbane , Queensland 4072 , Australia
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18
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Ojeda PG, Cardoso MH, Franco OL. Pharmaceutical applications of cyclotides. Drug Discov Today 2019; 24:2152-2161. [PMID: 31541712 DOI: 10.1016/j.drudis.2019.09.010] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 09/05/2019] [Accepted: 09/12/2019] [Indexed: 02/06/2023]
Abstract
Cyclotides are cyclic peptides, present in several plant families, that show diverse biological properties. Structurally, cyclotides share a distinctive head-to-tail circular knotted topology of three disulfide bonds. This framework provides cyclotides with extraordinary resistance to thermal and chemical denaturation. There is increasing interest in the therapeutic potential of cyclotides, which combine several promising pharmaceutical properties, including binding affinity, target selectivity, and low toxicity towards healthy mammalian cells. Recently, cyclotides have been reported to be orally bioavailable and have proved to be amenable to modifications. Here, we provide an overview of the structure, properties, and pharmaceutical applications of cyclotides.
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Affiliation(s)
- Paola G Ojeda
- Escuela de Química y Farmacia, Facultad de Medicina, Universidad Católica del Maule, Av. San Miguel 3605, Talca 3480112, Chile
| | - Marlon H Cardoso
- Programa de Pós-Graduação em Ciências Genômicas e Biotecnologia, Centro de Análises Proteômicas e Bioquímicas, Universidade Católica de Brasília, Brasília, Brazil; 3S-Inova Biotech, Programa de Pós-Graduação em Biotecnologia, Universidade Católica Dom Bosco, Campo Grande, Brazil
| | - Octávio L Franco
- Programa de Pós-Graduação em Ciências Genômicas e Biotecnologia, Centro de Análises Proteômicas e Bioquímicas, Universidade Católica de Brasília, Brasília, Brazil; 3S-Inova Biotech, Programa de Pós-Graduação em Biotecnologia, Universidade Católica Dom Bosco, Campo Grande, Brazil.
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19
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Oguis GK, Gilding EK, Jackson MA, Craik DJ. Butterfly Pea ( Clitoria ternatea), a Cyclotide-Bearing Plant With Applications in Agriculture and Medicine. FRONTIERS IN PLANT SCIENCE 2019; 10:645. [PMID: 31191573 PMCID: PMC6546959 DOI: 10.3389/fpls.2019.00645] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Accepted: 04/29/2019] [Indexed: 05/16/2023]
Abstract
The perennial leguminous herb Clitoria ternatea (butterfly pea) has attracted significant interest based on its agricultural and medical applications, which range from use as a fodder and nitrogen fixing crop, to applications in food coloring and cosmetics, traditional medicine and as a source of an eco-friendly insecticide. In this article we provide a broad multidisciplinary review that includes descriptions of the physical appearance, distribution, taxonomy, habitat, growth and propagation, phytochemical composition and applications of this plant. Notable amongst its repertoire of chemical components are anthocyanins which give C. ternatea flowers their characteristic blue color, and cyclotides, ultra-stable macrocyclic peptides that are present in all tissues of this plant. The latter are potent insecticidal molecules and are implicated as the bioactive agents in a plant extract used commercially as an insecticide. We include a description of the genetic origin of these peptides, which interestingly involve the co-option of an ancestral albumin gene to produce the cyclotide precursor protein. The biosynthesis step in which the cyclic peptide backbone is formed involves an asparaginyl endopeptidase, of which in C. ternatea is known as butelase-1. This enzyme is highly efficient in peptide ligation and has been the focus of many recent studies on peptide ligation and cyclization for biotechnological applications. The article concludes with some suggestions for future studies on this plant, including the need to explore possible synergies between the various peptidic and non-peptidic phytochemicals.
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Affiliation(s)
| | | | | | - David J. Craik
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD, Australia
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20
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Abstract
ABSTRACT
For most of the proteins synthesized in the endoplasmic reticulum (ER), disulfide bond formation accompanies protein folding in a process called oxidative folding. Oxidative folding is catalyzed by a number of enzymes, including the family of protein disulfide isomerases (PDIs), as well as other proteins that supply oxidizing equivalents to PDI family proteins, like ER oxidoreductin 1 (Ero1). Oxidative protein folding in the ER is a basic vital function, and understanding its molecular mechanism is critical for the application of plants as protein production tools. Here, I review the recent research and progress related to the enzymes involved in oxidative folding in the plant ER. Firstly, nine groups of plant PDI family proteins are introduced. Next, the enzymatic properties of plant Ero1 are described. Finally, the cooperative folding by multiple PDI family proteins and Ero1 is described.
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Affiliation(s)
- Reiko Urade
- Institute for Integrated Radiation and Nuclear Science, Kyoto University, Osaka, Japan
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21
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Olsson V, Joos L, Zhu S, Gevaert K, Butenko MA, De Smet I. Look Closely, the Beautiful May Be Small: Precursor-Derived Peptides in Plants. ANNUAL REVIEW OF PLANT BIOLOGY 2019; 70:153-186. [PMID: 30525926 DOI: 10.1146/annurev-arplant-042817-040413] [Citation(s) in RCA: 92] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
During the past decade, a flurry of research focusing on the role of peptides as short- and long-distance signaling molecules in plant cell communication has been undertaken. Here, we focus on peptides derived from nonfunctional precursors, and we address several key questions regarding peptide signaling. We provide an overview of the regulatory steps involved in producing a biologically active peptide ligand that can bind its corresponding receptor(s) and discuss how this binding and subsequent activation lead to specific cellular outputs. We discuss different experimental approaches that can be used to match peptide ligands with their receptors. Lastly, we explore how peptides evolved from basic signaling units regulating essential processes in plants to more complex signaling systems as new adaptive traits developed and how nonplant organisms exploit this signaling machinery by producing peptide mimics.
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Affiliation(s)
- Vilde Olsson
- Section for Genetics and Evolutionary Biology, Department of Biosciences, University of Oslo, 0316 Oslo, Norway;
| | - Lisa Joos
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium;
- VIB-UGent Center for Plant Systems Biology, 9052 Ghent, Belgium
| | - Shanshuo Zhu
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium;
- VIB-UGent Center for Plant Systems Biology, 9052 Ghent, Belgium
- VIB-UGent Center for Medical Biotechnology, 9000 Ghent, Belgium
- Department of Biomolecular Medicine, Ghent University, 9000 Ghent, Belgium
| | - Kris Gevaert
- VIB-UGent Center for Medical Biotechnology, 9000 Ghent, Belgium
- Department of Biomolecular Medicine, Ghent University, 9000 Ghent, Belgium
| | - Melinka A Butenko
- Section for Genetics and Evolutionary Biology, Department of Biosciences, University of Oslo, 0316 Oslo, Norway;
| | - Ive De Smet
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium;
- VIB-UGent Center for Plant Systems Biology, 9052 Ghent, Belgium
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22
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Papain-like cysteine proteases prepare plant cyclic peptide precursors for cyclization. Proc Natl Acad Sci U S A 2019; 116:7831-7836. [PMID: 30944220 DOI: 10.1073/pnas.1901807116] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Cyclotides are plant defense peptides that have been extensively investigated for pharmaceutical and agricultural applications, but key details of their posttranslational biosynthesis have remained elusive. Asparaginyl endopeptidases are crucial in the final stage of the head-to-tail cyclization reaction, but the enzyme(s) involved in the prerequisite steps of N-terminal proteolytic release were unknown until now. Here we use activity-guided fractionation to identify specific members of papain-like cysteine proteases involved in the N-terminal cleavage of cyclotide precursors. Through both characterization of recombinantly produced enzymes and in planta peptide cyclization assays, we define the molecular basis of the substrate requirements of these enzymes, including the prototypic member, here termed kalatase A. The findings reported here will pave the way for improving the efficiency of plant biofactory approaches for heterologous production of cyclotide analogs of therapeutic or agricultural value.
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23
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Zeng R, Farooq MU, Wang L, Su Y, Zheng T, Ye X, Jia X, Zhu J. Study on Differential Protein Expression in Natural Selenium-Enriched and Non-Selenium-Enriched Rice Based on iTRAQ Quantitative Proteomics. Biomolecules 2019; 9:biom9040130. [PMID: 30935009 PMCID: PMC6523350 DOI: 10.3390/biom9040130] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Revised: 03/18/2019] [Accepted: 03/25/2019] [Indexed: 12/14/2022] Open
Abstract
This work was designated to scrutinize the protein differential expression in natural selenium-enriched and non-selenium-enriched rice using the Isobaric-tags for relative and absolute quantification (iTRAQ) proteomics approach. The extracted proteins were subjected to enzyme digestion, desalting, and identified by iTRAQ coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) technology. High pH C18 separation analysis was performed, and the data were then analyzed by Protein PilotTM (V4.5) search engine. Protein differential expression was searched out by comparing relatively quantified proteins. The analysis was conducted using gene ontology (GO), cluster of orthologous groups of proteins (COG) and Kyoto encyclopedia of genes and genomes (KEGG) metabolic pathways. A total of 3235 proteins were detected and 3161 proteins were quantified, of which 401 were differential proteins. 208 down-regulated and 193 up-regulated proteins were unveiled. 77 targeted significant differentially expressed proteins were screened out for further analysis, and were classified into 10 categories: oxidoreductases, transferases, isomerases, heat shock proteins, lyases, hydrolases, ligases, synthetases, tubulin, and actin. The results indicated that the anti-stress, anti-oxidation, active oxygen metabolism, carbohydrate and amino acid metabolism of natural selenium-enriched rice was higher than that of non-selenium rice. The activation of the starch synthesis pathway was found to be bounteous in non-selenium-enriched rice. Cysteine synthase (CYS) and methyltransferase (metE) might be the two key proteins that cause amino acid differences. OsAPx02, CatC, riPHGPX, HSP70 and HSP90 might be the key enzymes regulating antioxidant and anti-stress effect differences in two types of rice. This study provides basic information about deviations in protein mechanism and secondary metabolites in selenium-enriched and non-selenium-enriched rice.
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Affiliation(s)
- Rui Zeng
- Demonstration Base for International Science & Technology Cooperation of Sichuan Province, Rice Research Institute, Sichuan Agricultural University, Chengdu 611130, Sichuan, China.
- Dujiangyan Agricultural and Rural Bureau, Dujiangyan 611830, Sichuan, China.
| | - Muhammad Umer Farooq
- Demonstration Base for International Science & Technology Cooperation of Sichuan Province, Rice Research Institute, Sichuan Agricultural University, Chengdu 611130, Sichuan, China.
| | - Li Wang
- Meishan Vocational & Technical College, Meishan 62000, Sichuan, China.
| | - Yang Su
- Demonstration Base for International Science & Technology Cooperation of Sichuan Province, Rice Research Institute, Sichuan Agricultural University, Chengdu 611130, Sichuan, China.
| | - Tengda Zheng
- Demonstration Base for International Science & Technology Cooperation of Sichuan Province, Rice Research Institute, Sichuan Agricultural University, Chengdu 611130, Sichuan, China.
| | - Xiaoying Ye
- Demonstration Base for International Science & Technology Cooperation of Sichuan Province, Rice Research Institute, Sichuan Agricultural University, Chengdu 611130, Sichuan, China.
| | - Xiaomei Jia
- Demonstration Base for International Science & Technology Cooperation of Sichuan Province, Rice Research Institute, Sichuan Agricultural University, Chengdu 611130, Sichuan, China.
| | - Jianqing Zhu
- Demonstration Base for International Science & Technology Cooperation of Sichuan Province, Rice Research Institute, Sichuan Agricultural University, Chengdu 611130, Sichuan, China.
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24
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Gene-guided discovery and engineering of branched cyclic peptides in plants. Proc Natl Acad Sci U S A 2018; 115:E10961-E10969. [PMID: 30373830 DOI: 10.1073/pnas.1813993115] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The plant kingdom contains vastly untapped natural product chemistry, which has been traditionally explored through the activity-guided approach. Here, we describe a gene-guided approach to discover and engineer a class of plant ribosomal peptides, the branched cyclic lyciumins. Initially isolated from the Chinese wolfberry Lycium barbarum, lyciumins are protease-inhibiting peptides featuring an N-terminal pyroglutamate and a macrocyclic bond between a tryptophan-indole nitrogen and a glycine α-carbon. We report the identification of a lyciumin precursor gene from L. barbarum, which encodes a BURP domain and repetitive lyciumin precursor peptide motifs. Genome mining enabled by this initial finding revealed rich lyciumin genotypes and chemotypes widespread in flowering plants. We establish a biosynthetic framework of lyciumins and demonstrate the feasibility of producing diverse natural and unnatural lyciumins in transgenic tobacco. With rapidly expanding plant genome resources, our approach will complement bioactivity-guided approaches to unlock and engineer hidden plant peptide chemistry for pharmaceutical and agrochemical applications.
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25
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Zhang Z, Liu X, Li R, Yuan L, Dai Y, Wang X. Identification and Functional Analysis of a Protein Disulfide Isomerase ( AtPDI1) in Arabidopsis thaliana. FRONTIERS IN PLANT SCIENCE 2018; 9:913. [PMID: 30073003 PMCID: PMC6060501 DOI: 10.3389/fpls.2018.00913] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Accepted: 06/08/2018] [Indexed: 05/30/2023]
Abstract
Protein disulfide isomerase (PDI) catalyzes the conversion of thiol-disulfide and plays an important role in various physiological events in animals. A PDI (OaPDI) from a tropical plant was detailed studied and it was found to be involved in response of biotic stress (Gruber et al., 2007). However, the activities of PDI related to physiological functions in plants are poorly understood. In the present study, a homolog of human PDI in Arabidopsis (AtPDI1), encoded by the gene (At3g54960), was characterized. The recombinant AtPDI1 protein had disulfide isomerase activity in vitro and two pairs of conservative cysteines in catalytic domains play a crucial role in the PDI activities. Expression of AtPDI1 in Escherichia coli significantly enhanced stress tolerance of cells and the mutations of critical cysteines almost lose this function. In plants, AtPDI1 was strongly induced by abiotic stresses and exogenous abscisic acid. An ArabidopsisAtPDI1 knockdown mutant (pdi1) and overexpression lines of transgenic plants obtained by this investigation were used to further examine the function of AtPDI1. The mutant line was more sensitive to stresses than the wild-type, while overexpressing AtPDI1 increased tolerance of seedlings to abiotic stresses, with a higher germination ratio and longer length of roots than the wild-type. Our results suggested AtPDI1 played roles in anti-stresses in Arabidopsis, which relate to the activities of PDI.
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26
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Hellinger R, Thell K, Vasileva M, Muhammad T, Gunasekera S, Kümmel D, Göransson U, Becker CW, Gruber CW. Chemical Proteomics for Target Discovery of Head-to-Tail Cyclized Mini-Proteins. Front Chem 2017; 5:73. [PMID: 29075625 PMCID: PMC5641551 DOI: 10.3389/fchem.2017.00073] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Accepted: 09/19/2017] [Indexed: 11/24/2022] Open
Abstract
Target deconvolution is one of the most challenging tasks in drug discovery, but a key step in drug development. In contrast to small molecules, there is a lack of validated and robust methodologies for target elucidation of peptides. In particular, it is difficult to apply these methods to cyclic and cysteine-stabilized peptides since they exhibit reduced amenability to chemical modification and affinity capture; however, such ribosomally synthesized and post-translationally modified peptide natural products are rich sources of promising drug candidates. For example, plant-derived circular peptides called cyclotides have recently attracted much attention due to their immunosuppressive effects and oral activity in the treatment of multiple sclerosis in mice, but their molecular target has hitherto not been reported. In this study, a chemical proteomics approach using photo-affinity crosslinking was developed to determine a target for the circular peptide [T20K]kalata B1. Using this prototypic nature-derived peptide enabled the identification of a possible functional modulation of 14-3-3 proteins. This biochemical interaction was validated via competition pull down assays as well as a cellular reporter assay indicating an effect on 14-3-3-dependent transcriptional activity. As proof of concept, the presented approach may be applicable for target elucidation of various cyclic peptides and mini-proteins, in particular cyclotides, which represent a promising class of molecules in drug discovery and development.
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Affiliation(s)
- Roland Hellinger
- Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Kathrin Thell
- Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Mina Vasileva
- Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Taj Muhammad
- Division of Pharmacognosy, Department of Medicinal Chemistry, Uppsala University, Uppsala, Sweden
| | - Sunithi Gunasekera
- Division of Pharmacognosy, Department of Medicinal Chemistry, Uppsala University, Uppsala, Sweden
| | - Daniel Kümmel
- School of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany
| | - Ulf Göransson
- Division of Pharmacognosy, Department of Medicinal Chemistry, Uppsala University, Uppsala, Sweden
| | - Christian W Becker
- Department of Chemistry, Institute of Biological Chemistry, University of Vienna, Vienna, Austria
| | - Christian W Gruber
- Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria.,School of Biomedical Sciences, Faculty of Medicine, University of Queensland, St. Lucia, QLD, Australia
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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] [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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Craik DJ, Lee MH, Rehm FBH, Tombling B, Doffek B, Peacock H. Ribosomally-synthesised cyclic peptides from plants as drug leads and pharmaceutical scaffolds. Bioorg Med Chem 2017; 26:2727-2737. [PMID: 28818463 DOI: 10.1016/j.bmc.2017.08.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Revised: 07/12/2017] [Accepted: 08/06/2017] [Indexed: 12/28/2022]
Abstract
Owing to their exceptional stability and favourable pharmacokinetic properties, plant-derived cyclic peptides have recently attracted significant attention in the field of peptide-based drug design. This article describes the three major classes of ribosomally-synthesised plant peptides - the cyclotides, the PawS-derived peptides and the orbitides - and reviews their applications as leads or scaffolds in drug design. These ribosomally-produced peptides have a range of biological activities, including anti-HIV, cytotoxic and immunomodulatory activity. In addition, recent interest has focused on their use as scaffolds to stabilise bioactive peptide sequences, thereby enhancing their biopharmaceutical properties. There are now more than 30 published papers on such 'grafting' applications, most of which have been reported only in the last few years, and several such studies have reported in vivo activity of orally delivered cyclic peptides. In this article, we describe approaches to the synthesis of cyclic peptides and their pharmaceutically-grafted derivatives as well as outlining their biosynthetic routes. Finally, we describe possible bioproduction routes for pharmaceutically active cyclic peptides, involving plants and plant suspension cultures.
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Affiliation(s)
- David J Craik
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia.
| | - Meng-Han Lee
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Fabian B H Rehm
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Benjamin Tombling
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Benjamin Doffek
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Hayden Peacock
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
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29
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Okuda A, Matsusaki M, Masuda T, Urade R. Identification and characterization of GmPDIL7, a soybean ER membrane-bound protein disulfide isomerase family protein. FEBS J 2017; 284:414-428. [PMID: 27960051 DOI: 10.1111/febs.13984] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2016] [Revised: 11/04/2016] [Accepted: 12/05/2016] [Indexed: 01/19/2023]
Abstract
Most proteins synthesized in the endoplasmic reticulum (ER) possess intramolecular and intermolecular disulfide bonds, which play an important role in the conformational stability and function of proteins. Hence, eukaryotic cells contain protein disulfide bond formation pathways such as the protein disulfide isomerase (PDI)-ER oxidoreductin 1 (Ero1) system in the ER lumen. In this study, we identified soybean PDIL7 (GmPDIL7), a novel soybean ER membrane-bound PDI family protein, and determined its enzymatic properties. GmPDIL7 has a putative N-terminal signal sequence, a thioredoxin domain with an active center motif (CGHC), and a putative C-terminal transmembrane region. Likewise, we demonstrated that GmPDIL7 is ubiquitously expressed in soybean tissues and is localized in the ER membrane. Furthermore, GmPDIL7 associated with other soybean PDI family proteins in vivo and GmPDIL7 mRNA was slightly upregulated under ER stress. The redox potential of recombinant GmPDIL7 expressed in Escherichia coli was -187 mV, indicating that GmPDIL7 could oxidize unfolded proteins. GmPDIL7 exhibited a dithiol oxidase activity level that was similar to other soybean PDI family proteins. However, the oxidative refolding activity of GmPDIL7 was lower than other soybean PDI family proteins. GmPDIL7 was well oxidized by GmERO1. Taken together, our results indicated that GmPDIL7 primarily plays a role as a supplier of disulfide bonds in nascent proteins for oxidative folding on the ER membrane. DATABASE The nucleotide sequence data for the GmPDIL7 cDNA are available in the DNA Data Bank of Japan (DDBJ) databases under the accession numbers LC158001. ENZYME Protein disulfide isomerase: EC 5.3.4.1.
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Affiliation(s)
- Aya Okuda
- Division of Agronomy and Horticultural Science, Graduate School of Agriculture, Kyoto University, Uji, Japan
| | - Motonori Matsusaki
- Division of Agronomy and Horticultural Science, Graduate School of Agriculture, Kyoto University, Uji, Japan
| | - Taro Masuda
- Division of Agronomy and Horticultural Science, Graduate School of Agriculture, Kyoto University, Uji, Japan
| | - Reiko Urade
- Division of Agronomy and Horticultural Science, Graduate School of Agriculture, Kyoto University, Uji, Japan
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30
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Qu H, Smithies BJ, Durek T, Craik DJ. Synthesis and Protein Engineering Applications of Cyclotides. Aust J Chem 2017. [DOI: 10.1071/ch16589] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Cyclotides are a group of plant-derived peptides with a head-to-tail cyclized backbone that is stabilized by three knotted disulfide bonds. Their exceptional stability and tolerance for residue substitutions have led to interest in their application as drug design scaffolds. To date, chemical synthesis has been the dominant methodology for producing cyclotides and their analogues. Native chemical ligation is the most common strategy to generate the cyclic backbone and has been highly successful at producing a wide range of cyclotides for studies of structure–activity relationships. Both this and other chemical approaches require a specific linker at the C-terminus and typically involve a non-directed folding (disulfide oxidation) regimen, which can sometimes be a limiting factor in final yields. Following the recent discovery of enzymes involved in peptide cyclization in planta, site-specific and highly efficient enzymatic ligations have been used for synthetic cyclotide backbone cyclization. In this review, chemical synthesis strategies and approaches involving cyclization via enzymes for the production of cyclotides are described.
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31
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Du N, Shi L, Yuan Y, Li B, Shu S, Sun J, Guo S. Proteomic Analysis Reveals the Positive Roles of the Plant-Growth-Promoting Rhizobacterium NSY50 in the Response of Cucumber Roots to Fusarium oxysporum f. sp. cucumerinum Inoculation. FRONTIERS IN PLANT SCIENCE 2016; 7:1859. [PMID: 28018395 PMCID: PMC5155491 DOI: 10.3389/fpls.2016.01859] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Accepted: 11/25/2016] [Indexed: 05/30/2023]
Abstract
Plant-growth-promoting rhizobacteria (PGPR) can both improve plant growth and enhance plant resistance against a variety of environmental stresses. To investigate the mechanisms that PGPR use to protect plants under pathogenic attack, transmission electron microscopy analysis and a proteomic approach were designed to test the effects of the new potential PGPR strain Paenibacillus polymyxa NSY50 on cucumber seedling roots after they were inoculated with the destructive phytopathogen Fusarium oxysporum f. sp. cucumerinum (FOC). NSY50 could apparently mitigate the injury caused by the FOC infection and maintain the stability of cell structures. The two-dimensional electrophoresis (2-DE) approach in conjunction with MALDI-TOF/TOF analysis revealed a total of 56 proteins that were differentially expressed in response to NSY50 and/or FOC. The application of NSY50 up-regulated most of the identified proteins that were involved in carbohydrate metabolism and amino acid metabolism under normal conditions, which implied that both energy generation and the production of amino acids were enhanced, thereby ensuring an adequate supply of amino acids for the synthesis of new proteins in cucumber seedlings to promote plant growth. Inoculation with FOC inhibited most of the proteins related to carbohydrate and energy metabolism and to protein metabolism. The combined inoculation treatment (NSY50+FOC) accumulated abundant proteins involved in defense mechanisms against oxidation and detoxification as well as carbohydrate metabolism, which might play important roles in preventing pathogens from attacking. Meanwhile, western blotting was used to analyze the accumulation of enolase (ENO) and S-adenosylmethionine synthase (SAMs). NSY50 further increased the expression of ENO and SAMs under FOC stress. In addition, NSY50 adjusted the transcription levels of genes related to those proteins. Taken together, these results suggest that P. polymyxa NSY50 may promote plant growth and alleviate FOC-induced damage by improving the metabolism and activation of defense-related proteins in cucumber roots.
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Affiliation(s)
- Nanshan Du
- Key Laboratory of Southern Vegetable Crop Genetic Improvement in Ministry of Agriculture, College of Horticulture, Nanjing Agricultural UniversityNanjing, China
| | - Lu Shi
- Key Laboratory of Southern Vegetable Crop Genetic Improvement in Ministry of Agriculture, College of Horticulture, Nanjing Agricultural UniversityNanjing, China
| | - Yinghui Yuan
- Key Laboratory of Southern Vegetable Crop Genetic Improvement in Ministry of Agriculture, College of Horticulture, Nanjing Agricultural UniversityNanjing, China
| | - Bin Li
- Department of Horticulture, Shanxi Agricultural UniversityTaigu, China
| | - Sheng Shu
- Key Laboratory of Southern Vegetable Crop Genetic Improvement in Ministry of Agriculture, College of Horticulture, Nanjing Agricultural UniversityNanjing, China
- Suqian Academy of Protected Horticulture, Nanjing Agricultural UniversitySuqian, China
| | - Jin Sun
- Key Laboratory of Southern Vegetable Crop Genetic Improvement in Ministry of Agriculture, College of Horticulture, Nanjing Agricultural UniversityNanjing, China
- Suqian Academy of Protected Horticulture, Nanjing Agricultural UniversitySuqian, China
| | - Shirong Guo
- Key Laboratory of Southern Vegetable Crop Genetic Improvement in Ministry of Agriculture, College of Horticulture, Nanjing Agricultural UniversityNanjing, China
- Suqian Academy of Protected Horticulture, Nanjing Agricultural UniversitySuqian, China
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32
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Mahatmanto T. Review seed biopharmaceutical cyclic peptides: From discovery to applications. Biopolymers 2016; 104:804-14. [PMID: 26385189 DOI: 10.1002/bip.22741] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Revised: 08/17/2015] [Accepted: 09/16/2015] [Indexed: 02/02/2023]
Abstract
Mini-proteins (or peptides) with disulfide bond/s and a cyclic backbone offer exciting opportunities for applications in medicine, as these ribosomally synthesized and posttranslationally modified peptides are exceptionally stable and amenable to grafting epitopes with desirable activities. Here I discuss important aspects of the discovery and applications of disulfide-bonded cyclic peptides from seeds, i.e., the trypsin inhibitor cyclotides and the preproalbumin with sunflower trypsin inhibitor-derived peptides, focusing on bioanalytical methods for and insights generated from their discovery as well as their potential use as engineering scaffolds for peptide-based drug design. The recent discovery of their precursors and processing enzymes could potentially enable in planta production of designer disulfide-bonded cyclic peptides, preferably in edible seeds, and address the demand for new biopharmaceutical peptides in a cost-effective manner.
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Affiliation(s)
- Tunjung Mahatmanto
- Department of Agricultural Product Technology, Faculty of Agricultural Technology, Brawijaya University, Malang, East Java, 65145, Indonesia
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33
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Slazak B, Kapusta M, Malik S, Bohdanowicz J, Kuta E, Malec P, Göransson U. Immunolocalization of cyclotides in plant cells, tissues and organ supports their role in host defense. PLANTA 2016; 244:1029-1040. [PMID: 27394154 PMCID: PMC5052299 DOI: 10.1007/s00425-016-2562-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Accepted: 06/20/2016] [Indexed: 05/02/2023]
Abstract
The distribution of cyclotides was visualized in plant cells, tissues and organs using immunohistochemistry. Finding of cyclotides in tissues potentially vulnerable to pathogen attacks supports their role as defense molecules. The cyclotide family of plant peptides is characterized by the cyclic cystine knot motif and its diverse biological activities. Given their insecticidal and antimicrobial properties, the role of cyclotides in planta is probably associated with host defense. Our current understanding of the cellular compartmentalization of cyclotides in the vacuole is based on indirect studies on transgenic model plants that do not express cyclotides naturally. Matrix-assisted laser desorption ionization (MALDI) imaging has also been used to study the distribution of cyclotides, but the technique's resolution was insufficient to determine their tissue or cell distribution. To avoid the limitations of these approaches, immunohistochemical visualization methods were used. Antibodies were raised in rabbits using cycloviolacin O2 (cyO2), and their specificity was determined by Western and dot blot experiments. Slides for immunohistochemical analysis were prepared from leaf, petiole and root fragments of Viola odorata and Viola uliginosa, and specimens were visualized using indirect epifluorescence microscopy. The antibodies against cyclotides were specific against selected bracelet cyclotides with high similarity (cyO2, cyO3, cyO8, cyO13) and suitable for immunohistochemistry. The tissue distribution of the cyclotides visualized in this way is consistent with their proposed role in host defense-relatively large quantities were observed in the leaf and petiole epidermis in both Viola species. Cyclotides were also found in vascular tissue in all the assessed plant organs. The vacuole storage of cyclotides was directly shown.
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Affiliation(s)
- Blazej Slazak
- W. Szafer Institute of Botany, Polish Academy of Science, 46 Lubicz St, 31-512, Cracow, Poland.
- Division of Pharmacognosy, Department of Medicinal Chemistry, Uppsala University, Biomedical Center, Box 574, 751 23, Uppsala, Sweden.
| | - Małgorzata Kapusta
- Department of Plant Cytology and Embryology, Faculty of Biology, University of Gdańsk, 59 Wita Stwosza St, 80-308, Gdańsk, Poland
| | - Sohaib Malik
- Division of Pharmacognosy, Department of Medicinal Chemistry, Uppsala University, Biomedical Center, Box 574, 751 23, Uppsala, Sweden
| | - Jerzy Bohdanowicz
- Department of Plant Cytology and Embryology, Faculty of Biology, University of Gdańsk, 59 Wita Stwosza St, 80-308, Gdańsk, Poland
| | - Elżbieta Kuta
- Department of Plant Cytology and Embryology, Institute of Botany, Jagiellonian University, 9 Gronostajowa St, 30-387, Cracow, Poland
| | - Przemysław Malec
- Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 7 Gronostajowa St, 30-387, Cracow, Poland
| | - Ulf Göransson
- Division of Pharmacognosy, Department of Medicinal Chemistry, Uppsala University, Biomedical Center, Box 574, 751 23, Uppsala, Sweden
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34
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Slazak B, Kapusta M, Malik S, Bohdanowicz J, Kuta E, Malec P, Göransson U. Immunolocalization of cyclotides in plant cells, tissues and organ supports their role in host defense. PLANTA 2016. [PMID: 27394154 DOI: 10.1016/10.1007/s00425-016-2562-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
The distribution of cyclotides was visualized in plant cells, tissues and organs using immunohistochemistry. Finding of cyclotides in tissues potentially vulnerable to pathogen attacks supports their role as defense molecules. The cyclotide family of plant peptides is characterized by the cyclic cystine knot motif and its diverse biological activities. Given their insecticidal and antimicrobial properties, the role of cyclotides in planta is probably associated with host defense. Our current understanding of the cellular compartmentalization of cyclotides in the vacuole is based on indirect studies on transgenic model plants that do not express cyclotides naturally. Matrix-assisted laser desorption ionization (MALDI) imaging has also been used to study the distribution of cyclotides, but the technique's resolution was insufficient to determine their tissue or cell distribution. To avoid the limitations of these approaches, immunohistochemical visualization methods were used. Antibodies were raised in rabbits using cycloviolacin O2 (cyO2), and their specificity was determined by Western and dot blot experiments. Slides for immunohistochemical analysis were prepared from leaf, petiole and root fragments of Viola odorata and Viola uliginosa, and specimens were visualized using indirect epifluorescence microscopy. The antibodies against cyclotides were specific against selected bracelet cyclotides with high similarity (cyO2, cyO3, cyO8, cyO13) and suitable for immunohistochemistry. The tissue distribution of the cyclotides visualized in this way is consistent with their proposed role in host defense-relatively large quantities were observed in the leaf and petiole epidermis in both Viola species. Cyclotides were also found in vascular tissue in all the assessed plant organs. The vacuole storage of cyclotides was directly shown.
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Affiliation(s)
- Blazej Slazak
- W. Szafer Institute of Botany, Polish Academy of Science, 46 Lubicz St, 31-512, Cracow, Poland.
- Division of Pharmacognosy, Department of Medicinal Chemistry, Uppsala University, Biomedical Center, Box 574, 751 23, Uppsala, Sweden.
| | - Małgorzata Kapusta
- Department of Plant Cytology and Embryology, Faculty of Biology, University of Gdańsk, 59 Wita Stwosza St, 80-308, Gdańsk, Poland
| | - Sohaib Malik
- Division of Pharmacognosy, Department of Medicinal Chemistry, Uppsala University, Biomedical Center, Box 574, 751 23, Uppsala, Sweden
| | - Jerzy Bohdanowicz
- Department of Plant Cytology and Embryology, Faculty of Biology, University of Gdańsk, 59 Wita Stwosza St, 80-308, Gdańsk, Poland
| | - Elżbieta Kuta
- Department of Plant Cytology and Embryology, Institute of Botany, Jagiellonian University, 9 Gronostajowa St, 30-387, Cracow, Poland
| | - Przemysław Malec
- Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 7 Gronostajowa St, 30-387, Cracow, Poland
| | - Ulf Göransson
- Division of Pharmacognosy, Department of Medicinal Chemistry, Uppsala University, Biomedical Center, Box 574, 751 23, Uppsala, Sweden
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35
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Song T, Chu M, Lahlali R, Yu F, Peng G. Shotgun Label-free Proteomic Analysis of Clubroot (Plasmodiophora brassicae) Resistance Conferred by the Gene Rcr1 in Brassica rapa. FRONTIERS IN PLANT SCIENCE 2016; 7:1013. [PMID: 27462338 PMCID: PMC4939851 DOI: 10.3389/fpls.2016.01013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2016] [Accepted: 06/27/2016] [Indexed: 05/23/2023]
Abstract
Clubroot, caused by the plasmodiophorid pathogen Plasmodiophora brassicae, is one of the most serious diseases on Brassica crops worldwide and a major threat to canola production in western Canada. Host resistance is the key strategy for clubroot management on canola. Several clubroot resistance (CR) genes have been identified, but the mechanisms associated with these CR genes are poorly understood. In the current study, a label-free shotgun proteomic approach was used to profile and compare the proteomes of Brassica rapa carrying and not carrying the CR gene Rcr1 in response to P. brassicae infection. A total of 527 differentially accumulated proteins (DAPs) were identified between the resistant (with Rcr1) and susceptible (without Rcr1) samples, and functional annotation of these DAPs indicates that the perception of P. brassicae and activation of defense responses are triggered via an unique signaling pathway distinct from common modes of recognition receptors reported with many other plant-pathogen interactions; this pathway appears to act in a calcium-independent manner through a not-well-defined cascade of mitogen-activated protein kinases and may require the ubiquitin-26S proteasome found to be related to abiotic stresses, especially the cold-stress tolerance in other studies. Both up-regulation of defense-related and down-regulation of pathogenicity-related metabolism was observed in plants carrying Rcr1, and these functions may all contribute to the CR mediated by Rcr1. These results, combined with those of transcriptomic analysis reported earlier, improved our understanding of molecular mechanisms associated with Rcr1 and CR at large, and identified candidate metabolites or pathways related to specific resistance mechanisms. Deploying CR genes with different modes of action may help improve the durability of CR.
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Affiliation(s)
- Tao Song
- Department of Agriculture and Agri-Food Canada, Saskatoon Research and Development CenterSaskatoon, SK, Canada
| | - Mingguang Chu
- Department of Agriculture and Agri-Food Canada, Saskatoon Research and Development CenterSaskatoon, SK, Canada
| | - Rachid Lahlali
- Department of Agriculture and Agri-Food Canada, Saskatoon Research and Development CenterSaskatoon, SK, Canada
- Canadian Light Source Inc.Saskatoon, SK, Canada
| | - Fengqun Yu
- Department of Agriculture and Agri-Food Canada, Saskatoon Research and Development CenterSaskatoon, SK, Canada
| | - Gary Peng
- Department of Agriculture and Agri-Food Canada, Saskatoon Research and Development CenterSaskatoon, SK, Canada
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36
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Nguyen KNT, Nguyen GKT, Nguyen PQT, Ang KH, Dedon PC, Tam JP. Immunostimulating and Gram-negative-specific antibacterial cyclotides from the butterfly pea (Clitoria ternatea). FEBS J 2016; 283:2067-90. [DOI: 10.1111/febs.13720] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Revised: 02/05/2016] [Accepted: 03/22/2016] [Indexed: 12/18/2022]
Affiliation(s)
- Kim Ngan T. Nguyen
- School of Biological Sciences; Nanyang Technological University; Singapore City Singapore
| | - Giang Kien Truc Nguyen
- School of Biological Sciences; Nanyang Technological University; Singapore City Singapore
| | | | - Koon Hwee Ang
- School of Biological Sciences; Nanyang Technological University; Singapore City Singapore
| | - Peter C. Dedon
- Department of Biological Engineering; Massachusetts Institute of Technology; Cambridge MA USA
| | - James P. Tam
- School of Biological Sciences; Nanyang Technological University; Singapore City Singapore
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Oral activity of a nature-derived cyclic peptide for the treatment of multiple sclerosis. Proc Natl Acad Sci U S A 2016; 113:3960-5. [PMID: 27035952 DOI: 10.1073/pnas.1519960113] [Citation(s) in RCA: 98] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Multiple sclerosis (MS) is the most common autoimmune disease affecting the central nervous system. It is characterized by auto-reactive T cells that induce demyelination and neuronal degradation. Treatment options are still limited and several MS medications need to be administered by parenteral application but are modestly effective. Oral active drugs such as fingolimod have been weighed down by safety concerns. Consequently, there is a demand for novel, especially orally active therapeutics. Nature offers an abundance of compounds for drug discovery. Recently, the circular plant peptide kalata B1 was shown to silence T-cell proliferation in vitro in an IL-2-dependent mechanism. Owing to this promising effect, we aimed to determine in vivo activity of the cyclotide [T20K]kalata B1 using the MS mouse model experimental autoimmune encephalomyelitis (EAE). Treatment of mice with the cyclotide resulted in a significant delay and diminished symptoms of EAE by oral administration. Cyclotide application substantially impeded disease progression and did not exhibit adverse effects. Inhibition of lymphocyte proliferation and the reduction of proinflammatory cytokines, in particular IL-2, distinguish the cyclotide from other marketed drugs. Considering their stable structural topology and oral activity, cyclotides are candidates as peptide therapeutics for pharmaceutical drug development for treatment of T-cell-mediated disorders.
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Tam JP, Wang S, Wong KH, Tan WL. Antimicrobial Peptides from Plants. Pharmaceuticals (Basel) 2015; 8:711-57. [PMID: 26580629 PMCID: PMC4695807 DOI: 10.3390/ph8040711] [Citation(s) in RCA: 276] [Impact Index Per Article: 30.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Revised: 08/06/2015] [Accepted: 09/01/2015] [Indexed: 12/25/2022] Open
Abstract
Plant antimicrobial peptides (AMPs) have evolved differently from AMPs from other life forms. They are generally rich in cysteine residues which form multiple disulfides. In turn, the disulfides cross-braced plant AMPs as cystine-rich peptides to confer them with extraordinary high chemical, thermal and proteolytic stability. The cystine-rich or commonly known as cysteine-rich peptides (CRPs) of plant AMPs are classified into families based on their sequence similarity, cysteine motifs that determine their distinctive disulfide bond patterns and tertiary structure fold. Cystine-rich plant AMP families include thionins, defensins, hevein-like peptides, knottin-type peptides (linear and cyclic), lipid transfer proteins, α-hairpinin and snakins family. In addition, there are AMPs which are rich in other amino acids. The ability of plant AMPs to organize into specific families with conserved structural folds that enable sequence variation of non-Cys residues encased in the same scaffold within a particular family to play multiple functions. Furthermore, the ability of plant AMPs to tolerate hypervariable sequences using a conserved scaffold provides diversity to recognize different targets by varying the sequence of the non-cysteine residues. These properties bode well for developing plant AMPs as potential therapeutics and for protection of crops through transgenic methods. This review provides an overview of the major families of plant AMPs, including their structures, functions, and putative mechanisms.
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Affiliation(s)
- James P Tam
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore.
| | - Shujing Wang
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore.
- Department of Pharmacology and Pharmaceutical Sciences, School of Medicine, Tsinghua University, Beijing 100084, China.
| | - Ka H Wong
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore.
| | - Wei Liang Tan
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore.
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Hellinger R, Koehbach J, Soltis DE, Carpenter EJ, Wong GKS, Gruber CW. Peptidomics of Circular Cysteine-Rich Plant Peptides: Analysis of the Diversity of Cyclotides from Viola tricolor by Transcriptome and Proteome Mining. J Proteome Res 2015; 14:4851-62. [PMID: 26399495 PMCID: PMC4642221 DOI: 10.1021/acs.jproteome.5b00681] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
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Cyclotides are plant-derived mini proteins. They are genetically
encoded as precursor proteins that become post-translationally modified
to yield circular cystine-knotted molecules. Because of this structural
topology cyclotides resist enzymatic degradation in biological fluids,
and hence they are considered as promising lead molecules for pharmaceutical
applications. Despite ongoing efforts to discover novel cyclotides
and analyze their biodiversity, it is not clear how many individual
peptides a single plant specimen can express. Therefore, we investigated
the transcriptome and cyclotide peptidome of Viola tricolor. Transcriptome mining enabled the characterization of cyclotide
precursor architecture and processing sites important for biosynthesis
of mature peptides. The cyclotide peptidome was explored by mass spectrometry
and bottom-up proteomics using the extracted peptide sequences as
queries for database searching. In total 164 cyclotides were discovered
by nucleic acid and peptide analysis in V. tricolor. Therefore, violaceous plants at a global scale may be the source
to as many as 150 000 individual cyclotides. Encompassing the
diversity of V. tricolor as a combinatorial library
of bioactive peptides, this commercially available medicinal herb
may be a suitable starting point for future bioactivity-guided screening
studies.
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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.,School of Biomedical Sciences, The University of Queensland , St. Lucia, Queensland 4072, Australia
| | - Douglas E Soltis
- Florida Museum of Natural History, University of Florida , Gainesville, Florida 32611, United States
| | - Eric J Carpenter
- Department of Biological Sciences, University of Alberta , Edmonton, Alberta T6G 2E9, Canada
| | - Gane Ka-Shu Wong
- Department of Biological Sciences, University of Alberta , Edmonton, Alberta T6G 2E9, Canada.,Department of Medicine, University of Alberta , Edmonton, Alberta T6G 2E1, Canada.,BGI-Shenzhen, Beishan Industrial Zone, Yantian District, Shenzhen 518083, China
| | - Christian W Gruber
- Center for Physiology and Pharmacology, Medical University of Vienna , Schwarzspanierstrasse 17, 1090 Vienna, Austria.,School of Biomedical Sciences, The University of Queensland , St. Lucia, Queensland 4072, Australia
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Kimura S, Higashino Y, Kitao Y, Masuda T, Urade R. Expression and characterization of protein disulfide isomerase family proteins in bread wheat. BMC PLANT BIOLOGY 2015; 15:73. [PMID: 25849633 PMCID: PMC4355359 DOI: 10.1186/s12870-015-0460-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2014] [Accepted: 02/13/2015] [Indexed: 05/09/2023]
Abstract
BACKGROUND The major wheat seed proteins are storage proteins that are synthesized in the rough endoplasmic reticulum (ER) of starchy endosperm cells. Many of these proteins have intra- and intermolecular disulfide bonds. In eukaryotes, the formation of most intramolecular disulfide bonds in the ER is thought to be catalyzed by protein disulfide isomerase (PDI) family proteins. The cDNAs that encode eight groups of bread wheat (Triticum aestivum L.) PDI family proteins have been cloned, and their expression levels in developing wheat grains have been determined. The purpose of the present study was to characterize the enzymatic properties of the wheat PDI family proteins and clarify their expression patterns in wheat caryopses. RESULTS PDI family cDNAs, which are categorized into group I (TaPDIL1Aα, TaPDIL1Aβ, TaPDIL1Aγ, TaPDIL1Aδ, and TaPDIL1B), group II (TaPDIL2), group III (TaPDIL3A), group IV (TaPDIL4D), and group V (TaPDIL5A), were cloned. The expression levels of recombinant TaPDIL1Aα, TaPDIL1B, TaPDIL2, TaPDIL3A, TaPDIL4D, and TaPDIL5A in Escherichia coli were established from the cloned cDNAs. All recombinant proteins were expressed in soluble forms and purified. Aside from TaPDIL3A, the recombinant proteins exhibited oxidative refolding activity on reduced and denatured ribonuclease A. Five groups of PDI family proteins were distributed throughout wheat caryopses, and expression levels of these proteins were higher during grain filling than in the late stage of maturing. Localization of these proteins in the ER was confirmed by fluorescent immunostaining of the immature caryopses. In mature grains, the five groups of PDI family proteins remained in the aleurone cells and the protein matrix of the starchy endosperm. CONCLUSIONS High expression of PDI family proteins during grain filling in the starchy endosperm suggest that these proteins play an important role in forming intramolecular disulfide bonds in seed storage proteins. In addition, these PDI family proteins that remain in the aleurone layers of mature grains likely assist in folding newly synthesized hydrolytic enzymes during germination.
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Affiliation(s)
- Shizuka Kimura
- Division of Agronomy and Horticultural Science, Graduate School of Agriculture, Kyoto University, Uji, Kyoto 611-0011 Japan
| | - Yuki Higashino
- Division of Agronomy and Horticultural Science, Graduate School of Agriculture, Kyoto University, Uji, Kyoto 611-0011 Japan
| | - Yuki Kitao
- Division of Agronomy and Horticultural Science, Graduate School of Agriculture, Kyoto University, Uji, Kyoto 611-0011 Japan
| | - Taro Masuda
- Division of Agronomy and Horticultural Science, Graduate School of Agriculture, Kyoto University, Uji, Kyoto 611-0011 Japan
| | - Reiko Urade
- Division of Agronomy and Horticultural Science, Graduate School of Agriculture, Kyoto University, Uji, Kyoto 611-0011 Japan
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41
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Proteomic analysis of responsive stem proteins of resistant and susceptible cashew plants after Lasiodiplodia theobromae infection. J Proteomics 2015; 113:90-109. [DOI: 10.1016/j.jprot.2014.09.022] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Revised: 09/25/2014] [Accepted: 09/26/2014] [Indexed: 11/21/2022]
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Hosseini P, Matthews BF. Regulatory interplay between soybean root and soybean cyst nematode during a resistant and susceptible reaction. BMC PLANT BIOLOGY 2014; 14:300. [PMID: 25421055 PMCID: PMC4262236 DOI: 10.1186/s12870-014-0300-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Accepted: 10/22/2014] [Indexed: 05/20/2023]
Abstract
BACKGROUND Plant-parasitic nematodes (PPNs) are obligate parasites that feed on the roots of living host plants. Often, these nematodes can lay hundreds of eggs, each capable of surviving without a host for as long as 12 years. When it comes to wreaking havoc on agricultural yield, few nematodes can compare to the soybean cyst nematode (SCN). Quantifying soybean (Glycine max) transcription factor binding sites (TFBSs) during a late-stage SCN resistant and susceptible reaction can shed light onto the systematic interplay between host and pathogen, thereby elucidating underlying cis-regulatory mechanisms. RESULTS We sequenced the soybean root transcriptome at 6 and 8 days upon independent inoculation with a virulent and avirulent SCN population. Genes such as β-1,4 glucanase, chalcone synthase, superoxide dismutase and various heat shock proteins (HSPs) exhibited reaction-specific expression profiles. Several likely defense-response genes candidates were also identified which are believed to confer SCN resistance. To explore magnitude of TFBS representation during SCN pathogenesis, a multivariate statistical software identified 46 over-represented TFBSs which capture soybean regulatory dynamics across both reactions. CONCLUSIONS Our results reveal a set of soybean TFBSs which are over-represented solely throughout a resistant and susceptible SCN reaction. This set furthers our understanding of soybean cis-regulatory dynamics by providing reaction-specific levels of over-representation at 6 and 8 days after inoculation (dai) with SCN.
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Affiliation(s)
- Parsa Hosseini
- />School of Systems Biology, George Mason University, Manassas, VA USA
- />Computational Biology Branch, National Center for Biotechnology Information, National Institutes of Health, Bethesda, MD USA
- />Soybean Genomics and Improvement Laboratory, United States Department of Agriculture, Beltsville, MD USA
| | - Benjamin F Matthews
- />Soybean Genomics and Improvement Laboratory, United States Department of Agriculture, Beltsville, MD USA
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Morphological and proteomic analysis reveal the role of pistil under pollination in Liriodendron chinense (Hemsl.) Sarg. PLoS One 2014; 9:e99970. [PMID: 24924488 PMCID: PMC4055720 DOI: 10.1371/journal.pone.0099970] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Accepted: 05/21/2014] [Indexed: 11/19/2022] Open
Abstract
Pollination is an important physiological process during which interaction between pollen and pistil occurs. This interaction could determine whether or not fertilization will occur and hence the ratio of plant seed setting. Liriodendron chinense (Hemsl.) Sarg. (L. chinense) exhibits a distinct phenomenon where seed setting ratio is not more than 10% in natural environment. To explore the origin of this phenomenon, we conducted a comparative morphological and proteomic analysis on L. chinense pistils upon pollination. The morphological analysis showed that pollen grows well in vitro, but much slower on pistil or nutrient medium containing pistil extract. Proteomic analysis showed that 493 proteins had changed the expression after pollination. Among them, 468 and 51 proteins were identified by isobaric tags for relative and absolute quantitation and two-dimensional gel electrophoresis respectively, and 26 proteins were common in the two methods. After proteins functional categorization, 66 differentially expressed proteins that are involved in reproduction process were found. Further analysis showed that among the reproductive process related proteins, protein disulfide-isomerase A6 and four embryo-defective proteins showed closer relations with the low seed setting phenomenon. The results indicated that the element from pistil might be the main reason leading to low seed setting in L. chinense, which will provide new insights in the mechanisms underlying L. chinense reproduction process.
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Burman R, Gunasekera S, Strömstedt AA, Göransson U. Chemistry and biology of cyclotides: circular plant peptides outside the box. JOURNAL OF NATURAL PRODUCTS 2014; 77:724-36. [PMID: 24527877 DOI: 10.1021/np401055j] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Cyclotides stand out as the largest family of circular proteins of plant origin hitherto known, with more than 280 sequences isolated at peptide level and many more predicted from gene sequences. Their unusual stability resulting from the signature cyclic cystine knot (CCK) motif has triggered a broad interest in these molecules for potential therapeutic and agricultural applications. Since the time of the first cyclotide discovery, our laboratory in Uppsala has been engaged in cyclotide discovery as well as the development of protocols to isolate and characterize these seamless peptides. We have also developed methods to chemically synthesize cyclotides by Fmoc-SPPS, which are useful in protein grafting applications. In this review, experience in cyclotide research over two decades and the recent literature related to their structures, synthesis, and folding as well the recent proof-of-concept findings on their use as "epitope" stabilizing scaffolds are summarized.
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Affiliation(s)
- Robert Burman
- Division of Pharmacognosy, Department of Medicinal Chemistry, Uppsala University , Biomedical Centre, Box 574, SE-751 23 Uppsala, Sweden
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45
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Hellinger R, Koehbach J, Fedchuk H, Sauer B, Huber R, Gruber CW, Gründemann C. Immunosuppressive activity of an aqueous Viola tricolor herbal extract. JOURNAL OF ETHNOPHARMACOLOGY 2014; 151:299-306. [PMID: 24216163 PMCID: PMC3918579 DOI: 10.1016/j.jep.2013.10.044] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2013] [Revised: 10/16/2013] [Accepted: 10/23/2013] [Indexed: 05/02/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Heartsease (Viola tricolor L.), a member of the Violaceae family, has a long history as a medicinal plant and has been documented in the Pharmacopoeia of Europe. Due to its anti-inflammatory properties it is regarded as a traditional remedy against skin diseases, for example for the treatment of scabs, itching, ulcers, eczema or psoriasis, and it is also used in the treatment of inflammation of the lungs and chest such as bronchitis or asthma. Because T-cells play an important role in the pathological process of inflammatory diseases we investigated the effect of an aqueous Viola extract on lymphocyte functions and explored the 'active' principle of the extract using bioactivity-guided fractionation. MATERIAL AND METHODS An aqueous Viola extract was prepared by C18 solid-phase extraction. Effects on proliferation of activated lymphocytes (using the cell membrane permeable fluorescein dye CFSE), apoptosis and necrosis (using annexin V and propidium iodide staining), interleukin-2 (IL-2) receptor expression (using fluorochrome-conjugated antibodies) and IL-2 cytokine secretion (using an ELISA-based bead array system) were measured by flow cytometry. Influence on lymphocyte polyfunctionality was characterized by Viola extract-induced production of IFN-γ and TNF-α, as well as its influence on lymphocyte degranulation activity. Fractionation and phytochemical analysis of the extract were performed by RP-HPLC and mass spectrometry. RESULTS The aqueous Viola extract inhibited proliferation of activated lymphocytes by reducing IL-2 cytokine secretion without affecting IL-2 receptor expression. Similarly, effector functions were affected as indicated by the reduction of IFN-γ and TNF-α production; degranulation capacity of activated lymphocytes remained unaffected. Bioassay-guided fractionation and phytochemical analysis of the extract led to identification of circular plant peptides, so called cyclotides, as bioactive components. CONCLUSION An aqueous Viola extract contains bioactive cyclotides, which inhibit proliferation of activated lymphocytes in an IL-2 dependent manner. The findings provide a rationale for use of herbal Viola preparations in the therapy of disorders related to an overactive immune system. However, further studies to evaluate its clinical potency and potential risks have to be performed.
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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
| | - Halyna Fedchuk
- Center for Complementary Medicine, Department of Environmental Health Sciences, University Medical Center Freiburg, Breisacher Street 115B, 79106 Freiburg, Germany
| | - Barbara Sauer
- Center for Complementary Medicine, Department of Environmental Health Sciences, University Medical Center Freiburg, Breisacher Street 115B, 79106 Freiburg, Germany
| | - Roman Huber
- Center for Complementary Medicine, Department of Environmental Health Sciences, University Medical Center Freiburg, Breisacher Street 115B, 79106 Freiburg, Germany
| | - Christian W. Gruber
- Center for Physiology and Pharmacology, Medical University of Vienna, Schwarzspanierstrasse 17, 1090 Vienna, Austria
| | - Carsten Gründemann
- Center for Complementary Medicine, Department of Environmental Health Sciences, University Medical Center Freiburg, Breisacher Street 115B, 79106 Freiburg, Germany
- Corresponding author. Tel.: +49 761 270 83170; fax: +49 761 270 83230. (C. Gründemann)
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Thell K, Hellinger R, Schabbauer G, Gruber CW. Immunosuppressive peptides and their therapeutic applications. Drug Discov Today 2013; 19:645-53. [PMID: 24333193 PMCID: PMC4042018 DOI: 10.1016/j.drudis.2013.12.002] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Revised: 11/12/2013] [Accepted: 12/04/2013] [Indexed: 12/21/2022]
Abstract
T cell signaling has a pivotal role in autoimmunity and immunosuppression. Immunosuppressive pharmaceuticals often exhibit severe side-effects in patients. Gene-encoded peptides have potential as immunosuppressive drug candidates. Cyclotides are stable peptides that offer enhanced oral administration properties.
The immune system is vital for detecting and evading endogenous and exogenous threats to the body. Failure to regulate this homeostasis leads to autoimmunity, which is often associated with malfunctioning T cell signaling. Several medications are available to suppress over-reactive T lymphocytes, but many of the currently marketed drugs produce severe and life-threatening side-effects. Ribosomally synthesized peptides are gaining recognition from the pharmaceutical industry for their enhanced selectivity and decreased toxicity compared with small molecules; in particular, circular peptides exhibit remarkable stability and increased oral administration properties. For example, plant cyclotides effectively inhibit T lymphocyte proliferation. They are composed of a head-to-tail cyclized backbone and a cystine-knot motif, which confers them with remarkable stability, thus making them attractive pharmaceutical tools.
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Affiliation(s)
- Kathrin Thell
- Center for Physiology and Pharmacology, Medical University of Vienna, Schwarzspanierstr. 17, A-1090 Vienna, Austria
| | - Roland Hellinger
- Center for Physiology and Pharmacology, Medical University of Vienna, Schwarzspanierstr. 17, A-1090 Vienna, Austria
| | - Gernot Schabbauer
- Center for Physiology and Pharmacology, Medical University of Vienna, Schwarzspanierstr. 17, A-1090 Vienna, Austria
| | - Christian W Gruber
- Center for Physiology and Pharmacology, Medical University of Vienna, Schwarzspanierstr. 17, A-1090 Vienna, Austria.
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Yuen CYL, Matsumoto KO, Christopher DA. Variation in the Subcellular Localization and Protein Folding Activity among Arabidopsis thaliana Homologs of Protein Disulfide Isomerase. Biomolecules 2013; 3:848-69. [PMID: 24970193 PMCID: PMC4030966 DOI: 10.3390/biom3040848] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Revised: 09/27/2013] [Accepted: 10/12/2013] [Indexed: 12/18/2022] Open
Abstract
Protein disulfide isomerases (PDIs) catalyze the formation, breakage, and rearrangement of disulfide bonds to properly fold nascent polypeptides within the endoplasmic reticulum (ER). Classical animal and yeast PDIs possess two catalytic thioredoxin-like domains (a, a') and two non-catalytic domains (b, b'), in the order a-b-b'-a'. The model plant, Arabidopsis thaliana, encodes 12 PDI-like proteins, six of which possess the classical PDI domain arrangement (AtPDI1 through AtPDI6). Three additional AtPDIs (AtPDI9, AtPDI10, AtPDI11) possess two thioredoxin domains, but without intervening b-b' domains. C-terminal green fluorescent protein (GFP) fusions to each of the nine dual-thioredoxin PDI homologs localized predominantly to the ER lumen when transiently expressed in protoplasts. Additionally, expression of AtPDI9:GFP-KDEL and AtPDI10: GFP-KDDL was associated with the formation of ER bodies. AtPDI9, AtPDI10, and AtPDI11 mediated the oxidative folding of alkaline phosphatase when heterologously expressed in the Escherichia coli protein folding mutant, dsbA-. However, only three classical AtPDIs (AtPDI2, AtPDI5, AtPDI6) functionally complemented dsbA-. Interestingly, chemical inducers of the ER unfolded protein response were previously shown to upregulate most of the AtPDIs that complemented dsbA-. The results indicate that Arabidopsis PDIs differ in their localization and protein folding activities to fulfill distinct molecular functions in the ER.
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Affiliation(s)
- Christen Y L Yuen
- Department of Molecular Biosciences and Bioengineering, University of Hawaii at Manoa, Honolulu, HI 96822, USA.
| | - Kristie O Matsumoto
- Department of Molecular Biosciences and Bioengineering, University of Hawaii at Manoa, Honolulu, HI 96822, USA.
| | - David A Christopher
- Department of Molecular Biosciences and Bioengineering, University of Hawaii at Manoa, Honolulu, HI 96822, USA.
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Filonova A, Haemsch P, Gebauer C, Weisheit W, Wagner V. Protein disulfide isomerase 2 of Chlamydomonas reinhardtii is involved in circadian rhythm regulation. MOLECULAR PLANT 2013; 6:1503-17. [PMID: 23475997 DOI: 10.1093/mp/sst048] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Protein disulfide isomerases (PDIs) are known to play important roles in the folding of nascent proteins and in the formation of disulfide bonds. Recently, we identified a PDI from Chlamydomonas reinhardtii (CrPDI2) by a mass spectrometry approach that is specifically enriched by heparin affinity chromatography in samples taken during the night phase. Here, we show that the recombinant CrPDI2 is a redox-active protein. It is reduced by thioredoxin reductase and catalyzes itself the reduction of insulin chains and the oxidative refolding of scrambled RNase A. By immunoblots, we confirm a high-amplitude change in abundance of the heparin-bound CrPDI2 during subjective night. Interestingly, we find that CrPDI2 is present in protein complexes of different sizes at both day and night. Among three identified interaction partners, one (a 2-cys peroxiredoxin) is present only during the night phase. To study a potential function of CrPDI2 within the circadian system, we have overexpressed its gene. Two transgenic lines were used to measure the rhythm of phototaxis. In the transgenic strains, a change in the acrophase was observed. This indicates that CrPDI2 is involved in the circadian signaling pathway and, together with the night phase-specific interaction of CrPDI2 and a peroxiredoxin, these findings suggest a close coupling of redox processes and the circadian clock in C. reinhardtii.
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Affiliation(s)
- Anna Filonova
- Institute of General Botany and Plant Physiology, Friedrich-Schiller-Universität Jena, 07743 Jena, Germany
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Koehbach J, Attah AF, Berger A, Hellinger R, Kutchan TM, Carpenter EJ, Rolf M, Sonibare MA, Moody JO, Ka-Shu Wong G, Dessein S, Greger H, Gruber CW. Cyclotide discovery in Gentianales revisited--identification and characterization of cyclic cystine-knot peptides and their phylogenetic distribution in Rubiaceae plants. Biopolymers 2013; 100:438-52. [PMID: 23897543 PMCID: PMC3816352 DOI: 10.1002/bip.22328] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Accepted: 06/07/2013] [Indexed: 11/06/2022]
Abstract
Cyclotides are a unique class of ribosomally synthesized cysteine-rich miniproteins characterized by a head-to-tail cyclized backbone and three conserved disulfide-bonds in a knotted arrangement. Originally they were discovered in the coffee-family plant Oldenlandia affinis (Rubiaceae) and have since been identified in several species of the violet, cucurbit, pea, potato, and grass families. However, the identification of novel cyclotide-containing plant species still is a major challenge due to the lack of a rapid and accurate analytical workflow in particular for large sampling numbers. As a consequence, their phylogeny in the plant kingdom remains unclear. To gain further insight into the distribution and evolution of plant cyclotides, we analyzed ∼300 species of >40 different families, with special emphasis on plants from the order Gentianales. For this purpose, we have developed a refined screening methodology combining chemical analysis of plant extracts and bioinformatic analysis of transcript databases. Using mass spectrometry and transcriptome-mining, we identified nine novel cyclotide-containing species and their related cyclotide precursor genes in the tribe Palicoureeae. The characterization of novel peptide sequences underlines the high variability and plasticity of the cyclotide framework, and a comparison of novel precursor proteins from Carapichea ipecacuanha illustrated their typical cyclotide gene architectures. Phylogenetic analysis of their distribution within the Psychotria alliance revealed cyclotides to be restricted to Palicourea, Margaritopsis, Notopleura, Carapichea, Chassalia, and Geophila. In line with previous reports, our findings confirm cyclotides to be one of the largest peptide families within the plant kingdom and suggest that their total number may exceed tens of thousands.
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Affiliation(s)
- Johannes Koehbach
- Center for Physiology and Pharmacology, Medical University of Vienna, Schwarzspanierstrasse 17, 1090 Vienna, Austria
| | - Alfred F. Attah
- Center for Physiology and Pharmacology, Medical University of Vienna, Schwarzspanierstrasse 17, 1090 Vienna, Austria
- Department of Pharmacognosy, Faculty of Pharmacy, University of Ibadan, Ibadan, Nigeria
| | - Andreas Berger
- Department of Systematic and Evolutionary Botany, University of Vienna, Rennweg 14, 1030 Vienna, Austria
| | - Roland Hellinger
- Center for Physiology and Pharmacology, Medical University of Vienna, Schwarzspanierstrasse 17, 1090 Vienna, Austria
| | | | - Eric J. Carpenter
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
- Department of Medicine, University of Alberta, Edmonton, AB, Canada
| | - Megan Rolf
- Donald Danforth Plant Science Center, St. Louis, MO
| | - Mubo A. Sonibare
- Department of Pharmacognosy, Faculty of Pharmacy, University of Ibadan, Ibadan, Nigeria
| | - Jones O. Moody
- Department of Pharmacognosy, Faculty of Pharmacy, University of Ibadan, Ibadan, Nigeria
| | - Gane Ka-Shu Wong
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
- Department of Medicine, University of Alberta, Edmonton, AB, Canada
- BGI-Shenzhen, Bei Shan Industrial Zone, Yantian District, Shenzhen, China
| | - Steven Dessein
- National Botanic Garden of Belgium, Domein van Bouchout, 1860 Meise, Belgium
| | - Harald Greger
- Department of Systematic and Evolutionary Botany, University of Vienna, Rennweg 14, 1030 Vienna, Austria
| | - Christian W. Gruber
- Center for Physiology and Pharmacology, Medical University of Vienna, Schwarzspanierstrasse 17, 1090 Vienna, Austria
- Department of Pharmacognosy, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria
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Abstract
SIGNIFICANCE Disulfide-bonded proteins in chloroplasts from green plants exist in the envelope and the thylakoid membrane, and in the stroma and the lumen. The formation of disulfide bonds in proteins is referred to as oxidative folding and is linked to the import and folding of chloroplast proteins as well as the assembly and repair of thylakoid complexes. It is also important in the redox regulation of enzymes and signal transfer. RECENT ADVANCES Green-plant chloroplasts contain enzymes that can form and isomerize disulfide bonds in proteins. In Arabidopsis thaliana, four proteins are identified that are relevant for the catalysis of disulfide bond formation in chloroplast proteins. The proteins' low quantum yield of Photosystem II 1 (LQY1, At1g75690) and snowy cotyledon 2 (SCO2, At3g19220) exhibits protein disulfide isomerase activity and is suggested to function in the assembly and repair of Photosystem II (PSII), and the biogenesis of thylakoids in cotyledons, respectively. The thylakoid-located Lumen thiol oxidoreductase 1 (LTO1, At4g35760) can catalyze the formation of the disulfide bond of the extrinsic PsbO protein of PSII. In addition, the stroma-located protein disulfide isomerase PDIL1-3 (At3g54960) may have a role in oxidative folding. CRITICAL ISSUES Research on oxidative folding in chloroplasts plants is in an early stage and little is known about the mechanisms of disulfide bond formation in chloroplast proteins. FUTURE DIRECTIONS The close link between the import and folding of chloroplast proteins suggests that Hsp93, a component of the inner envelope's import apparatus, may have co-chaperones that can catalyze disulfide bond formation in newly imported proteins.
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