1
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Kam A, Loo S, Qiu Y, Liu CF, Tam JP. Ultrafast Biomimetic Oxidative Folding of Cysteine-rich Peptides and Microproteins in Organic Solvents. Angew Chem Int Ed Engl 2024; 63:e202317789. [PMID: 38342764 DOI: 10.1002/anie.202317789] [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: 11/21/2023] [Revised: 02/07/2024] [Accepted: 02/08/2024] [Indexed: 02/13/2024]
Abstract
Disulfides in peptides and proteins are essential for maintaining a properly folded structure. Their oxidative folding is invariably performed in an aqueous-buffered solution. However, this process is often slow and can lead to misfolded products. Here, we report a novel concept and strategy that is bio-inspired to mimic protein disulfide isomerase (PDI) by accelerating disulfide exchange rates many thousand-fold. The proposed strategy termed organic oxidative folding is performed under organic solvents to yield correctly folded cysteine-rich microproteins instantaneously without observable misfolded or dead-end products. Compared to conventional aqueous oxidative folding strategies, enormously large rate accelerations up to 113,200-fold were observed. The feasibility and generality of the organic oxidative folding strategy was successfully demonstrated on 15 cysteine-rich microproteins of different hydrophobicity, lengths (14 to 58 residues), and numbers of disulfides (2 to 5 disulfides), producing the native products in a second and in high yield.
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Affiliation(s)
- Antony Kam
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore, 637551, Singapore
- Department of Biological Sciences, Xi'an Jiaotong-Liverpool University, Wuzhong No.111, Renai Road, Suzhou, Jiangsu, 215123, People's Republic of China
| | - Shining Loo
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore, 637551, Singapore
- Wisedom Lake Academy of Pharmacy, Xi'an Jiaotong-Liverpool University, Wuzhong No. 111, Renai Road, Suzhou, Jiangsu, 215123, People's Republic of China
| | - Yibo Qiu
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore, 637551, Singapore
| | - Chuan-Fa Liu
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore, 637551, Singapore
| | - James P Tam
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore, 637551, Singapore
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2
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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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3
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Loo S, Kam A, Dutta B, Zhang X, Feng N, Sze SK, Liu CF, Wang X, Tam JP. Broad-spectrum ginsentides are principal bioactives in unraveling the cure-all effects of ginseng. Acta Pharm Sin B 2024; 14:653-666. [PMID: 38322337 PMCID: PMC10840477 DOI: 10.1016/j.apsb.2023.10.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Revised: 09/12/2023] [Accepted: 10/16/2023] [Indexed: 02/08/2024] Open
Abstract
Stress and illness connection is complex and involves multiple physiological systems. Panax ginsengs, reputed for their broad-spectrum "cure-all" effect, are widely prescribed to treat stress and related illnesses. However, the identity of ginseng's "cure-all" medicinal compounds that relieve stress remains unresolved. Here, we identify ginsentides as the principal bioactives that coordinate multiple systems to restore homeostasis in response to stress. Ginsentides are disulfide-rich, cell-penetrating and proteolytic-stable microproteins. Using affinity-enrichment mass spectrometry target identification together with in vitro, ex vivo and in vivo validations, we show that highly purified or synthetic ginsentides promote vasorelaxation by producing nitric oxide through endothelial cells via intracellular PI3K/Akt signaling pathway, alleviate α1-adrenergic receptor overactivity by reversing phenylephrine-induced constriction of aorta, decrease monocyte adhesion to endothelial cells via CD166/ESAM/CD40 and inhibit P2Y12 receptors to reduce platelet aggregation. Orally administered ginsentides were effective in animal models to reduce ADP-induced platelet aggregation, to prevent collagen and adrenaline-induced pulmonary thrombosis as well as anti-stress behavior of tail suspension and forced swimming tests in mice. Together, these results strongly suggest that ginsentides are the principal panacea compounds of ginsengs because of their ability to target multiple extra- and intra-cellular proteins to reverse stress-induced damages.
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Affiliation(s)
- Shining Loo
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
- Academy of Pharmacy, Xi'an Jiaotong–Liverpool University, Suzhou 215123, China
| | - Antony Kam
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
- Department of Biological Sciences, Xi'an Jiaotong–Liverpool University, Suzhou 215123, China
| | - Bamaprasad Dutta
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
| | - Xiaohong Zhang
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
| | - Nan Feng
- Institute of Materia Medica, Chinese Academy of Medical Sciences, Beijing 100050, China
| | - Siu Kwan Sze
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
- Department of Health Sciences, Brock University, Niagara Region, ON L2S 3A1, Canada
| | - Chuan-Fa Liu
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
| | - Xiaoliang Wang
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
- Institute of Materia Medica, Chinese Academy of Medical Sciences, Beijing 100050, China
| | - James P. Tam
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
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Arguelles J, Lee J, Cardenas LV, Govind S, Singh S. In Silico Analysis of a Drosophila Parasitoid Venom Peptide Reveals Prevalence of the Cation-Polar-Cation Clip Motif in Knottin Proteins. Pathogens 2023; 12:pathogens12010143. [PMID: 36678491 PMCID: PMC9865768 DOI: 10.3390/pathogens12010143] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 01/10/2023] [Accepted: 01/11/2023] [Indexed: 01/18/2023] Open
Abstract
As generalist parasitoid wasps, Leptopilina heterotoma are highly successful on many species of fruit flies of the genus Drosophila. The parasitoids produce specialized multi-strategy extracellular vesicle (EV)-like structures in their venom. Proteomic analysis identified several immunity-associated proteins, including the knottin peptide, LhKNOT, containing the structurally conserved inhibitor cysteine knot (ICK) fold, which is present in proteins from diverse taxa. Our structural and docking analysis of LhKNOT's 36-residue core knottin fold revealed that in addition to the knottin motif itself, it also possesses a Cation-Polar-Cation (CPC) clip. The CPC clip motif is thought to facilitate antimicrobial activity in heparin-binding proteins. Surprisingly, a majority of ICKs tested also possess the CPC clip motif, including 75 bona fide plant and arthropod knottin proteins that share high sequence and/or structural similarity with LhKNOT. Like LhKNOT and these other 75 knottin proteins, even the Drosophila Drosomycin antifungal peptide, a canonical target gene of the fly's Toll-NF-kappa B immune pathway, contains this CPC clip motif. Together, our results suggest a possible defensive function for the parasitoid LhKNOT. The prevalence of the CPC clip motif, intrinsic to the cysteine knot within the knottin proteins examined here, suggests that the resultant 3D topology is important for their biochemical functions. The CPC clip is likely a highly conserved structural motif found in many diverse proteins with reported heparin binding capacity, including amyloid proteins. Knottins are targets for therapeutic drug development, and insights into their structure-function relationships will advance novel drug design.
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Affiliation(s)
- Joseph Arguelles
- Department of Biology, Brooklyn College, Brooklyn, NY 11210, USA
| | - Jenny Lee
- Department of Biology, Brooklyn College, Brooklyn, NY 11210, USA
| | - Lady V. Cardenas
- Department of Biology, The City College of New York, New York, NY 10031, USA
| | - Shubha Govind
- Department of Biology, The City College of New York, New York, NY 10031, USA
- PhD Program in Biochemistry, The Graduate Center of the City University of New York, New York, NY 10016, USA
- PhD Program in Biology, The Graduate Center of the City University of New York, New York, NY 10016, USA
| | - Shaneen Singh
- Department of Biology, Brooklyn College, Brooklyn, NY 11210, USA
- PhD Program in Biochemistry, The Graduate Center of the City University of New York, New York, NY 10016, USA
- PhD Program in Biology, The Graduate Center of the City University of New York, New York, NY 10016, USA
- Correspondence:
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Loo S, Kam A, Tam JP. Hyperstable EGF-like bleogen derived from cactus accelerates corneal healing in rats. Front Pharmacol 2022; 13:942168. [PMID: 36052138 PMCID: PMC9424907 DOI: 10.3389/fphar.2022.942168] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Accepted: 07/26/2022] [Indexed: 11/13/2022] Open
Abstract
Corneal scarring reduces corneal transparency, compromises vision, and is a major cause of vision loss worldwide. Epidermal growth factor (EGF), which is the prototypic member of the EGF receptor (EGFR) agonists, is present in tears to provide repair and regeneration. Recently, we discovered bleogen pB1 in the cactus plant Pereskia bleo and showed that it is a non-canonical and hyperstable EGFR agonist with EGF-like wound healing properties for diabetic rats. Here, we apply bleogen pB1 to accelerate corneal wound healing in rats. To assess the corneal healing effects of bleogen pB1, we induced an acute alkali burn to the right eye of male Wistar rats. After five consecutive ophthalmic applications, fluorescein staining and opacity scores of the bleogen pB1-treated, and the positive control EGF-treated groups improved significantly compared to the saline control group. Immunohistochemical analyses revealed that infiltrated CD68+ macrophages and the expression of the myofibroblast marker alpha smooth muscle actin (α-SMA) were significantly decreased in the bleogen pB1- and the EGF-treated groups. By employing a differential gene expression analysis of bleogen pB1- and EGF-treated keratinocytes through RNA-seq, we demonstrated that bleogen pB1 or EGF treatments can affect the expression of genes associated with inflammatory responses and extracellular matrix remodeling. Taken together, our results indicate that the plant-derived EGFR agonist bleogen pB1 can produce similar effects to those of EGF in accelerating corneal wound healing as well as in reducing persistent inflammation and myofibroblast accumulation in the cornea.
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Baindara P, Mandal SM. Plant-Derived Antimicrobial Peptides: Novel Preservatives for the Food Industry. Foods 2022; 11:foods11162415. [PMID: 36010415 PMCID: PMC9407122 DOI: 10.3390/foods11162415] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 08/01/2022] [Accepted: 08/08/2022] [Indexed: 11/18/2022] Open
Abstract
Food spoilage is a widespread issue brought on by the undesired growth of microbes in food products. Thousands of tons of usable food or food products are wasted every day due to rotting in different parts of the world. Several food preservation techniques are employed to prevent food from rotting, including the use of natural or manufactured chemicals or substances; however, the issue persists. One strategy for halting food deterioration is the use of plant-derived antimicrobial peptides (AMPs), which have been investigated for possible bioactivities against a range of human, plant, and food pathogens. The food industry may be able to benefit from the development of synthetic AMPs, produced from plants that have higher bioactivity, better stability, and decreased cytotoxicity as a means of food preservation. In order to exploit plant-derived AMPs in various food preservation techniques, in this review, we also outline the difficulties in developing AMPs for use as commercial food preservatives. Nevertheless, as technology advances, it will soon be possible to fully explore the promise of plant-derived AMPs as food preservatives.
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Affiliation(s)
- Piyush Baindara
- Departments of Molecular Microbiology & Immunology, School of Medicine, University of Missouri, Columbia, MO 65211, USA
- Correspondence:
| | - Santi M. Mandal
- Central Research Facility, Indian Institute of Technology Kharagpur, Kharagpur 721302, West Bengal, India
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7
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Loo S, Tay SV, Kam A, Lee W, Tam JP. Hololectin Interdomain Linker Determines Asparaginyl Endopeptidase-Mediated Maturation of Antifungal Hevein-Like Peptides in Oats. FRONTIERS IN PLANT SCIENCE 2022; 13:899740. [PMID: 35620686 PMCID: PMC9127739 DOI: 10.3389/fpls.2022.899740] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2022] [Accepted: 04/20/2022] [Indexed: 05/28/2023]
Abstract
Heveins and hevein-containing (hev-) lectins play important roles in stress and pathogenic responses in plants but cause health concerns in humans. Hev-hololectins contain multiple modular hev-peptide domains and are abundantly present in cereals and pseudocereals. However, it is unclear why some cereal hev-hololectins are presented as different forms of proteolytically processed proteoforms. Here we show the precursor architectures of hev-hololectins lead to different processing mechanisms to give either hololectins or hevein-like peptides. We used mass spectrometry and datamining to screen hev-peptides from common cereals, and identified from the oat plant Avena sativa nine novel hevein-like peptides, avenatide aV1-aV9. Bioinformatic analysis revealed that asparaginyl endopeptidase (AEP) can be responsible for the maturation of the highly homologous avenatides from five oat hev-hololectin precursors, each containing four tandemly repeating, hev-like avenatide domains connected by AEP-susceptible linkers with 13-16 residues in length. Further analysis of cereal hev-hololectins showed that the linker lengths provide a distinguishing feature between their cleavable and non-cleavable precursors, with the cleavables having considerably longer linkers (>13 amino acids) than the non-cleavables (<6 amino acids). A detailed study of avenatide aV1 revealed that it contains eight cysteine residues which form a structurally compact, metabolic-resistant cystine-knotted framework with a well-defined chitin-binding site. Antimicrobial assays showed that avenatide aV1 is anti-fungal and inhibits the growth of phyto-pathogenic fungi. Together, our findings of cleavable and non-cleavable hololectins found in cereals expand our knowledge to their biosynthesis and provide insights for hololectin-related health concerns in human.
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8
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SANDATE-FLORES L, MÉNDEZ-ZAMORA G, MORALES-CELAYA MF, LARA-REYES JA, AGUIRRE-ARZOLA VE, GUTIÉRREZ-DIEZ A, TORRES-CASTILLO JA, SINAGAWA-GARCÍA SR. Biofunctional properties of the bioactive peptide from protein isolates of jiotilla (Escontria chiotilla) and pitaya (Stenocereus pruinosus) seeds. FOOD SCIENCE AND TECHNOLOGY 2022. [DOI: 10.1590/fst.57922] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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9
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Liew HT, To J, Zhang X, Hemu X, Chan NY, Serra A, Sze SK, Liu CF, Tam JP. The legumain McPAL1 from Momordica cochinchinensis is a highly stable Asx-specific splicing enzyme. J Biol Chem 2021; 297:101325. [PMID: 34710371 PMCID: PMC8600085 DOI: 10.1016/j.jbc.2021.101325] [Citation(s) in RCA: 4] [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] [Received: 08/07/2021] [Revised: 10/09/2021] [Accepted: 10/11/2021] [Indexed: 11/29/2022] Open
Abstract
Legumains, also known as asparaginyl endopeptidases (AEPs), cleave peptide bonds after Asn/Asp (Asx) residues. In plants, certain legumains also have ligase activity that catalyzes biosynthesis of Asx-containing cyclic peptides. An example is the biosynthesis of MCoTI-I/II, a squash family-derived cyclic trypsin inhibitor, which involves splicing to remove the N-terminal prodomain and then N-to-C-terminal cyclization of the mature domain. To identify plant legumains responsible for the maturation of these cyclic peptides, we have isolated and characterized a legumain involved in splicing, McPAL1, from Momordica cochinchinensis (Cucurbitaceae) seeds. Functional studies show that recombinantly expressed McPAL1 displays a pH-dependent, trimodal enzymatic profile. At pH 4 to 6, McPAL1 selectively catalyzed Asp-ligation and Asn-cleavage, but at pH 6.5 to 8, Asn-ligation predominated. With peptide substrates containing N-terminal Asn and C-terminal Asp, such as is found in precursors of MCoTI-I/II, McPAL1 mediates proteolysis at the Asn site and then ligation at the Asp site at pH 5 to 6. Also, McPAL1 is an unusually stable legumain that is tolerant of heat and high pH. Together, our results support that McPAL1 is a splicing legumain at acidic pH that can mediate biosynthesis of MCoTI-I/II. We purport that the high thermal and pH stability of McPAL1 could have applications for protein engineering.
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Affiliation(s)
- Heng Tai Liew
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Janet To
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Xiaohong Zhang
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Xinya Hemu
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Ning-Yu Chan
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Aida Serra
- IMDEA Food Research Institute, +Pec Proteomics, Campus of International Excellence UAM+CSIC, Old Cantoblanco Hospital, Cantoblanco, Madrid, Spain; Proteored - Instituto de Salud Carlos III (ISCIII), Campus UAM, Cantoblanco, Madrid, Spain
| | - Siu Kwan Sze
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Chuan-Fa Liu
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - James P Tam
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore.
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10
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Anti-Fungal Hevein-like Peptides Biosynthesized from Quinoa Cleavable Hololectins. Molecules 2021; 26:molecules26195909. [PMID: 34641455 PMCID: PMC8512870 DOI: 10.3390/molecules26195909] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 09/25/2021] [Accepted: 09/26/2021] [Indexed: 11/20/2022] Open
Abstract
Chitin-binding hevein-like peptides (CB-HLPs) belong to a family of cysteine-rich peptides that play important roles in plant stress and defense mechanisms. CB-HLPs are ribosomally synthesized peptides that are known to be bioprocessed from the following two types of three-domain CB-HLP precursor architectures: cargo-carrying and non-cargo-carrying. Here, we report the identification and characterization of chenotides biosynthesized from the third type of precursors, which are cleavable hololectins of the quinoa (Chenopodium quinoa) family. Chenotides are 6-Cys-CB-HLPs of 29–31 amino acids, which have a third type of precursor architecture that encompasses a canonical chitin-binding domain that is involved in chitin binding and anti-fungal activities. Microbroth dilution assays and microscopic analyses showed that chenotides are effective against phyto-pathogenic fungi in the micromolar range. Structure determination revealed that chenotides are cystine knotted and highly compact, which could confer resistance against heat and proteolytic degradation. Importantly, chenotides are connected by a novel 18-residue Gly/Ala-rich linker that is a target for bioprocessing by cathepsin-like endopeptidases. Taken together, our findings reveal that chenotides are a new family of CB-HLPs from quinoa that are synthesized as a single multi-modular unit and bioprocessed to yield individual mature CB-HLPs. Importantly, such precursors constitute a new family of cleavable hololectins. This unusual feature could increase the biosynthetic efficiency of anti-fungal CB-HLPs, to provide an evolutionary advantage for plant survival and reproduction.
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11
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Loo S, Kam A, Li BB, Feng N, Wang X, Tam JP. Discovery of Hyperstable Noncanonical Plant-Derived Epidermal Growth Factor Receptor Agonist and Analogs. J Med Chem 2021; 64:7746-7759. [PMID: 34015925 DOI: 10.1021/acs.jmedchem.1c00551] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Here, we report the discovery of the first plant-derived and noncanonical epidermal growth factor receptor (EGFR) agonist, the 36-residue bleogen pB1 from Pereskia bleo of the Cactaceae family. We show that bleogen pB1 is a low-affinity EGFR agonist using a suite of chemical, biochemical, cellular, and animal experiments which include incisor eruption and wound-healing mouse models. A focused positional scanning pB1 library of Ala- and d-amino acid scans yielded a high-affinity pB1 analog, [K29k]pB1, with a 60-fold-improved EGFR affinity and mitogenicity. We show that the potency of [K29k]pB1 and the epidermal growth factor (EGF) is comparable in a diabetic mouse wound-healing model. We also show that both bleogen pB1 and [K29k]pB1 are hyperstable, being >100-fold more stable than EGF against proteolytic degradation. Overall, our discovery of a noncanonical proteolytic-resistant EGFR agonist scaffold could open new avenues for developing wound healing and skin regeneration therapeutics and biomaterials.
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Affiliation(s)
- Shining Loo
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore
| | - Antony Kam
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore
| | - Bin Bin Li
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore
| | - Nan Feng
- Institute of Materia Medica, Chinese Academy of Medical Sciences, 1 Xian Nong Tan Street, Beijing 100050, China
| | - Xiaoliang Wang
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore.,Institute of Materia Medica, Chinese Academy of Medical Sciences, 1 Xian Nong Tan Street, Beijing 100050, China
| | - James P Tam
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore
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12
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Parthasarathy A, Borrego EJ, Savka MA, Dobson RCJ, Hudson AO. Amino acid-derived defense metabolites from plants: A potential source to facilitate novel antimicrobial development. J Biol Chem 2021; 296:100438. [PMID: 33610552 PMCID: PMC8024917 DOI: 10.1016/j.jbc.2021.100438] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 02/16/2021] [Accepted: 02/17/2021] [Indexed: 12/23/2022] Open
Abstract
For millennia, humanity has relied on plants for its medicines, and modern pharmacology continues to reexamine and mine plant metabolites for novel compounds and to guide improvements in biological activity, bioavailability, and chemical stability. The critical problem of antibiotic resistance and increasing exposure to viral and parasitic diseases has spurred renewed interest into drug treatments for infectious diseases. In this context, an urgent revival of natural product discovery is globally underway with special attention directed toward the numerous and chemically diverse plant defensive compounds such as phytoalexins and phytoanticipins that combat herbivores, microbial pathogens, or competing plants. Moreover, advancements in “omics,” chemistry, and heterologous expression systems have facilitated the purification and characterization of plant metabolites and the identification of possible therapeutic targets. In this review, we describe several important amino acid–derived classes of plant defensive compounds, including antimicrobial peptides (e.g., defensins, thionins, and knottins), alkaloids, nonproteogenic amino acids, and phenylpropanoids as potential drug leads, examining their mechanisms of action, therapeutic targets, and structure–function relationships. Given their potent antibacterial, antifungal, antiparasitic, and antiviral properties, which can be superior to existing drugs, phytoalexins and phytoanticipins are an excellent resource to facilitate the rational design and development of antimicrobial drugs.
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Affiliation(s)
- Anutthaman Parthasarathy
- Rochester Institute of Technology, Thomas H. Gosnell School of Life Sciences, Rochester, New York, USA
| | - Eli J Borrego
- Rochester Institute of Technology, Thomas H. Gosnell School of Life Sciences, Rochester, New York, USA
| | - Michael A Savka
- Rochester Institute of Technology, Thomas H. Gosnell School of Life Sciences, Rochester, New York, USA
| | - Renwick C J Dobson
- Biomolecular Interaction Centre and School of Biological Sciences, University of Canterbury, Christchurch, New Zealand; Bio21 Molecular Science and Biotechnology Institute, Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Victoria, Australia
| | - André O Hudson
- Rochester Institute of Technology, Thomas H. Gosnell School of Life Sciences, Rochester, New York, USA.
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13
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Identification and characterization of a wolfberry carboxypeptidase inhibitor from Lycium barbarum. Food Chem 2021; 351:129338. [PMID: 33647700 DOI: 10.1016/j.foodchem.2021.129338] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2020] [Revised: 01/22/2021] [Accepted: 02/06/2021] [Indexed: 01/13/2023]
Abstract
Hyperstable cysteine-rich peptides (CRPs) represent an underexplored superfamily of bioactives in functional foods. An example is wolfberry of the Lycium barbarum family. Previously, we discovered a CRP, designated α-lybatide, from L. barbarum bark. Herein, we report the discovery of β-lybatide, a novel carboxypeptidase inhibitor belonging to a different CRP family from the wolfberry plant. Proteomic and transcriptomic analyses showed that β-lybatide contains 36 amino acids with six cysteine residues. NMR spectroscopy revealed that β-lybatide displays a knottin-like structure that renders it highly resistant to thermal, chemical and enzymatic degradation, conditions important for keeping its structural integrity in gastrointestinal tract. Biochemical assays showed that β-lybatide is a potent carboxypeptidase inhibitor which could contribute to the wolfberry biological activities. Bioinformatics analysis revealed an additional 49 β-lybatide-like plant carboxypeptidase inhibitors. Together, our results show that β-lybatide is the first and the smallest plant-derived hyperstable carboxypeptidase inhibitor discovered from a functional food.
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Parsley NC, Williams OL, Hicks LM. Exploring the Diversity of Cysteine-Rich Natural Product Peptides via MS/MS Fingerprint Ions. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2020; 31:1833-1843. [PMID: 32872784 PMCID: PMC7816094 DOI: 10.1021/jasms.0c00078] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Natural product extracts present inherently complex matrices in which the identification of novel bioactive peptide species is challenged by low-abundance masses and significant structural and sequence diversity. Additionally, discovery efforts often result in the re-identification of known compounds, where modifications derived in vivo or during sample handling may obscure true sequence identity. Herein, we identify mass spectral (MS2) "fingerprint" ions characteristic of cyclotides, a diverse and biologically active family of botanical cysteine-rich peptides, based on regions of high sequence homology. We couple mass shift analysis with MS2 spectral fingerprint ions cross referenced with CyBase-a cyclotide database-to discern unique mass species in Viola communis extracts from mass species that are likely already characterized and those with common modifications. The approach is extended to a related class of cysteine-rich peptides, the trypsin inhibitors, using the characterized botanical species Lagenaria siceraria. Coupling the observation of highly abundant MS2 ions with mass shift analysis, we identify a new set of small, highly disulfide-bound cysteine-rich L. siceraria peptides.
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Affiliation(s)
| | | | - Leslie M. Hicks
- Address Correspondence to: Leslie M. Hicks, 125 South Road, CB#3290, Kenan Laboratories, C045, Chapel Hill, NC 27599, [T] 919-843-6903, [E]
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15
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Guevara-Lora I, Bras G, Karkowska-Kuleta J, González-González M, Ceballos K, Sidlo W, Rapala-Kozik M. Plant-Derived Substances in the Fight Against Infections Caused by Candida Species. Int J Mol Sci 2020; 21:ijms21176131. [PMID: 32854425 PMCID: PMC7504544 DOI: 10.3390/ijms21176131] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 08/19/2020] [Accepted: 08/21/2020] [Indexed: 02/06/2023] Open
Abstract
Yeast-like fungi from the Candida genus are predominantly harmless commensals that colonize human skin and mucosal surfaces, but under conditions of impaired host immune system change into dangerous pathogens. The pathogenicity of these fungi is typically accompanied by increased adhesion and formation of complex biofilms, making candidal infections challenging to treat. Although a variety of antifungal drugs have been developed that preferably attack the fungal cell wall and plasma membrane, these pathogens have acquired novel defense mechanisms that make them resistant to standard treatment. This causes an increase in the incidence of candidiasis and enforces the urgent need for an intensified search for new specifics that could be helpful, alone or synergistically with traditional drugs, for controlling Candida pathogenicity. Currently, numerous reports have indicated the effectiveness of plant metabolites as potent antifungal agents. These substances have been shown to inhibit growth and to alter the virulence of different Candida species in both the planktonic and hyphal form and during the biofilm formation. This review focuses on the most recent findings that provide evidence of decreasing candidal pathogenicity by different substances of plant origin, with a special emphasis on the mechanisms of their action. This is a particularly important issue in the light of the currently increasing frequency of emerging Candida strains and species resistant to standard antifungal treatment.
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Affiliation(s)
- Ibeth Guevara-Lora
- Department of Analytical Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University in Krakow, Gronostajowa 7, 30–387 Krakow, Poland; (I.G.-L.); (K.C.)
| | - Grazyna Bras
- Department of Comparative Biochemistry and Bioanalytics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University in Krakow, Gronostajowa 7, 30–387 Krakow, Poland; (G.B.); (J.K.-K.); (M.G.-G.); (W.S.)
| | - Justyna Karkowska-Kuleta
- Department of Comparative Biochemistry and Bioanalytics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University in Krakow, Gronostajowa 7, 30–387 Krakow, Poland; (G.B.); (J.K.-K.); (M.G.-G.); (W.S.)
| | - Miriam González-González
- Department of Comparative Biochemistry and Bioanalytics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University in Krakow, Gronostajowa 7, 30–387 Krakow, Poland; (G.B.); (J.K.-K.); (M.G.-G.); (W.S.)
- Institute of Zoology and Biomedical Research, Faculty of Biology, Jagiellonian University in Krakow, Gronostajowa 9, 30–387 Krakow, Poland
| | - Kinga Ceballos
- Department of Analytical Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University in Krakow, Gronostajowa 7, 30–387 Krakow, Poland; (I.G.-L.); (K.C.)
| | - Wiktoria Sidlo
- Department of Comparative Biochemistry and Bioanalytics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University in Krakow, Gronostajowa 7, 30–387 Krakow, Poland; (G.B.); (J.K.-K.); (M.G.-G.); (W.S.)
| | - Maria Rapala-Kozik
- Department of Comparative Biochemistry and Bioanalytics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University in Krakow, Gronostajowa 7, 30–387 Krakow, Poland; (G.B.); (J.K.-K.); (M.G.-G.); (W.S.)
- Correspondence:
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16
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Tam JP, Kam A, Loo S. Hyperstable Cell‐Penetrating Peptides from Medicinal Plants. FASEB J 2020. [DOI: 10.1096/fasebj.2020.34.s1.02847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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17
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Hemu X, To J, Zhang X, Tam JP. Immobilized Peptide Asparaginyl Ligases Enhance Stability and Facilitate Macrocyclization and Site-Specific Ligation. J Org Chem 2019; 85:1504-1512. [DOI: 10.1021/acs.joc.9b02524] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Xinya Hemu
- School of Biological Sciences, Nanyang Technological University, 637551 Singapore
| | - Janet To
- School of Biological Sciences, Nanyang Technological University, 637551 Singapore
| | - Xiaohong Zhang
- School of Biological Sciences, Nanyang Technological University, 637551 Singapore
| | - James P. Tam
- School of Biological Sciences, Nanyang Technological University, 637551 Singapore
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18
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Kam A, Loo S, Fan JS, Sze SK, Yang D, Tam JP. Roseltide rT7 is a disulfide-rich, anionic, and cell-penetrating peptide that inhibits proteasomal degradation. J Biol Chem 2019; 294:19604-19615. [PMID: 31727740 DOI: 10.1074/jbc.ra119.010796] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Revised: 11/02/2019] [Indexed: 12/21/2022] Open
Abstract
Disulfide-rich plant peptides with molecular masses of 2-6 kDa represent an expanding class of peptidyl-type natural products with diverse functions. They are structurally compact, hyperstable, and underexplored as cell-penetrating agents that inhibit intracellular functions. Here, we report the discovery of an anionic, 34-residue peptide, the disulfide-rich roseltide rT7 from Hibiscus sabdariffa (of the Malvaceae family) that penetrates cells and inhibits their proteasomal activities. Combined proteomics and NMR spectroscopy revealed that roseltide rT7 is a cystine-knotted, six-cysteine hevein-like cysteine-rich peptide. A pair-wise comparison indicated that roseltide rT7 is >100-fold more stable against protease degradation than its S-alkylated analog. Confocal microscopy studies and cell-based assays disclosed that after roseltide rT7 penetrates cells, it causes accumulation of ubiquitinated proteins, inhibits human 20S proteasomes, reduces tumor necrosis factor-induced IκBα degradation, and decreases expression levels of intercellular adhesion molecule-1. Structure-activity studies revealed that roseltide rT7 uses a canonical substrate-binding mechanism for proteasomal inhibition enabled by an IIML motif embedded in its proline-rich and exceptionally long intercysteine loop 4. Taken together, our results provide mechanistic insights into a novel disulfide-rich, anionic, and cell-penetrating peptide, representing a potential lead for further development as a proteasomal inhibitor in anti-cancer or anti-inflammatory therapies.
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Affiliation(s)
- Antony Kam
- School of Biological Sciences, Nanyang Technological University, Singapore 637551
| | - Shining Loo
- School of Biological Sciences, Nanyang Technological University, Singapore 637551
| | - Jing-Song Fan
- Department of Biological Sciences, National University of Singapore, Singapore 117543
| | - Siu Kwan Sze
- School of Biological Sciences, Nanyang Technological University, Singapore 637551
| | - Daiwen Yang
- Department of Biological Sciences, National University of Singapore, Singapore 117543
| | - James P Tam
- School of Biological Sciences, Nanyang Technological University, Singapore 637551
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19
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Finkina EI, Melnikova DN, Bogdanov IV, Ovchinnikova TV. Peptides of the Innate Immune System of Plants. Part II. Biosynthesis, Biological Functions, and Possible Practical Applications. RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY 2019. [DOI: 10.1134/s1068162019020043] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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20
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Kam A, Loo S, Tam JP. Discovery of a Plant‐derived Cell‐penetrating Proteasome Inhibitor. FASEB J 2019. [DOI: 10.1096/fasebj.2019.33.1_supplement.634.6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Antony Kam
- Nanyang Technological UniversitySingapore, Singapore
| | - Shining Loo
- Nanyang Technological UniversitySingapore, Singapore
| | - James P Tam
- Nanyang Technological UniversitySingapore, Singapore
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21
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Loo S, Kam A, Tam JP. Identification of a Naturally‐occurring Heparin‐binding Peptide Preferentially Targeting the Nucleolus. FASEB J 2019. [DOI: 10.1096/fasebj.2019.33.1_supplement.471.13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Shining Loo
- Nanyang Technological UniversitySingapore, Singapore
| | - Antony Kam
- Nanyang Technological UniversitySingapore, Singapore
| | - James P Tam
- Nanyang Technological UniversitySingapore, Singapore
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22
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Finkina EI, Melnikova DN, Bogdanov IV, Ovchinnikova TV. Peptides of the Innate Immune System of Plants. Part I. Structure, Biological Activity, and Mechanisms of Action. RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY 2019. [DOI: 10.1134/s1068162019010060] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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23
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Kam A, Loo S, Dutta B, Sze SK, Tam JP. Plant-derived mitochondria-targeting cysteine-rich peptide modulates cellular bioenergetics. J Biol Chem 2019; 294:4000-4011. [PMID: 30674551 DOI: 10.1074/jbc.ra118.006693] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2018] [Revised: 01/07/2019] [Indexed: 12/16/2022] Open
Abstract
Mitochondria are attractive therapeutic targets for developing agents to delay age-related frailty and diseases. However, few promising leads have been identified from natural products. Previously, we identified roseltide rT1, a hyperstable 27-residue cysteine-rich peptide from Hibiscus sabdariffa, as a knottin-type neutrophil elastase inhibitor. Here, we show that roseltide rT1 is also a cell-penetrating, mitochondria-targeting peptide that increases ATP production. Results from flow cytometry, live-cell imaging, pulldown assays, and genetically-modified cell lines supported that roseltide rT1 enters cells via glycosaminoglycan-dependent endocytosis, and enters the mitochondria through TOM20, a mitochondrial protein import receptor. We further showed that roseltide rT1 increases cellular ATP production via mitochondrial membrane hyperpolarization. Using biotinylated roseltide rT1 for target identification and proteomic analysis, we showed that human mitochondrial membrane ATP synthase subunit O is an intramitochondrial target. Collectively, these data support our discovery that roseltide rT1 is a first-in-class mitochondria-targeting, cysteine-rich peptide with potentials to be developed into tools to further our understanding of mitochrondria-related diseases.
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Affiliation(s)
- Antony Kam
- From the School of Biological Sciences, Nanyang Technological University, 637551 Singapore
| | - Shining Loo
- From the School of Biological Sciences, Nanyang Technological University, 637551 Singapore
| | - Bamaprasad Dutta
- From the School of Biological Sciences, Nanyang Technological University, 637551 Singapore
| | - Siu Kwan Sze
- From the School of Biological Sciences, Nanyang Technological University, 637551 Singapore
| | - James P Tam
- From the School of Biological Sciences, Nanyang Technological University, 637551 Singapore
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24
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A structural perspective of plant antimicrobial peptides. Biochem J 2018; 475:3359-3375. [PMID: 30413680 DOI: 10.1042/bcj20180213] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2018] [Revised: 10/12/2018] [Accepted: 10/14/2018] [Indexed: 12/26/2022]
Abstract
Among the numerous strategies plants have developed to fend off enemy attack, antimicrobial peptides (AMPs) stand out as one of the most prominent defensive barriers that grant direct and durable resistance against a wide range of pests and pathogens. These small proteins are characterized by a compact structure and an overall positive charge. AMPs have an ancient origin and widespread occurrence in the plant kingdom but show an unusually high degree of variation in their amino acid sequences. Interestingly, there is a strikingly conserved topology among the plant AMP families, suggesting that the defensive properties of these peptides are not determined by their primary sequences but rather by their tridimensional structure. To explore and expand this idea, we here discuss the role of AMPs for plant defense from a structural perspective. We show how specific structural properties, such as length, charge, hydrophobicity, polar angle and conformation, are essential for plant AMPs to act as a chemical shield that hinders enemy attack. Knowledge on the topology of these peptides is facilitating the isolation, classification and even structural redesign of AMPs, thus allowing scientists to develop new peptides with multiple agronomical and pharmacological potential.
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25
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Ginsentides: Cysteine and Glycine-rich Peptides from the Ginseng Family with Unusual Disulfide Connectivity. Sci Rep 2018; 8:16201. [PMID: 30385768 PMCID: PMC6212409 DOI: 10.1038/s41598-018-33894-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Accepted: 10/08/2018] [Indexed: 12/21/2022] Open
Abstract
Ginseng, a popular and valuable traditional medicine, has been used for centuries to maintain health and treat disease. Here we report the discovery and characterization of ginsentides, a novel family of cysteine and glycine-rich peptides derived from the three most widely-used ginseng species: Panax ginseng, Panax quinquefolius, and Panax notoginseng. Using proteomic and transcriptomic methods, we identified 14 ginsentides, TP1-TP14 which consist of 31-33 amino acids and whose expression profiles are species- and tissues-dependent. Ginsentides have an eight-cysteine motif typical of the eight-cysteine-hevein-like peptides (8C-HLP) commonly found in medicinal herbs, but lack a chitin-binding domain. Transcriptomic analysis showed that the three-domain biosynthetic precursors of ginsentides differ from known 8C-HLP precursors in architecture and the absence of a C-terminal protein-cargo domain. A database search revealed an additional 50 ginsentide-like precursors from both gymnosperms and angiosperms. Disulfide mapping and structure determination of the ginsentide TP1 revealed a novel disulfide connectivity that differs from the 8C-HLPs. The structure of ginsentide TP1 is highly compact, with the N- and C-termini topologically fixed by disulfide bonds to form a pseudocyclic structure that confers resistance to heat, proteolysis, and acid and serum-mediated degradation. Together, our results expand the chemical space of natural products found in ginseng and highlight the occurrence, distribution, disulfide connectivity, and precursor architectures of cysteine- and glycine-rich ginsentides as a class of novel non-chitin-binding, non-cargo-carrying 8C-HLPs.
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Parsley NC, Kirkpatrick CL, Crittenden CM, Rad JG, Hoskin DW, Brodbelt JS, Hicks LM. PepSAVI-MS reveals anticancer and antifungal cycloviolacins in Viola odorata. PHYTOCHEMISTRY 2018; 152:61-70. [PMID: 29734037 PMCID: PMC6003877 DOI: 10.1016/j.phytochem.2018.04.014] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Revised: 04/12/2018] [Accepted: 04/24/2018] [Indexed: 05/07/2023]
Abstract
Widespread resistance to antimicrobial and cancer therapeutics is evolving in every country worldwide and has a direct impact on global health, agriculture and the economy. The specificity and selectivity of bioactive peptide natural products present a possible stopgap measure to address the ongoing deficit of new therapeutic compounds. PepSAVI-MS (Statistically-guided bioActive Peptides prioritized VIa Mass Spectrometry) is an adaptable method for the analysis of natural product libraries to rapidly identify bioactive peptides. This pipeline was validated via screening of the cyclotide-rich botanical species Viola odorata and identification of the known antimicrobial and anticancer cyclotide cycloviolacin O2. Herein we present and validate novel bioactivities of the anthelmintic V. odorata cyclotide, cycloviolacin O8 (cyO8), including micromolar anticancer activity against PC-3 prostate, MDA-MB-231 breast, and OVCAR-3 ovarian cancer cell lines and antifungal activity against the agricultural pathogen Fusarium graminearum. A reduction/alkylation strategy in tandem with PepSAVI-MS analysis also revealed several previously uncharacterized putatively bioactive cyclotides. Downstream implementation of ultraviolet photodissociation (UVPD) tandem mass spectrometry is demonstrated for cyO8 as a method to address traditionally difficult-to-sequence cyclotide species. This work emphasizes the therapeutic and agricultural potential of natural product bioactive peptides and the necessity of developing robust analytical tools to deconvolute nature's complexity.
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Affiliation(s)
- Nicole C Parsley
- Department of Chemistry, University of North Carolina at Chapel Hill, NC, USA
| | | | | | | | - David W Hoskin
- Department of Pathology, Dalhousie University, Nova Scotia, Canada; Department of Microbiology and Immunology, Dalhousie University, Nova Scotia, Canada; Department of Surgery, Dalhousie University, Nova Scotia, Canada
| | | | - Leslie M Hicks
- Department of Chemistry, University of North Carolina at Chapel Hill, NC, USA.
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