| 33577650 |
Heterologous production of new protease inhibitory peptide marinostatin E |
10.1093/bbb/zbaa011. |
Biosci Biotechnol Biochem |
Heterologous production of new protease inhibitory peptide marinostatin E
Abstract
- Bicyclic peptides, marinostatins, are protease inhibitors derived from the marine bacterium Algicola sagamiensis. The biosynthetic gene cluster of marinostatin was previously identified, although no heterologous production was reported. In this report, the biosynthetic gene cluster of marinostatin (mstA and mstB) was cloned into the expression vector pET-41a(+). As a result of the coexpression experiment, a new analogous peptide named marinostatin E was successfully produced using Escherichia coli BL21(DE3). The structure of marinostatin E was determined by a combination of chemical treatments and tandem mass spectrometry experiments. Marinostatin E exhibited inhibitory activities against chymotrypsin and subtilisin with an IC50 of 4.0 and 39.6 μm, respectively.
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| 33586251 |
Solid-phase synthesis and bioactivity evaluation of cherimolacyclopeptide E |
10.1002/psc.3308. |
J Pept Sci |
Solid-phase synthesis and bioactivity evaluation of cherimolacyclopeptide E
Abstract
- Cherimolacylopeptide E (1) is a cyclic hexapeptide isolated from the seeds of Annona cherimola. Peptide 1 reportedly exhibits potent cytotoxicity against KB cells (IC 0.017 μM). To confirm the structure and bioactivity of 1, we conducted a total synthesis of its proposed structure. The synthesis was accomplished via solid-phase peptide elongation and macrocyclization by employing Fmoc/OAll-protected amino acids on 2-Cl-trityl resin. NMR analysis revealed that synthetic 1 exists in two conformations in pyridine-d . As the spectroscopic data of the major conformer of synthetic 1 were consistent with those of natural 1, the structure of cherimolacyclopeptide E was confirmed to be 1. However, our synthetic 1 exhibited low cytotoxicity against KB cells (IC > 100 μM). In contrast to previously-reported findings, our synthetic 1 exhibited little antibacterial activity against Escherichia coli.
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| 33651072 |
Targeting SARS-CoV-2 spike protein by stapled hACE2 peptides |
10.1039/d0cc08387a. |
Chem Commun (Camb) |
Targeting SARS-CoV-2 spike protein by stapled hACE2 peptides
Abstract
- SARS-CoV-2 Spike protein RBD interacts with the hACE2 receptor to initiate cell entry and infection. We set out to develop lactam-based i,i + 4 stapled hACE2 peptides targeting SARS-CoV-2. In vitro screening demonstrates the inhibition of the Spike protein RBD-hACE2 complex formation by the hACE2A36K-F40E stapled peptide (IC: 3.6 μM, K: 2.1 μM), suggesting that hACE2 peptidomimetics could form the basis for the development of anti-COVID-19 therapeutics.
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| 33755843 |
Malformin C, an algicidal peptide from marine fungus Aspergillus species |
10.1007/s10646-021-02389-3. |
Ecotoxicology |
Malformin C, an algicidal peptide from marine fungus Aspergillus species
Abstract
- A natural compound with the algicidal effect was isolated from the culture medium of Aspergillus sp. SCSIOW2 and was identified as malformin C, which was based on the data of H-NMR, C-NMR, and ESI-MS. Malformin C exhibited dose-dependent algicidal activities against two strains of noxious red tide algae, Akashiwo sanguinea and Chattonella marina. The activity against A. sanguinea was stronger than that against C. marina (the algicidal activity of 58 and 36% at 50 μM treatment for 2 h, respectively). Morphology changes including perforation, plasmolysis, and fragmentation of algal cells were observed. Malformin C induced a significant increase in ROS level, caused the damage of SOD activity, and led to the massive generation of MDA contents in algae cells. To our knowledge, this is the first report of the cyclic peptide described as an algicidal compound against HABs.
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| 33769052 |
Solid-Phase Total Synthesis of Dehydrotryptophan-Bearing Cyclic Peptides Tunicyclin B, Sclerotide A, CDA3a, and CDA4a using a Protected β-Hydroxytryptophan Building Block |
10.1021/acs.orglett.1c00717. |
Org Lett |
Solid-Phase Total Synthesis of Dehydrotryptophan-Bearing Cyclic Peptides Tunicyclin B, Sclerotide A, CDA3a, and CDA4a using a Protected β-Hydroxytryptophan Building Block
Abstract
- A new approach to the synthesis of -dehydrotryptophan (ΔTrp) peptides is described. This approach uses Fmoc-β-HOTrp(Boc)(TBS)-OH as a building block, which is readily prepared in high yield and incorporated into peptides using solid-phase Fmoc chemistry. The -butyldimethylsilyl-protected indolic alcohol is eliminated during global deprotection/resin cleavage to give ΔTrp peptides exclusively as the thermodynamically favored Z isomer. This approach was applied to the solid-phase synthesis of tunicyclin B, sclerotide A, CDA3a, and CDA4a.
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| 33902275 |
Engineered Conotoxin Differentially Blocks and Discriminates Rat and Human α7 Nicotinic Acetylcholine Receptors |
10.1021/acs.jmedchem.0c02079. |
J Med Chem |
Engineered Conotoxin Differentially Blocks and Discriminates Rat and Human α7 Nicotinic Acetylcholine Receptors
Abstract
- The α7 nicotinic acetylcholine receptor (nAChR) is present in the central nervous system and plays an important role in cognitive function and memory. α-Conotoxin LvIB, identified from genomic DNA of , its three isomers and four globular isomer analogues were synthesized and screened at a wide range of nAChR subtypes. One of the analogues, amidated [Q1G,ΔR14]LvIB, was found to be a potent blocker of rat α7 nAChRs. Importantly, it differentiates between α7 nAChRs of human (IC: 1570 nM) and rat (IC: 97 nM). Substitutions between rat and human α7 nAChRs at three key mutation sites revealed that no single mutant could completely change the activity profile of amidated [Q1G,ΔR14]LvIB. Rather, we found that the combined influence of Gln141, Asn184, and Lys186 determines the α7 nAChR species specificity of this peptide. This engineered α4/4 conotoxin has potential applications as a template for designing ligands to selectively block human α7 nAChRs.
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| 33927999 |
Isolation and characterization of cyclotides from the leaves of L. using peptidomic and bioinformatic approach |
10.1007/s13205-021-02763-2. |
3 Biotech |
Isolation and characterization of cyclotides from the leaves of L. using peptidomic and bioinformatic approach
Abstract
- Cyclotides are true gene products characterized by the presence of six conserved cysteine residues and knotted arrangement of three disulfide bonds. These macrocyclic peptides show exceptional resistance to thermal, chemical and enzymatic degradation which is defined due to their three-dimensional folding. The current study describes an efficient strategy involving reduction, enzymatic digestion and mass spectroscopy sequencing for the identification of the precursor sequences and the cyclotide domains present in the leaf tissue of . We observed 122 partial peptide sequences containing 31 cyclotide domains along with 19 unique sequences consisting of putative novel cyclotides and acyclotides. Four precursor sequences consisting of putative new and already reported domains were further characterized for cyclotide domains, their structure and subfamilies. The sequences revealed the presence of classic knotted cyclotide folds with similar six characteristic loops but different amino acid residues. Molecular modeling indicated that the secondary structures present in the cyclotides are mainly α-helix and random coils. Variation in the sequences and conservation in cysteine residues in the cyclotides was revealed by protein diversity wheel. The significant information observed in the current study expands our knowledge about the structure and type of cyclic peptides in leaves.
The online version contains supplementary material available at 10.1007/s13205-021-02763-2.
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| 33932786 |
Tropical vibes from Sri Lanka - cyclotides from Viola betonicifolia by transcriptome and mass spectrometry analysis |
10.1016/j.phytochem.2021.112749. |
Phytochemistry |
Tropical vibes from Sri Lanka - cyclotides from Viola betonicifolia by transcriptome and mass spectrometry analysis
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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| 34127703 |
Cyclotide host-defense tailored for species and environments in violets from the Canary Islands |
10.1038/s41598-021-91555-y. |
Sci Rep |
Cyclotide host-defense tailored for species and environments in violets from the Canary Islands
Abstract
- Cyclotides are cyclic peptides produced by plants. Due to their insecticidal properties, they are thought to be involved in host defense. Violets produce complex mixtures of cyclotides, that are characteristic for each species and variable in different environments. Herein, we utilized mass spectrometry (LC-MS, MALDI-MS), transcriptomics and biological assays to investigate the diversity, differences in cyclotide expression based on species and different environment, and antimicrobial activity of cyclotides found in violets from the Canary Islands. A wide range of different habitats can be found on these islands, from subtropical forests to dry volcano peaks at high altitudes. The islands are inhabited by the endemic Viola palmensis, V. cheiranthifolia, V. anagae and the common V. odorata. The number of cyclotides produced by a given species varied in plants from different environments. The highest diversity was noted in V. anagae which resides in subtropical forest and the lowest in V. cheiranthifolia from the Teide volcano. Transcriptome sequencing and LC-MS were used to identify 23 cyclotide sequences from V. anagae. Cyclotide extracts exhibited antifungal activities with the lowest minimal inhibitory concentrations noted for V. anagae (15.62 μg/ml against Fusarium culmorum). The analysis of the relative abundance of 30 selected cyclotides revealed patterns characteristic to both species and populations, which can be the result of genetic variability or environmental conditions in different habitats. The current study exemplifies how plants tailor their host defense peptides for various habitats, and the usefulness of cyclotides as markers for chemosystematics.
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| 34157574 |
Phototransformation of an emerging cyanotoxin (Aerucyclamide A) in simulated natural waters |
10.1016/j.watres.2021.117339. |
Water Res |
Phototransformation of an emerging cyanotoxin (Aerucyclamide A) in simulated natural waters
Abstract
- Aerucyclamide A (ACA) is an emerging cyanopeptide toxin produced by cyanobacteria, and its transformation pathway has rarely been reported. In the present study, ACA was purified from cyanobacterial extracts, and photodegradation processes were investigated in dissolved organic matter (DOM) solutions. Under simulated solar irradiation, the photodegradation of ACA was dominated by OH oxidation, accounting for ~72% of the indirect photodegradation. The bimolecular reaction rate constant of ACA with OH was (6.4 ± 0.2) × 10M s . Our results indicated that the major reactive sites of ACA toward OH are thiazoline and thiazole moieties. Product analysis via high-resolution mass spectrometry suggested that hydrogen abstraction and gradual hydroxylation are the main photodegradation pathways. The acute toxicity assessment indicate that the products generated in photolysis process did not show any measurable toxicity to Thamnocephalus platyurus. Photodegradation experiments with various DOM-phycocyanin mixtures demonstrated that the half-life of ACA is much longer than that of microcystin-LR.
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| 34161094 |
Discovery of Methylene Thioacetal-Incorporated α-RgIA Analogues as Potent and Stable Antagonists of the Human α9α10 Nicotinic Acetylcholine Receptor for the Treatment of Neuropathic Pain |
10.1021/acs.jmedchem.1c00802. |
J Med Chem |
Discovery of Methylene Thioacetal-Incorporated α-RgIA Analogues as Potent and Stable Antagonists of the Human α9α10 Nicotinic Acetylcholine Receptor for the Treatment of Neuropathic Pain
Abstract
- α9-Containing nicotinic acetylcholine receptors (nAChRs) are key targets for the treatment of neuropathic pain. α-Conotoxin RgIA4 is a peptide antagonist of human α9α10 nAChRs with high selectivity. However, structural rearrangement reveals a potential liability for clinical applications. We herein report our designer RgIA analogues stabilized by methylene thioacetal as nonopioid analgesic agents. We demonstrate that replacing disulfide loop I [Cys-Cys] with methylene thioacetal in the RgIA skeleton results in activity loss, whereas substitution of loop II [Cys-Cys] can be accommodated. The lead molecule, RgIA-5524, exhibits highly selective inhibition of α9α10 nAChRs with an IC of 0.9 nM and much reduced degradation in human serum. studies showed that RgIA-5524 relieves chemotherapy-induced neuropathic pain in wild type but not α9 knockout mouse models, demonstrating that α9-containing nAChRs are necessary for the therapeutic effects. This work highlights the application of methylene thioacetal as a disulfide surrogate in conotoxin-based, disulfide-rich peptide drugs.
|
| 34206990 |
Human Defensins Inhibit SARS-CoV-2 Infection by Blocking Viral Entry |
10.3390/v13071246. |
Viruses |
Human Defensins Inhibit SARS-CoV-2 Infection by Blocking Viral Entry
Abstract
- Innate immunity during acute infection plays a critical role in the disease severity of severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS), and is likely to contribute to COVID-19 disease outcomes. Defensins are highly abundant innate immune factors in neutrophils and epithelial cells, including intestinal Paneth cells, and exhibit antimicrobial and immune-modulatory activities. In this study, we investigated the effects of human α- and β-defensins and RC101, a θ-defensin analog, on SARS-CoV-2 infection. We found that human neutrophil peptides (HNPs) 1-3, human defensin (HD) 5 and RC101 exhibited potent antiviral activity against pseudotyped viruses expressing SARS-CoV-2 spike proteins. HNP4 and HD6 had weak anti-SARS-CoV-2 activity, whereas human β-defensins (HBD2, HBD5 and HBD6) had no effect. HNP1, HD5 and RC101 also inhibited infection by replication-competent SARS-CoV-2 viruses and SARS-CoV-2 variants. Pretreatment of cells with HNP1, HD5 or RC101 provided some protection against viral infection. These defensins did not have an effect when provided post-infection, indicating their effect was directed towards viral entry. Indeed, HNP1 inhibited viral fusion but not the binding of the spike receptor-binding domain to hACE2. The anti-SARS-CoV-2 effect of defensins was influenced by the structure of the peptides, as linear unstructured forms of HNP1 and HD5 lost their antiviral function. Pro-HD5, the precursor of HD5, did not block infection by SARS-CoV-2. High virus titers overcame the effect of low levels of HNP1, indicating that defensins act on the virion. HNP1, HD5 and RC101 also blocked viral infection of intestinal and lung epithelial cells. The protective effects of defensins reported here suggest that they may be useful additives to the antivirus arsenal and should be thoroughly studied.
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| 34251165 |
Identifying the Cellular Target of Cordyheptapeptide A and Synthetic Derivatives |
10.1021/acschembio.1c00094. |
ACS Chem Biol |
Identifying the Cellular Target of Cordyheptapeptide A and Synthetic Derivatives
Abstract
- Cordyheptapeptide A is a lipophilic cyclic peptide from the prized fungal genus that shows potent cytotoxicity in multiple cancer cell lines. To better understand the bioactivity and physicochemical properties of cordyheptapeptide A with the ultimate goal of identifying its cellular target, we developed a solid-phase synthesis of this multiply -methylated cyclic heptapeptide which enabled rapid access to both side chain- and backbone-modified derivatives. Removal of one of the backbone amide -methyl (N-Me) groups maintained bioactivity, while membrane permeability was also preserved due to the formation of a new intramolecular hydrogen bond in a low dielectric solvent. Based on its cytotoxicity profile in the NCI-60 cell line panel, as well as its phenotype in a microscopy-based cytological assay, we hypothesized that cordyheptapeptide was acting on cells as a protein synthesis inhibitor. Further studies revealed the molecular target of cordyheptapeptide A to be the eukaryotic translation elongation factor 1A (eEF1A), a target shared by other lipophilic cyclic peptide natural products. This work offers a strategy to study and improve cyclic peptide natural products while highlighting the ability of these lipophilic compounds to effectively inhibit intracellular disease targets.
|
| 34322026 |
Cyclotides Isolated From Violet Plants of Cameroon Are Inhibitors of Human Prolyl Oligopeptidase |
10.3389/fphar.2021.707596. |
Front Pharmacol |
Cyclotides Isolated From Violet Plants of Cameroon Are Inhibitors of Human Prolyl Oligopeptidase
Abstract
- Traditional medicine and the use of herbal remedies are well established in the African health care system. For instance, Violaceae plants are used for antimicrobial or anti-inflammatory applications in folk medicine. This study describes the phytochemical analysis and bioactivity screening of four species of the violet Allexis found in Cameroon. , , and were evaluated for the expression of circular peptides (cyclotides) by mass spectrometry. The unique cyclic cystine-rich motif was identified in several peptides of all four species. Knowing that members of this peptide family are protease inhibitors, the plant extracts were evaluated for the inhibition of human prolyl oligopeptidase (POP). Since all four species inhibited POP activity, a bioactivity-guided fractionation approach was performed to isolate peptide inhibitors. These novel cyclotides, alca 1 and alca 2 exhibited IC values of 8.5 and 4.4 µM, respectively. To obtain their amino acid sequence information, combinatorial enzymatic proteolysis was performed. The proteolytic fragments were evaluated in MS/MS fragmentation experiments and the full-length amino acid sequences were obtained by annotation of fragment ions. In summary, this study identified inhibitors of the human protease POP, which is a drug target for inflammatory or neurodegenerative disorders.
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| 34337875 |
Integrated pan-cancer of AURKA expression and drug sensitivity analysis reveals increased expression of AURKA is responsible for drug resistance |
10.1002/cam4.4161. |
Cancer Med |
Integrated pan-cancer of AURKA expression and drug sensitivity analysis reveals increased expression of AURKA is responsible for drug resistance
Abstract
- The AURKA gene encodes a protein kinase involved in cell cycle regulation and plays an oncogenic role in many cancers. The main objective of this study is to analyze AURKA expression in 13 common cancers and its role in prognostic and drug resistance.
Using the cancer genome atlas (TCGA) as well as CCLE and GDSC data, the level of AURKA gene expression and its role in prognosis and its association with drug resistance were evaluated, respectively. In addition, the expression level of AURKA was assessed in colorectal cancer (CRC) and gastric cancer (GC) samples. Besides, using Gene Expression Omnibus (GEO) data, drugs that could affect the expression level of this gene were also identified.
The results indicated that the expression level of AURKA gene in 13 common cancers increased significantly compared to normal samples or it survived poorly (HR >1, p < 0.01) in lung, prostate, kidney, bladder, and uterine cancers. Also, the gene expression data showed increased expression in CRC and GC samples compared to normal ones. The level of AURKA was significantly associated with the resistance to SB 505124, NU-7441, and irinotecan drugs (p < 0.01). Eventually, GEO data showed that JQ1, actinomycin D1, and camptothecin could reduce the expression of AURKA gene in different cancer cell lines (logFC < 1, p < 0.01).
Increased expression of AURKA is observed in prevalent cancers and associated with poor prognostic and the development of drug resistance. In addition, some chemotherapy drugs can reduce the expression of this gene.
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