| 28152596 |
Contryphan Genes and Mature Peptides in the Venom of Nine Cone Snail Species by Transcriptomic and Mass Spectrometric Analysis |
10.1021/acs.jproteome.6b00776. |
J Proteome Res |
Contryphan Genes and Mature Peptides in the Venom of Nine Cone Snail Species by Transcriptomic and Mass Spectrometric Analysis
Abstract
- The occurrence of contryphans, a class of single-disulfide-bond-containing peptides, is demonstrated by the analysis of the venom of nine species of cone snails. Ten full gene sequences and two partial gene sequences coding for contryphan precursor proteins have been identified by next-generation sequencing and compared with available sequences. The occurrence of mature peptides in isolated venom has been demonstrated by LC-ESI-MS/MS analysis. De novo sequencing of reduced, alkylated contryphans from C. frigidus and C. araneosus provides evidence of sequence variation and post-translational modification, notably gamma carboxylation of glutamic acid. The characterization of Fr965 (C. frigidus) provides a rare example of a sequence lacking Pro at position 5 in the disulfide loop. The widespread occurrence of contryphan genes and mature peptides in the venom of diverse cone snails is suggestive of their potential biological significance.
|
| 28161429 |
mZD7349 peptide-conjugated PLGA nanoparticles directed against VCAM-1 for targeted delivery of simvastatin to restore dysfunctional HUVECs |
10.1016/j.mvr.2017.02.002. |
Microvasc Res |
mZD7349 peptide-conjugated PLGA nanoparticles directed against VCAM-1 for targeted delivery of simvastatin to restore dysfunctional HUVECs
Abstract
- Endothelial dysfunction is initial and critical step of atherosclerosis. Impaired bioavailability of endothelial nitric oxide synthase (eNOS) is one of the main reasons of endothelial dysfunction. Improving bioavailability of eNOS by increasing its expression or activity using statins is an effective therapeutic strategy in restoring endothelial dysfunction. In this study, simvastatin (SIM) as a poorly water-soluble drug was loaded in poly (lactic-co-glycolic acid) (PLGA) nanoparticles (SIM-PLGA-NPs). NPs were then conjugated with mZD7349 peptide (mZD7349-SIM-PLGA-NPs) and directed against vascular cell adhesion molecule 1 (VCAM-1). In vitro evaluation of the NPs for targeted delivery of SIM was performed on activated Human Umbilical Cord Vascular Endothelial Cells (HUVECs) by tumor necrosis factor alpha (TNF-α). Effect of mZD7349-SIM-PLGA-NPs and SIM-PLGA-NPs was compared on eNOS phosphorylation (ser-1177). Results of western blot showed SIM post-treatment increased significantly phosphor-eNOS (Ser1177) expression but no total eNOS expression. The study showed that mZD7349-SIM-PLGA-NPs have particle size, zeta potential value, polydispersity index (PDI) and encapsulation efficacy % of 233±18nm, -9.6±1.1mV, 0.59±0.066 and 69±17.3%, respectively. Also phosphor-eNOS (Ser1177) expression in activated HUVECs treated with mZD7349-SIM-PLGA-NPs was significantly (p<0.05) better than treated cells with SIM-PLGA-NPs. The results suggest that mZD7349-SIM-PLGA-NPs may be usable as an appropriate drug carrier for restoring endothelial dysfunction.
|
| 28167938 |
Comparative Analysis of the Bacterial Membrane Disruption Effect of Two Natural Plant Antimicrobial Peptides |
10.3389/fmicb.2017.00051. |
Front Microbiol |
Comparative Analysis of the Bacterial Membrane Disruption Effect of Two Natural Plant Antimicrobial Peptides
Abstract
- In the genome about 700 genes code for nodule-specific cysteine-rich (NCR) small peptides that are expressed in the symbiotic organ, the root nodule, where they control terminal differentiation of the endosymbiotic rhizobium bacteria to nitrogen-fixing bacteroids. Cationic NCR peptides were predicted to have antimicrobial activities. Here antibacterial activities of NCR247, NCR335, polymyxin B (PMB), and streptomycin were investigated and compared on two foodborne pathogens and as representatives of Gram-negative and Gram-positive bacteria. The integrity of the bacterial membrane was seriously compromised by these NCR peptides. Different localization was observed for NCR247 and NCR335 in the treated bacteria, the peptides mostly accumulated in the cytosol in while they remained in the bacterial membrane in . Scanning electron microscopy revealed distinct membrane morphology of the peptide-treated bacteria. Complete cell disruption was induced by PMB and NCR335 in while NCR247 treatment resulted in extensive budding observed on the cell surface of . PMB had no effect on while NCR335 and NCR247 provoked morphological changes on this bacterium, the whole cell content was released in response to NCR335 treatment.
|
| 28216409 |
Structure and activity of contryphan-Vc2: Importance of the d-amino acid residue |
10.1016/j.toxicon.2017.02.012. |
Toxicon |
Structure and activity of contryphan-Vc2: Importance of the d-amino acid residue
Abstract
- In natural proteins and peptides, amino acids exist almost invariably as l-isomers. There are, however, several examples of naturally-occurring peptides containing d-amino acids. In this study we investigated the role of a naturally-occurring d-amino acid in a small peptide identified in the transcriptome of a marine cone snail. This peptide belongs to a family of peptides known as contryphans, all of which contain a single d-amino acid residue. The solution structure of this peptide was solved by NMR, but further investigations with molecular dynamics simulations suggest that its solution behaviour may be more dynamic than suggested by the NMR ensemble. Functional tests in mice uncovered a novel bioactivity, a depressive phenotype that contrasts with the hyperactive phenotypes typically induced by contryphans. Trp3 is important for bioactivity, but this role is independent of the chirality at this position. The d-chirality of Trp3 in this peptide was found to be protective against enzymatic degradation. Analysis by NMR and molecular dynamics simulations indicated an interaction of Trp3 with lipid membranes, suggesting the possibility of a membrane-mediated mechanism of action for this peptide.
|
| 28275006 |
Polymyxins: Antibacterial Activity, Susceptibility Testing, and Resistance Mechanisms Encoded by Plasmids or Chromosomes |
10.1128/CMR.00064-16. |
Clin Microbiol Rev |
Polymyxins: Antibacterial Activity, Susceptibility Testing, and Resistance Mechanisms Encoded by Plasmids or Chromosomes
Abstract
- Polymyxins are well-established antibiotics that have recently regained significant interest as a consequence of the increasing incidence of infections due to multidrug-resistant Gram-negative bacteria. Colistin and polymyxin B are being seriously reconsidered as last-resort antibiotics in many areas where multidrug resistance is observed in clinical medicine. In parallel, the heavy use of polymyxins in veterinary medicine is currently being reconsidered due to increased reports of polymyxin-resistant bacteria. Susceptibility testing is challenging with polymyxins, and currently available techniques are presented here. Genotypic and phenotypic methods that provide relevant information for diagnostic laboratories are presented. This review also presents recent works in relation to recently identified mechanisms of polymyxin resistance, including chromosomally encoded resistance traits as well as the recently identified plasmid-encoded polymyxin resistance determinant MCR-1. Epidemiological features summarizing the current knowledge in that field are presented.
|
| 28333237 |
New Paenibacillus strain produces a family of linear and cyclic antimicrobial lipopeptides: cyclization is not essential for their antimicrobial activity |
10.1093/femsle/fnx049. |
FEMS Microbiol Lett |
New Paenibacillus strain produces a family of linear and cyclic antimicrobial lipopeptides: cyclization is not essential for their antimicrobial activity
Abstract
- A new bacterial isolate, Paenibacillus sp. OSY-N, showed potent antimicrobial activity against Gram-negative and Gram-positive bacteria. Antimicrobials produced by this strain were purified by reverse-phase high-performance liquid chromatography. Structural analysis, using mass spectrometry, of a single active HPLC fraction revealed two known cyclic lipopeptides (BMY-28160 and permetin A), a new cyclic lipopeptide, and the linear counterparts of these cyclic compounds. The latter were designated as paenipeptins A, B and C, respectively. The paenipeptins have not been reported before as naturally occurring products. Paenipeptins B and C differ at the acyl side chain; paenipeptin C contains a C8-, instead of C7-fatty acyl side chain. To demonstrate unequivocally the antimicrobial activity of the linear forms of this family of cyclic lipopeptides, analogs of the paenipeptins were synthesized chemically and their antimicrobial activity was tested individually. The synthetic linear lipopeptide with an octanoic acid side chain (designated as paenipeptin C΄) showed potent antimicrobial activity with minimum inhibitory concentrations of 0.5-4.0 μg/mL for Gram-negative and 0.5-32 μg/mL for Gram-positive bacteria. Findings demonstrated that peptide cyclization in this lipopeptide family is not essential for their antimicrobial activity. Most importantly, linear lipopeptides are more accessible than their cyclic counterparts through chemical synthesis.
|
| 28333296 |
Stepwise Evolution of a Buried Inhibitor Peptide over 45 My |
10.1093/molbev/msx104. |
Mol Biol Evol |
Stepwise Evolution of a Buried Inhibitor Peptide over 45 My
Abstract
- The de novo evolution of genes and the novel proteins they encode has stimulated much interest in the contribution such innovations make to the diversity of life. Most research on this de novo evolution focuses on transcripts, so studies on the biochemical steps that can enable completely new proteins to evolve and the time required to do so have been lacking. Sunflower Preproalbumin with SFTI-1 (PawS1) is an unusual albumin precursor because in addition to producing albumin it also yields a potent, bicyclic protease-inhibitor called SunFlower Trypsin Inhibitor-1 (SFTI-1). Here, we show how this inhibitor peptide evolved stepwise over tens of millions of years. To trace the origin of the inhibitor peptide SFTI-1, we assembled seed transcriptomes for 110 sunflower relatives whose evolution could be resolved by a chronogram, which allowed dates to be estimated for the various stages of molecular evolution. A genetic insertion event in an albumin precursor gene ∼45 Ma introduced two additional cleavage sites for protein maturation and conferred duality upon PawS1-Like genes such that they also encode a small buried macrocycle. Expansion of this region, including two Cys residues, enlarged the peptide ∼34 Ma and made the buried peptides bicyclic. Functional specialization into a protease inhibitor occurred ∼23 Ma. These findings document the evolution of a novel peptide inside a benign region of a pre-existing protein. We illustrate how a novel peptide can evolve without de novo gene evolution and, critically, without affecting the function of what becomes the protein host.
|
| 28335479 |
Phakellistatins: An Underwater Unsolved Puzzle |
10.3390/md15030078. |
Mar Drugs |
Phakellistatins: An Underwater Unsolved Puzzle
Abstract
- A critical summary on the discovery of the nineteen members of the phakellistatin family (phakellistatin 1-19), cytotoxic proline-rich cyclopeptides of marine origin, is reported. Isolation, structural elucidation, and biological properties of the various-sized natural macrocycles are described, along with the total syntheses and the enigmatic issues of the cytotoxic activity reproducibility.
|
| 28340427 |
Identification and characterization of a β-defensin gene involved in the immune defense response of channel catfish, Ictalurus punctatus |
10.1016/j.molimm.2017.03.009. |
Mol Immunol |
Identification and characterization of a β-defensin gene involved in the immune defense response of channel catfish, Ictalurus punctatus
Abstract
- Antimicrobial peptides are small peptides that play important roles in a host's innate immune response. As an important antimicrobial peptide, β-defensin widely distribute in mammals, insects and plants with broad-spectrum antimicrobial activity. In this study, the β-defensin gene of the channel catfish, Ictalurus punctatus, was cloned, sequenced, and subjected to a bioinformatic analysis. The β-defensin gene of the channel catfish contains three exons and two introns, and encodes a precursor peptide consisting of two domains: a signal peptide of 24 amino acid residues and a mature peptide of 43 amino acid residues. The mature peptide is estimated to have a molecular mass of 7.1kDa and a theoretical isoelectric point of 8.21. Channel catfish β-defensin (ccBD) has six conserved cysteine residues, forming three disulfide bridges at C1-C5, C2-C4, and C3-C6, and a β-sheet in the predicted three-dimensional structure. A phylogenetic analysis suggests that ccBD belongs to the type 1 β-defensins. Real-time quantitative PCR showed that channel catfish β-defensin transcripts are constitutively expressed in various tissues in healthy fish, with highest expression in the skin. The expression of ccBD in vivo increased significantly in the head kidney (2.9-fold), gill (2.2-fold), and skin (6.6-fold) at 48h after bacterial (Edwardsiella ictaluri) challenge. In vitro, lipopolysaccharide (LPS), a bacterial mimic, induced significant changes in ccBD expression in leukocytes from the spleen (3.4-fold) and head kidney (3.9-fold) 24h after stimulation. Chemically synthesized ccBD displayed marked inhibitory activity against a broad range of bacteria. These results suggest that ccBD is involved in the innate antibacterial defenses of the channel catfish.
|
| 28361878 |
Structural mechanisms for α-conotoxin activity at the human α3β4 nicotinic acetylcholine receptor |
10.1038/srep45466. |
Sci Rep |
Structural mechanisms for α-conotoxin activity at the human α3β4 nicotinic acetylcholine receptor
Abstract
- Nicotinic acetylcholine receptors (nAChR) are therapeutic targets for a range of human diseases. α-Conotoxins are naturally occurring peptide antagonists of nAChRs that have been used as pharmacological probes and investigated as drug leads for nAChR related disorders. However, α-conotoxin interactions have been mostly characterised at the α7 and α3β2 nAChRs, with interactions at other subtypes poorly understood. This study provides novel structural insights into the molecular basis for α-conotoxin activity at α3β4 nAChR, a therapeutic target where subtype specific antagonists have potential to treat nicotine addiction and lung cancer. A co-crystal structure of α-conotoxin LsIA with Lymnaea stagnalis acetylcholine binding protein guided the design and functional characterisations of LsIA analogues that identified the minimum pharmacophore regulating α3β4 antagonism. Interactions of the LsIA R10F with β4 K57 and the conserved -NN- α-conotoxin motif with β4 I77 and I109 conferred α3β4 activity to the otherwise inactive LsIA. Using these structural insights, we designed LsIA analogues with α3β4 activity. This new understanding of the structural basis of protein-protein interactions between α-conotoxins and α3β4 may help rationally guide the development of α3β4 selective antagonists with therapeutic potential.
|
| 28406289 |
Phylogenomic Analysis of the Microviridin Biosynthetic Pathway Coupled with Targeted Chemo-Enzymatic Synthesis Yields Potent Protease Inhibitors |
10.1021/acschembio.7b00124. |
ACS Chem Biol |
Phylogenomic Analysis of the Microviridin Biosynthetic Pathway Coupled with Targeted Chemo-Enzymatic Synthesis Yields Potent Protease Inhibitors
Abstract
- Natural products and their semisynthetic derivatives are an important source of drugs for the pharmaceutical industry. Bacteria are prolific producers of natural products and encode a vast diversity of natural product biosynthetic gene clusters. However, much of this diversity is inaccessible to natural product discovery. Here, we use a combination of phylogenomic analysis of the microviridin biosynthetic pathway and chemo-enzymatic synthesis of bioinformatically predicted microviridins to yield new protease inhibitors. Phylogenomic analysis demonstrated that microviridin biosynthetic gene clusters occur across the bacterial domain and encode three distinct subtypes of precursor peptides. Our analysis shed light on the evolution of microviridin biosynthesis and enabled prioritization of their chemo-enzymatic production. Targeted one-pot synthesis of four microviridins encoded by the cyanobacterium Cyanothece sp. PCC 7822 identified a set of novel and potent serine protease inhibitors, the most active of which had an IC value of 21.5 nM. This study advances the genome mining techniques available for natural product discovery and obviates the need to culture bacteria.
|
| 28471681 |
Understanding the Diversity and Distribution of Cyclotides from Plants of Varied Genetic Origin |
10.1021/acs.jnatprod.7b00061. |
J Nat Prod |
Understanding the Diversity and Distribution of Cyclotides from Plants of Varied Genetic Origin
Abstract
- Cyclotides are a large family of naturally occurring plant-derived macrocyclic cystine-knot peptides, with more than 400 having been identified in species from the Violaceae, Rubiaceae, Cucurbitaceae, Fabaceae, and Solanaceae families. Nevertheless, their specialized distribution within the plant kingdom remains poorly understood. In this study, the diversity of cyclotides was explored through the screening of 197 plants belonging to 43 different families. In total, 28 cyclotides were sequenced from 15 plant species, one of which belonged to the Rubiaceae and 14 to the Violaceae. Every Violaceae species screened contained cyclotides, but they were only sparsely represented in Rubiaceae and xistent in other families. The study thus supports the hypothesis that cyclotides are ubiquitous in the Violaceae, and it adds to the list of plants found to express kalata S and cycloviolacin O12. Finally, previous studies suggested the existence of cyclotide isoforms with either an Asn or an Asp at the C-terminal processing site of the cyclotide domain within the precursor proteins. Here we found that despite the discovery of a few cyclotides genuinely containing an Asp in loop 6 as evidenced by gene sequencing, deamidation of Asn during enzymatic digestion resulted in the artifactual presence of Asp isoforms. This result is consistent with studies suggesting that peptides can undergo deamidation after being subjected to external factors, including pH, temperature, and enzymatic digestion.
|
| 28541699 |
Kohamamides A, B, and C, Cyclic Depsipeptides from an Okeania sp. Marine Cyanobacterium |
10.1021/acs.jnatprod.7b00256. |
J Nat Prod |
Kohamamides A, B, and C, Cyclic Depsipeptides from an Okeania sp. Marine Cyanobacterium
Abstract
- Kohamamides A, B, and C (1-3), new cyclic depsipeptides that belong to the kulolide superfamily, were isolated from an Okeania sp. marine cyanobacterium. Their structures were elucidated by spectroscopic analyses and degradation reactions. Kohamamide B (2) exhibited moderate cytotoxicity against HL60 cells. Although many natural products in the kulolide superfamily have been isolated from cyanobacteria collected in various parts of the world, kohamamides 1-3 are the first members to be isolated from the East Asian marine environment. In addition, unlike other members of this superfamily, kohamamides 1-3 contain a Leu residue adjacent to the Pro residue, rather than another lipophilic amino acid.
|
| 28547390 |
Mono-substitution effects on antimicrobial activity of stapled heptapeptides |
10.1007/s12272-017-0922-1. |
Arch Pharm Res |
Mono-substitution effects on antimicrobial activity of stapled heptapeptides
Abstract
- We previously reported a de novo design of antimicrobial heptapeptide helices using Verdine's all-hydrocarbon peptide stapling system. One of the important structure-activity relationships we found from these previous studies was that extending of the hydrophobic face by replacing of alanine with leucine in positon 5 increases antimicrobial activity. In this study, to further improve the activity profile of this peptide series, we investigated the substitution effects of position 5 on conformational and proteolytic stability as well as antimicrobial and hemolytic activity. We found that antimicrobial activity and cell selectivity can differ depending on the physicochemical properties of the residue in that specific position. The results shown in this work suggest that the stapled amphipathic heptapeptide helix can serve as a promising platform for developing new antibiotics that can cope with antibiotic resistance problem.
|
| 28554994 |
Total Synthesis and Pharmacological Investigation of Cordyheptapeptide A |
10.3390/molecules22060682. |
Molecules |
Total Synthesis and Pharmacological Investigation of Cordyheptapeptide A
Abstract
- The present investigation reports the synthesis of a phenylalanine-rich -methylated cyclopeptide, cordyheptapeptide A (), previously isolated from the insect pathogenic fungus sp. BCC 1788, accomplished through the coupling of -methylated tetrapeptide and tripeptide fragments followed by cyclization of the linear heptapeptide unit. Structure elucidation of the newly synthesized cyclopolypeptide was performed by means of FT-IR, ¹H-NMR, C-NMR, and fast atom bombardment mass spectrometry (FABMS), and screened for its antibacterial, antidermatophytic, and cytotoxic potential. According to the antimicrobial activity results, the newly synthesized -Methylated cyclopeptide exhibited potent antibacterial activity against Gram-negative bacteria and and antifungal activity against dermatophytes and at a concentration of 6 μg/mL, in comparison to the reference drugs, gatifloxacin and griseofulvin. In addition, cyclopolypeptide displayed suitable levels of cytotoxicity against (DLA) and (EAC) cell lines.
|
