Investigating the effect of different positioning of lysine residues along the peptide chain of mastoparans for their secondary structures and biological activities

Unwrapping the structural and functional features of antimicrobial peptides from wasp venoms

The study of wasp venoms has captured attention due to the presence of a wide variety of active compounds, revealing a diverse array of biological effects. Among these compounds, certain antimicrobial peptides (AMPs) such as mastoparans and chemotactic peptides have emerged as significant players, characterized by their unique amphipathic short linear alpha-helical structure. These peptides exhibit not only antibiotic properties but also a range of other biological activities, which are related to their ability to interact with biological membranes to varying degrees. This review article aims to provide updated insights into the structure/function relationships of AMPs derived from wasp venoms, linking this knowledge to the potential development of innovative treatments against infections.

Characterization of the Hemolytic Activity of Mastoparan Family Peptides from Wasp Venoms

Biologically active peptides have attracted increasing attention in research on the development of new drugs. Mastoparans, a group of wasp venom linear cationic α-helical peptides, have a variety of biological effects, including mast cell degranulation, activation of protein G, and antimicrobial and anticancer activities. However, the potential hemolytic activity of cationic α-helical peptides greatly limits the clinical applications of mastoparans. Here, we systematically and comprehensively studied the hemolytic activity of mastoparans based on our wasp venom mastoparan family peptide library. The results showed that among 55 mastoparans, 18 had strong hemolytic activity (EC50 ≤ 100 μM), 14 had modest hemolytic activity (100 μM < EC50 ≤ 400 μM) and 23 had little hemolytic activity (EC50 > 400 μM), suggesting functional variation in the molecular diversity of mastoparan family peptides from wasp venom. Based on these data, structure-function relationships were further explored, and, hydrophobicity, but not net charge and amphiphilicity, was found to play a critical role in the hemolytic activity of mastoparans. Combining the reported antimicrobial activity with the present hemolytic activity data, we found that four mastoparan peptides, Parapolybia-MP, Mastoparan-like peptide 12b, Dominulin A and Dominulin B, have promise for applications because of their high antimicrobial activity (MIC ≤ 10 μM) and low hemolytic activity (EC50 ≥ 400 μM). Our research not only identified new leads for the antimicrobial application of mastoparans but also provided a large chemical space to support the molecular design and optimization of mastoparan family peptides with low hemolytic activity regardless of net charge or amphiphilicity.

Study of IsCT analogue peptide against Candida albicans and toxicity/teratogenicity in zebrafish embryos (Danio rerio)

Aim: An IsCT analogue peptide (PepM3) was designed based on structural studies of wasp mastoparans and tested against Candida albicans. Its effects on fungal cell membranes and toxicity were evaluated. Materials & methods: Antifungal activity was analyzed using a microdilution susceptibility test. Toxicity was assessed using human skin keratinocytes (HaCaT) and zebrafish embryos. Results: PepM3 demonstrated activity against C. albicans and a synergistic effect with amphotericin B. The peptide presented fungicidal action with damage to the fungal cell membrane, low toxicity in HaCat cells and was nonteratogenic in zebrafish embryos. Conclusion: Evaluating structural modifications is essential for the development of new agents with potential activity against fungal pathogens and for the reduction of toxic and teratogenic effects.

Effect of substituting glutamine with lysine on structural and biological properties of antimicrobial peptide Polybia-MP1

The natural antimicrobial peptide Polybia-MP1 is a promising candidate for developing new treatment therapy for infection and cancer. It showed broad-spectrum antimicrobial and anticancer activity with high safety on healthy cells. However, previous sequence modification usually resulted in at least one of two consequences: a notable increase in hemolytic activity or a considerable decrease in activity against Gram-negative bacteria and cancer cells. Herein, a new approach was applied by replacing the amino acid Glutamine at position 12 with Lysine and generating the MP1-Q12K analog. Our preliminary data suggested an enhancement in antibacterial and antifungal activity, whereas the anticancer and hemolytic activity of the two peptides were comparable. Moreover, MP1-Q12K was found to be less self-assembly than Polybia-MP1, which further supports the enhancement of antimicrobial properties. Hence, this study provides new information regarding the structure-activity relationships of Polybia-MP1 and support for the development of potent, selective antimicrobial peptides.

Characterization of the Molecular Diversity and Degranulation Activity of Mastoparan Family Peptides from Wasp Venoms

Wasp stings have become an increasingly serious public health problem because of their high incidence and mortality rates in various countries and regions. Mastoparan family peptides are the most abundant natural peptides in hornet venoms and solitary wasp venom. However, there is a lack of systematic and comprehensive studies on mastoparan family peptides from wasp venoms. In our study, for the first time, we evaluated the molecular diversity of 55 wasp mastoparan family peptides from wasp venoms and divided them into four major subfamilies. Then, we established a wasp peptide library containing all 55 known mastoparan family peptides by chemical synthesis and C-terminal amidation modification, and we systematically evaluated their degranulation activities in two mast cell lines, namely the RBL-2H3 and P815 cell lines. The results showed that among the 55 mastoparans, 35 mastoparans could significantly induce mast cell degranulation, 7 mastoparans had modest mast cell degranulation activity, and 13 mastoparans had little mast cell degranulation activity, suggesting functional variation in mastoparan family peptides from wasp venoms. Structure-function relationship studies found that the composition of amino acids in the hydrophobic face and amidation in the C-terminal region are critical for the degranulation activity of mastoparan family peptides from wasp venoms. Our research will lay a theoretical foundation for studying the mechanism underlying the degranulation activity of wasp mastoparans and provide new evidence to support the molecular design and molecular optimization of natural mastoparan peptides from wasp venoms in the future.

Mastoparans: A Group of Multifunctional α-Helical Peptides With Promising Therapeutic Properties

Biologically active peptides have been attracting increasing attention, whether to improve the understanding of their mechanisms of action or in the search for new therapeutic drugs. Wasp venoms have been explored as a remarkable source for these molecules. In this review, the main findings on the group of wasp linear cationic α-helical peptides called mastoparans were discussed. These compounds have a wide variety of biological effects, including mast cell degranulation, activation of protein G, phospholipase A₂, C, and D activation, serotonin and insulin release, and antimicrobial, hemolytic, and anticancer activities, which could lead to the development of new therapeutic agents.

In Silico and In Vitro Structure-Activity Relationship of Mastoparan and Its Analogs

Antimicrobial peptides are an important class of therapeutic agent used against a wide range of pathogens such as Gram-negative and Gram-positive bacteria, fungi, and viruses. Mastoparan (MpVT) is an α-helix and amphipathic tetradecapeptide obtained from Vespa tropica venom. This peptide exhibits antibacterial activity. In this work, we investigate the effect of amino acid substitutions and deletion of the first three C-terminal residues on the structure–activity relationship. In this in silico study, the predicted structure of MpVT and its analog have characteristic features of linear cationic peptides rich in hydrophobic and basic amino acids without disulfide bonds. The secondary structure and the biological activity of six designed analogs are studied. The biological activity assays show that the substitution of phenylalanine (MpVT1) results in a higher antibacterial activity than that of MpVT without increasing toxicity. The analogs with the first three deleted C-terminal residues showed decreased antibacterial and hemolytic activity. The CD (circular dichroism) spectra of these peptides show a high content α-helical conformation in the presence of 40% 2,2,2-trifluoroethanol (TFE). In conclusion, the first three C-terminal deletions reduced the length of the α-helix, explaining the decreased biological activity. MpVTs show that the hemolytic activity of mastoparan is correlated to mean hydrophobicity and mean hydrophobic moment. The position and spatial arrangement of specific hydrophobic residues on the non-polar face of α-helical AMPs may be crucial for the interaction of AMPs with cell membranes.

Chemical approaches in the development of natural nontoxic peptide Polybia-MP1 as a potential dual antimicrobial and antitumor agent

Polybia-MP1 is a well-known natural antimicrobial peptide that has been intensively studied recently due to its therapeutic potential. MP1 exhibited not only potent antibacterial activity but also antifungal and anticancer properties. More importantly, MP1 shows relatively low hemolytic activity compared to other antimicrobial peptides having a similar origin. Thus, besides investigating possible mechanisms of action, great efforts have been invested to develop this peptide to become more "druggable". In this review, we summarized all the chemical approaches, both success and failure, that using MP1 as a lead compound to create modified analogs with better pharmacological properties. As there have been thousands of natural AMPs found and deposited in numerous databases, such useful information in both the success and failure will provide insight into the research and development of antimicrobial peptides and guiding for the next steps.

The effect of acidic pH on the adsorption and lytic activity of the peptides Polybia-MP1 and its histidine-containing analog in anionic lipid membrane: a biophysical study by molecular dynamics and spectroscopy

Antimicrobial peptides (AMPs) are part of the innate immune system of many species. AMPs are short sequences rich in charged and non-polar residues. They act on the lipid phase of the plasma membrane without requiring membrane receptors. Polybia-MP1 (MP1), extracted from a native wasp, is a broad-spectrum bactericide, an inhibitor of cancer cell proliferation being non-hemolytic and non-cytotoxic. MP1 mechanism of action and its adsorption mode is not yet completely known. Its adsorption to lipid bilayer and lytic activity is most likely dependent on the ionization state of its two acidic and three basic residues and consequently on the bulk pH. Here we investigated the effect of bulk acidic (pH 5.5) and neutral pH (7.4) solution on the adsorption, insertion, and lytic activity of MP1 and its analog H-MP1 to anionic (7POPC:3POPG) model membrane. H-MP1 is a synthetic analog of MP1 with lysines replaced by histidines. Bulk pH changes could modulate this peptide efficiency. The combination of different experimental techniques and molecular dynamics (MD) simulations showed that the adsorption, insertion, and lytic activity of H-MP1 are highly sensitive to bulk pH in opposition to MP1. The atomistic details, provided by MD simulations, showed peptides contact their N-termini to the bilayer before the insertion and then lay parallel to the bilayer. Their hydrophobic faces inserted into the acyl chain phase disturb the lipid-packing.

Wasp Venom Biochemical Components and Their Potential in Biological Applications and Nanotechnological Interventions

Wasps, members of the order Hymenoptera, are distributed in different parts of the world, including Brazil, Thailand, Japan, Korea, and Argentina. The lifestyles of the wasps are solitary and social. Social wasps use venom as a defensive measure to protect their colonies, whereas solitary wasps use their venom to capture prey. Chemically, wasp venom possesses a wide variety of enzymes, proteins, peptides, volatile compounds, and bioactive constituents, which include phospholipase A2, antigen 5, mastoparan, and decoralin. The bioactive constituents have anticancer, antimicrobial, and anti-inflammatory effects. However, the limited quantities of wasp venom and the scarcity of advanced strategies for the synthesis of wasp venom’s bioactive compounds remain a challenge facing the effective usage of wasp venom. Solid-phase peptide synthesis is currently used to prepare wasp venom peptides and their analogs such as mastoparan, anoplin, decoralin, polybia-CP, and polydim-I. The goal of the current review is to highlight the medicinal value of the wasp venom compounds, as well as limitations and possibilities. Wasp venom could be a potential and novel natural source to develop innovative pharmaceuticals and new agents for drug discovery.

Study of mastoparan analog peptides against Candida albicans and safety in zebrafish embryos (Danio rerio)

Aim: In this work, mastoparan analog peptides from wasp venom were tested against Candida albicans and safety assays were performed using cell culture and model zebrafish. Materials & methods: Minimal inhibitory concentration was determined and toxicity was performed using human skin keratinocyte and embryo zebrafish. Also, permeation of peptides through embryo chorion was performed. Results: The peptides demonstrated anti-C. albicans activity, with low cytotoxicity and nonteratogenicity in Danio rerio. The compounds had different permeation through chorion, suggesting that this occurs due to modifications in their amino acid sequence. Conclusion: The results showed that the studied peptides can be used as structural study models for novel potential antifungal agents.

Evaluation of the bioactivity of a mastoparan peptide from wasp venom and of its analogues designed through targeted engineering

Mastoparan is a typical cationic and amphipathic tetradecapeptide found in wasp venom and exhibits potent biological activities. Yet, compared with other insect-derived peptides, such as melittin from the bee venom, this family have been underrated. Herein, we evaluated the biological activities of mastoparan-C (MP-C), which was identified from the venom of the European Hornet (Vespa crabro), and rationally designed two analogues (a skeleton-based cyclization by two cysteine residues and an N-terminal extension via tat-linked) for enhancing the stability of the biological activity and membrane permeability, respectively. Three peptides possessed broadly efficacious inhibiting capacities towards common pathogens, resistant strains, as well as microbial biofilm. Although, cyclized MP-C showed longer half-life time than the parent peptide, the lower potency of antimicrobial activity and higher degree of haemolysis were observed. The tat-linked MP-C exhibited more potent anticancer activity than the parent peptide, but it also loses the specificity. The study revealed that MP-C is good candidate for developing antimicrobial agents and the targeted-design could improve the stability and transmembrane delivery, but more investigation would be needed to adjust the side effects brought from the design.

Arthropod toxins acting on neuronal potassium channels

Arthropod venoms are a rich mixture of biologically active compounds exerting different physiological actions across diverse phyla and affecting multiple organ systems including the central nervous system. Venom compounds can inhibit or activate ion channels, receptors and transporters with high specificity and affinity providing essential insights into ion channel function. In this review, we focus on arthropod toxins (scorpions, spiders, bees and centipedes) acting on neuronal potassium channels. A brief description of the K⁺ channels classification and structure is included and a compendium of neuronal K⁺ channels and the arthropod toxins that modify them have been listed. This article is part of the Special Issue entitled 'Venom-derived Peptides as Pharmacological Tools.'

Trypanocidal activity of mastoparan from Polybia paulista wasp venom by interaction with TcGAPDH

Chagas disease, considered a neglected disease, is a parasitic infection caused by Trypanosoma cruzi, which is endemic throughout the world. Previously, the antimicrobial effect of Mastoparan (MP) from Polybia paulista wasp venom against bacteria was described. To continue the study, we report in this short communication the antimicrobial effect of MP against Trypanosoma cruzi. MP inhibits all T. cruzi developmental forms through the inhibition of TcGAPDH suggested by the molecular docking. In conclusion, we suggest there is an antimicrobial effect also on T. cruzi.

Functional attributes of evolutionary conserved Arg45 of Wolbachia (Brugia malayi) translation initiation factor-1

AIM

Wolbachia is a promising antifilarial chemotherapeutic target. Translation initiation factor-1 (Tl IF-1) is an essential factor in prokaryotes. Functional characterization of Wolbachia's novel proteins/enzymes is necessary for the development of adulticidal drugs.

MATERIALS & METHODS

Mutant, Wol Tl IF-1 R45D was constructed by site directed mutagenesis. Fluorimetry and size exclusion chromatography were used to determine the biophysical characteristics. Mobility shift assay and fluorescence resonance energy transfer were used to investigate the functional aspect of Wol Tl IF-1 with its mutant.

RESULTS

Both wild and mutant were in monomeric native conformations. Wild exhibits nonspecific binding with ssRNA/ssDNA fragments under electrostatic conditions and showed annealing and displacement of RNA strands in comparison to mutant.

CONCLUSION

Point mutation impaired RNA chaperone activity of the mutant and its interaction with nucleotides.

Structure-activity relationship of mastoparan analogs: Effects of the number and positioning of Lys residues on secondary structure, interaction with membrane-mimetic systems and biological activity

In this study, a series of mastoparan analogs were engineered based on the strategies of Ala and Lys scanning in relation to the sequences of classical mastoparans. Ten analog mastoparans, presenting from zero to six Lys residues in their sequences were synthesized and assayed for some typical biological activities for this group of peptide: mast cell degranulation, hemolysis, and antibiosis. In relation to mast cell degranulation, the apparent structural requirement to optimize this activity was the existence of one or two Lys residues at positions 8 and/or 9. In relation to hemolysis, one structural feature that strongly correlated with the potency of this activity was the number of amino acid residues from the C-terminus of each peptide continuously embedded into the zwitterionic membrane of erythrocytes-mimicking liposomes, probably due to the contribution of this structural feature to the membrane perturbation. The antibiotic activity of mastoparan analogs was directly dependent on the apparent extension of their hydrophilic surface, i.e., their molecules must have from four to six Lys residues between positions 4 and 11 of the peptide chain to achieve activities comparable to or higher than the reference antibiotic compounds. The optimization of the antibacterial activity of the mastoparans must consider Lys residues at the positions 4, 5, 7, 8, 9, and 11 of the tetradecapeptide chain, with the other positions occupied by hydrophobic residues, and with the C-terminal residue in the amidated form. These requirements resulted in highly active AMPs with greatly reduced (or no) hemolytic and mast cell degranulating activities.

Peptidome profiling of venom from the social wasp Polybia paulista

Most crude venom from Polybia paulista is composed of short, linear peptides; however, only five of these peptides are structurally and functionally characterized. Therefore, the peptides in this venom were profiled using an HPLC-IT-TOF/MS and MS(n) system. The presence of type -d and -w ions that are generated from the fragmentation of the side chains was used to resolve I/L ambiguity. The distinction between K and Q residues was achieved through esterification of the α- and ε-amino groups in the peptide chains, followed by mass spectrometry analysis. Fourteen major peptides were detected in P. paulista venom and sequenced; all the peptides were synthesized on solid-phase and submitted to a series of bioassays. Five of them had been previously characterized, and nine were novel toxins. The novel peptides correspond to two wasp kinins, two chemotactic components, three mastoparans, and two peptides of unknown function. The seven novel peptides with identified functions appear to act synergistically with the previously known ones, constituting three well-known families of peptide toxins (wasp kinins, chemotactic peptides, and mastoparans) in the venom of social wasps. These multifunctional toxins can cause pain, oedema formation, haemolysis, chemotaxis of PMNLs, and mast cell degranulation in victims who are stung by wasps.

Pharmacological Alternatives for the Treatment of Neurodegenerative Disorders: Wasp and Bee Venoms and Their Components as New Neuroactive Tools

Neurodegenerative diseases are relentlessly progressive, severely impacting affected patients, families and society as a whole. Increased life expectancy has made these diseases more common worldwide. Unfortunately, available drugs have insufficient therapeutic effects on many subtypes of these intractable diseases, and adverse effects hamper continued treatment. Wasp and bee venoms and their components are potential means of managing or reducing these effects and provide new alternatives for the control of neurodegenerative diseases. These venoms and their components are well-known and irrefutable sources of neuroprotectors or neuromodulators. In this respect, the present study reviews our current understanding of the mechanisms of action and future prospects regarding the use of new drugs derived from wasp and bee venom in the treatment of major neurodegenerative disorders, including Alzheimer’s Disease, Parkinson’s Disease, Epilepsy, Multiple Sclerosis and Amyotrophic Lateral Sclerosis.

Design of imperfectly amphipathic α-helical antimicrobial peptides with enhanced cell selectivity

Antimicrobial peptides (AMPs), which are produced by multicellular organisms as a defense mechanism against competing pathogenic microbes, appear to be excellent candidates for the development of novel antimicrobial agents. Amphipathicity is traditionally believed to be crucial to the de novo design or systematic optimization of AMPs. In this study, we designed a series of short α-helical AMPs with imperfect amphipathicity to augment the arsenal of strategies and to gain further insights into their antimicrobial and hemolytic activity. These imperfectly amphipathic α-helical AMPs were designed by replacing the paired charged amino acid residues on the polar face of an amphipathic peptide with tryptophan residues on the basis of α-helical protein folding principles. PRW4, an imperfectly amphipathic α-helical AMP with hydrogen bonds formed by paired tryptophan residues, was observed to be more selective towards bacterial cells than toward human red blood cells. PRW4 was also effective against Gram-negative and Gram-positive bacteria, and fluorescence spectroscopy, flow cytometry, scanning electron microscopy and transmission electron microscopy indicated that PRW4 killed microbial cells by permeabilizing the cell membrane and damaging their membrane integrity. Therefore, disruptive amphipathicity has excellent potential for the rational design and optimization of AMPs with promising antimicrobial activities.

"It stings a bit but it cleans well": venoms of Hymenoptera and their antimicrobial potential

Venoms from Hymenoptera display a wide range of functions and biological roles. These notably include manipulation of the host, capture of prey and defense against competitors and predators thanks to endocrine and immune systems disruptors, neurotoxic, cytolytic and pain-inducing venom components. Recent works indicate that many hymenopteran species, whatever their life style, have also evolved a venom with properties which enable it to regulate microbial infections, both in stinging and stung animals. In contrast to biting insects and their salivary glands, stinging Hymenoptera seem to constitute an under-exploited ecological niche for agents of vector-borne disease. Few parasitic or mutualistic microorganisms have been reported to be hosted by venom-producing organs or to be transmitted to stung animals. This may result from the presence of potent antimicrobial molecules in venoms, histological features of venom apparatuses and selective effects of venoms on immune defenses of targeted organisms. The present paper reviews for the first time the venom antimicrobial potential of solitary and social Hymenoptera in molecular, ecological, and evolutionary perspectives.

New insight into the mechanism of action of wasp mastoparan peptides: lytic activity and clustering observed with giant vesicles

Antimicrobial peptides of the mastoparans family exert their bactericidal activity by binding to lipid membranes, inducing pores or defects and leaking the internal contents of vesicles and cells. However, this does not seem to be the only mechanism at play, and they might be important in the search for improved peptides with lower undesirable side effects. This work deals with three mastoparans peptides, Polybia-MP-1(MP-1), N2-Polybia-MP-1 (N-MP-1), and Mastoparan X (MPX), which exhibit high sequence homology. They all have three lysine residues and amidated C termini, but because of the presence of two, one, and no aspartic acid residues, respectively, they have +2, +3, and +4 net charges at physiological pH. Here we focus on the effects of these mastoparans peptides on anionic model membranes made of palmitoleyoilphosphatidylcholine (POPC) and palmitoleyoilphosphatidylglycerol (POPG) at 1:1 and 3:1 molar ratios in the presence and in the absence of saline buffer. Zeta potential experiments were carried out to measure the extent of the peptides' binding and accumulation at the vesicle surface, and CD spectra were acquired to quantify the helical structuring of the peptides upon binding. Giant unilamellar vesicles were observed under phase contrast and fluorescence microscopy. We found that the three peptides induced the leakage of GUVs at a gradual rate with many characteristics of the graded mode. This process was faster in the absence of saline buffer. Additionally, we observed that the peptides induced the formation of dense regions of phospholipids and peptides on the GUV surface. This phenomenon was easily observable for the more charged peptides (MPX > N-MP-1 > MP-1) and in the absence of added salt. Our data suggest that these mastoparans accumulate on the bilayer surface and induce a transient interruption to its barrier properties, leaking the vesicle contents. Next, the bilayer recovers its continuity, but this happens in an inhomogeneous way, forming a kind of ply with peptides sandwiched between two juxtaposed membranes. Eventually, a peptide-lipid aggregate forming a lump is formed at high peptide-to-lipid ratios.

Chemometric analysis of Hymenoptera toxins and defensins: A model for predicting the biological activity of novel peptides from venoms and hemolymph

When searching for prospective novel peptides, it is difficult to determine the biological activity of a peptide based only on its sequence. The "trial and error" approach is generally laborious, expensive and time consuming due to the large number of different experimental setups required to cover a reasonable number of biological assays. To simulate a virtual model for Hymenoptera insects, 166 peptides were selected from the venoms and hemolymphs of wasps, bees and ants and applied to a mathematical model of multivariate analysis, with nine different chemometric components: GRAVY, aliphaticity index, number of disulfide bonds, total residues, net charge, pI value, Boman index, percentage of alpha helix, and flexibility prediction. Principal component analysis (PCA) with non-linear iterative projections by alternating least-squares (NIPALS) algorithm was performed, without including any information about the biological activity of the peptides. This analysis permitted the grouping of peptides in a way that strongly correlated to the biological function of the peptides. Six different groupings were observed, which seemed to correspond to the following groups: chemotactic peptides, mastoparans, tachykinins, kinins, antibiotic peptides, and a group of long peptides with one or two disulfide bonds and with biological activities that are not yet clearly defined. The partial overlap between the mastoparans group and the chemotactic peptides, tachykinins, kinins and antibiotic peptides in the PCA score plot may be used to explain the frequent reports in the literature about the multifunctionality of some of these peptides. The mathematical model used in the present investigation can be used to predict the biological activities of novel peptides in this system, and it may also be easily applied to other biological systems.