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.

Antimicrobial Activities of Cysteine-rich Peptides Specific to Bacteriocytes of the Pea Aphid Acyrthosiphon pisum.

Aphids have a mutualistic relationship with the bacterial endosymbiont Buchnera aphidicola. We previously reported seven cysteine-rich peptides in the pea aphid Acyrthosiphon pisum and named them Bacteriocyte-specific Cysteine-Rich (BCR) peptides; these peptides are exclusively expressed in bacteriocytes, special aphid cells that harbor symbionts. Similar symbiotic organ-specific cysteine-rich peptides identified in the root nodules of leguminous plants are named Nodule-specific Cysteine-Rich (NCR) peptides. NCR peptides target rhizobia in the nodules and are essential for symbiotic nitrogen fixation. A BacA (membrane protein) mutant of Sinorhizobium is sensitive to NCR peptides and is unable to establish symbiosis. Based on the structural and expressional similarities between BCR peptides and NCR peptides, we hypothesized that aphid BCR peptides exhibit antimicrobial activity, similar to some NCR peptides. We herein synthesized BCR peptides and investigated their antimicrobial activities and effects on the bacterial membrane of Escherichia coli. The peptides BCR1, BCR3, BCR5, and BCR8 exhibited antimicrobial activities with increased membrane permeability. An sbmA mutant of E. coli, a homolog of bacA of S. meliloti, was more sensitive to BCR peptides than the wild type. Our results suggest that BCR peptides have properties that may be required to control the endosymbiont, similar to NCR peptides in legumes.

3D-QSAR based optimization of insect neuropeptide allatostatin analogs.

Allatostatins (AST) are neuropeptides originally described as inhibitors of juvenile hormone (JH) synthesis in insects. Consequently, they have been considered as potential lead compounds for the discovery of new insect growth regulators (IGRs). In the present work, receptor-based three-dimensional quantitative structure-activity relationship (3D-QSAR) was studied with 48 AST analogs, and a general approach for novel potent bioactive AST analogs is proposed. Hence, six novel AST analogs were designed and synthesized. Bioassays indicated that the majority novel analogs exhibited potent JH inhibitory activity, especially analog A6 (IC50: 3.79 nmol/L), which can be used as lead compound to develop new IGRs.

Chemical synthesis of the crustacean insulin-like peptide with four disulfide bonds.

Among the insulin-family peptides, two additional cysteine residues other than six conserved cysteines are sometimes found in invertebrate insulin-like peptides (ILPs), although the synthetic method for such four disulfide ILPs has not yet been well established. In this study, we synthesized a crustacean insulin-like androgenic gland factor with four disulfides by the regioselective disulfide bond formation reactions using four orthogonal Cys-protecting groups. Its disulfide isomer could be also synthesized by the same method, indicating that the synthetic strategy developed in this study might be useful for the synthesis of other four disulfide ILPs.

Functional structure and antimicrobial activity of persulcatusin, an antimicrobial peptide from the hard tick Ixodes persulcatus.

BACKGROUND: Antimicrobial peptides (AMPs) are considered promising candidates for the development of novel anti-infective agents. In arthropods such as ticks, AMPs form the first line of defense against pathogens in the innate immune response. Persulcatusin (IP) was found in the Ixodes persulcatus midgut, and its amino acid sequence was reported. However, the complete structure of IP has not been identified. We evaluated the relation between structural features and antimicrobial activity of IP, and its potential as a new anti-methicillin-resistant Staphylococcus aureus (MRSA) agent. METHODS: The structure of IP was predicted using homology modeling and molecular dynamics. IP and other tick AMPs were synthesized using a solid-phase method and purified by high-performance liquid chromatography. Methicillin-susceptible S. aureus (MSSA) and MRSA were used for the minimum inhibitory concentration (MIC) test and short-time killing assay of IP and other tick peptides. The influence of IP on mammalian fibroblasts and colon epithelial cells and each cell DNA and its hemolytic activity towards human erythrocytes were also examined. RESULTS: In the predicted IP structure, the structure with an S-S bond was more stable than that without an S-S bond. The MIC after 24 h of incubation with IP was 0.156-1.25 µg/mL for MSSA and 0.625-2.5 µg/mL for MRSA. Compared with the mammalian antimicrobial peptide and other tick peptides, IP was highly effective against MRSA. Moreover, IP showed a dose-dependent bactericidal effect on both MSSA and MRSA after 1 h of incubation. IP had no observable effect on mammalian cell growth or morphology, on each cell DNA and on human erythrocytes. CONCLUSIONS: We predicted the three-dimensional structure of IP and found that the structural integrity was maintained by three S-S bonds, which were energetically important for the stability and for forming α helix and ß sheet. IP has cationic and amphipathic properties, which might be related to its antimicrobial activity. Furthermore, the antimicrobial activity of IP against MRSA was stronger than that of other antimicrobial peptides without apparent damage to mammalian and human cells, demonstrating its possible application as a new anti-MRSA medicine.

Structure-activity relationships of the intramolecular disulfide bonds in coprisin, a defensin from the dung beetle.

Defensins, which are small cationic molecules produced by organisms as part of their innate immune response, share a common structural scaffold that is stabilized by three disulfide bridges. Coprisin is a 43-amino acid defensin-like peptide from Copris tripartitus. Here, we report the intramolecular disulfide connectivity of cysteine-rich coprisin, and show that it is the same as in other insect defensins. The disulfide bond pairings of coprisin were determined by combining the enzymatic cleavage and mass analysis. We found that the loss of any single disulfide bond in coprisin eliminated all antibacterial, but not antifungal, activity. Circular dichroism (CD) analysis showed that two disulfide bonds, Cys20-Cys39 and Cys24-Cys41, stabilize coprisin's α-helical region. Moreover, a BLAST search against UniProtKB database revealed that coprisin's α-helical region is highly homologous to those of other insect defensins.

Synthesis and antimicrobial activity of cysteine-free coprisin nonapeptides.

Coprisin is a 43-mer defensin-like peptide from the dung beetle, Copris tripartitus. CopA3 (LLCIALRKK-NH2), a 9-mer peptide containing a single free cysteine residue at position 3 of its sequence, was derived from the α-helical region of coprisin and exhibits potent antibacterial and anti-inflammatory activities. The single cysteine implies a tendency for dimerization; however, it remains unknown whether this cysteine residue is indispensible for CopA3's antimicrobial activity. To address this issue, in the present study we synthesized eight cysteine-substituted monomeric CopA3 analogs and two dimeric analogs, CopA3 (Dimer) and CopIK (Dimer), and evaluated their antimicrobial effects against bacteria and fungi, as well as their hemolytic activity toward human erythrocytes. Under physiological conditions, CopA3 (Mono) exhibits a 6/4 (monomer/dimer) molar ratio in HPLC area percent, indicating that its effects on bacterial strains likely reflect a CopA3 (Mono)/CopA3 (Dimer) mixture. We also report the identification of CopW, a new cysteine-free nonapeptide derived from CopA3 that has potent antimicrobial activity with virtually no hemolytic activity. Apparently, the cysteine residue in CopA3 is not essential for its antimicrobial function. Notably, CopW also exhibited significant synergistic activity with ampicillin and showed more potent antifungal activity than either wild-type coprisin or melittin.

The insect peptide CopA3 inhibits lipopolysaccharide-induced macrophage activation.

We recently demonstrated that the insect peptide CopA3 (LLCIALRKK), a disulfide-linked dimeric peptide, exerts antimicrobial and anti-inflammatory activities in a mouse colitis model. Here, we examined whether CopA3 inhibited activation of macrophages by LPS. Exposure of an unseparated mouse peritoneal cell population or isolated peritoneal macrophages to LPS markedly increased secretion of IL-6 and TNF-α; these effects were significantly inhibited by CopA3 treatment. The inhibitory effect of CopA3 was also evident in murine macrophage cell line, RAW 264.7. Western blotting revealed that LPS-induced activation of STAT1 and STAT5 in macrophages was significantly inhibited by CopA3. Inhibition of JAK (STAT1/STAT5 kinase) with AG490 markedly reduced the production of IL-6 and TNF-α in macrophages. Collectively, these observations suggest that CopA3 inhibits macrophage activation by inhibiting activating phosphorylations of the transcription factors, STAT1 and STAT5, and blocking subsequent production of IL-6 and TNF-α and indicate that CopA3 may be useful as an immune-modulating agent.

Agelaia MP-I: a peptide isolated from the venom of the social wasp, Agelaia pallipes pallipes, enhances insulin secretion in mice pancreatic islets.

Peptides isolated from animal venoms have shown the ability to regulate pancreatic beta cell function. Characterization of wasp venoms is important, since some components of these venoms present large molecular variability, and potential interactions with different signal transduction pathways. For example, the well studied mastoparan peptides interact with a diversity of cell types and cellular components and stimulate insulin secretion via the inhibition of ATP dependent K(+) (K(ATP)) channels, increasing intracellular Ca(2+) concentration. In this study, the insulin secretion of isolated pancreatic islets from adult Swiss mice was evaluated in the presence of synthetic Agelaia MP-I (AMP-I) peptide, and some mechanisms of action of this peptide on endocrine pancreatic function were characterized. AMP-I was manually synthesized using the Fmoc strategy, purified by RP-HPLC and analyzed using ESI-IT-TOF mass spectrometry. Isolated islets were incubated at increasing glucose concentrations (2.8, 11.1 and 22.2 mM) without (Control group: CTL) or with 10 µM AMP-I (AMP-I group). AMP-I increased insulin release at all tested glucose concentrations, when compared with CTL (P < 0.05). Since molecular analysis showed a potential role of the peptide interaction with ionic channels, insulin secretion was also analyzed in the presence of 250 µM diazoxide, a K(ATP) channel opener and 10 µM nifedipine, a Ca(2+) channel blocker. These drugs abolished insulin secretion in the CTL group in the presence of 2.8 and 11.1 mM glucose, whereas AMP-I also enhanced insulin secretory capacity, under these glucose conditions, when incubated with diazoxide and nifedipine. In conclusion, AMP-I increased beta cell secretion without interfering in K(ATP) and L-type Ca(2+) channel function, suggesting a different mechanism for this peptide, possibly by G protein interaction, due to the structural similarity of this peptide with Mastoparan-X, as obtained by modeling.

Synthetic Coprisin analog peptide, D-CopA3 has antimicrobial activity and pro-apoptotic effects in human leukemia cells.

Recently, we reported that the synthetic Coprisin analog peptide 9-mer dimer CopA3 (consisted of all-L amino acid sequence) was designed based on a defensin-like peptide, Coprisin isolated from Copris tripartitus. The 9-mer dimer CopA3 (L-CopA3) had antibacterial activity and induced apoptosis in human leukemia cells via a caspase-independent pathway. In this study, all of amino acid sequences of L-CopA3 were modified to all D-form amino acids (D-CopA3) to develop a more effective antimicrobial peptide. We investigated whether D-CopA3 had antimicrobial activities against pathogenic microorganisms and proapoptotic effects in human leukemia cells (U937, Jurkat, and AML-2). The synthetic peptide D-CopA3 had antimicrobial activities against various pathogenic bacteria and yeast fungus with MIC values in the 4~64 microM range. Moreover, D-CopA3 caused cell growth inhibition, and increased the chromosomal DNA fragmentation and the expression of inflammatory cytokines, TNF-alpha and IL1-beta, transcripts in human leukemia cells. The all-D amino acid peptide D-CopA3 proved as effective as the L-CopA3 reported previously. These results provide the basis for developing D-CopA3 as a new antibiotic peptide.

Effects of the synthetic coprisin analog peptide, CopA3 in pathogenic microorganisms and mammalian cancer cells.

A synthetic coprisin analog peptide, 9-mer dimer CopA3 (CopA3) was designed based on a defensin-like peptide, Coprisin, isolated from the bacteria-immunized dung beetle Copris tripartitus. Here, CopA3 was investigated for its antimicrobial activity and cancer cell growth inhibition. CopA3 showed antimicrobial activities against various pathogenic bacteria and yeast fungus with MIC values in 2~32 µM ranges, and inhibited the cell viabilities of pancreatic and hepatocellular cancer cells, except MIAPaca2, Hep3B, and HepG2 cells, in a dose-dependent manner. The average IC(50) values of CopA3 against pancreatic and hepatocellular cancer cells were 61.7 µM and 67.8 µM, respectively. The results indicate that CopA3 has potential in the treatments of pancreatic and hepatocellular cancers as well as microorganism infection disease.

CopA3 peptide from Copris tripartitus induces apoptosis in human leukemia cells via a caspase-independent pathway.

Our previous study demonstrated that CopA3, a disulfide dimer of the coprisin peptide analogue (LLCIALRKK), has antibacterial activity. In this study, we assessed whether CopA3 caused cellular toxicity in various mammalian cell lines. CopA3 selectively caused a marked decrease in cell viability in Jurkat T, U937, and AML-2 cells (human leukemia cells), but was not cytotoxic to Caki or Hela cells. Fragmentation of DNA, a marker of apoptosis, was also confirmed in the leukemia cell lines, but not in the other cells. CopA3-induced apoptosis in leukemia cells was mediated by apoptosis inducing factor (AIF), indicating induction of a caspase-independent signaling pathway.

Fast conventional Fmoc solid-phase peptide synthesis: a comparative study of different activators.

The ability to speed up conventional Fmoc solid-phase peptide synthesis (SPPS) has many advantages including increased productivity. One way to speed up conventional Fmoc SPPS is the choice of activator. Recently, several new activators have been introduced into the market, and they were evaluated along with some older activators for their ability to synthesize a range of peptides with shorter and longer reaction times. It was found that HDMC, PyClock, COMU, HCTU, and HATU worked well at shorter reaction times (2 × 1 min), but PyOxim and TFFH only worked well at longer reaction times. The performance of PyBOP at shorter reaction times was poor only for more difficult sequences. These results are important for selecting an appropriate activator for fast SPPS applications.

Design and production of a chimeric resilin-, elastin-, and collagen-like engineered polypeptide.

Protein-inspired biomaterials have gained great interest as an alternative to synthetic polymers, in particular, for their potential use as biomedical devices. The potential inspiring models are mainly proteins able to confer mechanical properties to tissues and organs, such as elasticity (elastin, resilin, spider silk) and strength (collagen, silk). The proper combination of repetitive sequences, each of them derived from different proteins, represents a useful tool for obtaining biomaterials with tailored mechanical properties and biological functions. In this report we describe the design, the production, and the preliminary characterization of a chimeric polypeptide, based on sequences derived from the highly resilient proteins resilin and elastin and from collagen-like sequences. The results show that the obtained chimeric recombinant material exhibits promising self-assembling properties. Young's modulus of the fibers was determined by AFM image analysis and lies in the range of 0.1-3 MPa in agreement with the expectations for elastin-like and resilin-like materials.

A cationic amphiphilic peptide ABP-CM4 exhibits selective cytotoxicity against leukemia cells.

Some cationic antibacterial peptides exhibit a broad spectrum of cytotoxic activity against cancer cells, which could provide a new class of anticancer drugs. In the present study, the anticancer activity of ABP-CM4, an antibacterial peptide from Bombyx mori, against leukemic cell lines THP-1, K562 and U937 was evaluated, and the cytotoxicity compared with the effects on non-cancerous mammalian cells, including peripheral blood mononuclear cells (PBMCs), HEK-293 and erythrocytes. ABP-CM4 reduced the number of viable cells of the leukemic cell lines after exposure for 24h. The reduction was concentration dependent, and the IC50 values ranged from 14 to 18 microM. Conversely, ABP-CM4, even at 120 microM, exhibited no cytotoxicity toward HEK-293 or PBMCs, indicating that there was no significant effect on these two types of non-cancer cells. ABP-CM4 at a concentration of 200 microM had no hemolytic activity on mammalian erythrocytes. Together, these results suggested a selective cytotoxicity in leukemia cells. Flow cytometry demonstrated that the binding activity of ABP-CM4 to leukemia cells was much higher than that to HEK-293 or PBMCs, and there was almost no binding to erythrocytes. FITC-labeled ABP-CM4 molecules were examined under a confocal microscope and found to be concentrated at the surface of leukemia cells and changes of the cell membrane were determined by a cell permeability assay, which led us to the conclusion that ABP-CM4 could act at the cell membrane for its anticancer activity on leukemia cells. Collectively, our results indicated that ABP-CM4 has the potential for development as a novel antileukemic agent.

Studies of insect peptides alloferon, Any-GS and their analogues. Synthesis and antiherpes activity.

The subject of these studies was synthesis and determination of biological properties of a series of insect peptides, such as alloferon, Any-GS and their analogues. The synthesis of 14 peptides was performed by the solid-phase method. Biological effect of these peptides was evaluated by the antiviral test against Human Herpes Virus type 1 (HHV-1) in vitro using a Vero cell line. It was found that the investigated peptides inhibit the replication of HHV-1 in Vero cells.

Desiccation-induced structuralization and glass formation of group 3 late embryogenesis abundant protein model peptides.

Anhydrobiotic (i.e., life without water) organisms are known to produce group 3 late embryogenesis abundant (G3LEA) proteins during adaptation to severely water-deficient conditions. Their primary amino acid sequences are composed largely of loosely conserved 11-mer repeat units. However, little information has been obtained for the structural and functional roles of these repeat units. In this study, we first explore the consensus sequences of the 11-mer repeat units for several native G3LEA proteins originating from anhydrobiotic organisms among insects (Polypedilum vanderplanki), nematodes, and plants. Next, we synthesize four kinds of model peptides (LEA models), each of which consists of four or two repeats of the 11-mer consensus sequences for each of the three organisms. The structural and thermodynamic properties of the LEA models were examined in solution, in dehydrated and rehydrated states, and furthermore in the presence of trehalose, since a great quantity of this sugar is known to be produced in the dried cells of most anhydrobiotic organisms. The results of Fourier transform infrared (FTIR) spectroscopic measurements indicate that all of the LEA models transform from random coils to alpha-helical coiled coils on dehydration and return to random coils again on rehydration, both with and without trehalose. In contrast, such structural changes were never observed for a control peptide with a randomized amino acid sequence. Furthermore, our differential scanning calorimetry (DSC) measurements provide the first evidence that the above 11-mer motif-containing peptides themselves vitrify with a high glass transition temperature (>100 degrees C) and a low enthalpy relaxation rate. In addition, they play a role in reinforcing the glassy matrix of the coexisting trehalose. On the basis of these results, we discuss the underlying mechanism of G3LEA proteins as desiccation stress protectants.

The synthesis and biological activity of linear and cyclic analogs of the two diuretic peptides of Diploptera punctata.

We have investigated the effect of analogs of the two Dippu diuretic hormones, Dippu-DH(46) and Dippu-DH(31), on fluid secretion by Malpighian tubules of male Diploptera punctata. We synthesized analogs containing the amino acid methyl-homoserine, to replace methionine residues, to render these modified peptides less subject to oxidation. We have also synthesized C-terminal fragments and their corresponding cyclic analogs to determine their effect on fluid secretion in D. punctata. Our results indicate that the modified peptides retain significant activity in the Ramsay secretion assay. The linear fragments displayed no activity or some inhibitory activity whereas the cyclic analog fragments showed stimulatory activity, in the case of DH(46), or slight inhibitory activity, in the case of DH(31).

A photoswitchable thioxopeptide bond facilitates the conformation-activity correlation study of insect kinin.

Thioxopeptide bond psi[CS-N], a nearly isosteric modification of the native peptide bond, was introduced into insect kinin active core pentapeptide to evaluate the impact of backbone cis/trans photoswitching on bioactivity. The thioxo analog Phe(1)-Tyr(2)-psi[CS-N]-Pro(3)-Trp(4)-Gly(5)-NH(2) (psi[CS-N](2)-kinin), was synthesized by Fmoc solid-phase peptide strategy. The reversible photoswitching property was characterized via spectroscopic methods and HPLC, which showed that the cis conformer increased from 15.7 to 47.7% after 254 nm UV irradiation. A slow thermal reisomerization (t(1/2) = 40 min) permitted us to determine the cockroach hindgut myotropic activity of the thioxopeptide in the photostationary state. The results indicated that the activity increased significantly after UV irradiation and recovered to the ground level after thermal re-equilibration. In the present study, by utilizing the phototriggered isomerization in a specific position of peptide backbone, we revealed that the cis psi[CS-N](2)-kinin conformer is the active conformation when interacting with kinin receptor on cockroach hindgut.

Alanine substitution and deletion analogues of Manduca sexta allatostatin: structure-activity relationship on the spontaneous contractions of the foregut of larval Lacanobia oleracea.

Manduca sexta allatostatin (Manse-AS) is a 15-residue non-amidated peptide with a blocked N-terminus and a disulphide bridge between the cysteine residues at positions 7 and 14. Analogues of Manse-AS were used to examine the structural requirements of Manse-AS for inhibitory activity on spontaneous foregut contractions of larval tomato moth (Lacanobia oleracea). Breaking the disulphide bond between C(7) and C(14) by reduction reduced the potency of the peptide, suggesting that the conformation of Manse-AS is important for its biological activity. When either of the cysteine residues were replaced with alanine the Manse-AS analogue had no measurable bioactivity. Alanine substitution at Q(6) was as potent as Manse-AS, all other alanine substitution analogues (R(5), Y(8), F(9), N(10), P(11), I(12) and S(13)), were myoinhibitory but less potent than native Manse-AS to varying degrees. Analogues with alanine substitution at amino acids with aromatic side chains (Y(8) and F(9)) were the least active. Amino-terminal deletion analogues Manse-AS(6-15) and Manse-AS(7-15) were inactive whereas Manse-AS(5-15) was fully active but not as potent as Manse-AS. The results show that amino acid residues both inside and outside the disulphide ring are important for biological activity.