Protein–Ligand Binding and Structural Modelling Studies of Pheromone-Binding Protein-like Sol g 2.1 from <i>Solenopsis geminata</i> Fire Ant Venom

Sol g 2 is the major protein in Solenopsis geminata fire ant venom. It shares the highest sequence identity with Sol i 2 (S. invicta) and shares high structural homology with LmaPBP (pheromone-binding protein (PBP) from the cockroach Leucophaea maderae). We examined the specific Sol g 2 protein ligands from fire ant venom. The results revealed that the protein naturally formed complexes with hydrocarbons, including decane, undecane, dodecane, and tridecane, in aqueous venom solutions. Decane showed the highest affinity binding (Kd) with the recombinant Sol g 2.1 protein (rSol g 2.1). Surprisingly, the mixture of alkanes exhibited a higher binding affinity with the rSol g 2.1 protein compared to a single one, which is related to molecular docking simulations, revealing allosteric binding sites in the Sol g 2.1 protein model. In the trail-following bioassay, we observed that a mixture of the protein sol g 2.1 and hydrocarbons elicited S. geminata worker ants to follow trails for a longer time and distance compared to a mixture containing only hydrocarbons. This suggests that Sol g 2.1 protein may delay the evaporation of the hydrocarbons. Interestingly, the piperidine alkaloids extracted have the highest attraction to the ants. Therefore, the mixture of hydrocarbons and piperidines had a synergistic effect on the trail-following of ants when both were added to the protein

Ontogeny of Nile tilapia (Oreochromis niloticus) Immunoglobulin Type M Antibody Response

Nile tilapia (Oreochromis niloticus, Cichlidae) are cultured worldwide, however, the study of humoral immunity in these fish has been neglected, leading to mismanagement of prevention of common diseases by vaccination. In this study we purified and characterized the Nile tilapia immunoglobulin type M (IgM). In addition, we have described the production of a mouse polyclonal antibody for the investigation of the onset of antibody responses. After one-step purification using protein G sepharose beads, SDSPAGE, and mass fingerprint analysis we found that the heavy chain of Nile tilapia IgM was 70 kDa, whereas the light chain was 27 kDa. Western immunoblotting techniques using mouse anti-Nile tilapia IgM antibody, produced by intraperitoneal injection with purified Nile tilapia IgM for 3, periods with booster inoculations every 10 days, could effectively detect the onset of antibody responses in Nile tilapia sera at 42 days post-hatch

Identification, expression and characterization of the recombinant Sol g 4.1 protein from the venom of the tropical fire ant Solenopsis geminata

Abstract Background Fire ant venom is a complex mixture consisting of basic piperidine alkaloids, various biologically active peptides and protein components, including a variety of major allergenic proteins. Tropical fire ant Solenopsis geminata is an important stinging ant species that causes anaphylaxis and serious medical problems. Although the biological activities of allergenic venom proteins that are unique to ant venom, particularly Solenopsis 2 and 4, are still unknown, these proteins are believed to play important roles in mediating the effects of the piperidine derivatives in the venom. Methods In the present study, the cDNA cloning, sequencing and three-dimensional structure of Sol g 4.1 venom protein are described. The recombinant Sol g 4.1 protein (rSol g 4.1) was produced in E. coli, and its possible function as a hydrophobic binding protein was characterized by paralyzing crickets using the 50% piperidine dose (PD50). Moreover, an antiserum was produced in mice to determine the allergenic properties of Sol g 4.1, and the antiserum was capable of binding to Sol g 4.1, as determined by Western blotting. Results The molecular weight of Sol g 4.1 protein is 16 kDa, as determined by SDS-PAGE. The complete cDNA is 414 bp in length and contains a leader sequence of 19 amino acids. The protein consists of six cysteines that presumably form three disulfide bonds, based on a predicted three-dimensional model, creating the interior hydrophobic pocket and stabilizing the structure. The rSol g 4.1 protein was expressed in inclusion bodies, as determined by SDS-PAGE. Dialysis techniques were used to refold the recombinant protein into the native form. Its secondary structure, which primarily consists of α-helices, was confirmed by circular dichroism analysis, and the three-dimensional model was also verified. The results of allergenic analysis performed on mice showed that the obtained protein was predicted to be allergenically active. Moreover, we report on the possible role of the Sol g 4.1 venom protein, which significantly reduced the PD50 from 0.027 to 0.013% in paralyzed crickets via synergistic effects after interactions with piperidine alkaloids. Conclusions The primary structure of Sol g 4.1 showed high similarity to that of venom proteins in the Solenopsis 2 and 4 family. Those proteins are life-threatening and produce IgE-mediated anaphylactic reactions in allergic individuals. The possible function of this protein is the binding of the interior hydrophobic pockets with piperidine alkaloids, as determined by the analysis of the structural model and PD50 test

Current advances in ant venom proteins causing hypersensitivity reactions in the Asia-Pacific region

The main insects causing allergy reactions to stinging insect in humans are Apidae (bees), Vespidae (wasps, yellow jackets and hornets) and Formicidae (ants). Their venom stings are composed of various biologically active peptides and protein components, some of which can cause toxicity or anaphylaxis in humans. The protein venom demonstrate some common allergenic activity such as for fire ants and vespids, which have two common allergens that are phospholipase A₁ (enzymatic activity) and antigen 5 with unknown biological activity. The common allergens seem to share some degree of immunological cross-reactivity, particularly when the sequence homology is above 70%. Therefore immunotherapeutic approaches targeting more than one specific species are of interest. Recent widespread increases of various ant species in many countries have resulted in higher number of reported about serious allergic reactions to stings. Most insect-allergy related cases have been reported for species from Solenopsis, Myrmecia and Pachycondyla genera, and their stings can often result in human fatalities. In addition, stinging ants can have serious health effects on livestock, agricultural damage adversely affecting the biodiversity of the region. This review discusses the impact of important ant species on human health in the Asia-Pacific region along with the molecular immunological aspects of the identified venoms and current status of diagnostics and therapeutics

Purification and biochemical characterization of VesT1s, a novel phospholipase A1 isoform isolated from the venom of the greater banded wasp Vespa tropica

Vespa tropica, a social wasp locally found in Thailand is responsible for many out off the record accidental stings due to close encounters with human activities and because of the animal's highly potent venom. Phospholipase (PLA) is one of the major proteins commonly found in insect venom. In this work, V. tropica phospholipase was successfully isolated, purified and characterized. Three isoforms PLAs have been purified using reversed phase HPLC, and are named VesT1s (VesT1.01a, VesT1.01b and VesT1.02). They are not glycoproteins. VesT1.01s has a molecular weight of 33.72 kDa while for VesT1.02 a mass of 34 kDa was found. The deduced sequence of the mature VesT1.02 protein is composed of 301 amino acid residues (1005 bp), including the catalytic triad (Ser-His-Asp), which is similar to other wasp venom PLAs. The 12 cysteine residues found are conserved among venom PLA1. They form six disulfide bonds, and therefore have no free sulfhydryl groups. Based on homology modelling, VesT1.02 belongs to the α/β hydrolase fold family. Its structure is composed of 10 β-sheets and 11 α-helixes, characterized by a β-strand/εSer/α-helix structural motif, which contains the Gly-X-Ser-X-Gly consensus sequence. The shortened lid and shortened β9 loop, which play important roles in substrate selectivity, cause this enzyme to only exhibit PLA activity. Moreover, these PLAs have been shown to be highly thermally stable after heating at 100 °C for 5 min. We propose that an inserted Pro residue might be involved in this high thermo-stability.status: publishe

Characterization and Localization of Sol g 2.1 Protein from <i>Solenopsis geminata</i> Fire Ant Venom in the Central Nervous System of Injected Crickets (<i>Acheta domestica</i>)

Solenopsis geminata is recognized for containing the allergenic proteins Sol g 1, 2, 3, and 4 in its venom. Remarkably, Sol g 2.1 exhibits hydrophobic binding and has a high sequence identity (83.05%) with Sol i 2 from S. invicta. Notably, Sol g 2.1 acts as a mediator, causing paralysis in crickets. Given its structural resemblance and biological function, Sol g 2.1 may play a key role in transporting hydrophobic potent compounds, which induce paralysis by releasing the compounds through the insect’s nervous system. To investigate this further, we constructed and characterized the recombinant Sol g 2.1 protein (rSol g 2.1), identified with LC-MS/MS. Circular dichroism spectroscopy was performed to reveal the structural features of the rSol g 2.1 protein. Furthermore, after treating crickets with S. geminata venom, immunofluorescence and immunoblotting results revealed that the Sol g 2.1 protein primarily localizes to the neuronal cell membrane of the brain and thoracic ganglia, with distribution areas related to octopaminergic neuron cell patterns. Based on protein—protein interaction predictions, we found that the Sol g 2.1 protein can interact with octopamine receptors (OctRs) in neuronal cell membranes, potentially mediating Sol g 2.1’s localization within cricket central nervous systems. Here, we suggest that Sol g 2.1 may enhance paralysis in crickets by acting as carriers of active molecules and releasing them onto target cells through pH gradients. Future research should explore the binding properties of Sol g 2.1 with ligands, considering its potential as a transporter for active molecules targeting pest nervous systems, offering innovative pest control prospects

Polydopamine Nanoparticles Functionalized Electrochemical DNA Aptasensor for Serum Glycated Albumin Detection

Polydopamine (PDA) has now been widely applied to electrochemical biosensing because of its excellent biocompatibility, abundant functional groups, and facile preparation. In this study, polydopamine nanoparticles (PDA-NPs)-functionalized electrochemical aptasensor was developed for the rapid, sensitive, and cost-effective detection of glycated albumin (GA), a promising biomarker for glycemic control in diabetic patients. PDA-NPs were synthesized at various pH conditions in Tris buffer. Cyclic voltammetry (CV) of PDA-NPs-coated screen-printed carbon electrodes (SPCEs) revealed that the materials were more conductive when PDA-NPs were synthesized at pH 9.5 and 10.5 than that at pH 8.5. At pH 10.5, the prepared PDA and PDA-aptamer NPs were monodispersed spherical morphology with an average size of 118.0 &plusmn; 1.9 and 127.8 &plusmn; 2.0 nm, respectively. When CV and electrochemical impedance spectrometry (EIS) were used for the characterization and detection of the electrochemical aptasensor under optimal conditions, the proposed aptasensor exhibited a broad linearity for detection of GA at a clinically relevant range of (1&ndash;10,000 &micro;g mL&minus;1), provided a low detection limit of 0.40 &micro;g mL&minus;1, appreciable reproducibility (less than 10%), and practicality (recoveries 90&ndash;104%). In addition, our developed aptasensor presented a great selectivity towards GA, compared to interfering substances commonly present in human serum, such as human serum albumin, urea, glucose, and bilirubin. Furthermore, the evaluation of the aptasensor performance against GA-spiked serum samples showed its probable applicability for clinical use. The developed PDA aptasensor demonstrated excellent sensitivity and selectivity towards GA detection with a simple and facile fabrication process. This proposed technique shows its potential application in GA measurement for improving the screening and management of diabetic patients in the future

Novel Antimicrobial Peptides from a Cecropin-Like Region of Heteroscorpine-1 from Heterometrus laoticus Venom with Membrane Disruption Activity

The increasing antimicrobial-resistant prevalence has become a severe health problem. It has led to the invention of a new antimicrobial agent such as antimicrobial peptides. Heteroscorpine-1 is an antimicrobial peptide that has the ability to kill many bacterial strains. It consists of 76 amino acid residues with a cecropin-like region in N-terminal and a defensin-like region in the C-terminal. The cecropin-like region from heteroscorpine-1 (CeHS-1) is similar to cecropin B, but it lost its glycine-proline hinge region. The bioinformatics prediction was used to help the designing of mutant peptides. The addition of glycine-proline hinge and positively charged amino acids, the deletion of negatively charged amino acids, and the optimization of the hydrophobicity of the peptide resulted in two mutant peptides, namely, CeHS-1 GP and CeHS-1 GPK. The new mutant peptide showed higher antimicrobial activity than the native peptide without increasing toxicity. The interaction of the peptides with the membrane showed that the peptides were capable of disrupting both the inner and outer bacterial cell membrane. Furthermore, the SEM analysis showed that the peptides created the pore in the bacterial cell membrane resulted in cell membrane disruption. In conclusion, the mutants of CeHS-1 had the potential to develop as novel antimicrobial peptides

The effect of edible bird's nests on the expression of MHC-II and costimulatory molecules of C57BL/6 mouse splenocytes

The glutinous nest that builds by the saliva secretion of swiftlet is recognizable as an edible bird's nest (EBN). It enriched a medicinal value and was regarded as supplementary food that exerts various beneficial health effects, especially immune boosters. This study's objective was to determine the impact of EBN on the expression of MHC-II and costimulatory molecules (CD86 and CD80) related to the initiation of T-cell activation. Both rEBN and pEBN samples were prepared with simulated gastrointestinal digestion for enhancing the bioaccessibility of bioactive compounds. Our result showed that digested EBN samples slightly influence the upregulation of MHC-II, CD86, and CD80 in gene expression of LPS-stimulated Raw 264.7 cells. The concern of endotoxin contamination in EBN samples, which may cause a false-positive result, was measured by quantitative PCR. We found that the inflammatory genes (IL-1β and TNF-α) were not induced by EBN treatments. Moreover, cell surface protein expression in splenocytes treated with EBN was assessed using flow cytometric analysis. Digested EBN samples demonstrated their capacity to promote the elevation of MHC-II, CD86, and CD80 cell surface protein expression. Finally, the digested-EBN-treated splenocytes only exhibited a specific response in the T-cells population. Thus, EBN is a source of the bioactive compound that has been proposed to exert a role in the stimulation of both MHC-II and costimulatory molecules for TCR/pMHC-II interaction leading to T-cell activation