Binary Protein Research Articles

Study on heat-induced aggregation and gelation behaviours of myofibrillar protein/casein mixtures

Abstract In this study, the aggregation and gelation behaviours of heat-induced fish myofibrillar protein (MP)/casein mixtures prepared with different mixing ratios (MP: casein = 1:0, 5:1, 1:1, 0:1) were investigated. The rheological results showed that casein significantly affected the rheological behaviour of MP, and the storage modulus decreased as the mixing ratio changed from 1:0 to 0:1. Results in turbidity, particle size, SEM and SDS-PAGE indicated that MP and M:C = 5:1 groups exhibited higher cross-linking aggregation especially under high-temperature heating. From 40 °C to 90 °C, the mixed systems showed higher total sulfhydryl contents and bromophenol blue binding amounts (P < 0.05) compared with individual systems, suggesting that hydrophobic interaction and disulfide bonds were probably the main forces for the formation of binary MP-casein complexes. Additionally, the M:C = 5:1 group presented obvious transition of α-helix to β-sheet with the α-helix decreasing from 15.58% to 9.00% and β-sheet increasing from 48.68% to 57.62%. Overall, when the mixing ratio of MP to casein was 5:1, it is more conducive to the formation a superior gel network. The present study helps to elucidate the correlation between protein aggregation behaviours in solution and the network structure in gel, providing a theoretical basis for the textural regulation of gel food based on binary protein system.

Controlling the co-aggregation and gelation of cod-soy binary proteins based on partially/fully denatured soy proteins

Structured binary protein networks offer a pathway for designing gel-based foods with less ecological and economic effects. This study investigated the heat-mediated interaction and gelation kinetics of cod-soy mixed proteins at molecular level. Results indicated that denaturation degree of soy proteins was fundamental in determining the protein-protein interactions during heating. Considerable non-natural β-sheet was generated in the heterogeneous structures to initiate their aggregation behavior. Cod actomyosin comprising myosin heavy chains and actin mainly regulated their aggregation below 70 °C. At higher temperatures, the formation of large-sized and intermediary-sized aggregates was dominated by disulfide bond exchange between cod actomyosin and soy A-B aggregates (≤ 85 °C) or dissociated B subunits (> 85 °C). These aggregates were further evidenced as essential components to form gel networks with higher storage modulus (G'). These findings provide fundamental insights for designing gel-based products with desirable nutritional and textural properties based on plant-animal binary proteins.

A new discrete-geometry approach for integrative docking of proteins using chemical crosslinks.

The structures of protein complexes allow us to understand and modulate the biological functions of the proteins. Integrative docking is a computational method to obtain the structures of a protein complex, given the atomic structures of the constituent proteins along with other experimental data on the complex, such as chemical crosslinks or SAXS profiles. Here, we develop a new discrete geometry-based method, wall-EASAL, for integrative rigid docking of protein pairs given the structures of the constituent proteins and chemical crosslinks. The method is an adaptation of EASAL (Efficient Atlasing and Search of Assembly Landscapes), a state-of-the-art discrete geometry method for efficient and exhaustive sampling of macromolecular configurations under pairwise inter-molecular distance constraints. We provide a mathematical proof that the method finds a structure satisfying the crosslink constraints under a natural condition satisfied by energy landscapes. We compare wall-EASAL with IMP (Integrative Modeling Platform), a commonly used integrative modeling method, on a benchmark, varying the numbers, types, and sources of input crosslinks, and sources of monomer structures. The wall-EASAL method performs better than IMP in terms of the average satisfaction of the configurations to the input crosslinks and the average similarity of the configurations to their corresponding native structures. The ensembles from IMP exhibit greater variability in these two measures. Further, wall-EASAL is more efficient than IMP. Although the current study uses crosslinks, the method is general and any source of distance constraints can be used for integrative docking with wall-EASAL. However, the current implementation only supports binary rigid protein docking, i.e., assumes that the monomer structures are known and remain rigid. Additionally, the current implementation is deterministic, i.e., it does not account for uncertainties in the crosslinking data beyond using distance bounds. Neither of these appears to be a theoretical or algorithmic limitation of the EASAL methodology. Structures from wall-EASAL can be incorporated in methods for modeling large macromolecular assemblies, for example by suggesting rigid bodies or restraints for use in these methods. This will facilitate the characterization of assemblies and cellular neighborhoods at increased efficiency, accuracy, and precision. The wall-EASAL method is available at https://bitbucket.org/geoplexity/easal-dev/src/Crosslink and the benchmark is available at https://github.com/isblab/Integrative_docking_benchmark.

Impact of Transglutaminase-Mediated Crosslinking on the Conformational Changes in a Dual-Protein System and IgE Reactivity of Soy Protein.

Transglutaminase (TGase)-catalyzed crosslinking has gained substantial traction as a novel strategy for reducing allergenic risk in food proteins, particularly within the realm of hypoallergenic food production. This study explored the impact of TGase crosslinking on conformational changes in a binary protein system composed of soy protein isolate (SPI) and sodium caseinate (SC) at varying mass ratios (10:0, 7:3, 5:5, 3:7 (w/w)). Specifically, the immunoglobulin E (IgE) binding capacity of soy proteins within this system was examined. Prolonged TGase crosslinking (ranging from 0 h to 15 h) resulted in a gradual reduction in IgE reactivity across all SPI-SC ratios, with the order of IgE-binding capability as follows: SPI > SPI5-SC5 > SPI7-SC3 > SPI3-SC7. These alterations in protein conformation following TGase crosslinking, as demonstrated by variable intrinsic fluorescence, altered surface hydrophobicity, increased ultraviolet absorption and reduced free sulfhydryl content, were identified as the underlying causes. Additionally, ionic bonds were found to play a significant role in maintaining the structure of the dual-protein system after crosslinking, with hydrophobic forces and hydrogen bonds serving as supplementary forces. Generally, the dual-protein system may exhibit enhanced efficacy in reducing the allergenicity of soy protein.

Development of pea protein nanoparticle/hydrolyzed rice glutelin fibril emulsion gels for encapsulation of curcumin

The potential of using emulsion gels stabilized by binary plant protein nanoparticle mixtures for the encapsulation and delivery of lipophilic nutraceuticals was evaluated. The particle characteristics, physical stability, water diffusivity, microrheology, large amplitude oscillating shear (LAOS) properties, and in vitro digestion of emulsion gels prepared by different ratios of hydrolyzed rice glutelin fibrils (HRGFs) and pea protein nanoparticle (PNP) were characterized. The emulsion gel with P/H = 2:1 (0.84 μm) exhibited the best storage stability and freeze-thaw stability, as seen by the smaller oil droplet size (1.02 and 1.42 μm, respectively). Low-field pulsed NMR indicated that the majority of water in samples was highly mobile. All the samples were predominantly elastic-like materials. The P/H 2:1 emulsion gel had the lowest FI value (6.21 × 10−4 Hz), the highest MVI value (5.57 s/nm2), G′/ G″ values and enclosed area, showing that it had denser 3D network structures, higher stiffness values, and a high sensitivity to changes in strain. Additionally, P/H 2:1 emulsion gel had a relatively high lipid digestibility (96.1 %), curcumin bioaccessibility (58.9 %), and curcumin stability (94.2 %). This study showed that emulsion gels stabilized by binary protein nanoparticle mixtures (PNP/HRGF) have potential as edible delivery systems for lipophilic nutraceuticals.

Constructing a strongly interacting Pea-Cod binary protein system by introducing metal cations toward enhanced gelling properties

Developing prospective plant-animal binary protein systems with desirable nutritional and rheological properties stands as a significant and challenging pursuit within the food industry. Our understanding of the effect of adding salt on the aggregation behavior of food proteins is currently based on single model protein systems, however, this knowledge is rather limited following binary protein systems. Herein, various ionic strength settings are used to mitigate the repulsive forces between pea-cod mixed proteins during the thermal process, which further benefits the construction of a strengthened gel network. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) collectively demonstrated that larger heat-induced protein aggregates were formed, which increased in size with higher ionic strength. In the presence of 2.5 mM CaCl2 and 50 mM NaCl, the disulfide bonds significantly increased from 19.3 to 27.53 and 30.5 μM/g, respectively. Notably, similar aggregation behavior could be found when introducing 2.5 mM CaCl2 or 25 mM NaCl, due to the enhanced aggregation tendency by specific binding of Ca2+ to proteins. With relevance to the strengthened cross-links between protein molecules, salt endowed composite gels with preferable gelling properties, evidenced by increased storage modulus. Additionally, the gelling temperature of mixed proteins decreased below 50 °C at elevated ionic strength. Simultaneously, the proportion of network proteins in composite gels increased remarkably from 82.05 % to 93.61 % and 92.31 % upon adding 5.0 mM CaCl2 and 100 mM NaCl, respectively. The findings provide a valuable foundation for designing economically viable and health-oriented plant-animal binary protein systems.

Repurposing FDA-approved disulfiram for targeted inhibition of diphtheria toxin and the binary protein toxins of Clostridium botulinum and Bacillus anthracis.

Many bacteria act pathogenic by the release of AB-type protein toxins that efficiently enter human or animal cells and act as enzymes in their cytosol. This leads to disturbed cell functions and the clinical symptoms characteristic for the individual toxin. Therefore, molecules that directly target and neutralize these toxins provide promising novel therapeutic options. Here, we found that the FDA-approved drug disulfiram (DSF), used for decades to treat alcohol abuse, protects cells from intoxication with diphtheria toxin (DT) from Corynebacterium diphtheria, the causative agent of diphtheria, lethal toxin (LT) from Bacillus anthracis, which contributes to anthrax, and C2 enterotoxin from Clostridium botulinum when applied in concentrations lower than those found in plasma of patients receiving standard DSF treatment for alcoholism (up to 20µM). Moreover, this inhibitory effect is increased by copper, a known enhancer of DSF activity. LT and C2 are binary toxins, consisting of two non-linked proteins, an enzyme (A) and a separate binding/transport (B) subunit. To act cytotoxic, their proteolytically activated B subunits PA63 and C2IIa, respectively, form barrel-shaped heptamers that bind to their cellular receptors and form complexes with their respective A subunits LF and C2I. The toxin complexes are internalized via receptor-mediated endocytosis and in acidified endosomes, PA63 and C2IIa form pores in endosomal membranes, which facilitate translocation of LF and C2I into the cytosol, where they act cytotoxic. In DT, A and B subunits are located within one protein, but DT also forms pores in endosomes that facilitate translocation of the A subunit. If cell binding, membrane translocation, or substrate modification is inhibited, cells are protected from intoxication. Our results implicate that DSF neither affects cellular binding nor the catalytic activity of the investigated toxins to a relevant extend, but interferes with the toxin pore-mediated translocation of the A subunits of DT, LT and C2 toxin, as demonstrated by membrane-translocation assays and toxin pore conductivity experiments in the presence or absence of DSF. Since toxin translocation across intracellular membranes represents a central step during cellular uptake of many bacterial toxins, DSF might neutralize a broad spectrum of medically relevant toxins.

Assembly Requirements for the Construction of Large-Scale Binary Protein Structures.

The precise assembly of multiple biomacromolecules into well-defined structures and materials is of great importance for various biomedical and nanobiotechnological applications. In this study, we investigate the assembly requirements for two-component materials using charged protein nanocages as building blocks. To achieve this, we designed several variants of ferritin nanocages to determine the surface characteristics necessary for the formation of large-scale binary three-dimensional (3D) assemblies. These nanocage variants were employed in protein crystallization experiments and macromolecular crystallography analyses, complemented by computational methods. Through the screening of nanocage variant combinations at various ionic strengths, we identified three essential features for successful assembly: (1) the presence of a favored crystal contact region, (2) the presence of a charged patch not involved in crystal contacts, and (3) sufficient distinctiveness between the nanocages. Surprisingly, the absence of noncrystal contact mediating patches had a detrimental effect on the assemblies, highlighting their unexpected importance. Intriguingly, we observed the formation of not only binary structures but also both negatively and positively charged unitary structures under previously exclusively binary conditions. Overall, our findings will inform future design strategies by providing some design rules, showcasing the utility of supercharging symmetric building blocks in facilitating the assembly of biomacromolecules into large-scale binary 3D assemblies.

Interactions between paramyosin and actin greatly improve their thermostability and gel properties.

Myofibrillar proteins, the main contributors to the quality of meat products, are the main structural protein component of muscle and have functional properties such as the formation of a 3D protein gel network and water binding. The susceptibility of meat-derived proteins to heat-induced aggregation is the functional constraint that hinders their applications in industry, and so establishing an effective but simple method to improve their thermostability of the proteins is of great importance. In the present study, we describe an easy approach to perform high colloidal thermostability of both paramyosin and actin by mixing them at low ionic strength. The improvement in thermal stability was found to be derived from intermolecular interactions between these two different proteins through non-covalent binding with each other. Consequently, such interactions protected each of them from thermal-induced degradation compared to individual components. Notably, this binary native protein mixture rather than single paramyosin or actin component has the ability to form protein hydrogels with a shear-thinning and reversible sol-gel transformation behavior, which is markedly different from most of reported heat-induced, denatured protein hydrogels. The present study not only presents a facile and effective strategy for improvement of the thermal stability and gel properties of a binary paramyosin and actin mixture, but also enhances our understanding of how mutual interactions of protein components affect their physicochemical and functional properties. © 2023 Society of Chemical Industry.

A facile strategy for fabricating structural rice-pea binary protein-based gel: Characterization and formation mechanism

The effects of different ratios of pea protein (PP) on the gel characteristics of rice protein (RP) and the formation mechanism of RP-PP binary mixed protein were investigated. The formation of the basic viscoelastic network by PP may aid in the gelatinization of RP. Results showed that the RP/PP (1:0.5) mixed protein had the highest gel strength and hardness (P < 0.05), and scanning electron microscopy (SEM) findings revealed that PP incorporation of the protein gel established a homogeneous and denser gel network structure. Furthermore, as the proportion of PP increased, the relaxation time of T2b, T21, T22 and surface hydrophobicity decreased, indicating that the hydrophobic interactions of binary proteins restricted water mobility. Results revealed that different behaviors of gels may be attributed to the secondary structure content of proteins. The formation mechanism of binary mixed protein gel was the interpenetration of independently-formed protein network by RP and PP, respectively. It was due to the hydrophobic interactions and hydrogen bonding between RP and PP enhancing the interactions and gel strength of mixed protein. In summary, results confirmed that PP could be used as a potential ingredient for improving the characteristics of RP/PP binary mixed protein gels.

Magnesium ions regulated ovalbumin-lysozyme heteroprotein complex: Aggregation kinetics, thermodynamics and morphologic structure

This study aims to investigate the mechanism of magnesium ions regulated ovalbumin-lysozyme (OVA-LYS) heteroprotein aggregation behavior via aggregation kinetics model, exploring the relationship between differential aggregation behavior and protein molecular structure, intermolecular interactions and thermal stability. Results showed that the aggregation rate (kapp) and maximum absorbance (Amax) of the OVA-LYS heteroprotein complex were located between OVA and LYS. Meanwhile, the thermal denaturation temperature (Td) and denaturation enthalpy (ΔH) were between the values of OVA and LYS as well. Compared with OVA, the thermal stability of the OVA-LYS heteroprotein complex increased owing to the electrostatic interactions between OVA and LYS, resulting in slower aggregation rate and lower aggregation degree. Molecular dynamics simulations revealed the molecular conformational changes during OVA-LYS binary protein binding and the stability of the complex conformation. Moreover, MgCl2 weakened the OVA-LYS interactions through Debye shielding while increasing thermal stability, allowing the two proteins to aggregate into amorphous precipitates rather than spherical coacervates. Overall, this study provides information to further understand the regulation mechanism of proteins differential aggregation behavior by ions.

In Vitro Reconstitution and Analysis of SARS-CoV-2/Host Protein-Protein Interactions.

The emergence of viral threats such as Ebola, ZIKA, and severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) requires a rapid and efficient approach for elucidating mechanisms of pathogenesis and development of therapeutics. In this context, cell-free protein synthesis (CFPS) holds a promise to resolve the bottlenecks of multiplexed protein production and interaction analysis among host and pathogen proteins. Here, we applied a eukaryotic CFPS system based on Leishmania tarentolae extract (LTE) protein expression in combination with AlphaLISA proximity-based protein interaction technology to identify intraviral and viral-human protein interactions of SARS-CoV-2 virus that can potentially be targeted by the existing or novel antiviral therapeutics. We produced and tested 54 putative human-viral protein pairs in vitro and identified 45 direct binary protein interactions. As a casing example of the assay's suitability for drug development applications, we analyzed the effect of a putative biologic on the human angiotensin-converting enzyme 2/receptor-binding domain (hACE2/RBD) interaction. This suggests that the presented pathogen characterization platform can facilitate the development of new therapeutic agents.

Fabrication and Study of Dextran/Sulfonated Polysulfone Blend Membranes for Low-Density Lipoprotein Adsorption.

The abnormal increase in low-density lipoprotein (LDL) in human blood is a main independent risk factor for the pathogenesis of atherosclerosis, whereas a reduced LDL level effectively lowers morbidity. It is important to develop LDL adsorption materials with high efficiency and selectivity, as well as to simplify their fabrication processes. In this paper, polysulfone (PSF), sulfonated polysulfone (SPSF), and sulfonated polysulfone/dextran (SPSF/GLU) membranes were successfully fabricated for LDL adsorption using a solution casting technique. Attenuated total reflectance Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy measurements confirmed the success of the preparation. The water contact angle decreased from 89.7 ± 3.4° (PSF) to 76.4 ± 3.2° (SPSF) and to 71.2 ± 1.9° (SPSF/GLU), respectively. BSA adsorption testing showed that the SPSF/GLU with surface enrichment of sulfonate groups and glycosyl groups possessed higher resistance to protein solution. The adsorption and desorption behaviors of the studied samples in single-protein or binary-protein solutions were systematically investigated by enzyme-linked immunosorbent assay (ELISA), The results showed that SPSF/GLU, which had excellent resistance to protein adsorption, possessed a similar adsorption capacity to that of PSF. SPSF membrane exhibited excellent selective affinity for LDL in single and binary protein solutions, suggesting potential applications in LDL removal.

Binary complexes of whey protein fibers/isolates and fish gelatins for emulsion stabilization

In this work, fish gelatins (FG) were mixed with whey protein fibers (WPF) and native whey protein isolates (WPI) under acidic and neutral pH conditions, respectively. The objective of this study was to explore how binary protein FG and WPI/WPF cooperated to stabilize oil-in-water emulsion systems. The emulsion, stabilized solely by WPI, flocculated and coalesced easily at both pH values. Fibrillation could increase surface hydrophobicity and interfacial activity at pH 7, resulting in improved creaming stability of emulsions compared to natural WPI. However, the improvement in creaming stability was limited. When FG cooperated with WPI and WPF, FG could contribute to the formation of a 3D network to enhance the physical stability of emulsions. In addition, WPI and WPF could contribute to surface activity in binary proteins. FG-WPF exhibited better compatibility than FG-WPI and a faster gelation rate, superior viscoelastic properties, and greater deformation resistance. In addition, WPF may help to improve the gelation behavior of FG-WPF at pH 3. This research introduced a new binary protein system consisting of whey protein fibers and fish gelatins that might be used as promising emulsifiers and stabilizers in emulsion systems.

Regulation of Ras-GTPase Signaling and Localization by Post-Translational Modifications

Ras, a GTP-GDP binary switch protein, transduces signals from diverse receptors to regulate various signaling networks. Three Ras genes encode for protein isoforms, namely, Harvey Ras (H-Ras), Kirsten Ras (K-Ras, with two splice variants, K-Ras4A and K-Ras4B), and Neuroblastoma Ras (N-Ras). The isoforms undergo a series of post-translational modifications that enable their membrane attachment and biological activity. The activation of Ras isoforms is tightly regulated, and any dysregulation affects cellular processes, such as cell division, apoptosis, differentiation, cell migration, etc. The Ras gene is highly prone to mutation, and ~30% of cancers carry somatic mutations in Ras, whereas germline mutations clinically manifest as various rasopathies. In addition to regulation by the Guanine nucleotide exchange factors and the GTPase activation proteins, Ras signaling, and localization are also regulated by phosphorylation-dephosphorylation, ubiquitination, nitrosylation, and acetylation. Herein, we review the regulation of Ras signaling and localization by various regulatory enzymes in depth and assess the current status of Ras drug discovery targeting these regulatory enzymes.

Effect of Wheat Gluten and Peanut Protein Ratio on the Moisture Distribution and Textural Quality of High-Moisture Extruded Meat Analogs from an Extruder Response Perspective.

Wheat gluten (WG) and peanut protein powder (PPP) mixtures were extruded at high moisture to investigate the potential application of this mixture in meat analog production. Multiple factors, including the water absorption index (WAI), water solubility index (WSI), rheological properties of the mixed raw materials, die pressure, torque and specific mechanical energy (SME) during high moisture extrusion, texture properties, color, water distribution, and water activity of extrudates were analyzed to determine the relationships among the raw material characteristics, extruder response parameters, and extrudate quality. At a WG ratio of 50%, the extrudates have the lowest hardness (2.76 kg), the highest springiness (0.95), and a fibrous degree of up to 1.75. The addition of WG caused a significant rightward shift in the relaxation time of hydrogen protons in the extrudates, representing increased water mobility and water activity. A ratio of 50:50 gave the smallest total color difference (ΔE) (about 18.12). When the added amount of WG was 50% or less, it improved the lightness and reduced the ΔE compared to >50% WG. Therefore, clarifying the relationship among raw material characteristics, extruder response parameters, and extruded product quality is helpful in the systematic understanding and regulation of the fiber textural process of binary protein meat analogs.

Next-generation large-scale binary protein interaction network for Drosophila melanogaster

Generating reference maps of interactome networks illuminates genetic studies by providing a protein-centric approach to finding new components of existing pathways, complexes, and processes. We apply state-of-the-art methods to identify binary protein-protein interactions (PPIs) for Drosophila melanogaster. Four all-by-all yeast two-hybrid (Y2H) screens of > 10,000 Drosophila proteins result in the ‘FlyBi’ dataset of 8723 PPIs among 2939 proteins. Testing subsets of data from FlyBi and previous PPI studies using an orthogonal assay allows for normalization of data quality; subsequent integration of FlyBi and previous data results in an expanded binary Drosophila reference interaction network, DroRI, comprising 17,232 interactions among 6511 proteins. We use FlyBi data to generate an autophagy network, then validate in vivo using autophagy-related assays. The deformed wings (dwg) gene encodes a protein that is both a regulator and a target of autophagy. Altogether, these resources provide a foundation for building new hypotheses regarding protein networks and function.

In Silico and In Vitro Investigation of Phytochemicals Against Shrimp AHPND Syndrome Causing PirA/B Toxins of Vibrio parahaemolyticus.

In Southeast Asia, the penaeid shrimp aquaculture production faces a new pandemic bacterial disease called acute hepatopancreatic necrosis disease (AHPND). The highly profitable pacific white shrimp, Litopenaeus vannamei, has become a challenging species due to severe lethal infections. Recent research has identified a critical pathogen, Vibrio parahaemolyticus, which caused significant loss in the shrimp industry. The disease pathway involves a virulence plasmid encoding binary protein toxins (PirA/B) that cause cell death. The protein toxins were inherited and conjugatively transferred to other Vibrio species through a post-segregational killing system. In this study, "in silico" (Glide, 2021) analysis identified four phytocompounds as myricetin (Myr), ( +)-taxifolin (TF), (-)-epigallocatechin gallate (EGCG), and strychnine (STN) which could be most effective against both the toxins concerning its docking score and affinity. The interactions of complexes and the critical amino acids involved in docking were analyzed using the Discovery Studio (version 2016). Molecular dynamic studies showed lower root mean square deviations (RMSD) and improved stabilization of ( +)-taxifolin (TF) and (-)-epigallocatechin-3-gallate (EGCG) against both the protein toxins. The antibacterial potential of all four selected compounds had tested against pathogenic strains of V. parahaemolyticus through minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The best MBC results were observed at concentrations of 1mg/mL for EGCG and 1.25mg/mL for TF. Moreover, the complete reduction of viable cell counts in the in vitro bactericidal activity had recorded after 24h of incubation.

Competitive adsorption of binary negatively charged proteins in egg white during foam evolution: From bulk solution to air-water interface

The molecular properties, adsorption behavior and interfacial film structure of the binary protein system formed by ovalbumin and ovomucoid in egg white during foam initiation and stabilization were investigated. Electrostatic repulsion facilitated the dispersion of the binary protein in the bulk phase. Surface hydrophobicity and molecular flexibility were positively correlated with the proportion of ovomucoid, while surface charge density was negatively correlated with it. Tyrosine and phenylalanine tended to be in contact with the bulk phase, while tryptophan migrated toward air. Although the Kdiff was low for both ovalbumin (0.447 mN/m/s1/2) and ovomucoid (0.472 mN/m/s1/2), the mixed system facilitated the diffusion of the proteins. Interfacial dilatation rheology concluded that ovomucoid enhanced the solid-like character of the binary system, although film formed by a single ovomucoid (slope = 0.59) had the poorest mechanical properties, which relied on strong protein-protein interactions (slope > 1) at the interface. During foam stabilization, the binary protein at the natural ratio (5:1) exhibited the best macroscopic stability (94.1%), which might be related to the less pronounced Plateau drainage in the late stabilization phase. Pearson correlation analysis suggested that foam formation and stability were influenced by multiple factors, and that an optimal balance between positive and negative factors was the key to obtaining desirable foam properties. This study would provide a new insight to understand the interfacial adsorption and film-forming behavior of negatively charged proteins and the directional regulation of egg white foam properties.

A novel binary pesticidal protein from Chryseobacterium arthrosphaerae controls western corn rootworm by a different mode of action to existing commercial pesticidal proteins.

The western corn rootworm (WCR) Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae) remains one of the economically most important pests of maize (Zea mays) due to its adaptive capabilities to pest management options. This includes the ability to develop resistance to some of the commercial pesticidal proteins originating from different strains of Bacillus thuringiensis. Although urgently needed, the discovery of new, environmentally safe agents with new modes of action is a challenge. In this study we report the discovery of a new family of binary pesticidal proteins isolated from several Chryseobacterium species. These novel binary proteins, referred to as GDI0005A and GDI0006A, produced as recombinant proteins, prevent growth and increase mortality of WCR larvae, as does the bacteria. These effects were found both in susceptible and resistant WCR colonies to Cry3Bb1 and Cry34Ab1/Cry35Ab1 (reassigned Gpp34Ab1/Tpp35Ab1). This suggests GDI0005A and GDI0006A may not share the same binding sites as those commercially deployed proteins and thereby possess a new mode of action. This paves the way towards the development of novel biological or biotechnological management solutions urgently needed against rootworms.