Kiwifruit defense protein, kiwellin (Act d 5) percutaneously sensitizes mouse models through the epidermal application of crude kiwifruit extract

Background: Kiwifruit is a popular fruit consumed worldwide and is also used as a cosmetic ingredient. However, it is known to cause allergic reactions in humans. Recent studies have suggested an association between food allergy and food allergens entering the body via the skin. However, percutaneously sensitizing kiwifruit allergens have not been identified in human studies or in animal models. Objective: This study aimed to identify kiwifruit proteins that percutaneously sensitized mice through the epidermal application of crude extracts from green and gold kiwifruit on the dorsal skin, and serum IgE and IgG1 levels were used as sensitization markers. Design: BALB/c mice were back-shaved and their skin was exposed to crude extracts from green and gold kiwifruit that contained sodium dodecyl sulfate. Specific IgE and IgG1 antibodies generated and secreted in response to antigens were measured using enzyme-linked immunosorbent assay or immunoblotting. Results: Skin exposure to kiwifruit extract induced an increase in the levels of kiwifruit-specific IgE and IgG1, which are helper T cell 2-related allergenic antibodies in mice. These antibodies reacted with 18, 23, and 24 kDa proteins found in both green and gold kiwifruits. Thus, three percutaneously sensitizing allergens were identified and purified. Their amino acid sequences partially matched with that of kiwellin (Act d 5). Discussion and conclusion: Kiwellin has been identified as a plant defense-related protein. Interestingly, many plant allergens are biodefense-related proteins belonging to the pathogenesis-related protein family. Kiwellin, which was discovered to be a transdermal sensitizing antigen, might also be categorized as a biodefense-related protein. This study is the first to identify kiwellin (Act d 5) as a percutaneously sensitizing kiwifruit allergen in a mouse model.

Bacterial-Specific Aggregation and Killing of Immunomodulatory Host Defense Peptides

This study involves the design and development of disulfide bridge-linked antimicrobial peptides using the host defense protein Angiogenin 4 (chAng4) as a template. The mini peptides derived from chAng4 (mCA4s) were evaluated for their antibacterial efficacies in various pathogenic bacterial strains, and the role of the oxidation state of thiols in the peptide sequence and its implication on antibacterial properties were explored. A remarkable property of these synthetic mCA4 peptides is their capability to flocculate bacteria and mediate bacterial-specific killing, in the absence of any other external stimulus. mCA4s were further evaluated for their cellular uptake, hemolytic activities, toxicities, and immunomodulatory activities in different eukaryotic cell lines. The results indicate that disulfide bridge-containing cationic amphipathic peptides show superior antibacterial efficacies, are nontoxic and nonhemolytic, and mediate bacterial flocculation and killing, in the absence of external stimuli.

Predictive structure and protein-ligand interface of novel lectin from rice bean (Vigna umbellata)

Lectins are an important group of multivalent glycoproteins having the property of selectively recognizing and precipitating glycoconjugates. Although lectins have been reported from diverse biological sources, legume lectins is the best-characterized family of plant lectins. We have successfully cloned and sequenced the RbL ORF of 843bp from immature rice bean seeds (Vigna umbellata). We report the results of in silico analysis of novel lectin precursor of 280 amino acids from rice bean. BlastP analysis revealed more than 90% sequence similarity of RbL protein with Vigna angularis lectin and Vigna aconitifolia lectin. ProtParam analysis revealed acidic, stable and hydrophobic nature of RbL protein. Template based 3D structure of RbL protein was modeled using I-TASSER tool and validated as good quality model. Structural analysis revealed the presence of β-sandwich (Jelly roll fold or lectin fold) in modeled RbL structure. RbL protein was functionally annotated as a plant defense protein. Molecular docking was performed to analyze interactions of RbL protein with predicted ligands (N-acetyl-D-glucosamine β-galactose, Lactose and Adenine) and two selected ligands (Glucose and Mannose). Molecular dynamics (MD) simulations of RbL-ligand complexes confirmed robust hydrogen bonding interactions between ligands and RbL protein. The novel information generated in the study would be useful in exploring RbL protein for different biomedical and biotechnological applications.

ROS Dependent Antifungal and Anticancer Modulations of Piper colubrinum Osmotin

Osmotin, a plant defense protein, has functional similarity to adiponectin, an insulin sensitizingsensitising hormone secreted by adipocytes. We speculated that Piper colubrinum Osmotin (PcOSM) could have functional roles in obesity-related cancers, especially breast cancer. Immunofluorescence assays, flow cytometry, cell cycle analysis and a senescence assay were employed to delineate the activity in MDAMB231 breast cancer cell line. PcOSM pre-treated P. nigrum leaves showed significant reduction in disease symptoms correlated with high ROS production. In silico analysis predicted that PcOSM has higher binding efficiency with adiponectin receptor compared to adiponectin. PcOSM was effectively taken up by MDAMB231 cancer cells which resulted in marked increase in intracellular ROS levels leading to senescence and cell cycle arrest in G2/M stage. This study provides evidence on the ROS mediated direct inhibitory activity of the plant derived osmotin protein on the phytopathogen Phytophthora capsici, and the additional functional roles of this plant defense protein on cancer cells through inducing ROS associated senescence. The strong leads produced from this study could be pursued further to obtain more insights into the therapeutic potential of osmotin in human cancers.

Therapeutic application of alpha-1-antitrypsin in COVID-19

Rationale: The treatment options for COVID-19 patients are sparse and do not show sufficient efficacy. Alpha-1-antitrypsin (AAT) is a multi-functional host-defense protein with anti-proteolytic and anti-inflammatory activities. Objectives: The aim of the present study was to evaluate whether AAT is a suitable candidate for treatment of COVID-19. Methods: AAT and inflammatory markers were measured in the serum of COVID-19 patients. Human cell cultures were employed to determine the cell-based anti-protease activity of AAT and to test whether AAT inhibits the host cell entry of vesicular stomatitis virus (VSV) particles bearing the spike (S) protein of SARS-CoV-2 and the replication of authentic SARS-CoV-2. Inhaled and / or intravenous AAT was applied to nine patients with mild-to-moderate COVID-19. Measurements and Main Results: The serum AAT concentration in COVID-19 patients was increased as compared to control patients. The relative AAT concentrations were decreased in severe COVID-19 or in non-survivors in ratio to inflammatory blood biomarkers. AAT inhibited serine protease activity in human cell cultures, the uptake of VSV-S into airway cell lines and the replication of SARS-CoV-2 in human lung organoids. All patients, who received AAT, survived and showed decreasing respiratory distress, inflammatory markers, and viral load. Conclusion: AAT has anti-SARS-CoV-2 activity in human cell models, is well tolerated in patients with COVID-19 and together with its anti-inflammatory properties might be a good candidate for treatment of COVID-19.

A tau class Glutathione-S-Transferase (OsGSTU5) acts as a negative regulator of VirE2 interaction with T-DNA during Agrobacterium infection in rice

During Agrobacterium-mediated transformation (AMT), T-DNA along with several virulence proteins like VirD2, VirE2, VirE3, VirD5, and VirF enter into the plant cytoplasm. VirE2 is supposed to serve as single-stranded DNA binding (SSB) protein and assist the cytoplasmic trafficking of T-DNA inside the host cell. In the present study, a rice glutathione-S-transferase (OsGSTU5) that interacts with VirE2 protein in plant cytoplasm has been identified. OsGSTU5 is observed to be involved in post-translational glutathionylation of VirE2 protein (gVirE2). In silico analysis revealed that 'gVirE2+ssDNA' complex is structurally less stable than 'VirE2+ ssDNA' complex. The gel shift activity confirms the attenuated SSB property of gVirE2 over VirE2 protein under in vitro condition. Moreover, knock-down and overexpression OsGSTU5 phenotypes of rice showed increased and decreased T-DNA expression, respectively after Agrobacterium infection. The present finding convincingly establishes the role of OsGSTU5 as defense protein in rice that can further serve as an important target for modulation of AMT efficiency in rice.

Antibacterial Activities of Physiologically Stable, Self-Assembled Peptide Nanoparticles

In this study, we report that host defense protein-derived ten amino acid long disulfide-linked peptides self-assemble in the form of β-sheets and β-turns, and exhibit concentration-dependent self-assembly in the form...