Coat Protein Research Articles

Molecular basis of TMED9 oligomerization and entrapment of misfolded protein cargo in the early secretory pathway.

Intracellular accumulation of misfolded proteins causes serious human proteinopathies. The transmembrane emp24 domain 9 (TMED9) cargo receptor promotes a general mechanism of cytotoxicity by entrapping misfolded protein cargos in the early secretory pathway. However, the molecular basis for this TMED9-mediated cargo retention remains elusive. Here, we report cryo-electron microscopy structures of TMED9, which reveal its unexpected self-oligomerization into octamers, dodecamers, and, by extension, even higher-order oligomers. The TMED9 oligomerization is driven by an intrinsic symmetry mismatch between the trimeric coiled coil domain and the tetrameric transmembrane domain. Using frameshifted Mucin 1 as an example of aggregated disease-related protein cargo, we implicate a mode of direct interaction with the TMED9 luminal Golgi-dynamics domain. The structures suggest and we confirm that TMED9 oligomerization favors the recruitment of coat protein I (COPI), but not COPII coatomers, facilitating retrograde transport and explaining the observed cargo entrapment. Our work thus reveals a molecular basis for TMED9-mediated misfolded protein retention in the early secretory pathway.

Bioinformatic and Phenotypic Analysis of AtPCP-Ba Crucial for Silique Development in Arabidopsis.

Silique development exerts significant impacts on crop yield. CRPs (Cysteine-rich peptides) can mediate cell-cell communication during plant reproduction and development. However, the functional characterization and regulatory mechanisms of CRPs in silique development remain unclear. In this study, we identified many CRP genes downstream of the CRP gene TPD1 (TAPETUM DETERMINANT1) during silique development using a microarray assay. The novel Arabidopsis thaliana pollen-borne CRPs, the PCP-Bs (for pollen coat protein B-class) gene AtPCP-Ba, along with TPD1, are essential for silique development. The AtPCP-Ba was significantly down-regulated in tpd1 flower buds but up-regulated in OE-TPD1 flower buds and siliques. The silencing of AtPCP-Ba compromised the wider silique of OE-TPD1 plants and inhibited the morphology of OE-TPD1 siliques to the size observed in the wild type. A total of 258 CRPs were identified with the bioinformatic analysis in Arabidopsis, Brassica napus, Glycine max, Oryza sativa, Sorghum bicolor, and Zea mays. Based on the evolutionary tree classification, all CRP members can be categorized into five subgroups. Notably, 107 CRP genes were predicted to exhibit abundant expression in flowers and fruits. Most cysteine-rich peptides exhibited high expression levels in Arabidopsis and Brassica napus. These findings suggested the involvement of the CRP AtPCP-Ba in the TPD1 signaling pathway, thereby regulating silique development in Arabidopsis.

Design, Synthesis, Anti-TMV Activity, and Structure-Activity Relationships of Seco-pregnane C21 Steroids and Their Derivatives.

seco-pregnane C21 steroids exhibit high antiviral activity against the tobacco mosaic virus (TMV). However, the structural modification of seco-pregnane C21 steroids and the structure-activity relationship (SAR) of the modified compounds remain unevaluated. Hence, the present study investigated how variations in the original skeletons of natural seco-pregnane C21 steroids affect their antiviral activity. A series of glaucogenin C and A derivatives were designed and synthesized for the first time, and their anti-TMV activity was evaluated. Bioassay results showed that most of the newly designed derivatives exhibited good to excellent antiviral activity; among these derivatives, 5g, 5j, and 5l with higher antiviral activity than that of ningnanmycin emerged as new antiviral candidates. Reverse transcription-polymerase chain reaction and Western blotting assay revealed reduced levels of TMV coat protein (TMV-CP) gene transcription and TMV-CP protein expression, which confirmed the antiviral activity of these derivatives. These compounds also downregulated the expression of NtHsp70-1 and NtHsp70-061. Computational simulations indicated that 5l displayed strong van der Waals energy and electrostatic with the TMV coat protein, affording a lower binding energy (ΔGbind = -56.2 kcal/mol) compared with Ribavirin (ΔGbind = -47.6 kcal/mol). The SAR of these compounds was also evaluated, which demonstrated for the first time that substitutions at C-3 and double bonds of C-5/C-6 and C-13/C-18 are crucial for maintaining high anti-TMV activity.

Characterization and genetic diversity of grapevine Pinot gris virus in Serbian vineyards

Sixty-five samples of grapevine from commercial vineyards in the Rasina district of Serbia were tested for the presence of grapevine Pinot gris virus (GPGV), using the reverse transcription-polymerase chain reaction. Fourteen samples of the grapevine varieties ‘Red Globe’, ‘Victoria’ and ‘Preobraženje’ were infected with GPGV. All the infected plants showed symptoms of leaf chlorotic mottling, puckering, and deformation, stunting, and reduced yields. The coding regions of the movement and coat protein (MP/CP) and a region of the RNA-dependent RNA polymerase (RdRP) domains of eight virus isolates were sequenced. Phylogenetic analyses of these genomic regions showed high nucleotide similarity among the Serbian GPGV isolates. This study is the first to describe genetic diversity of GPGV isolates in Serbia.

Molecular architecture of the assembly of Bacillus spore coat protein GerQ revealed by cryo-EM

Protein filaments are ubiquitous in nature and have diverse biological functions. Cryo-electron microscopy (cryo-EM) enables the determination of atomic structures, even from native samples, and is capable of identifying previously unknown filament species through high-resolution cryo-EM maps. In this study, we determine the structure of an unreported filament species from a cryo-EM dataset collected from Bacillus amyloiquefaciens biofilms. These filaments are composed of GerQ, a spore coat protein known to be involved in Bacillus spore germination. GerQ assembles into a structurally stable architecture consisting of rings containing nine subunits, which stacks to form filaments. Molecular dockings and model predictions suggest that this nine-subunit structure is suitable for binding CwlJ, a protein recruited by GerQ and essential for Ca2+-DPA induced spore germination. While the assembly state of GerQ within the spores and the direct interaction between GerQ and CwlJ have yet to be validated through further experiments, our findings provide valuable insights into the self-assembly of GerQ and enhance our understanding of its role in spore germination.

PCP-bε is a novel positive regulator of pollen germination in Arabidopsis thaliana

small cysteine-rich peptides play essential roles in different stages of the plant reproductive process. Pollen germination is a prerequisite for double fertilization and is directly related to seed formation and crop yield. However, the small cysteine-rich peptides that are involved in pollen germination remain to be identified. In this study, identification and phylogenetic analysis of PCP-Bε genes in sequenced Brassicaceae show that pollen coat protein B-class protein PCP-Bε gene is widespread in Arabidopsis and its high relatives, but lost in some Brassica species. Expression analyses display that AtPCP-Bε gene is expressed in Arabidopsis pollen. Arabidopsis PCP-Bε knockout mutants are generated by CRISPR/Cas9, Phenotypic analyses show that the absence of AtPCP-Bε obviously impairs in vitro pollen germination, but has no influence on pollen tube growth, which demonstrates that AtPCP-Bε is a novel positive regulator of pollen germination. It is speculated that AtPCP-Bε should interact with the receptor from pollen to perform its function. These findings are useful for further analysis on the molecular mechanism of pollen germination.

Molecular approaches for the management of papaya ringspot virus infecting papaya: a comprehensive review.

Papaya ringspot virus (PRSV) is a catastrophic disease that causes huge yield losses in papaya cultivation around the world. Yield losses in severely infected plants can be upto 100%. Because of this disease, papaya cultivation has been shifted to other crops in some areas of the world. Many conventional methods and breeding approaches are used against this disease, which turns out to be less effective. Considering the yield loss caused by PRSV in papaya, it is high time to focus on alternative control methods. To implement effective management strategies, molecular approaches such as Marker Assisted Breeding (MAS) or transgenic methods involving post-transcriptional gene silencing targeting the genome viz., coat protein, replicase gene, or HC Pro can be pursued. However, the public's reluctance to widely accept the transgenic approach due to health and environmental concerns necessitates a consideration of non-transgenic alternatives. Prioritizing safety and ensuring efficient virus control, non-transgenic approaches which encompass cross-protection, genome editing, and topical applications of dsRNA to induce gene silencing within the host, can be adopted. This review aims to provide comprehensive insights of various molecular tools used in managing PRSV which in turn will help in sustainable agriculture.

Molecular Identification of Three Potyviruses Infecting Allium cepa var. aggregatum and Allium sativum in Central Cultivation Areas of Indonesia

One hundred and twenty shallot (Allium cepa var. aggregatum) and 22 garlic (Allium sativum) samples were collected from major growing regions and markets to determine the distribution and molecular diversity of 3 potyviruses: leek yellow stripe virus (LYSV), onion yellow dwarf virus (OYDV), and shallot yellow stripe virus (SYSV) in Indonesia. The results of reverse transcription-polymerase chain reaction (RT-PCR) showed that 83% of shallot and all garlic samples were infected by at least 1 virus species. Coat protein (CP) region of 8 Indonesian LYSV, 19 OYDV, and 10 SYSV isolates were sequenced and given accession nos. OR772038-OR772082 in NCBI GenBank. Five isolates were recombinants according to analysis using the Recombination Detection Program (RDP v5.30). The phylogenetic tree deduced that 6 LYSV Indonesian and 2 China imported isolates belong to S-type. All tested OYDV isolates, including the 19 isolates, were clustered separately according to their respective hosts: onion and garlic. The 10 Indonesian SYSV isolates were clustered together in the same group and thus shown to be closely related. All isolates tested in this study were estimated to be still within their respective species demarcation according to percentage identity analysis. This was the most comprehensive molecular study on LYSV, OYDV, and SYSV that may help to find sustainable management strategies according to conditions in Indonesia and contribute to the global knowledge on the genetic diversity of the 3 viruses.

Recurrent Independent Pseudogenization Events of the Sperm Fertilization Gene ZP3r in Apes and Monkeys.

Many reproductive proteins show signatures of rapid evolution through sequence divergence and duplication. These features of reproductive genes may complicate the detection of orthologs across taxa, making it difficult to connect studies in model systems to human biology. In mice, ZP3r/sp56 is a binding partner to the egg coat protein ZP3 and may mediate induction of the acrosome reaction, a crucial step in fertilization. In rodents, ZP3r, as a member of the Regulators of Complement Activation cluster, is surrounded by paralogs, some of which have been shown to be evolving under positive selection. Although primate egg coats also contain ZP3, sequence divergence paired with paralogous relationships with neighboring genes has complicated the accurate identification of the human ZP3r ortholog. Here, we phylogenetically and syntenically resolve that the human ortholog of ZP3r is the pseudogene C4BPAP1. We investigate the evolution of this gene within primates. We observe independent pseudogenization events of ZP3r in all Apes with the exception of Orangutans, and independent pseudogenization events in many monkey species. ZP3r in both primates that retain ZP3r and in rodents contains positively selected sites. We hypothesize that redundant mechanisms mediate ZP3 recognition in mammals and ZP3r's relative importance to ZP recognition varies across species.

Genetic analysis of tomato brown rugose fruit virus reveals evolutionary adaptation and codon usage bias patterns

Tomato brown rugose fruit virus (ToBRFV) poses a significant threat to tomato production worldwide, prompting extensive research into its genetic diversity, evolutionary dynamics, and adaptive strategies. In this study, we conducted a comprehensive analysis of ToBRFV at the codon level, focusing on codon usage bias, selection pressures, and evolutionary patterns across multiple genes. Our analysis revealed distinct patterns of codon usage bias and selection pressures within the ToBRFV genome, with varying levels of genetic diversity and evolutionary constraints among different genes. We observed a transition/transversion bias of 2.07 across the entire ToBRFV genome, with the movement protein (MP) gene exhibiting the highest transition/transversion bias and SNP density, suggesting potential evolutionary pressures or a higher mutation rate in this gene. Furthermore, our study identified episodic positive selection primarily in the MP gene, highlighting specific codons subject to adaptive changes in response to host immune pressures or environmental factors. Comparative analysis of codon usage bias in the coat protein (CP) and RNA-dependent RNA polymerase (RdRp) genes revealed gene-specific patterns reflecting functional constraints and adaptation to the host's translational machinery. Our findings provide valuable insights into the molecular mechanisms driving ToBRFV evolution and adaptation, with implications for understanding viral pathogenesis, host-virus interactions, and the development of control strategies. Future research directions include further elucidating the functional significance of codon usage biases, exploring the role of episodic positive selection in viral adaptation, and leveraging these insights to inform the development of effective antiviral strategies and crop protection measures.

Effects of Confined Microenvironments with Protein Coating, Nanotopography, and TGF-β Inhibitor on Nasopharyngeal Carcinoma Cell Migration through Channels.

Distant metastasis is the primary cause of unsuccessful treatment in nasopharyngeal carcinoma (NPC), suggesting the crucial need to comprehend this process. A tumor related to NPC does not have flat surfaces, but consists of confined microenvironments, proteins, and surface topography. To mimic the complex microenvironment, three-dimensional platforms with microwells and connecting channels were designed and developed with a fibronectin (FN) coating or nanohole topography. The potential of the transforming growth factor-β (TGF-β) inhibitor (galunisertib) for treating NPC was also investigated using the proposed platform. Our results demonstrated an increased traversing probability of NPC43 cells through channels with an FN coating, which correlated with enhanced cell motility and dispersion. Conversely, the presence of nanohole topography patterned on the platform bottom and the TGF-β inhibitor led to a reduced cell traversing probability and decreased cell motility, likely due to the decrease in the F-actin concentration in NPC43 cells. This study highlights the significant impact of confinement levels, surface proteins, nanotopography, and the TGF-β inhibitor on the metastatic probability of cancer cells, providing valuable insights for the development of novel treatment therapies for NPC. The developed platforms proved to be useful tools for evaluating the metastatic potential of cells and are applicable for drug screening.

How coat proteins shape autophagy in plant cells.

Autophagy is a membrane trafficking pathway through which eukaryotic cells target their own cytoplasmic constituents for degradation in the lytic compartment. Proper biogenesis of autophagic organelles requires a conserved set of autophagy-related (ATG) proteins and their interacting factors, such as signalling phospholipid phosphatidylinositol 3-phosphate (PI3P) and coat complex II (COPII). The COPII machinery, which was originally identified as a membrane coat involved in the formation of vesicles budding from the endoplasmic reticulum, contributes to the initiation of autophagic membrane formation in yeast, metazoan, and plant cells; however, the exact mechanisms remain elusive. Recent studies using the plant model species Arabidopsis thaliana have revealed that plant-specific PI3P effectors are involved in autophagy. The PI3P effector FYVE2 interacts with the conserved PI3P effector ATG18 and with COPII components, indicating an additional role for the COPII machinery in the later stages of autophagosome biogenesis. In this Update, we examined recent research on plant autophagosome biogenesis and proposed working models on the functions of the COPII machinery in autophagy, including its potential roles in stabilizing membrane curvature and sealing the phagophore.

SDE19, a SEC-dependent effector from 'Candidatus Liberibacter asiaticus' suppresses plant immunity and targets Citrus sinensis Sec12 to interfere with vesicle trafficking.

Citrus huanglongbing (HLB), which is caused by the phloem-colonizing bacteria Candidatus Liberibacter asiaticus (CLas), poses a significant threat to citrus production worldwide. The pathogenicity mechanism of HLB remains poorly understood. SEC-dependent effectors (SDEs) have been suggested to play critical roles in the interaction between citrus and CLas. Here, we explored the function of CLIBASIA_05320 (SDE19), a core SDE from CLas, and its interaction with its host target. Our data revealed that SDE19 is expressed at higher level during infection of citrus than that during infection of the Asian citrus psyllid. Subcellular localization assays showed that SDE19 is localized in the nucleus and cytoplasm and is capable of moving from cell to cell in Nicotiana benthamiana. To investigate whether SDE19 facilitates pathogen infection, we generated transgenic Arabidopsis thaliana and citrus plants overexpressing SDE19. Transgenic A. thaliana and citrus plants were more susceptible to Pseudomonas syringae pv. tomato (Pst) and Xanthomonas citri subsp. citri (Xcc), respectively. In addition, RNA-seq analysis demonstrated that overexpression of SDE19 resulted in a reprogramming of expression of genes related to biotic stimulus responses. SDE19 interacts with Citrus sinensis Sec12, a guanine nucleotide exchange factor responsible for the assembly of plant COPII (coat protein II)-coated vesicles, which mediate vesicle trafficking from the ER to the Golgi. SDE19 colocalizes with Sec12 in the ER by binding to its N-terminal catalytic region, affecting the stability of Sec12 through the 26S proteasome. This interaction hinders the secretion of apoplastic defense-related proteins such as PR1, P69B, GmGIP1, and RCR3. Furthermore, the secretion of PR1 and callose deposition is decreased in SDE19-transgenic A. thaliana. Taken together, SDE19 is a novel virulent SDE secreted by CLas that interacts with Sec12 to disrupt vesicle trafficking, inhibit defense-related proteins secretion, and promote bacterial infection. This study sheds light on how CLas manipulates the host vesicle trafficking pathway to suppress the secretion of defense-related proteins and interfere with plant immunity.

Laccase surface-display for environmental tetracycline removal: From structure to function

Facing the increasingly prominent tetracycline pollution and the resulting environmental problems, how to find environmental and efficient treatment means is one of the current research hotspots. In this study, the laccase surface-display technology for tetracycline treatment was investigated. Via study, the type of anchoring protein had a minor influence on the laccase ability, while the type of laccase showed a major impact. Bacillus subtilis spore coat protein (CotA) exhibited higher laccase activity, stability, and efficiency in degrading tetracycline than Pleurotus ostreatus laccase 6 (Lacc6). The superiority of bacterial laccase over fungal laccase was elucidated from the perspective of crystal structure. Besides, a variety of technical means were used to verify the success of surface-display. pGSA-CotA surface-displayed bacteria exhibited good tolerance to high temperature, pH, and various heavy metals. Importantly, surface-displayed bacteria showed faster degradation efficiency and better treatment effects than the intracellular expression bacteria in tetracycline degradation. This implies that surface display technology has greater potential for laccase-mediated environmental remediation. Due to the adverse impacts of tetracycline on soil enzyme activity and microorganisms, our study found that pGSA-CotA surface-displayed bacteria can alleviate tetracycline stress in soil and partially activate the soil, thereby increasing soil enzyme activity and certain nitrogen cycling genes.

Myotubularin 2 interacts with SEC23A and negatively regulates autophagy at ER exit sites in Arabidopsis

ABSTRACT Starvation- or stress-induced phosphatidylinositol 3-phosphate (PtdIns3P/PI3P) production at the endoplasmic reticulum (ER) subdomains organizes phagophore assembly and autophagosome formation. Coat protein complex II (COPII) vesicles budding from ER exit site (ERES) also contribute to autophagosome formation. Whether any PtdIns3P phosphatase functions at ERES to inhibit macroautophagy/autophagy is unknown. Here we report Myotubularin 2 (MTM2) of Arabidopsis as a PtdIns3P phosphatase that localizes to ERES and negatively regulates autophagy. MTM2 binds PtdIns3P with its PH-GRAM domain in vitro and acts toward PtdIns3P in vivo. Transiently expressed MTM2 colocalizes with ATG14b, a subunit of the phosphatidylinositol 3-kinase (PtdIns3K) complex, and overexpression of MTM2 blocks autophagic flux and causes over-accumulation of ATG18a, ATG5, and ATG8a. The mtm2 mutant has higher levels of autophagy and is more tolerant to starvation, whereas MTM2 overexpression leads to reduced autophagy and sensitivity to starvation. The phenotypes of mtm2 are suppressed by ATG2 mutation, suggesting that MTM2 acts upstream of ATG2. Importantly, MTM2 does not affect the endosomal functions of PtdIns3P. Instead, MTM2 specifically colocalizes with COPII coat proteins and is cradled by the ERES-defining protein SEC16. MTM2 interacts with SEC23A with its phosphatase domain and inhibits COPII-mediated protein secretion. Finally, a role for MTM2 in salt stress response is uncovered. mtm2 resembles the halophyte Thellungiella salsuginea in its efficient vacuolar compartmentation of Na+, maintenance of chloroplast integrity, and timely regulation of autophagy-related genes. Our findings reveal a balance between PtdIns3P synthesis and turnover in autophagosome formation, and provide a new link between autophagy and COPII function.Abbreviations: ATG: autophagy related; BFA: brefeldin A; BiFC: bimolecular fluorescence complementation; CHX: cycloheximide; ConA: concanamycin A; COPII: coat protein complex II; ER: endoplasmic reticulum; ERES: ER exit site; MS: Murashige and Skoog; MTM: myotubularin; MVB: multivesicular body; PAS: phagophore assembly site; PI: phosphoinositide; TEM: transmission electron microscopy; WT: wild-type.

Influenza A Vaccine Candidates Based on Virus-like Particles Formed by Coat Proteins of Single-Stranded RNA Phages Beihai32 and PQ465.

Efficient control of influenza A infection can potentially be achieved through the development of broad-spectrum recombinant vaccines based on conserved antigens. The extracellular domain of the transmembrane protein M2 of influenza A virus (M2e) is highly conserved but poorly immunogenic and needs to be fused to an adjuvant protein or carrier virus-like particles (VLPs) to increase immunogenicity and provide protection against infection. In this study, we obtained VLPs based on capsid proteins (CPs) of single-stranded RNA phages Beihai32 and PQ465 bearing the M2e peptides. Four copies of the M2e peptide were linked to the C-terminus of the CP of phage Beihai32 and to the N and C termini of the CP of phage PQ465. The hybrid proteins, being expressed in Escherichia coli, formed spherical VLPs of about 30 nm in size. Immunogold transmission electron microscopy showed that VLPs formed by the phage PQ465 CP with a C-terminal M2e fusion present the M2e peptide on the surface. Subcutaneous immunization of mice with VLPs formed by both CPs containing four copies of the M2e peptide at the C termini induced high levels of M2e-specific IgG antibodies in serum and provided mice with protection against lethal influenza A virus challenge. In the case of an N-terminal fusion of M2e with the phage PQ465 CP, the immune response against M2e was significantly lower. CPs of phages Beihai32 and PQ465, containing four copies of the M2e peptide at their C termini, can be used to develop recombinant influenza A vaccine.

Coat Proteins of the Novel Victoriviruses FaVV1 and FaVV2 Suppress Sexual Reproduction and Virulence in the Pathogen of Fusarium Head Blight.

Fusarium head blight (FHB), a disease inflicted by Fusarium graminearum and F. asiaticum, poses a growing threat to wheat in China, particularly in the face of climate change and evolving agricultural practices. This study unveiled the discovery of the victorivirus FgVV2 from the F. asiaticum strain F16176 and comprehensively characterized the function of the two victoriviruses FaVV1 and FaVV2 in virulence. Through comparative analysis with a virus-free strain, we established that these mycoviruses markedly repress the sexual reproduction and pathogenicity of their fungal hosts. Furthermore, we synthesized the coat protein (CP) genes CP1 from FaVV1 and CP2 from FaVV2, which were fused with the green fluorescent protein (GFP) gene and successfully expressed in Fusarium strains in wild-type isolates of F. asiaticum and F. graminearum. Similar to virus-infected strains, the transformed strains expressing CPs showed a significant decrease in perithecia formation and pathogenicity. Notably, CP2 exhibited a stronger inhibitory effect than CP1, yet the suppression of sexual reproduction in F. graminearum was less pronounced than that in F. asiaticum. Additionally, the pathogenicity of the F. asiaticum and F. graminearum strains expressing CP1 or CP2 was substantially diminished against wheat heads. The GFP-tagged CP1 and CP2 revealed distinct cellular localization patterns, suggesting various mechanisms of interaction with the host. The findings of this study provide a significant research foundation for the study of the interaction mechanisms between FaVV1 and FaVV2 with their hosts, as well as for the exploration and utilization of fungal viral resources.

Serological detection of a novel ipomo-like virus infecting alfalfa in the U.S.

This study describes production of polyclonal antibodies against recently reported novel potyvirid infecting alfalfa (Medicago sativa L.). The virus was first found in alfalfa seed material and later identified in plant samples collected from commercial alfalfa fields in Arizona, USA. It was classified as a novel species related to the members of the genus Ipomovirus and potentially representing a new genus in the family Potyviridae (Nemchinov et al., 2023b). Polyclonal antibodies were produced against the predicted viral coat protein expressed in bacterial cells and used in different types of immunoassays for specific detection of this emerging virus. They could be helpful in plant virus certification programs, screening of alfalfa germplasm, research on pathogenicity, biology, and geographic distribution of this emerging virus.

Assessment of Nutraceuticals Potentials of Protein Isolates from Seed Coat of Four Melon Species

Recently, there has been more attention on the bioactivity of phytochemicals and other metabolites in agro-food by-products for the management of oxidative stress–related conditions. Hence, the objective of this paper is to assess the nutraceuticals potential by investigating antioxidant and α-amylase inhibitory potentials of seed coat protein isolates from four melon species namely: Citrullus colocynthis, Citrullus mucosospermus, Cucumeropsis mannii and Lagenaria siceraria using appropriate standard methods. At highest concentration, Lagenaria siceraria had the strongest free radical scavenging activity (38% inhibition). The strongest chelating effect was exhibited by C. mannii (IC50 = 0.59 ± 0.08 mg/ml), which also showed highest ferric reducing potential at all concentrations. At 0.05 mg/ml, C. colocynthis, C. mucosospermus, C. mannii, and L. siceraria seed coat protein extracts inhibited alpha-amylase activity by 43.2%, 16.76%, 2.6% and 22.3%, respectively, and inhibition of 60.9%, 28.6%, 38.3% and 29.5% were recorded for the seed protein extracts respectively, at 0.5 mg/ml. In conclusion, the various melon seed coat protein isolates showed appreciable levels of antioxidants and possessed inhibitory activity against α-amylase. Hence, the seed coats of the four melon varieties assessed in this study are promising potential sources of antioxidants for the supplementary treatment of oxidative stress–induced conditions.

Graphene oxide nanoparticles inhibit H9N2 influenza A virus infectivity by destroying viral coat proteins.

Nanoparticles have gained attention as potential antiviral agents, but the effects of graphene oxide nanoparticles (GONPs) on influenza virus remain unclear. In this study, we evaluated the antiviral activity of GONPs against influenza virus strain A/Hunan-Lengshuitan/11197/2013(H9N2). Our results show that GONPs with a diameter of 4 nm exerted an antiviral effect, whereas those with a diameter of 400 nm had no effect. Treatment with 4-nm GONPs reduced viral titers by more than 99% and inhibited viral nucleoprotein expression in a dose-dependent manner. We also confirmed that 4-nm GONPs inhibited the infectivity of H9N2 in MDCK cells. A transmission electron microscopic analysis revealed morphological abnormalities in the GONP-treated virus, including the destruction of the envelope glycoprotein spikes and an irregular shape, suggesting that GONPs cause the destruction of the viral coat proteins. Our results highlight the potential utility of GONPs in the prevention and treatment of viral infections, especially those of emerging and re-emerging viruses.