Biotechnological applications of versatile plant lipid transfer proteins (LTPs)

Defensin-like peptides from Capsicum chinense induce increased ROS, loss of mitochondrial functionality, and reduced growth of the fungus Colletotrichum scovillei

In the present study, we identified and characterized two defensin-like peptides in an antifungal fraction obtained from Capsicum chinense pepper fruits and inhibited the growth of Colletotrichum scovillei, which causes anthracnose. AMPs were extracted from the pericarp of C. chinense peppers and subjected to ion exchange, molecular exclusion, and reversed-phase in a high-performance liquid chromatography system. We investigated the endogenous increase in reactive oxygen species (ROS), the loss of mitochondrial functioning, and the ultrastructure of hyphae. The peptides obtained from the G3 fraction through molecular exclusion chromatography were subsequently fractionated using reverse-phase chromatography, resulting in the isolation of fractions F1, F2, F3, F4, and F5. The F1-Fraction suppressed C. scovillei growth by 90, 70.4, and 44% at 100, 50, and 25 μg mL-1, respectively. At 24 h, the IC50 and minimum inhibitory concentration were 21.5 μg mL-1 and 200 μg mL-1, respectively. We found an increase in ROS, which may have resulted in an oxidative burst, loss of mitochondrial functioning, and cytoplasm retraction, as well as an increase in autophagic vacuoles. MS/MS analysis of the F1-Fraction indicated the presence of two defensin-like proteins, and we were able to identify the expression of three defensin sequences in our C. chinense fruit extract. The F1-Fraction was also found to inhibit the activity of insect α-amylases. In summary, the F1-Fraction of C. chinense exhibits antifungal activity against a major pepper pathogen that causes anthracnose. These defensin-like compounds are promising prospects for further research into antifungal and insecticide biotechnology applications. © 2024 Society of Chemical Industry.

Understanding of lipid transfer protein sensitization patterns and its clinical significance in children

Background: Lipid transfer proteins (LTP) are the most common food allergens in the Mediterranean region. Objective: The study aimed to investigate co-sensitization patterns and cluster relationships between LTP allergen molecules across a broad range of allergen-specific sensitization patterns, and clinical outcomes in eastern Mediterranean children. Methods: Among 496 children evaluated for multiple sensitizations with multiplex testing, 105 children (21%) with 16 different LTP sensitizations were analyzed. Clinical reactivity was examined based on clear-cut history of immunoglobulin E mediated symptoms (oral allergy syndrome [OAS], systemic reactions, and anaphylaxis). Results: All children included were sensitive to food LTPs, but 56% were sensitive to pollen LTPs. The number of children with OAS and clinical reactivity was 12 and 59, respectively, and no cofactors were reported. The most common sensitizations were Pru p 3 (74%) and Cor a 8 (66%). Significant correlations were observed in the heatmap between the LTP molecules other than Par j 2 and Tri a 14. Overall, clinical reactivity was associated with increased age and number of LTP molecule positivity. Conclusion: In the eastern Mediterranean region, 21% of children with multiple food and/or pollen sensitizations were found to have LTP sensitization; however, almost half reported clinical reactivity. The hierarchical pathway highlights that distinct LTP allergen molecules can act as primary sensitizers. Clinical reactivity is linked to increasing numbers of LTP molecule positivity and increasing age.

Antifungal Action of Arabidopsis thaliana TCP21 via Induction of Oxidative Stress and Apoptosis

The realm of antimicrobial proteins in plants is extensive but remains relatively uncharted. Understanding the mechanisms underlying the action of plant antifungal proteins (AFPs) holds promise for antifungal strategies. This study aimed to bridge this knowledge gap by comprehensively screening Arabidopsis thaliana species to identify novel AFPs. Using MALDI-TOF analysis, we identified a member of the TEOSINTE BRANCHED1/CYCLOIDEA/PROLIFERATING CELL FACTOR1 (TCP) family of transcription factors as a novel AFP, A. thaliana TCP21 (AtTCP21; accession number NP_196450). Bacterially purified recombinant AtTCP21 inhibited the growth of various pathogenic fungal cells. AtTCP21 was more potent than melittin, a well-known AFP, in combating Colletotrichum gloeosporioides. Growth inhibition assays against various fungal pathogens and yeasts confirmed the pH-dependent antimicrobial activity of AtTCP21. Without inducing any membrane alterations, AtTCP21 penetrates the fungal cell wall and membrane, where it instigates a repressive milieu for fungal cell growth by generating intracellular reactive oxygen species and mitochondrial superoxides; resulting in morphological changes and apoptosis. Our findings demonstrate the redox-regulating effects of AtTCP21 and point to its potential as an antimicrobial agent.

Potent Antifungal Functions of a Living Modified Organism Protein, CP4-EPSPS, against Pathogenic Fungal Cells

Various proteins introduced into living modified organism (LMO) crops function in plant defense mechanisms against target insect pests or herbicides. This study analyzed the antifungal effects of an introduced LMO protein, 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) from Agrobacterium sp. strain CP4 (CP4-EPSPS). Pure recombinant CP4-EPSPS protein, expressed in Escherichia coli, inhibited the growth of human and plant fungal pathogens (Candida albicans, C. tropicalis, C. krusei, Colletotrichum gloeosporioides, Fusarium solani, F. graminearum, and Trichoderma virens), at minimum inhibitory concentrations (MICs) that ranged from 62.5 to 250 µg/mL. It inhibited fungal spore germination as well as cell proliferation on C. gloeosporioides. Rhodamine-labeled CP4-EPSPS accumulated on the fungal cell wall and within intracellular cytosol. In addition, the protein induced uptake of SYTOX Green into cells, but not into intracellular mitochondrial reactive oxygen species (ROS), indicating that its antifungal action was due to inducing the permeability of the fungal cell wall. Its antifungal action showed cell surface damage, as observed from fungal cell morphology. This study provided information on the effects of the LMO protein, EPSPS, on fungal growth.

Identification of potato Lipid transfer protein gene family and expression verification of drought genes StLTP1 and StLTP7

Lipid transfer proteins (LTPs) are widely distributed in plants and play an important role in the response to stress. Potato (Solanum tuberosum L.) is sensitive to a lack of water, and drought stress is one of the limiting factors for its yield. Therefore, mining candidate functional genes for drought stress and creating new types of potato germplasm for drought resistance is an effective way to solve this problem. There are few reports on the LTP family in potato. In this study, 39 members of the potato LTP family were identified. They were located on seven chromosomes, and the amino acid sequences encoded ranged from 101 to 345 aa. All 39 family members contained introns and had exons that ranged from one to four. Conserved motif analysis of potato LTP transcription factors showed that 34 transcription factors contained Motif 2 and Motif 4, suggesting that they were conserved motifs of potato LTP. Compared with the LTP genes of homologous crops, the potato and tomato (Solanum lycopersicum L.) LTPs were the mostly closely related. The StLTP1 and StLTP7 genes were screened by quantitative reverse transcription PCR combined with potato transcriptome data to study their expression in tissues and the characteristics of their responses to drought stress. The results showed that StLTP1 and StLTP7 were upregulated in the roots, stems, and leaves after PEG 6000 stress. Taken together, our study provides comprehensive information on the potato LTP family that will help to develop a framework for further functional studies.

Are Herbal-peptides Effective as Adjunctive Therapy in Coronavirus Disease COVID-19?

BACKGROUND

Plant antiviral peptides (AVP) are macromolecules that can inhibit the pathogenesis of viruses by affecting their pathogenic mechanism, but most of these peptides can bind to cell membranes, inhibit viral receptors, and prevent viruses. Recently, due to the coronavirus pandemic, the availability of appropriate drugs with low side effects is needed. In this article, the importance of plant peptides in viral inhibition, especially viral inhibition of the coronavirus family, will be discussed.

METHODS

By searching the databases of PubMed, Scopus, Web of Science, the latest articles on plant peptides effective on the COVID-19 virus were collected and reviewed.

RESULTS

Some proteins can act against the COVID-19 virus by blocking sensitive receptors in COVID-19, such as angiotensin-converting enzyme 2 (ACE2). The 23bp sequence of the ACE2 alpha receptor chain can be considered as a target for therapeutic peptides. Protease and RNAP inhibitors and other important receptors that are active against COVID-19 should also be considered.

CONCLUSION

Herbal medicines with AVP, especially those with a long history of antiviral effects, might be a good choice in complement therapy against the COVID-19 virus.

A review of plant antipathogenic constituents: Source, activity and mechanism

Green prevention and control of plant pathogens is a development direction of sustainable and low-carbon agriculture given the limitation of traditional chemicals. Plant-derived antipathogenic constituents (PAPCs) exhibit the advantages of being environmental benign and a broad spectrum of target pathogens over traditional chemicals. Here, we review the research advances on plant sources, chemical compositions, activities of antipathogenic constituents in the past 20 years. Reported PAPCs are classified into categories of phenols, flavonoids, terpenoids, alkaloids and antimicrobial peptides. Angiosperms, gymnosperms and some lower plants are the main plant source of detected PAPCs. The PAPCs act on pathogens through multiple pathways including destroying cell structures, blocking key composition synthesis and inhibiting cell metabolism. The development trends of PAPCs are finally prospected. This review serves as a comprehensive review on the study of plant antipathogenic constituents and a key reference for forecasting the source, characteristic and activity of PAPC.

Screening for cysteine-stabilized scaffolds for developing proteolytic-resistant AMPs

Antimicrobial peptides (AMP) are present in all organisms and can present several activities and potential applications in human and animal health. Screening these molecules scaffolds represents a key point for discovering and developing novel biotechnological products, including antimicrobial, antiviral and anticancer drugs candidates and insecticidal molecules with potential applications in agriculture. Therefore, considering the amount of biological data currently deposited on public databases, computational approaches have been commonly used to predicted and identify novel cysteine-rich peptides scaffolds with known or unknown biological properties. Here, we describe a step-by-step in silico screening for cysteine-rich peptides employing molecular modeling (with a core focus on comparative modeling) and atomistic molecular dynamics simulations. Moreover, we also present the concept of additional tools aiming at the computer-aided screening of new Cs-AMPs based drug candidates. After the computational screening and peptide chemical synthesis, we also provide the reader with a step-by-step in vitro activity evaluation of these candidates, including antibacterial, antifungal, and antiviral assays.

Plant-Derived Antimicrobial Peptides as Potential Antiviral Agents in Systemic Viral Infections

Numerous studies have led to a better understanding of the mechanisms of action of viruses in systemic infections for the development of prevention strategies and very promising antiviral therapies. Viruses still remain one of the main causes of human diseases, mainly because the development of new vaccines is usually challenging and drug resistance has become an increasing concern in recent decades. Therefore, the development of potential antiviral agents remains crucial and is an unmet clinical need. One abundant source of potential therapeutic molecules are plants: they biosynthesize a myriad of compounds, including peptides which can have antimicrobial activity. Our objective is to summarize the literature on peptides with antiviral properties derived from plants and to identify key features of these peptides and their application in systemic viral infections. This literature review highlights studies including clinical trials which demonstrated that plant cyclotides have the ability to inhibit the growth of viruses causing human diseases, defensin-like peptides possess anti-HIV-1 activity, and lipid transfer proteins and some lectins exhibit a varied antimicrobial profile. To conclude, plant peptides remain interesting to explore in the context of emerging and re-emerging infectious diseases.