ATP-Binding Cassette Transporter Regulates N,N'-diacetylchitobiose Transportation and Chitinase Production in Trichoderma asperellum T4

Production and characterization of Trichoderma asperellum chitinases and their use in synergy with Bacillus thuringiensis for lepidopteran control

BACKGROUND

Despite their known negative effects on ecosystems and human health, synthetic pesticides are still largely used to control crop insect pests. Currently, the biopesticide market for insect biocontrol mainly relies on the entomopathogenic bacterium Bacillus thuringiensis (Bt). New biocontrol tools for crop protection might derive from fungi, in particular from Trichoderma spp., which are known producers of chitinases and other bioactive compounds able to negatively affect insect survival.

RESULTS

In this study, we first developed an environmentally sustainable production process for obtaining chitinases from Trichoderma asperellum ICC012. Then, we investigated the biological effects of this chitinase preparation - alone or in combination with a Bt-based product - when orally administered to two lepidopteran species. Our results demonstrate that T. asperellum efficiently produces a multi-enzymatic cocktail able to alter the chitin microfibril network of the insect peritrophic matrix, resulting in delayed development and larval death. The co-administration of T. asperellum chitinases and sublethal concentrations of Bt toxins increased larval mortality. This synergistic effect was likely due to the higher amount of Bt toxins that passed the damaged peritrophic matrix and reached the target receptors on the midgut cells of chitinase-treated insects.

CONCLUSION

Our findings may contribute to the development of an integrated pest management technology based on fungal chitinases that increase the efficacy of Bt-based products, mitigating the risk of Bt-resistance development. © 2024 Society of Chemical Industry.

Emerging Role of ABC Transporters in Glia Cells in Health and Diseases of the Central Nervous System

ATP-binding cassette (ABC) transporters play a crucial role for the efflux of a wide range of substrates across different cellular membranes. In the central nervous system (CNS), ABC transporters have recently gathered significant attention due to their pivotal involvement in brain physiology and neurodegenerative disorders, such as Alzheimer's disease (AD). Glial cells are fundamental for normal CNS function and engage with several ABC transporters in different ways. Here, we specifically highlight ABC transporters involved in the maintenance of brain homeostasis and their implications in its metabolic regulation. We also show new aspects related to ABC transporter function found in less recognized diseases, such as Huntington's disease (HD) and experimental autoimmune encephalomyelitis (EAE), as a model for multiple sclerosis (MS). Understanding both their impact on the physiological regulation of the CNS and their roles in brain diseases holds promise for uncovering new therapeutic options. Further investigations and preclinical studies are warranted to elucidate the complex interplay between glial ABC transporters and physiological brain functions, potentially leading to effective therapeutic interventions also for rare CNS disorders.

Exploration of genes encoding KEGG pathway enzymes in rhizospheric microbiome of the wild plant Abutilon fruticosum

The operative mechanisms and advantageous synergies existing between the rhizobiome and the wild plant species Abutilon fruticosum were studied. Within the purview of this scientific study, the reservoir of genes in the rhizobiome, encoding the most highly enriched enzymes, was dominantly constituted by members of phylum Thaumarchaeota within the archaeal kingdom, phylum Proteobacteria within the bacterial kingdom, and the phylum Streptophyta within the eukaryotic kingdom. The ensemble of enzymes encoded through plant exudation exhibited affiliations with 15 crosstalking KEGG (Kyoto Encyclopaedia of Genes and Genomes) pathways. The ultimate goal underlying root exudation, as surmised from the present investigation, was the biosynthesis of saccharides, amino acids, and nucleic acids, which are imperative for the sustenance, propagation, or reproduction of microbial consortia. The symbiotic companionship existing between the wild plant and its associated rhizobiome amplifies the resilience of the microbial community against adverse abiotic stresses, achieved through the orchestration of ABA (abscisic acid) signaling and its cascading downstream effects. Emergent from the process of exudation are pivotal bioactive compounds including ATP, D-ribose, pyruvate, glucose, glutamine, and thiamine diphosphate. In conclusion, we hypothesize that future efforts to enhance the growth and productivity of commercially important crop plants under both favorable and unfavorable environmental conditions may focus on manipulating plant rhizobiomes.

Blood-brain barrier transporters: An overview of function, dysfunction in Alzheimer's disease and strategies for treatment

The blood-brain-barrier (BBB) has a major function in maintaining brain homeostasis by regulating the entry of molecules from the blood to the brain. Key players in BBB function are BBB transporters which are highly expressed in brain endothelial cells (BECs) and critical in mediating the exchange of nutrients and waste products. BBB transporters can also influence drug delivery into the brain by inhibiting or facilitating the entry of brain targeting therapeutics for the treatment of brain disorders, such as Alzheimer's disease (AD). Recent studies have shown that AD is associated with a disrupted BBB and transporter dysfunction, although their roles in the development in AD are not fully understand. Modulation of BBB transporter activity may pose a novel approach to enhance the delivery of drugs to the brain for enhanced treatment of AD. In this review, we will give an overview of key functions of BBB transporters and known changes in AD. In addition, we will discuss current strategies for transporter modulation for enhanced drug delivery into the brain.

Proteomic and Transcriptomic Analyses to Decipher the Chitinolytic Response of Jeongeupia spp

In nature, chitin, the most abundant marine biopolymer, does not accumulate due to the action of chitinolytic organisms, whose saccharification systems provide instructional blueprints for effective chitin conversion. Therefore, discovery and deconstruction of chitinolytic machineries and associated enzyme systems are essential for the advancement of biotechnological chitin valorization. Through combined investigation of the chitin-induced secretome with differential proteomic and transcriptomic analyses, a holistic system biology approach has been applied to unravel the chitin response mechanisms in the Gram-negative Jeongeupia wiesaeckerbachi. Hereby, the majority of the genome-encoded chitinolytic machinery, consisting of various glycoside hydrolases and a lytic polysaccharide monooxygenase, could be detected extracellularly. Intracellular proteomics revealed a distinct translation pattern with significant upregulation of glucosamine transport, metabolism, and chemotaxis-associated proteins. While the differential transcriptomic results suggested the overall recruitment of more genes during chitin metabolism compared to that of glucose, the detected protein-mRNA correlation was low. As one of the first studies of its kind, the involvement of over 350 unique enzymes and 570 unique genes in the catabolic chitin response of a Gram-negative bacterium could be identified through a three-way systems biology approach. Based on the cumulative data, a holistic model for the chitinolytic machinery of Jeongeupia spp. is proposed.

The role of pH transcription factor Appacc in upregulation of pullulan biosynthesis in Aureobasidium pullulans using potato waste as a substrate

pH is one of the important environmental factors affecting the growth, development and secondary metabolites of fungi. To better utilize potato waste for the production of pullulan by fermentation, in this study, the amino acid sequence and structural domain of pH transcription factor Appacc were analyzed using the bioinformatics methods. Appacc showed three typically conserved zinc finger domains, with the closest homology to Zymoseptoria brevis. The function of Appacc was characterized by ΔAppacc and OEXpacc mutants. The mycelium growth of ΔApacc mutants was inhibited, especially, under alkaline conditions. Furthermore, the pullulan production of ΔAppacc mutant was reduced and the expression of pullulan synthetic genes also decreased. Moreover, the OEXpacc mutant further demonstrated that pacc could regulate the expression of pullulan synthesis genes. The yield of pullulan polysaccharide increased from 13.6 g/L to 17.8 g/L by direct fermentation without changing the pH of potato waste. These results suggest that Appacc played a vital role in the growth of Aureobasidium pullulans and that the production of pullulan from potato waste can be increased by overexpression of pacc gene.

Identification of a Novel Pleiotropic Transcriptional Regulator Involved in Sporulation and Secondary Metabolism Production in Chaetomium globosum

Chaetoglobosin A (CheA), a well-known macrocyclic alkaloid with prominently highly antimycotic, antiparasitic, and antitumor properties, is mainly produced by Chaetomium globosum. However, a limited understanding of the transcriptional regulation of CheA biosynthesis has hampered its application and commercialization in agriculture and biomedicine. Here, a comprehensive study of the CgXpp1 gene, which encodes a basic helix-loop-helix family regulator with a putative role in the regulation of fungal growth and CheA biosynthesis, was performed by employing CgXpp1-disruption and CgXpp1-complementation strategies in the biocontrol species C. globosum. The results suggest that the CgXpp1 gene could be an indirect negative regulator in CheA production. Interestingly, knockout of CgXpp1 considerably increased the transcription levels of key genes and related regulatory factors associated with the CheA biosynthetic. Disruption of CgXpp1 led to a significant reduction in spore production and attenuation of cell development, which was consistent with metabolome analysis results. Taken together, an in-depth analysis of pleiotropic regulation influenced by transcription factors could provide insights into the unexplored metabolic mechanisms associated with primary and secondary metabolite production.

New insight into the production improvement and resource generation of chaetoglobosin A in Chaetomium globosum

Chaetoglobosin A is a complex macrocyclic alkaloid with potent antimycotic, antiparasitic and antitumor properties. However, the low output and high cost of chaetoglobosin A biosynthesis have hampered the application and commercialization of chaetoglobosin A in agriculture and biomedicine. Here, the CgMfs1 gene, which encodes the major facilitator superfamily secondary transporter, was identified based on bioinformatics analysis, and an intensive study of its effects on chaetoglobosin A biosynthesis and secretion was performed using CgMfs1‐silencing and CgMfs1‐overexpression strategies. Inactivation of CgMfs1 caused a notable decrease in chaetoglobosin A yield from 58.66 mg/L to 19.95 mg/L (MFS1–3) and 17.13 mg/L (MFS1–4). The use of an efficient expression plasmid in Chaetomium globosum W7 to generate the overexpression mutant OEX13 resulted in the highest chaetoglobosin A increase to 298.77 mg/L. Interestingly, the transcription level of the polyketide synthase gene significantly fluctuated with the change in CgMfs1, confirming that the predicted efflux gene CgMfs1 could play a crucial role in chaetoglobosin A transportation. Effective efflux of chaetoglobosin A could possibly alleviate feedback inhibition, resulting in notable increase in the expression of the polyketide synthase gene. Furthermore, we utilized cornstalk as the fermentation substrate to produce chaetoglobosin A, and scanning electron microscopy and Fourier transform‐infrared spectroscopy revealed that the strain OEX13 could well degrade cornstalk, presenting significant increases in the chaetoglobosin A yield, when compared with that produced by the wild‐type strain (from 40.32 to 191.90 mg/L). Thus, this research provides a novel analogous engineering strategy for the construction of high‐yielding strain and offers new insight into large‐scale chaetoglobosin A production.

Current Perspectives on Chitinolytic Enzymes and Their Agro-Industrial Applications

Chitinases are a large and diversified category of enzymes that break down chitin, the world's second most prevalent polymer after cellulose. GH18 is the most studied family of chitinases, even though chitinolytic enzymes come from a variety of glycosyl hydrolase (GH) families. Most of the distinct GH families, as well as the unique structural and catalytic features of various chitinolytic enzymes, have been thoroughly explored to demonstrate their use in the development of tailor-made chitinases by protein engineering. Although chitin-degrading enzymes may be found in plants and other organisms, such as arthropods, mollusks, protozoans, and nematodes, microbial chitinases are a promising and sustainable option for industrial production. Despite this, the inducible nature, low titer, high production expenses, and susceptibility to severe environments are barriers to upscaling microbial chitinase production. The goal of this study is to address all of the elements that influence microbial fermentation for chitinase production, as well as the purifying procedures for attaining high-quality yield and purity.

The impact of ATP-binding cassette transporters on metabolic diseases

Currently, many people worldwide suffer from metabolic diseases caused by heredity and external factors, such as diet. One of the symptoms of metabolic diseases is abnormal lipid metabolism. ATP binding cassette (ABC) transporters are one of the largest transport protein superfamilies that exist in nearly all living organisms and are mainly located on lipid-processing cells. ABC transporters have been confirmed to be closely related to the pathogenesis of diseases such as metabolic diseases, cancer and Alzheimer's disease based on their transport abilities. Notably, the capability to transport lipids makes ABC transporters critical in metabolic diseases. In addition, gene polymorphism in ABC transporters has been reported to be a risk factor for metabolic diseases, and it has been reported that relevant miRNAs have significant roles in regulating ABC transporters. In this review, we integrate recent studies to examine the roles of ABC transporters in metabolic diseases and aim to build a network with ABC transporters as the core, linking their transport abilities with metabolic and other diseases.

Characterisation and antifungal activity of extracellular chitinase from a biocontrol fungus, Trichoderma asperellum PQ34

Trichoderma species were known as biological control agents against phytopathogenic fungi because they produce a variety of chitinases. Chitinases are hydrolytic enzymes that break down glycosidic bonds in chitin, a major component of the cell walls of fungi. The present study shows that extracellular chitinase activity reached a maximum value of approximately 22 U/mL after 96 h of T. asperellum PQ34 strain culture. The optimal temperature and pH of enzyme are 40°C and 7, respectively, whereas the thermal and pH stability range from 25°C to 50°C and 4 to 10, respectively. Chitinase at 60 U/mL inhibited nearly completely in vitro growth of Colletotrichum sp. (about 95%) and Sclerotium rolfsii (about 97%). In peanut plants, 20 U/mL of chitinase significantly reduced the incidence of S. rolfsii infection compared to controls. The fungal infection incidence of seeds before germination and 30 days after germination was only 2.22% and 2.38%, while the control was 13.33% and 17.95%. Besides, chitinase from T. asperellum PQ34 can also prevent anthracnose that is caused by Colletotrichum sp. on both mango and chilli fruits up to 72 h after enzyme pre-treatment at 40 U/mL. In mango and chilli fruits infected with anthracnose, 40 U/mL dose of chitinase inhibited the growth of fungi after 96 h of treatment, the diameter of lesion was only 0.88 cm for mango and 1.45 cm for chilli, while the control was 1.67 cm and 2.85 cm, respectively.