Strategies to Better Target Fungal Squalene Monooxygenase

Comparative transcriptomic insights into the domestication of Pleurotus abieticola for coniferous cultivation

Introduction: Pleurotus abieticola, a promising edible fungus in the Pleurotaceae family, especially its ability to utilize coniferous substrate, holds significant potential for commercial cultivation. However, few reports on the adaptation of P. abieticola to coniferous substrate from the perspective of omics. Methods: This study explores the biological characteristics, domestication process, and nutritional composition of P. abieticola, along with its adaptability to coniferous substrates using transcriptomics. We assessed biological characteristics, optimizing mycelial growth on agar medium with varied carbon and nitrogen sources, temperature, and pH. Additionally, the optimization process extended to fruiting bodies, where impact on the differentiation were evaluated under varying light conditions. Fruiting body nutrient composition was analyzed per the Chinese National Food Safety Standard. Transcriptome sequencing focused on P. abieticola mycelial colonized coniferous and broadleaved substrates. Results and Discussion: The optimal conditions for mycelial growth were identified: dextrin (carbon source), diammonium hydrogen phosphate (nitrogen source), 25°C (temperature), and pH 7.0. White light promoted fruiting body growth and differentiation. Larch substrate exhibited superior yield (190 g) and biological efficiency (38.0%) compared to oak (131 g, 26.2%) and spruce (166 g, 33.2%). P. abieticola showcased high dietary fiber, protein, and total sugar content, low fat, and sufficient microelements. Transcriptome analysis revealed significant key genes involved in lignocellulose degradation, stress-resistant metabolism, and endocytosis metabolism, underscoring their pivotal for coniferous adaptation. This study offers valuable insights for the commercial development and strain breeding of P. abieticola, efficiently leveraging conifer resources. The findings underscore its potential as a valuable source for food, medicinal products, and biotechnological applications.

Artemisia argyi extract subfraction exerts an antifungal effect against dermatophytes by disrupting mitochondrial morphology and function

Artemisia argyi (A. argyi), a plant with a longstanding history as a raw material for traditional medicine and functional diets in Asia, has been used traditionally to bathe and soak feet for its disinfectant and itch-relieving properties. Despite its widespread use, scientific evidence validating the antifungal efficacy of A. argyi water extract (AAWE) against dermatophytes, particularly Trichophyton rubrum, Trichophyton mentagrophytes, and Microsporum gypseum, remains limited. This study aimed to substantiate the scientific basis of the folkloric use of A. argyi by evaluating the antifungal effects and the underlying molecular mechanisms of its active subfraction against dermatophytes. The results indicated that AAWE exhibited excellent antifungal effects against the three aforementioned dermatophyte species. The subfraction AAWE6, isolated using D101 macroporous resin, emerged as the most potent subfraction. The minimum inhibitory concentrations (MICs) of AAWE6 against T. rubrum, M. gypseum, and T. mentagrophytes were 312.5, 312.5, and 625 μg·mL-1, respectively. Transmission electron microscopy (TEM) results and assays of enzymes linked to cell wall integrity and cell membrane function indicated that AAWE6 could penetrate the external protective barrier of T. rubrum, creating breaches ("small holes"), and disrupt the internal mitochondrial structure ("granary"). Furthermore, transcriptome data, quantitative real-time PCR (RT-qPCR), and biochemical assays corroborated the severe disruption of mitochondrial function, evidenced by inhibited tricarboxylic acid (TCA) cycle and energy metabolism. Additionally, chemical characterization and molecular docking analyses identified flavonoids, primarily eupatilin (131.16 ± 4.52 mg·g-1) and jaceosidin (4.17 ± 0.18 mg·g-1), as the active components of AAWE6. In conclusion, the subfraction AAWE6 from A. argyi exerts antifungal effects against dermatophytes by disrupting mitochondrial morphology and function. This research validates the traditional use of A. argyi and provides scientific support for its anti-dermatophytic applications, as recognized in the Chinese patent (No. ZL202111161301.9).

Investigation of the response of Platycodongrandiflorus (Jacq.) A. DC to salt stress using combined transcriptomics and metabolomics

BACKGROUND

Platycodon grandiflorus (Jacq.) A. DC is a famous traditional Chinese medicine in China and an authentic medicine in Inner Mongolia. It has been traditionally used as an expectorant in cough and also has anti-inflammatory and other pharmacological effects. As a homologous plant of medicine and food, P. grandiflorus is widely planted in Northeast China. Soil salinity isa limiting factor for its cultivation. In this study, we comprehensively described the physiological characteristics of P. grandiflorus and combined transcriptomics and metabolomics to study the response of roots of P. grandiflorus to salt stress.

RESULTS

Overall, 8,988 differentially expressed genes were activated and significantly altered the metabolic processes. In total, 428 differentially abundant metabolites were affected by salt stress. After moderate and severe salt stress, most of the differentially abundant metabolites were enriched in the L-phenylalanine metabolic pathway. Through the comprehensive analysis of the interaction between key genes and metabolites, the main pathways such as lignin compound biosynthesis and triterpene saponin biosynthesis were completed. The relative content of compounds related to lignin biosynthesis, such as caffeic acid, coniferin, and syringing, increased under salt stress, and the related genes such as PAL, C4H, and the key enzyme gene UGT72E2 were activated to adapt to the salt stress. Platycodon saponin is one of the major triterpene saponins in P. grandiflorus, and Platycodin D is its most abundant major bioactive component. Under severe salt stress, Platycodin D level increased by nearly 1.77-fold compared with the control group. Most of the genes involved insynthetic pathway of Platycodin D, such as HMGCR, GGPS, SE, and LUP, were upregulated under salt stress.

CONCLUSION

Salt stress led to a decrease in the biomass and affected the activities of antioxidant enzymes and contents of osmotic regulators in the plant. These results provided not only novel insights into the underlying mechanisms of response of P. grandiflorus to salt stress but also a foundation for future studies on the function of genes related to salt tolerance in the triterpenoid saponin biosynthesis pathway.

Allylamines, Benzylamines, and Fungal Cell Permeability: A Review of Mechanistic Effects and Usefulness against Fungal Pathogens

Allylamines, naftifine and terbinafine, and the benzylamine, butenafine, are antifungal agents with activity on the fungal cell membrane. These synthetic compounds specifically inhibit squalene epoxidase, a key enzyme in fungal sterol biosynthesis. This results in a deficiency in ergosterol, a major fungal membrane sterol that regulates membrane fluidity, biogenesis, and functions, and whose damage results in increased membrane permeability and leakage of cellular components, ultimately leading to fungal cell death. With the fungal cell membrane being predominantly made up of lipids including sterols, these lipids have a vital role in the pathogenesis of fungal infections and the identification of improved therapies. This review will focus on the fungal cell membrane structure, activity of allylamines and benzylamines, and the mechanistic damage they cause to the membrane. Furthermore, pharmaceutical preparations and clinical uses of these drugs, mainly in dermatophyte infections, will be reviewed.

Modulation of yeast Erg1 expression and terbinafine susceptibility by iron bioavailability

Ergosterol is a specific sterol component of yeast and fungal membranes. Its biosynthesis is one of the most effective targets for antifungal treatments. However, the emergent resistance to multiple sterol‐based antifungal drugs emphasizes the need for new therapeutic approaches. The allylamine terbinafine, which selectively inhibits squalene epoxidase Erg1 within the ergosterol biosynthetic pathway, is mainly used to treat dermatomycoses, whereas its effectiveness in other fungal infections is limited. Given that ergosterol biosynthesis depends on iron as an essential cofactor, in this report, we used the yeast Saccharomyces cerevisiae to investigate how iron bioavailability influences Erg1 expression and terbinafine susceptibility. We observed that both chemical and genetic depletion of iron decrease ERG1 expression, leading to an increase in terbinafine susceptibility. Deletion of either ROX1 transcriptional repressor or CTH1 and CTH2 post‐transcriptional repressors of ERG1 expression led to an increase in Erg1 protein levels and terbinafine resistance. On the contrary, overexpression of CTH2 led to the opposite effect, lowering Erg1 levels and increasing terbinafine susceptibility. Although strain‐specific particularities exist, opportunistic pathogenic strains of S. cerevisiae displayed a response similar to the laboratory strain. These data indicate that iron bioavailability and particular regulatory factors could be used to modulate susceptibility to terbinafine.

Biosynthetic pathways of triterpenoids and strategies to improve their Biosynthetic Efficiency

"Triterpenoids" can be considered natural products derived from the cyclization of squalene, yielding 3-deoxytriterpenes (hydrocarbons) or 3-hydroxytriterpenes. Triterpenoids are metabolites of these two classes of triterpenes, produced by the functionalization of their carbon skeleton. They can be categorized into different groups based on their structural formula/design. Triterpenoids are an important group of compounds that are widely used in the fields of pharmacology, food, and industrial biotechnology. However, inadequate synthetic methods and insufficient knowledge of the biosynthesis of triterpenoids, such as their structure, enzymatic activity, and the methods used to produce pure and active triterpenoids, are key problems that limit the production of these active metabolites. Here, we summarize the derivatives, pharmaceutical properties, and biosynthetic pathways of triterpenoids and review the enzymes involved in their biosynthetic pathway. Furthermore, we concluded the screening methods, identified the genes involved in the pathways, and highlighted the appropriate strategies used to enhance their biosynthetic production to facilitate the commercial process of triterpenoids through the synthetic biology method.

Cold atmospheric pressure plasma (CAPP) as a new alternative treatment method for onychomycosis caused by Trichophyton verrucosum: in vitro studies

PURPOSE

Anthropophilic dermatophytes as etiological factors of onychomycoses are more common than zoophilic fungi. In the case of the latter, reverse zoonoses are possible, which poses a threat to the persistence of dermatophytes in the environment. Nevertheless, without treatment, both types of tinea unguium may lead to complete nail plate destruction and secondary mixed infections with fungi and bacteria. One of the zoophilic dermatophytes that cause onychomycosis is Trichophyton verrucosum, whose prevalence has been increasing in recent years. Such infections are usually treated with allylamines and/or azoles, but such a conventional treatment of infections caused by T. verrucosum often fails or is discontinued by patients.

METHODS

Herein, we reveal the results of our in vitro studies related to direct application of cold atmospheric pressure plasma (CAPP) on Trichophyton verrucosum growth, germination and adherence to nail as a new alternative treatment method of such types of dermatomycoses.

RESULTS

Our in vitro studies showed that, while exposure to CAPP for 10 min delays germination of conidia and clearly impairs the fitness of the fungal structures, 15 min is enough to kill all fungal elements exposed to plasma. Moreover, the SEM images revealed that T. verrucosum cultures exposed to CAPP for 10 and 15 min were not able to invade the nail fragments.

CONCLUSION

The results revealed that single exposure to CAPP was able to inhibit T. verrucosum growth and infection capacity. Hence, cold atmospheric pressure plasma should be considered as a promising alternative treatment of onychomycoses.