Roles of phospholipid methyltransferases in pycnidia development, stress tolerance and secondary metabolism in the taxol-producing fungus Pestalotiopsis microspore

Role of cell membrane homeostasis in the pathogenicity of pathogenic filamentous fungi

The cell membrane forms a fundamental part of all living cells and participates in a variety of physiological processes, such as material exchange, stress response, cell recognition, signal transduction, cellular immunity, apoptosis, and pathogenicity. Here, we review the mechanisms and functions of the membrane structure (lipid components of the membrane and the biosynthesis of unsaturated fatty acids), membrane proteins (transmembrane proteins and proteins contributing to membrane curvature), transcriptional regulation, and cell wall components that influence the virulence and pathogenicity of filamentous fungi.

Phosphatidylcholine levels regulate hyphal elongation and differentiation in the filamentous fungus Aspergillus oryzae

Filamentous fungi are eukaryotic microorganisms that differentiate into diverse cellular forms. Recent research demonstrated that phospholipid homeostasis is crucial for the morphogenesis of filamentous fungi. However, phospholipids involved in the morphological regulation are yet to be systematically analyzed. In this study, we artificially controlled the amount of phosphatidylcholine (PC), a primary membrane lipid in many eukaryotes, in a filamentous fungus Aspergillus oryzae, by deleting the genes involved in PC synthesis or by repressing their expression. Under the condition where only a small amount of PC was synthesized, A. oryzae hardly formed aerial hyphae, the basic structures for asexual development. In contrast, hyphae were formed on the surface or in the interior of agar media (we collectively called substrate hyphae) under the same conditions. Furthermore, we demonstrated that supplying sufficient choline to the media led to the formation of aerial hyphae from the substrate hyphae. We suggested that acyl chains in PC were shorter in the substrate hyphae than in the aerial hyphae by utilizing the strain in which intracellular PC levels were controlled. Our findings suggested that the PC levels regulate hyphal elongation and differentiation processes in A. oryzae and that phospholipid composition varied depending on the hyphal types.

Comprehensive analysis of the composition of the major phospholipids during the asexual life cycle of the filamentous fungus Aspergillus nidulans

Filamentous fungi undergo significant cellular morphological changes during their life cycle. It has recently been reported that deletions of genes that are involved in phospholipid synthesis led to abnormal hyphal morphology and differentiation in filamentous fungi. Although these results suggest the importance of phospholipid balance in their life cycle, comprehensive analyses of cellular phospholipids are limited. Here, we performed lipidomic analysis of A. nidulans during morphological changes in a liquid medium and of colonies on a solid medium. We observed that the phospholipid composition and transcription of the genes involved in phospholipid synthesis changed dynamically during the life cycle. Specifically, the levels of phosphatidylethanolamine, and highly unsaturated phospholipids increased during the establishment of polarity. Furthermore, we demonstrated that the phospholipid composition in the hyphae at colony margins is similar to that during conidial germination. Furthermore, we demonstrated that common and characteristic phospholipid changes occurred during germination in A. nidulans and A. oryzae, and that species-specific changes also occurred. These results suggest that the exquisite regulation of phospholipid composition is crucial for the growth and differentiation of filamentous fungi.

Recent advances on Pestalotiopsis genus: chemistry, biological activities, structure-activity relationship, and biosynthesis

Strains of the fungal genus Pestalotiopsis are reported as large promising sources of structurally varied biologically active metabolites. Many bioactive secondary metabolites with diverse structural features have been derived from Pestalotiopsis. Moreover, some of these compounds can potentially be developed into lead compounds. Herein, we have systematically reviewed the chemical constituents and bioactivities of the fungal genus Pestalotiopsis, covering a period ranging from January 2016 to December 2022. As many as 307 compounds, including terpenoids, coumarins, lactones, polyketides, and alkaloids, were isolated during this period. Furthermore, for the benefit of readers, the biosynthesis and potential medicinal value of these new compounds are also discussed in this review. Finally, the perspectives and directions for future research and the potential applications of the new compounds are summarized in various tables.

Dual RNA-Sequencing and Liquid Chromatography-Mass Spectrometry Unveil Specific Insights on the Pathogenicity of Trichophyton mentagrophytes Complex

Trichophyton mentagrophytes is increasingly considered to be a public health hazard because it causes the most severe manifestations of dermatophytosis. In this study, we performed a series of studies to determine the pathogenicity of the T. mentagrophytes complex. We show that the T. mentagrophytes complex interacts with keratinocytes through pattern-recognition receptors‒MAPK/noncanonical NF-κB pathways and that the hyphal form of T. mentagrophytes is responsible for the increased inflammatory responses in keratinocytes. Moreover, SN-38 is likely a toxin of T. mentagrophytes that induces apoptosis in keratinocytes both in vivo and in vitro. Our results explain the severe pathogenicity and destructiveness of T. mentagrophytes observed in the clinic and pave the way for designing novel toxin-directed therapies to improve patient outcomes.

Pestalotiopsis Diversity: Species, Dispositions, Secondary Metabolites, and Bioactivities

Pestalotiopsis species have gained attention thanks to their structurally complex and biologically active secondary metabolites. In past decades, several new secondary metabolites were isolated and identified. Their bioactivities were tested, including anticancer, antifungal, antibacterial, and nematicidal activity. Since the previous review published in 2014, new secondary metabolites were isolated and identified from Pestalotiopsis species and unidentified strains. This review gathered published articles from 2014 to 2021 and focused on 239 new secondary metabolites and their bioactivities. To date, 384 Pestalotiopsis species have been discovered in diverse ecological habitats, with the majority of them unstudied. Some may contain secondary metabolites with unique bioactivities that might benefit pharmacology.

The impact of phenanthrene on membrane phospholipids and its biodegradation by Sphingopyxis soli

The direct interactions of bacterial membranes and polycyclic aromatic hydrocarbons (PAHs) strongly influence the biological processes, such as metabolic activity and uptake of substrates due to changes in membrane lipids. However, the elucidation of adaptation mechanisms as well as membrane phospholipid alterations in the presence of phenanthrene (PHE) from α-proteobacteria has not been fully explored. This study was conducted to define the degradation efficiency of PHE by Sphingopyxis soli strain KIT-001 in a newly isolated from Jeonju river sediments and to characterize lipid profiles in the presence of PHE in comparison to cells grown on glucose using quantitative lipidomic analysis. This strain was able to respectively utilize 1-hydroxy-2-naphthoic acid and salicylic acid as sole carbon source and approximately 90% of PHE (50 mg/L) was rapidly degraded via naphthalene route within 1 day incubation. In the cells grown on PHE, strain KIT-001 appeared to dynamically change profiles of metabolite and lipid in comparison to cells grown on glucose. The levels of primary metabolites, phosphatidylethanolamines (PE), and phosphatidic acids (PA) were significantly decreased, whereas the levels of phosphatidylcholines (PC) and phosphatidylglycerols (PG) were significantly increased. The adaptation mechanism of Sphingopyxis sp. regarded mainly the accumulation of bilayer forming lipids and anionic lipids to adapt more quickly under restricted nutrition and toxicity condition. Hence, these findings are conceivable that strain KIT-001 has a good adaptive ability and biodegradation for PHE through the alteration of phospholipids, and will be helpful for applications for effective bioremediation of PAHs-contaminated sites.