Proteomic analysis on the regulation of DOPA-melanin synthesis in Talaromyces marneffei

Antifungal activity of bamemacrolactine C against Talaromyces marneffei and its possible mechanisms of action

AIMS

The present study aims to investigate the in vitro antifungal activity and mechanism of action of bamemacrolactine C (BAC), a new 24-membered macrolide compound, against Talaromyces marneffei.

METHODS AND RESULTS

The test drug BAC initially demonstrated antifungal activity through a paper disk diffusion assay, followed by determination of the minimum inhibitory concentration value of 35.29 μg ml-1 using microdilution. The association study revealed that combination therapy exhibited additive effects (0.5 < FICI < 1.0) when combined BAC with either amphotericin B or fluconazole. A time-growth assay confirmed that treatment with 35.29 μg ml-1 of BAC completely inhibited the growth of T. marneffei and exhibited antifungal effects. Micromorphological analysis using scanning electron microscopy and transmission electron microscopy photomicrographs revealed that BAC treatment induced morphological damage in fungal cells compared to the control group. Transmembrane protein assays showed a significant reduction in the levels of Na+/K+-ATPase (P < .05) and Ca2+-ATPase (P < .01) compared to the control group. Intracellular enzyme assays demonstrated that BAC treatment significantly decreased ATP, malate dehydrogenase, and succinate dehydrogenase content (P < .01). The combination of proteomics and parallel reaction monitoring (PRM) verification indicated that BAC exhibits an antifungal mechanism against T. marneffei by downregulating ATP citric acid lyase (ACLY) levels , potentially affecting the tricarboxylic acid (TCA) cycle. Besides, the binding model of BAC and the ACLY also shows a good docking score.

CONCLUSIONS

The findings suggest that BAC exhibits antifungal activity against T. marneffei, elucidating its multifaceted mechanism of action involving disruption of cell membranes' integrity and inhibition of intracellular enzyme activities, in which the modulation of ACLY in the TCA cycle may play an important role.

Yeast Proteins: Proteomics, Extraction, Modification, Functional Characterization, and Structure: A Review

Proteins are essential for human tissues and organs, and they require adequate intake for normal physiological functions. With a growing global population, protein demand rises annually. Traditional animal and plant protein sources rely heavily on land and water, making it difficult to meet the increasing demand. The high protein content of yeast and the complete range of amino acids in yeast proteins make it a high-quality source of supplemental protein. Screening of high-protein yeast strains using proteomics is essential to increase the value of yeast protein resources and to promote the yeast protein industry. However, current yeast extraction methods are mainly alkaline solubilization and acid precipitation; therefore, it is necessary to develop more efficient and environmentally friendly techniques. In addition, the functional properties of yeast proteins limit their application in the food industry. To improve these properties, methods must be selected to modify the secondary and tertiary structures of yeast proteins. This paper explores how proteomic analysis can be used to identify nutrient-rich yeast strains, compares the process of preparing yeast proteins, and investigates how modification methods affect the function and structure of yeast proteins. It provides a theoretical basis for solving the problem of inadequate protein intake in China and explores future prospects.

Transcriptional convergence after repeated duplication of an amino acid transporter gene leads to the independent emergence of the black husk/pericarp trait in barley and rice

The repeated emergence of the same trait (convergent evolution) in distinct species is an interesting phenomenon and manifests visibly the power of natural selection. The underlying genetic mechanisms have important implications to understand how the genome evolves under environmental challenges. In cereal crops, both rice and barley can develop black-coloured husk/pericarp due to melanin accumulation. However, it is unclear if this trait shares a common origin. Here, we fine-mapped the barley HvBlp gene controlling the black husk/pericarp trait and confirmed its function by gene silencing. The result was further supported by a yellow husk/pericarp mutant with deletion of the HvBlp gene, derived from gamma ray radiation of the wild-type W1. HvBlp encodes a putative tyrosine transporter homologous to the black husk gene OsBh4 in rice. Surprisingly, synteny and phylogenetic analyses showed that HvBlp and OsBh4 belonged to different lineages resulted from dispersed and tandem duplications, respectively, suggesting that the black husk/pericarp trait has emerged independently. The dispersed duplication (dated at 21.23 MYA) yielding HvBlp occurred exclusively in the common ancestor of Triticeae. HvBlp and OsBh4 displayed converged transcription in husk/pericarp tissues, contributing to the black husk/pericarp trait. Further transcriptome and metabolome data identified critical candidate genes and metabolites related to melanin production in barley. Taken together, our study described a compelling case of convergent evolution resulted from transcriptional convergence after repeated gene duplication, providing valuable genetic insights into phenotypic evolution. The identification of the black husk/pericarp genes in barley also has great potential in breeding for stress-resilient varieties with higher nutritional values.

The Role of Melanin in the Biology and Ecology of Nematophagous Fungi

Melanin is a heteropolymer formed by the polymerization of phenolic and indolic compounds. It occurs in organisms across all biological kingdoms and has a range different of functions, thus indicating its important evolutionary role. The presence of melanin offers several protective advantages, including against ultraviolet radiation, traumatic damage, oxidative stress, extreme temperatures, and pressure. For many species of fungi, melanin also participates directly in the process of virulence and pathogenicity. These organisms can synthesize melanin in two main ways: using a substrate of endogenous origin, involving 1,8-dihydroxynaphthalene (DHN); alternatively, in an exogenous manner with the addition of L-3, 4-dihydroxyphenylalanine (L-DOPA or levodopa). As melanin is an amorphous and complex substance, its study requires expensive and inaccessible technologies and analyses are often difficult to perform with conventional biochemical techniques. As such, details about its chemical structure are not yet fully understood, particularly for nematophagous fungi that remain poorly studied. Thus, this review presents an overview of the different types of melanin, with an emphasis on fungi, and discusses the role of melanin in the biology and ecology of nematophagous fungi.