Yeast最新文献

Given the biotechnological potential of yeast-derived oils for oleochemical production, genes encoding lipid metabolism enzymes are key targets for metabolic engineering. Genetic engineering tools such as Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/Cas9, Transcription Activator-Like Effector Nucleases (TALENs), Zinc-Finger Nucleases (ZFNs), RNA interference (RNAi), and integrative plasmids can be used to modulate fatty acid biosynthesis and optimize lipid production. Among them, the CRISPR/Cas9 system, recognized for its simplicity and efficiency, has been deployed as a tool to create oleaginous yeast strains with high lipid productivity and features suitable for application in biorefineries. Species such as Cutaneotrichosporon oleaginosus, Rhodotorula toruloides, Candida spp., and Yarrowia lipolytica have already been engineered using CRISPR/Cas9 to enhance the production of fatty acids and their derivatives. However, designing and constructing an efficient CRISPR/Cas9 platform for oleaginous yeasts faces several hurdles, including low transformation efficiency, difficulties in expressing Cas9 and sgRNAs efficiently and consistently, the lack of well-characterized promoters, limited availability of PAM sequences, and poorly understood DNA repair mechanisms. Here, we address the application of the CRISPR/Cas9 system in oleaginous yeasts, laying out the challenges to developing efficient platforms and highlighting key trends in the field. We compare and discuss alternative CRISPR-Cas9 expression strategies to provide an overview of the current landscape and support the development of new approaches.

Maillard reaction products (MRPs) are formed during the thermal processing of foods and exhibit important sensory attributes. Furanic compounds are a subset of MRPs commonly found in food products that are toxic to eukarytoic cells, although the mechanisms of toxicity are poorly understood. We used budding yeast to explore uptake mechanisms of common furanic compounds: 5-hydroxymethylfurfural (HMF), furfural (FUR), and 2-Furyl methyl ketone (FMK). Titrations of each furanic compound were used to identify concentrations that have an inhibitory effect on growth. We identified HMF as a potential substrate of the Pdr5 multidrug resistance pump and linked HMF and FUR toxicity to surface nutrient transporter levels. Live cell imaging shows that HMF disrupts mitochondria whilst FUR affects the endolysosomal system. Results indicate these furanic compounds may have distinct uptake, efflux, and toxicity mechanisms. As many of these cellular components are conserved throughout evolution, this work could shed light on the metabolism of toxic compounds commonly found within animal food sources.

This study aimed to isolate, identify, and evaluate yeasts originating from urban honeys as potential starters for mead production. Honey samples from urban apiaries from Poland were analyzed. A total of 47 yeast isolates were obtained and identified as belonging to eight genera: Starmerella, Zygosaccharomyces, Saccharomyces, Rhodotorula, Dothiora, Cystobasidium, Schizosaccharomyces, and Filobasidium. Among them, Starmerella magnoliae was predominant (24 isolates). Zygosaccharomyces rouxii and Z. mellis also occurred frequently. Three Saccharomyces cerevisiae strains (CMIFS 189, CMIFS 191, CMIFS 208) were selected for further trials and applied in the fermentation of trójniak-type meads (honey-to-water ratio 1:2), together with a reference mead starter, Enovini® HONEY (Browin, Poland). Physicochemical analysis showed ethanol contents of 12.22%-15.49%, with CMIFS 191 producing the lowest alcohol but the highest extract. Glycerol levels (0.62%-0.85%) were lower than literature values, while volatile acidity ranged from 0.80 to 1.27 g/L and total acidity from 2.97 to 3.45 g/L. Polyphenol levels (270-299 µg/mL) were high, and antioxidant assays (ABTS, DPPH, RP) showed strain-dependent effects. Volatile analysis revealed alcohols as the dominant group, followed by esters and aldehydes, shaping fruity and floral aroma notes. Based on sensory evaluation, CMIFS 191 showed the highest overall acceptability, whereas the Enovini® HONEY reference starter obtained the lowest sensory scores under the applied conditions. Overall, honey-derived S. cerevisiae strains showed strong potential as novel starters for mead production.

Six yeast isolates were recovered from Ipomoea flowers collected in the Cerrado biome of Tocantins, Brazil. Sequence analyses of the ITS-5.8S region and the D1/D2 domains of the large subunit (LSU) rRNA gene indicated that these isolates represent a novel species of the genus Candidozyma, phylogenetically related to Candidozyma auris and Ca. ruelliae. A phylogenomic analysis based on 2116 single-copy orthologs from Candidozyma species with available whole-genome sequences showed that the new species, represented by strain UFMG-CM-Y6065, is a sister species to Ca. ruelliae. The name Candidozyma cisalpinoae sp. nov. (MycoBank no. 861366) is proposed to accommodate the new species. The holotype is CBS16108. Sporulation or other evidence of sexual reproduction was not observed, although the genome sequence showed the presence of a functional mating type locus (MATa) and functional pheromone peptides, indicating that the species is haplontic and heterothallic. The species exhibited resistance to multiple antifungals, growth at 42°C, biofilm formation, adhesion to buccal epithelial cells, and expression of efflux pumps, traits of clinical relevance that have been reported for other species in the genus Candidozyma.

To maintain the integrity of the genome, cells have evolved a complex signalling system, termed the DNA damage response (DDR), which detects DNA damage and promotes DNA repair. To date, over 600 proteins have been identified that play an integral role in the DDR. RAD9, encoding a DDR mediator protein, was the prototypical DNA damage checkpoint gene, establishing the genetic regulation of transient cell-cycle delays upon DNA damage. Rad9, identified 38 years ago in the budding yeast Saccharomyces cerevisiae as a damage-dependent cell-cycle regulator, is now known to regulate additional responses to DNA damage including both cell-cycle recovery and repair. The Rad9 protein is extensively phosphorylated both during a normal cell cycle and following DNA damage and several of these modifications have been linked to specific Rad9 roles within the DDR. Proteins structurally and functionally related to Rad9 exist in mammalian cells (e.g., 53BP1, BRCA1, MDC1) and insights into their regulation and mechanism of action have been informed by studies in yeast. This review will discuss the cellular mechanisms governing the DDR with an emphasis on the multifaceted role of Rad9 in sensing and responding to DNA damage, and how phosphorylation events regulate its function within the DDR. As the cellular events governing the DDR are well conserved, discoveries in yeast can be extrapolated to humans and may lead to the identification of additional novel protein targets, with several DDR inhibitors currently in clinical use or showing promise in clinical trials.

Here, we review the use of Saccharomyces cerevisiae as a powerful model organism for studying cellular processes implicated in neurodegenerative disorders, including stress responses, proteostasis impairment, and vesicle trafficking defects. Over the last two decades, baker's yeast models have been developed for complex diseases such as Parkinson's, Alzheimer's, Huntington's, and Amyotrophic lateral sclerosis (ALS). Yeast cells expressing human proteins, such as amyloid-β, α-synuclein, huntingtin, and TDP-43, have become crucial tools for high-throughput drug screening aimed at counteracting disease progression. These yeast models have unveiled key components involved in the metabolism and toxicity of these proteins, enabling the identification of interacting partners and novel factors within each pathway. Importantly, these pathways were subsequently shown to be conserved in mammalian models. Furthermore, drug candidates identified using yeast models have provided significant leads for drug discovery, highlighting their potential for developing treatments for these neurodegenerative diseases.

Saccharomyces cerevisiae yeast cells have been shown to produce 18S and 25S ribosomal RNA molecules that are resistant to degradation by exonucleases, which require a 5' monophosphate for activity. These resistant RNA species accumulate during the diauxic shift, a phase marked by reduced TOR signaling. To further investigate the link between TOR activity and the accumulation of resistant rRNA, we examined the effects of pharmacological TOR inhibition. Treatment with rapamycin, an active TOR suppressor, led to increased levels of resistant 18S and 25S RNA. Importantly, this accumulation was also observed in cells with constitutively active RNA polymerase I (CARA), indicating that the resistant RNA species arise independently of RNA Pol I transcriptional regulation. Similarly, a TOR1-deleted mutant of Saccharomyces cerevisiae produces resistant 18S and 25S rRNA species in a sustained manner. Thiouracil labeling revealed that rRNA molecules generated during the logarithmic growth phase can be converted into the resistant form, suggesting a posttranscriptional modification process. Furthermore, thiouracil uptake assays demonstrated that overall rRNA synthesis decreases during the diauxic phase. Notably, decapping of the resistant rRNAs restored their sensitivity to exonucleases, indicating that the resistance is conferred by 5' end modifications, likely involving the addition of one or more phosphate groups.

The yeast Kluyveromyces marxianus (K. marxianus), characterized by its thermotolerance and rapid growth, is emerging as a promising new platform organism for the production of recombinant proteins. In this study, we constructed an expression vector designed for the efficient expression of exogenous proteins in K. marxianus. Initially, qPCR was employed to assess the expression efficiency of endogenous promoters within the yeast. The PDC1 promoter was selected, and its ability to drive the expression of EGFP was validated. The constructed vector exhibited high stability, maintaining approximately 5.2-fold higher copy numbers than the K. marxianus genome after 72 hours of cultivation without hygromycin selection. Notably, the fluorescence signal intensity of K. marxianus harboring the vector was approximately 15.6-fold higher than that of the wild-type strain at 72 h. Subsequently, the cap gene of porcine circovirus type 3 (PCV3) was integrated into the vector, resulting in the production of soluble PCV3 cap protein. Electron microscopy analysis revealed that the PCV3 cap protein self-assembled into virus-like particles (VLPs). This study successfully established the expression vector and characterized its key elements in K. marxianus, which will facilitate further research on the expression of exogenous proteins in this yeast species. Moreover, the soluble expression of the PCV3 cap protein and its formation of VLPs provide a solid foundation for the future development of PCV3 vaccines.

Yeasts have been intimately connected with human civilization for millennia, originally used for fermentation in food and beverage production. This article explores the multifaceted roles of yeasts-particularly Saccharomyces cerevisiae-as both a model organism and a cell factory. The historical journey of yeast research is chronicled from early fermentation practices to its central role in the molecular biology revolution. Notable discoveries using yeast have led to numerous Nobel Prizes, demonstrating its power in elucidating fundamental biological processes such as the eukaryal cell cycle, protein trafficking, transcription, and autophagy. The deep conservation of cellular pathways between yeast and humans, such as AMPK/Snf1 and TORC1/Tor1 signaling, further underscores yeast's value in biomedical research. Beyond its use in basic science, S. cerevisiae has become a preferred host for industrial biotechnology due to its genetic tractability, safety status, and ability to scale fermentation processes. Yeast has been engineered to produce a broad range of chemicals, fuels, and pharmaceuticals. Advanced tools in metabolic engineering-including genome-scale metabolic models, multi-omics analyses, and adaptive laboratory evolution-have driven remarkable improvements in yield, productivity, and strain robustness. These tools also offer insights into fundamental metabolic regulation and cellular adaptation. As the article discusses, yeast has not only illuminated the molecular workings of eukaryal life but also transformed industrial biotechnology. Its legacy and continued evolution affirm its indispensable role in science and technology.