Yeast最新文献

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.

A novel Saccharomycotina yeast strain, yHQL494, was isolated from the rose hip of the wild rose Rosa californica from Castle Crags State Park, California, USA. Phylogenetic analyses of both whole genome data and the sequences from the D1/D2 region of the large ribosomal subunit (LSU) rRNA gene placed strain yHQL494 within the genus Lachancea and grouped it into a clade with Lachancea lanzarotensis and Lachancea meyersii. Taxogenomic analyses were conducted on publicly available genome sequences to gain a deeper insight into the carbon and nitrogen gene-trait associations across the Lachancea clade. The results of these analyses were found to be consistent across Lachancea species. Growth assays and microscopic analyses were conducted to determine the physiological characteristics of strain yHQL494, including the presence of hyphae or pseudohyphae, ascospore formation, fermentation abilities, and assimilation of carbon and nitrogen compounds. Based on the phenotypic and genomic characteristics of the strain yHQL494^T (=NRRL Y-64858^T, =CBS 18,574^T), we propose a new species, Lachancea rosae sp. nov. f.a.

The methylotrophic yeast Komagataella phaffii (formerly known as Pichia pastoris) is an essential host for biotechnological production. Here, we present the complete and annotated genome sequence of CBS 2612 T = NRRL Y-7556T, the type strain of K. phaffii. CBS 2612 has a genome length of 9,387,549 bp with 5412 predicted and 5389 annotated genes, of which 144 are tRNA genes including the previously missing tRNAs for tryptophan, tyrosine, and serine, and 34 rRNA genes. In total, 4 SNPs were found compared to the biotechnologically most commonly used strain, CBS 7435. Additionally, 34 lncRNA candidates could be identified, including candidates that affect telomere-regulation and flocculin genes.

Polyphosphate (polyP) is an intriguing polymer with diverse biological and industrial applications. Chemical polyP production is energy-intensive and limited in chain length at large-scale production. Alternatively, biological production offers a sustainable solution. Recent research endeavors highlighted Saccharomyces cerevisiae as a promising organism for polyP hyperaccumulation, achieving up to 28% (w/w) polyP (as KPO₃). P_i starvation and P_i feeding are essential for this hyperaccumulation phenotype. Prior research demonstrated that trace elements and vitamins increase polyP production in S. cerevisiae when added to the cultivation medium during P_i starvation. However, the role of trace elements and vitamins in enhancing polyP accumulation remained unclear. This study identified inositol and zinc to drive polyP accumulation across various laboratory and industrial S. cerevisiae strains. Moreover, these components influence the energy metabolism of yeasts. Our findings suggest that zinc boosts the phosphate-responsive signal transduction (PHO) pathway during P_i starvation. The influence of inositol on polyP hyperaccumulation remains elusive, as it does not influence the PHO pathway directly. These findings add to the ever-growing understanding of polyP metabolism in S. cerevisiae and provide further targets for optimizing biological polyP production.

The primary challenge in tarhana production is the occurrence of spontaneous fermentation, which leads to non-standardized products. Thus, we investigated the effects of backslopping, a traditional method for inoculating fermented foods, on the yeast and volatile aroma compound diversity of tarhana dough. Backslopping fermentations were conducted at different temperatures (25°C and 30°C), pHs (3.70 and 4.00), and inoculation rates (5%, 10%, and 15%). The results revealed that the fermentation temperature and pH significantly influenced the diversity of yeast species and the volatile compound profile of the tarhana dough. However, despite some variations in the PCR-DGGE profiles, the metagenomic analysis revealed that the inoculation rate had minimal effect on yeast diversity, with species diversity remaining relatively constant over the cycles. Kazachstania humilis, Kazachstania bulderi, and Pichia kluyveri were the most prevalent yeast species across all experimental conditions. Pichia membranifaciens was exclusively detected in doughs fermented at 25°C and pH 4.00, whereas Saccharomyces cerevisiae was observed only in doughs fermented at 30°C. Tarhana doughs had a wide range of volatile compounds, the most abundant of which were terpenes and terpenoids, followed by esters, alcohols, aldehydes, and phenols. Doughs fermented at 25°C and pH 3.70 were differentiated from other groups, particularly for their content of esters (e.g., ethyl acetate, ethyl lactate, ethyl decanoate, and ethyl octanoate) and alcohols (e.g., ethyl alcohol, isobutyl alcohol, benzyl alcohol). This study highlights the direct influence of backslopping on yeast diversity and its indirect impact on the aroma profile of tarhana dough, providing insights into the optimization of fermentation conditions for improved product standardization.

The thermotolerant yeast Ogataea polymorpha TBRC 4839 is a promising host for heterologous protein expression using sucrose and molasses as low-cost carbon sources, making it suitable for industrial applications. This study analyzed the genome and transcriptome of O. polymorpha under sucrose-induced conditions. The nuclear genome of strain TBRC 4839 measures 8.9 Mbp with a GC content of 47.87%, consistent with other Ogataea species. The genome encodes 5184 protein-coding genes, comparable to related strains. Additionally, the mitochondrial genome spans 49.4 Kbp and has a low GC content of approximately 20%. Transcriptomic analysis revealed that sucrose induction triggers a metabolic shift characterized by increased carbohydrate metabolism and decreased amino acid biosynthesis, stress signaling, and cell division, enabling efficient energy utilization in sucrose-rich environments. Among the identified genes with up-regulated expression, five were notable: FUN_000066 (hypothetical protein), FUN_001144 (maltose permease), FUN_001145 (maltase), FUN_002060 (mitochondrial NAD-dependent malic enzyme), and FUN_002263 (hypothetical protein). The promoter efficiency was evaluated by expressing the fungal xylanase gene under sucrose-inducing conditions using these promoters. The maltase (MAL) promoter exhibited the highest xylanase production efficiency, outperforming other promoters. Furthermore, the MAL promoter proved effective for xylanase production when molasses was used as the carbon source. These findings underscore the potential of O. polymorpha TBRC 4839 and the MAL promoter for industrial protein production.

Dynamic downregulation of the endogenous farnesyl pyrophosphate (FPP) synthase (Erg20p) is crucial to engineer heterologous monoterpene production in the yeast Saccharomyces cerevisiae. FPP downstream metabolite geranylgeranyl pyrophosphate (GGPP) can induce the degradation of 3-hydroxy-3-methylglutaryl (HMG)-CoA reductase 2 (Hmg2p) through its N-terminal GGPP-sensing endoplasmic reticulum transmembrane domain (Hmg2p^N) in S. cerevisiae. Here, we investigate the use of Hmg2p^N to regulate Erg20p, aiming to restrict FPP synthesis and redirect metabolic flux to monoterpene production. While using the ERG1 promoter to regulate ERG20 transcription improved monoterpene limonene by ~10-fold, combinatory fusion of Hmg2p^N to Erg20p N-terminus further improved limonene production by 40% to 0.52 g L^-1 in synthetic minimal media. This approach yielded 0.5 g L^-1 geraniol in batch cultivation, comparable to levels achieved using the N-end-rule degron K3K15 or an auxin-inducible degron to regulate Erg20p. In rich complex media, this approach was superior, leading to 2.1 g L^-1 geraniol production in semi-fed batch cultivation. In summary, the Hmg2p^N domain is an efficient tool to constrain FPP synthesis for improved monoterpene production in S. cerevisiae.