Search Results (169)

Background/Objectives: RNA polymerase II is a multifunctional complex that is critical for gene regulation and environmental responses. Its POLR2I subunit in humans is associated with various pathologies, including cancer chemoresistance. However, much of our understanding of how POLR2I functions is inferred from studies of its homologs in yeasts called Rpb9. Here, we endogenously humanized the rpb9 gene of the fission yeast Schizosaccharomyces pombe to examine the functional capabilities of POLR2I. Methods: We edited the genomic rpb9 locus in S. pombe so that it encodes the human POLR2I protein, and investigated functional and structural conservation. Results: With our humanized yeast system, we find widespread functional complementation by human POLR2I of S. pombe rpb9 roles in yeast growth, chronological aging, and stress responses. We also find that POLR2I complements novel roles for yeast rpb9 in facultative heterochromatin assembly, resistance against the chemotherapy 5-fluorouracil, and resistance against the fungicide thiabendazole. In contrast, we find that POLR2I cannot complement the role of rpb9 in resistance against the transcription elongation inhibitor 6-azauracil (6-AU) in our system. Interestingly, POLR2I could complement 6-AU resistance if ectopically expressed. Lastly, we observe extensive structural homology between Rpb9 and POLR2I proteins. Conclusions: Our study establishes an endogenous cross-species gene complementation strategy that uncovers both conserved and rewired functions of fission yeast rpb9 and its human homolog, POLR2I. In addition to validating conserved roles, we also identified conservation of previously unrecognized roles of rpb9 in heterochromatin formation and chemoresistance. Full article

Metal homeostasis, which coordinates the influx and efflux of essential elements such as iron (Fe) and manganese (Mn) in chloroplasts, is essential for optimum photosynthesis, especially in metal-accumulating plants. Brassica juncea (Indian mustard) is a metal-tolerant species with a strong metal accumulation capacity, making it a suitable model for studying transition metal homeostasis. In this study, we identified two efflux transporters, BjYSL6.1 and BjYSL6.4, that localize in the endomembrane system of Schizosaccharomyces pombe and interact with the chloroplast Mn influx transporter BjNRAMP4.1 at the plasma membrane and within the chloroplasts. Bimolecular fluorescence complementation and split-ubiquitin yeast two-hybrid assays confirmed specific protein–protein interactions among these transporters, as well as with the membrane-bound thioredoxin BjHCF164, a known regulator of photosynthetic electron transport. Gene expression studies revealed that BjNRAMP4.1 and BjYSL6 isoforms are inversely regulated under Fe and Mn stress conditions, with BjNRAMP4.1 being strongly induced under deficiency, whereas BjYSL6.1 and BjYSL6.4 are downregulated. These findings suggest that a coordinated network involving BjNRAMP4.1, BjYSL6s, and BjHCF164 modulates metal influx and efflux at the chloroplast and plasma membrane interfaces, thereby maintaining metal homeostasis, which is critical for photosynthetic efficiency in B. juncea. Full article

Optical density (OD)-based cell growth measurement is commonly used in high-throughput screening (HTS) during drug discovery or when deciphering the pharmaceutical mechanism of action. While resuspending the cells via a mixing step is often assumed to be necessary prior to OD measurement, its essentiality in HTS workflows has not been systematically verified. Here, through the measurement of the growth of several strains of the microbial yeast Schizosaccharomyces pombe cells, we compared the overall growth dynamics between samples that have been mixed and not mixed. Using statistical quantification by a two-tailed paired t-test followed by multiple comparison corrections, we concluded from the comparison of the doubling time of cells growing in the exponential phase that mixing did not significantly affect the biological interpretation compared to unmixed samples. Doubling time quantification between mixed and unmixed samples showed a difference of approximately 10% on average based on the assessment of the growth of eight strains. As such, if the experimental outcome can accommodate this level of variability, incorporating a mixing step before OD determination would not be necessary. These observations support the simplification of HTS processes, improving the cost efficacy and process efficiency of readouts, yet maintaining the accuracy of data acquisition. Full article

Fusarium graminaerum causes Fusarium Head Blight (FHB) on wheat, reduces yield, and contaminates food and feed. It is therefore of paramount importance to control its growth or convert its harmful mycotoxins. This study aimed to find yeasts with biocontrol activity against F. graminearum, and to identify genes with potential detoxifying activities, using microbiological, molecular methods and bioinformatics. Co-cultivation tests showed that Schizosaccharomyces japonicus was able to inhibit the growth of F. graminearum. Transcriptomic analysis of the yeast cells co-cultured with F. graminearum highlighted differentially expressed genes (DEGs) encoding various enzymes, such as oxidoreductases, transferases, hydrolases, or genes involved in transmembrane transport. Three trichothecene-3-O-acetyltransferase homologous genes, which can convert trichothecenes to less toxic forms, were also among them. A database search showed that several yeast species contained this gene, including S. japonicus, which unexpectedly had seven copies. Real-time PCR analysis and mycotoxin tolerance tests confirmed that some of these genes could be induced by deoxynivalenol (DON), and S. japonicus had stronger DON tolerance than the related S. pombe, whose genome did not contain such a gene. This study is the first to report the biocontrol efficacy of S. japonicus against F. graminearum and the identification of its potential detoxification genes, offering promising new avenues for biotechnological applications in food safety. Full article

Glycerophosphocholine (GPC) and glycerophosphoinositol (GPI) are phospholipid metabolites generated by phospholipase-mediated deacylation. In budding yeast, they enter cells via the Git1 permease; in fission yeast, the homolog is Tgp1. This study investigates why GPC is toxic to asp1-STF mutants, where Tgp1 is upregulated due to loss of Asp1 pyrophosphatase, resulting in elevated inositol pyrophosphate 1,5-IP₈. We show that S. pombe Tgp1 specifically transports GPC, explaining why GPC, but not GPI, impairs growth. Increased GPC uptake slows doubling time but does not reduce viability. Toxicity is relieved by deletion of Gde1, a phosphodiesterase that hydrolyzes GPC to choline and glycerol-3-phosphate. Mutations in either the Gde1 active site or SPX domain also suppress toxicity, and radiolabeling confirms both domains are required for enzymatic activity. GPC is toxic in cells vastly overexpressing Tgp1 even without elevated IP₈, but Gde1 loss does not suppress this effect. Similarly, in S. cerevisiae overexpressing the Candida albicans Git3 transporter, GPC provision causes toxicity independent of Gde1. Loss of Gpc1, the acyltransferase converting GPC to lysophosphatidylcholine, does not alter toxicity in either yeast. These findings highlight a conserved process by which GPC regulates growth and reveal a role for IP₈ in modulating this process. Full article

Yeasts, especially the conventional species Saccharomyces cerevisiae and Schizosaccharomyces pombe, as well as some unconventional species such as Pichia pastoris, Kluyveromyces marxianus and Yarrowia lipolytica, have become fundamental model organisms for understanding the molecular mechanisms underlying human diseases. Their eukaryotic cell organization, genetic simplicity, and strong conservation of essential biological pathways make them indispensable in biomedical research. This review provides a comprehensive overview of the role of different yeast species in modeling human disorders, highlighting historical milestones and groundbreaking discoveries that have shaped current knowledge. The article discusses the applications of yeast models in studying neurodegenerative diseases such as Alzheimer’s and Huntington’s, as well as metabolic diseases, infectious diseases and mitochondrial disorders, and their growing importance in cancer research and drug discovery. Special attention is given to humanized yeast models, which enable the expression and functional analysis of human genes and the heterologous synthesis of human proteins within yeast cells. Finally, the paper addresses the limitations and challenges of yeast as a model system while outlining future directions and emphasizing the organism’s continued relevance in personalized medicine and functional genomics. Full article

Winemaking is facing significant challenges caused by industrialization of the process, climate change, and increased consumer awareness regarding the use of chemical preservatives. Although several solutions have been proposed, the utilization of non-Saccharomyces species seems to be the most efficient one. Several non-Saccharomyces species have been employed for this purpose, with Hanseniaspora uvarum, H. vineae, Kluyveromyces marxianus, Lachancea thermotolerans, Metschnikowia pulcherrima, Pichia fermentans, P. kluyveri, Schizosaccharomyces pombe, Starmerella bacillaris, Torulaspora delbrueckii, and Wickerhamomyces anomalus being the most promising ones. However, only a restricted amount of metabolic activities can be reliably attributed to the species level, while most of them are characterized by strain variability and are also affected by the Saccharomyces cerevisiae strains used to carry out alcoholic fermentation, as well as the efficient supply of precursor molecules by the grape varieties and the conditions for their effective bioconversion. This variability necessitates the application of optimization strategies, taking into consideration all these parameters. This review article aims to assist in this direction by collecting the data referring to the winemaking practice of the most interesting non-Saccharomyces species, presenting clearly and comprehensively their most relevant features, and highlighting the effect of strain diversity. Full article

The human BUD31 gene has been associated with various processes including cancer. To better understand its function, we used genetic methods to study Schizosaccharomyces pombe cells lacking the BUD31 homologous gene (cwf14) and performed sequence analysis using bioinformatics methods. Mutant cells lacking the cwf14 gene showed cell size and division defects, altered stress response, rapamycin sensitivity, enhanced chronological aging, and increased sporulation tendency. These processes are known to be regulated by the TOR pathway. The cwf14-TOR link was also supported by further experiments. We demonstrated that most protein-coding genes affected by cwf14 deletion are upregulated, encode hydrolases, oxidoreductases, and are often involved in transport. GO enrichment drew our attention to genes related to nitrogen transport, while additional data pointed to a nutrient/nitrogen (N) sensing problem. Although Cwf14 protein is associated with spliceosome complex, most genes affected by the absence of cwf14 do not contain introns, suggesting that they are influenced indirectly by the cwf14 gene. In silico experiments have revealed that BUD31 orthologous genes are found from yeast to humans, are evolutionarily conserved with a high degree of sequence identity, conserved motifs, and structures. Since the human gene partially complemented the mutant phenotype of S. pombe cells, indicating functional homology, our data can help better understand pathological mechanisms observed in human cancer cells. Full article

NRDE2 is a highly conserved protein implicated in post-transcriptional gene silencing in Schizosaccharomyces pombe and Caenorhabditis elegans and has been shown to modulate splicing in mammals. To explore whether NRDE2 participates in additional processes in human cells, we performed tandem affinity purification followed by proteomic analysis of NRDE2 from nuclear extracts of HEK293T and HeLa cells. Our analysis confirmed the interaction of NRDE2 with its well-characterized partner, the MTR4 helicase (MTREX), as well as with multiple splicing factors. Notably, we also identified interactions with chromatin-associated proteins involved in transcription, including the Polymerase-Associated Factor 1 (PAF1) complex and elongating forms of RNA polymerase II (RNAPII). To further investigate NRDE2 function, we conducted RNA-seq following its transient depletion. Differential expression analysis revealed that loss of NRDE2 alters the expression of thousands of genes. Consistent with earlier reports, we observed splicing defects, particularly intron retention; however, our results indicate that the impact of NRDE2 on intron retention is more extensive than previously recognized. Moreover, intron retention was frequently associated with reduced mRNA expression. Together, these findings suggest that NRDE2 associates with both transcriptional and splicing machineries and plays a broader role in RNA processing than previously appreciated. Full article

Discovering new yeast species can be crucial for creating new types of beers. In this study, we investigated three new yeast species, Saccharomyces bayanus, Schizosaccharomyces japonicus and Schizosaccharomyces pombe var. malidevorans, which have not been previously used in the brewing industry. Colour, total acidity, bitterness, aroma profile, total phenolic, flavonoid, mineral content and organoleptic characteristics of beers fermented by these strains were analysed to discover their applicability in the brewing industry. They did not significantly affect the nutritional value and colour of the beers, but showed increased acidity compared to the control Saccharomyces cerevisiae. GC-MS (Gas Chromatography-Mass Spectrometry) analysis revealed 33 aroma compounds, some of which were identical and some unique. S. cerevisiae and S. bayanus produced a similar number (19–20) of aroma compounds, while S. japonicus produced the fewest, including some undesirable compounds. Isobutyl alcohol, isoamyl alcohol, acetol, dimethylpyrazine, acetic acid, 4-cyclopentene-1,3-dione, butyrolactone, 2-furanmethanol, phenylethyl alcohol, maltol and pyranone that provide desired aromas in beers could be found in every sample. The new yeasts significantly increased polyphenols and decreased flavonoid content. Based on the results above and the taste scores, the strains S. bayanus and S. pombe var. malidevorans may be suitable for brewing, while S. japonicus is less or only suitable for combined fermentation. Full article

Mitochondria possess their own genome, which encodes subunits of the electron transport chain, rendering mitochondrial protein translation essential for cellular energy metabolism. Mitochondrial dysfunction affects nuclear transcription through the retrograde response. We applied RNA-seq to investigate whether and how the inhibition of mitochondrial translation by chloramphenicol (CAP) affects transcriptome regulation in proliferating or stationary-phase cells of Schizosaccharomyces pombe growing in fermentative or respiratory media. Stationary-phase cells in glucose medium exhibited the strongest transcriptome response to CAP, characterized by expression signatures similar to those observed under other stresses, including the retrograde response. The induced genes were also significantly enriched in cytoplasmic carbon metabolism pathways, reflecting a transcriptional reprogramming from respiration to fermentation. The transcription factors Scr1 and Rst2, regulators of carbon catabolite repression (CCR), controlled a common set of carbon metabolism genes in CAP-treated stationary-phase cells, and they showed opposing effects on the lifespan of these cells. Rst2 was required for the induction of carbon metabolism genes and maintained nuclear localization in CAP-treated stationary-phase cells. A systematic genetic interaction screen revealed functional relationships of Rst2 with processes related to stress and starvation responses. These findings uncover a complex transcriptional program in stationary-phase cells that adapt to inhibited mitochondrial translation, including stress- and retrograde-like responses, contributions of the CCR factors Scr1 and Rst2, and adjustment of carbon metabolism to deal with mitochondrial dysfunction. Full article

Chromosome transmission fidelity is vital for organism fitness. Yet, extrinsic and intrinsic changes can affect this process, leading to aneuploidy, the loss/gain of chromosomes, which is a hallmark of cancer. Here, using a haploid fission yeast Schizosaccharomyces pombe strain with a segmental aneuploidy, we assayed genome stability under different temperatures and altered gene dosage. We find that S. pombe genome stability is temperature-dependent and is unexpectedly modulated by intracellular levels of inorganic polyphosphate polymers (polyP). The vtc4⁺ gene, encoding a subunit of the polyP-generating VTC complex, is present twice due to the segmental aneuploidy resulting in a gene-dosage-coupled increase in polyP. Using strains with different amounts of polyP, we find a direct negative correlation between polyP and chromosome segregation fidelity. PolyP modulates the function of the conserved CCAN kinetochore subcomplex, as the abnormal growth phenotype caused by the mutant CCAN protein Fta2-291 was rescued in the absence of polyP, while extra polyP had the opposite effect. Importantly, this appears to occur in part by modulation of the nucleolin Gar2. Gar2 is the functional homolog of the Saccharomyces cerevisiae Nsr1 protein, whose function is modulated by posttranslational polyP-mediated polyphosphorylation. Thus, polyP modulates genome stability, linking cellular metabolism to chromosome transmission fidelity. Full article

Nucleoside analogues are used as drugs and as labels in laboratory-based research. However, the effect of different nucleoside analogue mechanism(s) on cell sensitivity or mutagenesis is unclear. This is particularly important in cancer treatments where checkpoint proteins and DNA damage factors are often mutated. We tested six nucleoside analogues in fission yeast, Schizosaccharomyces pombe. We found that the mutations in the DNA replication checkpoint cause unique sensitivity profiles towards chemotherapeutic nucleoside analogues (gemcitabine, 5-fluorouracil, cytarabine) and the non-clinical analogue bromodeoxyuridine. Antiretroviral compounds, zidovudine and lamivudine, did not alter cell growth. We compared half-maximal inhibitory concentration (IC50) doses between checkpoint deficient yeast strains, examining culture growth and DNA mis-segregation. Intriguingly, gemcitabine and bromodeoxyuridine doses above the IC50 promoted better growth. Above each compound’s IC50 dose we saw that cells were insensitive to nucleoside analogue re-exposure, particularly in DNA replication checkpoint mutants (cds1∆, rad3∆). Thus, pairing nucleoside analogue use with personal genomics may inform drug choice, dose, and schedule. Finally, these data indicate that resistance may be predictable, informing clinical strategy. Full article

Dormancy is a physiological state that enables cells to survive under adverse conditions by halting their proliferation while retaining the capacity to resume growth when conditions become favorable. This remarkable transition between dormant and proliferative states occurs across a wide range of species, including bacteria, fungi, plants, and tardigrades. Among these organisms, yeast cells have emerged as powerful model systems for elucidating the molecular and biophysical principles governing dormancy and dormancy breaking. In this review, we provide a comprehensive summary of current knowledge on the molecular mechanisms underlying cellular dormancy, with particular focus on the two major model yeasts: Saccharomyces cerevisiae and Schizosaccharomyces pombe. Recent advances in multifaceted approaches—such as single-cell RNA-seq, proteomic analysis, and live-cell imaging—have revealed dynamic changes in gene expression, proteome composition, and viability. Furthermore, insights into the biophysical properties of the cytoplasm have offered new understanding of dormant cell regulation through changes in cytoplasmic fluidity. These properties contribute to both the remarkable stability of dormant cells and their capacity to exit dormancy upon environmental cues, deepening our understanding of fundamental cellular survival strategies across diverse species. Full article

Translation initiation in mitochondria involves unique mechanisms distinct from those in the cytosol or in bacteria. The Schizosaccharomyces pombe mitochondrial translation initiation factor 2 (Mti2) is the ortholog of human MTIF2, which plays a vital role in synthesizing proteins in mitochondria. Here, we investigate the insertion domain of Mti2, which stabilizes its interaction with the ribosome and is crucial for efficient translation initiation. Our results show that the insertion domain is critical for the proper folding and function of Mti2. The absence of the insertion domain disrupts cell growth and affects the expression of genes encoded by mitochondrial DNA. Additionally, we show that Mti2 physically interacts with the small subunits of mitoribosomes (mtSSU), and deletion of the insertion domain dissociates mitochondrial initiation factors from the mitoribosome, reducing the efficiency of mitochondrial translation. Altogether, these findings highlight the conserved role of the insertion domain in facilitating translation initiation in fission yeast and thus reveal shared principles of mitochondrial translation initiation in both fission yeast and humans. Full article