Roles of High Osmolarity Glycerol and Cell Wall Integrity Pathways in Cadmium Toxicity in Saccharomyces cerevisiae.
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ABSTRACT:
SUBMITTER: Zhao Y
PROVIDER: S-EPMC8226467 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:During fermentation, a high ethanol concentration is a major stress that influences the vitality and viability of yeast cells, which in turn leads to a termination of the fermentation process. In this study, we show that the BCK1 and SLT2 genes encoding mitogen-activated protein kinase kinase kinase (MAPKKK) and mitogen-activated protein kinase (MAPK) of the cell wall integrity (CWI) pathway, respectively, are essential for ethanol tolerance, suggesting that the CWI pathway is involved in the response to ethanol-induced cell wall stress. Upon ethanol exposure, the CWI pathway induces the expression of specific cell wall-remodeling genes, including FKS2, CRH1, and PIR3 (encoding β-1,3-glucan synthase, chitin transglycosylase, and O-glycosylated cell wall protein, respectively), which eventually leads to the remodeling of the cell wall structure. Our results revealed that in response to ethanol stress, the high-osmolarity glycerol (HOG) pathway plays a collaborative role with the CWI pathway in inducing cell wall remodeling via the upregulation of specific cell wall biosynthesis genes such as the CRH1 gene. Furthermore, the substantial expression of CWI-responsive genes is also triggered by external hyperosmolarity, suggesting that the adaptive changes in the cell wall are crucial for protecting yeast cells against not only cell wall stress but also osmotic stress. On the other hand, the cell wall stress-inducing agent calcofluor white has no effect on promoting the expression of GPD1, a major target gene of the HOG pathway. Collectively, these findings suggest that during ethanol stress, the CWI and HOG pathways collaboratively regulate the transcription of specific cell wall biosynthesis genes, thereby leading to adaptive changes in the cell wall.IMPORTANCE The budding yeast Saccharomyces cerevisiae has been widely used in industrial fermentations, including the production of alcoholic beverages and bioethanol. During fermentation, an increased ethanol concentration is the main stress that affects yeast metabolism and inhibits ethanol production. This work presents evidence that in response to ethanol stress, both CWI and HOG pathways cooperate to control the expression of cell wall-remodeling genes in order to build the adaptive strength of the cell wall. These findings will contribute to a better understanding of the molecular mechanisms underlying adaptive responses and tolerance of yeast to ethanol stress, which is essential for successful engineering of yeast strains for improved ethanol tolerance.
| S-EPMC6643247 | biostudies-literature
Project description:The basidiomycetous fungus Wallemia ichthyophaga grows between 1.7 and 5.1 M NaCl and is the most halophilic eukaryote described to date. Like other fungi, W. ichthyophaga detects changes in environmental salinity mainly by the evolutionarily conserved high-osmolarity glycerol (HOG) signaling pathway. In Saccharomyces cerevisiae, the HOG pathway has been extensively studied in connection to osmotic regulation, with a valuable knock-out strain collection established. In the present study, we reconstructed the architecture of the HOG pathway of W. ichthyophaga in suitable S. cerevisiae knock-out strains, through heterologous expression of the W. ichthyophaga HOG pathway proteins. Compared to S. cerevisiae, where the Pbs2 (ScPbs2) kinase of the HOG pathway is activated via the SHO1 and SLN1 branches, the interactions between the W. ichthyophaga Pbs2 (WiPbs2) kinase and the W. ichthyophaga SHO1 branch orthologs are not conserved: as well as evidence of poor interactions between the WiSho1 Src-homology 3 (SH3) domain and the WiPbs2 proline-rich motif, the absence of a considerable part of the osmosensing apparatus in the genome of W. ichthyophaga suggests that the SHO1 branch components are not involved in HOG signaling in this halophilic fungus. In contrast, the conserved activation of WiPbs2 by the S. cerevisiae ScSsk2/ScSsk22 kinase and the sensitivity of W. ichthyophaga cells to fludioxonil, emphasize the significance of two-component (SLN1-like) signaling via Group III histidine kinase. Combined with protein modeling data, our study reveals conserved and non-conserved protein interactions in the HOG signaling pathway of W. ichthyophaga and therefore significantly improves the knowledge of hyperosmotic signal processing in this halophilic fungus.
| S-EPMC4904012 | biostudies-literature
Project description:To identify novel functions for the Cdc34/SCF ubiquitination complex, we analyzed genomewide transcriptional profiles of cdc53-1 and cdc34-2 Saccharomyces cerevisiae mutants. This analysis revealed altered expression for several gene families, including genes involved in the regulation of cell wall organization and biosynthesis. This led us to uncover a role for the Cdc34/SCF complex in the regulation of cell wall integrity. In support of this, cdc53-1 and cdc34-2 mutants exhibit phenotypes characteristic of cell wall integrity mutants, such as SDS sensitivity and temperature-sensitive suppression by osmotic stabilizers. Examination of these mutants revealed defects in their induction of Slt2 phosphorylation, indicating defects in Pkc1-Slt2 MAPK signaling. Consistent with this, synthetic genetic interactions were observed between the genes encoding the Cdc34/SCF complex and key components of the Pck1-Slt2 MAPK pathway. Further analysis revealed that Cdc34/SCF mutants have reduced levels of active Rho1, suggesting that these defects stem from the deregulated activity of the Rho1 GTPase. Altering the activity of Rho1 via manipulation of the Rho1-GAPs LRG1 or SAC7 affected Cdc34/SCF mutant growth. Strikingly, however, deletion of LRG1 rescued the growth defects associated with Cdc34/SCF mutants, whereas deletion of SAC7 enhanced these defects. Given the differential roles that these GAPs play in the regulation of Rho1, these observations indicate the importance of coordinating Cdc34/SCF activity with specific Rho1 functions.
| S-EPMC1698636 | biostudies-literature
Project description:The adaptation of Saccharomyces cerevisiae to situations in which cell wall integrity is seriously compromised mainly involves the cell wall integrity (CWI) pathway. However, in a recent work ( Bermejo, C., Rodriguez, E., García, R., Rodríguez-Peña, J. M., Rodríguez de la Concepción, M. L., Rivas, C., Arias, P., Nombela, C., Posas, F., and Arroyo, J. (2008) Mol. Biol. Cell 19, 1113-1124 ) we have demonstrated the co-participation of the high osmotic response (HOG) pathway to ensure yeast survival to cell wall stress mediated by zymolyase, which hydrolyzes the beta-1,3 glucan network. Here we have characterized the role of both pathways in the regulation of the overall yeast transcriptional responses to zymolyase treatment using whole genome expression profiling. A main group of yeast genes is dependent on both MAPKs, Slt2 and Hog1, for their induction. The transcriptional activation of these genes depends on the MAPKKK Bck1, the transcription factor Rlm1, and elements of the sho1 branch of the HOG pathway, but not on the sensors of the CWI pathway. A second group of genes is dependent on Slt2 but not Hog1 or Pbs2. However, the induction of these genes is dependent on upstream elements of the HOG pathway such as Sho1, Ste50, and Ste11, in accordance with a sequential activation of the HOG and CWI pathways. Zymolyase also promotes an osmotic-like transcriptional response with the activation of a group of genes dependent on elements of the Sho1 branch of HOG pathway but not on Slt2, with the induction of many of them dependent on Msn2/4. Additionally, in the absence of Hog1, zymolyase induces an alternative response related to mating and filamentation as a consequence of the cross-talk between these pathways and the HOG pathway. Finally, in the absence of Slt2, zymolyase increases the induction of genes associated with osmotic adaptation with respect to the wild type, suggesting an inhibitory effect of the CWI pathway over the HOG pathway. These studies clearly reveal the complexity of the signal transduction machinery responsible for regulating yeast adaptation responses to cell wall stress.
| S-EPMC2667776 | biostudies-literature
Project description:The filamentous fungus Aspergillus fumigatus can cause a distinct set of clinical disorders in humans. Invasive aspergillosis (IA) is the most common life-threatening fungal disease of immunocompromised humans. The mitogen-activated protein kinase (MAPK) signaling pathways are essential to the adaptation to the human host. Fungal cell survival is highly dependent on the organization, composition, and function of the cell wall. Here, an evaluation of the global A. fumigatus phosphoproteome under cell wall stress caused by the cell wall-damaging agent Congo red (CR) revealed 485 proteins potentially involved in the cell wall damage response. Comparative phosphoproteome analyses with the ?sakA, ?mpkC, and ?sakA ?mpkC mutant strains from the osmotic stress MAPK cascades identify their additional roles during the cell wall stress response. Our phosphoproteomics allowed the identification of novel kinases and transcription factors (TFs) involved in osmotic stress and in the cell wall integrity (CWI) pathway. Our global phosphoproteome network analysis showed an enrichment for protein kinases, RNA recognition motif domains, and the MAPK signaling pathway. In contrast to the wild-type strain, there is an overall decrease of differentially phosphorylated kinases and phosphatases in ?sakA, ?mpkC, and ?sakA ?mpkC mutants. We constructed phosphomutants for the phosphorylation sites of several proteins differentially phosphorylated in the wild-type and mutant strains. For all the phosphomutants, there is an increase in the sensitivity to cell wall-damaging agents and a reduction in the MpkA phosphorylation upon CR stress, suggesting these phosphosites could be important for the MpkA modulation and CWI pathway regulation.IMPORTANCE Aspergillus fumigatus is an opportunistic human pathogen causing allergic reactions or systemic infections, such as invasive pulmonary aspergillosis in immunocompromised patients. The mitogen-activated protein kinase (MAPK) signaling pathways are essential for fungal adaptation to the human host. Fungal cell survival, fungicide tolerance, and virulence are highly dependent on the organization, composition, and function of the cell wall. Upon cell wall stress, MAPKs phosphorylate multiple target proteins involved in the remodeling of the cell wall. Here, we investigate the global phosphoproteome of the ?sakA and ?mpkC A. fumigatus and high-osmolarity glycerol (HOG) pathway MAPK mutants upon cell wall damage. This showed the involvement of the HOG pathway and identified novel protein kinases and transcription factors, which were confirmed by fungal genetics to be involved in promoting tolerance of cell wall damage. Our results provide understanding of how fungal signal transduction networks modulate the cell wall. This may also lead to the discovery of new fungicide drug targets to impact fungal cell wall function, fungicide tolerance, and virulence.
| S-EPMC7002344 | biostudies-literature
Project description:The highly conserved family of septin proteins has important functions in cytokinesis in mitotically proliferating cells. A different form of cytokinesis occurs during gametogenesis in Saccharomyces cerevisiae, in which four haploid meiotic products become encased by prospore membrane (PSMs) and specialized, stress-resistant spore walls. Septins are known to localize in a series of structures near the growing PSM, but previous studies noted only mild sporulation defects upon septin mutation. We report that directed PSM extension fails in many septin-mutant cells, and, for those that do succeed, walls are abnormal, leading to increased susceptibility to heating, freezing, and digestion by the Drosophila gut. Septin mutants mislocalize the leading-edge protein (LEP) complex required for normal PSM and wall biogenesis, and ectopic expression of the LEP protein Ssp1 perturbs mitotic septin localization and function, suggesting a functional interaction. Strikingly, extra copies of septin CDC10 rescue sporulation and LEP localization in cells lacking Sma1, a phospholipase D-associated protein dispensable for initiation of PSM assembly and PSM curvature but required for PSM extension. These findings point to key septin functions in directing efficient membrane and cell wall synthesis during budding yeast gametogenesis.
| S-EPMC4751596 | biostudies-literature
Project description:We have used Saccharomyces cerevisiae to identify toxicologically important proteins and pathways involved in arsenic-induced toxicity and carcinogenicity in humans. We performed a systemic screen of the complete set of 4733 haploid S. cerevisiae single-gene-deletion mutants to identify those that have decreased or increased growth, relative to wild type, after exposure to sodium arsenite (NaAsO(2)). IC(50) values for all mutants were determined to further validate our results. Ultimately we identified 248 mutants sensitive to arsenite and 5 mutants resistant to arsenite exposure. We analyzed the proteins corresponding to arsenite-sensitive mutants and determined that they belonged to functional categories that include protein binding, phosphate metabolism, vacuolar/lysosomal transport, protein targeting, sorting, and translocation, cell growth/morphogenesis, cell polarity and filament formation. Furthermore, these data were mapped onto a protein interactome to identify arsenite-toxicity-modulating networks. These networks are associated with the cytoskeleton, ubiquitination, histone acetylation and the MAPK signaling pathway. Our studies have potential implications for understanding toxicity and carcinogenesis in arsenic-induced human conditions, such as cancer and aging.
| S-EPMC2763962 | biostudies-literature
Project description:BackgroundQuercetin is a naturally occurring flavonol with antioxidant, anticancer and anti-ageing properties. In this study we aimed to identify genes differentially expressed in yeast cells treated with quercetin and its role in oxidative stress protection.MethodsA microarray analysis was performed to characterize changes in the transcriptome and the expression of selected genes was validated by RT-qPCR. Biological processes significantly affected were identified by using the FUNSPEC software and their relevance in H(2)O(2) resistance induced by quercetin was assessed.ResultsGenes associated with RNA metabolism and ribosome biogenesis were down regulated in cells treated with quercetin, whereas genes associated with carbohydrate metabolism, endocytosis and vacuolar proteolysis were up regulated. The induction of genes related to the metabolism of energy reserves, leading to the accumulation of the stress protectant disaccharide trehalose, and the activation of the cell wall integrity pathway play a key role in oxidative stress resistance induced by quercetin.ConclusionsThese results suggest that quercetin may act as a modulator of cell signaling pathways related to carbohydrate metabolism and cell integrity to exert its protective effects against oxidative stress.
| S-EPMC3445532 | biostudies-literature
Project description:The yeast cell wall is an extracellular structure that is dependent on secretory and membrane proteins for its construction. We investigated the role of protein quality control mechanisms in cell wall integrity and found that the unfolded protein response (UPR) and, to a lesser extent, endoplasmic reticulum (ER)-associated degradation (ERAD) pathways are required for proper cell wall construction. Null mutation of IRE1, double mutation of ERAD components (hrd1Delta and ubc7Delta) and ire1Delta, or expression of misfolded proteins show phenotypes similar to mutation of cell wall proteins, including hypersensitivity to cell wall-targeted molecules, alterations to cell wall protein layer, decreased cell wall thickness by electron microscopy, and increased cellular aggregation. Consistent with its important role in cell wall integrity, UPR is activated by signaling through the cell wall integrity mitogen-activated protein (MAP) kinase pathway during cell wall stress and unstressed vegetative growth. Both cell wall stress and basal UPR activity is mediated by Swi6p, a regulator of cell cycle and cell wall stress gene transcription, in a manner that is independent of its known coregulatory molecules. We propose that the cellular responses to ER and cell wall stress are coordinated to buffer the cell against these two related cellular stresses.
| S-EPMC2613099 | biostudies-literature
Project description:Saccharomyces cerevisiae produces the sphingolipid ceramide by de novo synthesis as well as by hydrolysis of complex sphingolipids by Isc1p (inositolphosphoceramide-phospholipase C), which is homologous with the mammalian neutral sphingomyelinases. Though the roles of sphingolipids in yeast stress responses are well characterized, it has been unclear whether Isc1p contributes to stress-induced sphingolipids. The present study was undertaken in order to distinguish the relative roles of de novo sphingolipid biosynthesis versus Isc1p-mediated sphingolipid production in the heat-stress response. Ceramide production was measured at normal and increased temperature in an ISC1 deletion and its parental strain (ISC1 being the gene that codes for Isc1p). The results showed that Isc1p contributes specifically to the formation of the C24-, C24:1- and C26-dihydroceramide species. The interaction between these two pathways of sphingolipid production was confirmed by the finding that ISC1 deletion is synthetically lethal with the lcb1-100 mutation. Interestingly, Isc1p did not contribute significantly to transient cell-cycle arrest or growth at elevated temperature, responses known to be regulated by the de novo pathway. In order to define specific contributions of ISC1, microarray hybridizations were performed, and analyses showed misregulation of genes involved in carbon source utilization and sexual reproduction, which was corroborated by defining a sporulation defect of the isc1Delta strain. These results indicate that the two pathways of ceramide production in yeast interact, but differ in their regulation of ceramides of distinct molecular species and serve distinct cellular functions.
| S-EPMC1360726 | biostudies-literature