| 1. |
- Martinez Ruiz, Jose Luis, 1981, et al.
(författare)
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The impact of respiration and oxidative stress response on recombinant ?-amylase production by Saccharomyces cerevisiae
- 2016
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Ingår i: Metabolic Engineering Communications. - : Elsevier BV. - 2214-0301. ; 3, s. 205-210
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Tidskriftsartikel (refereegranskat)abstract
- Studying protein production is important for fundamental research on cell biology and applied research for biotechnology. Yeast Saccharomyces cerevisiae is an attractive workhorse for production of recombinant proteins as it does not secrete many endogenous proteins and it is therefore easy to purify a secreted product. However, recombinant production at high rates represents a significant metabolic burden for the yeast cells, which results in oxidative stress and ultimately affects the protein production capacity. Here we describe a method to reduce the overall oxidative stress by overexpressing the endogenous HAP1 gene in a S. cerevisiae strain overproducing recombinant α-amylase. We demonstrate how Hap1p can activate a set of oxidative stress response genes and meanwhile contribute to increase the metabolic rate of the yeast strains, therefore mitigating the negative effect of the ROS accumulation associated to protein folding and hence increasing the production capacity during batch fermentations.
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| 2. |
- Bao, Jichen, 1988, et al.
(författare)
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Balanced trafficking between the ER and the Golgi apparatus increases protein secretion in yeast
- 2018
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Ingår i: AMB Express. - : Springer Science and Business Media LLC. - 2191-0855. ; 8:1
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Tidskriftsartikel (refereegranskat)abstract
- The yeast Saccharomyces cerevisiae is widely used as a cell factory to produce recombinant proteins. However, S. cerevisiae naturally secretes only a few proteins, such as invertase and the mating alpha factor, and its secretory capacity is limited. It has been reported that engineering protein anterograde trafficking from the endoplasmic reticulum to the Golgi apparatus by the moderate overexpression of SEC16 could increase recombinant protein secretion in S. cerevisiae. In this study, the retrograde trafficking in a strain with moderate overexpression of SEC16 was engineered by overexpression of ADP-ribosylation factor GTP activating proteins, Gcs1p and Glo3p, which are involved in the process of COPI-coated vesicle formation. Engineering the retrograde trafficking increased the secretion of α-amylase but did not induce production of reactive oxygen species. An expanded ER membrane was detected in both the GCS1 and GLO3 overexpressio n strains. Physiological characterizations during batch fermentation showed that GLO3 overexpression had better effect on recombinant protein secretion than GCS1 overexpression. Additionally, the GLO3 overexpression strain had higher secretion of two other recombinant proteins, endoglucanase I from Trichoderma reesei and glucan-1,4-α-glucosidase from Rhizopus oryzae, indicating overexpression of GLO3 in a SEC16 moderate overexpression strain might be a general strategy for improving production of secreted proteins by yeast.
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| 3. |
- Bao, Jichen, 1988, et al.
(författare)
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Moderate Expression of SEC16 Increases Protein Secretion by Saccharomyces cerevisiae
- 2017
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Ingår i: Applied and Environmental Microbiology. - 1098-5336 .- 0099-2240. ; 83:14, s. Article no. UNSP e03400-16
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Tidskriftsartikel (refereegranskat)abstract
- The yeast Saccharomyces cerevisiae is widely used to produce biopharmaceutical proteins. However, the limited capacity of the secretory pathway may reduce its productivity. Here, we increased the secretion of a heterologous beta-amylase, a model protein used for studying the protein secretory pathway in yeast, by moderately overexpressing SEC16, which is involved in protein translocation from the endoplasmic reticulum to the Golgi apparatus. The moderate overexpression of SEC16 increased beta-amylase secretion by generating more endoplasmic reticulum exit sites. The production of reactive oxygen species resulting from the heterologous beta-amylase production was reduced. A genome-wide expression analysis indicated decreased endoplasmic reticulum stress in the strain that moderately overexpressed SEC16, which was consistent with a decreased volume of the endoplasmic reticulum. Additionally, fewer mitochondria were observed. Finally, the moderate overexpression of SEC16 was shown to improve the secretion of two other recombinant proteins, Trichoderma reesei endoglucanase I and Rhizopus oryzae glucan-1,4-beta-glucosidase, indicating that this mechanism is of general relevance. IMPORTANCE There is an increasing demand for recombinant proteins to be used as enzymes and pharmaceuticals. The yeast Saccharomyces cerevisiae is a cell factory that is widely used to produce recombinant proteins. Our study revealed that moderate overexpression of SEC16 increased recombinant protein secretion in S. cerevisiae. This new strategy can be combined with other targets to engineer cell factories to efficiently produce protein in the future.
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| 4. |
- Carmona-Gutierrez, D., et al.
(författare)
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Guidelines and recommendations on yeast cell death nomenclature
- 2018
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Ingår i: Microbial Cell. - : Shared Science Publishers OG. - 2311-2638. ; 5:1, s. 4-31
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Forskningsöversikt (refereegranskat)abstract
- Elucidating the biology of yeast in its full complexity has major implications for science, medicine and industry. One of the most critical processes determining yeast life and physiology is cellular demise. However, the investigation of yeast cell death is a relatively young field, and a widely accepted set of concepts and terms is still missing. Here, we propose unified criteria for the definition of accidental, regulated, and programmed forms of cell death in yeast based on a series of morphological and biochemical criteria. Specifically, we provide consensus guidelines on the differential definition of terms including apoptosis, regulated necrosis, and autophagic cell death, as we refer to additional cell death routines that are relevant for the biology of (at least some species of) yeast. As this area of investigation advances rapidly, changes and extensions to this set of recommendations will be implemented in the years to come. Nonetheless, we strongly encourage the authors, reviewers and editors of scientific articles to adopt these collective standards in order to establish an accurate framework for yeast cell death research and, ultimately, to accelerate the progress of this vibrant field of research.
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| 5. |
- Derouiche, Abderahmane, 1980, et al.
(författare)
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Bacillus subtilis single-stranded DNA-binding protein SsbA is phosphorylated at threonine 38 by the serine/threonine kinase YabT
- 2016
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Ingår i: Periodicum Biologorum. - : Hrvatski Prirodoslovno Drustvo (Croatian Society for Natural Sciences). - 0031-5362 .- 1849-0964. ; 118:4, s. 399-404
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Tidskriftsartikel (refereegranskat)abstract
- © 2016, Croatian Society of Natural Sciences. All rights reserved.Background and purpose: Single-stranded DNA-binding proteins participate in all stages of DNA metabolism that involve single-stranded DNA, from replication, recombination, repair of DNA damage, to natural competence in species such as Bacillus subtilis. B. subtilis single-stranded DNA-binding proteins have previously been found to be phosphorylated on tyrosine and arginine residues. While tyrosine phosphorylation was shown to enhance the DNA-binding properties of SsbA, arginine phosphorylation was not functionally characterized. Materials and methods: We used mass spectrometry analysis to detect phosphorylation of SsbA purified from B. subtilis cells. The detected phosphorylation site was assessed for its influence on DNA-binding in vitro, using electrophoretic mobility shift assays. The ability of B. subtilis serine/ threonine kinases to phosphorylate SsbA was assessed using in vitro phosphorylation assays. Results: In addition to the known tyrosine phosphorylation of SsbA on tyrosine 82, we identified a new phosphorylation site: threonine 38. The in vitro assays demonstrated that SsbA is preferentially phosphorylated by the B. subtilis Hanks-type kinase YabT, and phosphorylation of threonine 38 leads to enhanced cooperative binding to DNA. Conclusions: Our findings contribute to the emerging picture that bacterial proteins, exemplified here by SsbA, undergo phosphorylation at multiple residues. This results in a complex regulation of cellular functions, and suggests that the complexity of the bacterial cellular regulation may be underestimated.
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| 6. |
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| 7. |
- Huang, Mingtao, 1984, et al.
(författare)
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Efficient protein production by yeast requires global tuning of metabolism
- 2017
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Ingår i: Nature Communications. - : Nature Publishing Group. - 2041-1723. ; 8:1
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Tidskriftsartikel (refereegranskat)abstract
- The biotech industry relies on cell factories for production of pharmaceutical proteins, of which several are among the top-selling medicines. There is, therefore, considerable interest in improving the efficiency of protein production by cell factories. Protein secretion involves numerous intracellular processes with many underlying mechanisms still remaining unclear. Here, we use RNA-seq to study the genome-wide transcriptional response to protein secretion in mutant yeast strains. We find that many cellular processes have to be attuned to support efficient protein secretion. In particular, altered energy metabolism resulting in reduced respiration and increased fermentation, as well as balancing of amino-acid biosynthesis and reduced thiamine biosynthesis seem to be particularly important. We confirm our findings by inverse engineering and physiological characterization and show that by tuning metabolism cells are able to efficiently secrete recombinant proteins. Our findings provide increased understanding of which cellular regulations and pathways are associated with efficient protein secretion.
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| 8. |
- Huang, Mingtao, 1984, et al.
(författare)
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Engineering the protein secretory pathway of Saccharomyces cerevisiae enables improved protein production
- 2018
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 115:47, s. E11025-E11032
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Tidskriftsartikel (refereegranskat)abstract
- Baker’s yeast Saccharomyces cerevisiae is one of the most important and widely used cell factories for recombinant protein production. Many strategies have been applied to engineer this yeast for improving its protein production capacity, but productivity is still relatively low, and with increasing market demand, it is important to identify new gene targets, especially targets that have synergistic effects with previously identified targets. Despite improved protein production, previous studies rarely focused on processes associated with intracellular protein retention. Here we identified genetic modifications involved in the secretory and trafficking pathways, the histone deacetylase complex, and carbohydrate metabolic processes as targets for improving protein secretion in yeast. Especially modifications on the endosome-to-Golgi trafficking was found to effectively reduce protein retention besides increasing protein secretion. Through combinatorial genetic manipulations of several of the newly identified gene targets, we enhanced the protein production capacity of yeast by more than fivefold, and the best engineered strains could produce 2.5 g/L of a fungal α-amylase with less than 10% of the recombinant protein retained within the cells, using fed-batch cultivation.
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| 9. |
- Huang, Mingtao, 1984, et al.
(författare)
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Microfluidic screening and whole-genome sequencing identifies mutations associated with improved protein secretion by yeast
- 2015
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 112:34, s. E4689-E4696
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Tidskriftsartikel (refereegranskat)abstract
- There is an increasing demand for biotech-based production of recombinant proteins for use as pharmaceuticals in the food and feed industry and in industrial applications. Yeast Saccharomyces cerevisiae is among preferred cell factories for recombinant protein production, and there is increasing interest in improving its protein secretion capacity. Due to the complexity of the secretory machinery in eukaryotic cells, it is difficult to apply rational engineering for construction of improved strains. Here we used high-throughput microfluidics for the screening of yeast libraries, generated by UV mutagenesis. Several screening and sorting rounds resulted in the selection of eight yeast clones with significantly improved secretion of recombinant a-amylase. Efficient secretion was genetically stable in the selected clones. We performed whole-genome sequencing of the eight clones and identified 330 mutations in total. Gene ontology analysis of mutated genes revealed many biological processes, including some that have not been identified before in the context of protein secretion. Mutated genes identified in this study can be potentially used for reverse metabolic engineering, with the objective to construct efficient cell factories for protein secretion. The combined use of microfluidics screening and whole-genome sequencing to map the mutations associated with the improved phenotype can easily be adapted for other products and cell types to identify novel engineering targets, and this approach could broadly facilitate design of novel cell factories.
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| 10. |
- Liu, Lifang, 1979, et al.
(författare)
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Improving heterologous protein secretion at aerobic conditions by activating hypoxia-induced genes in Saccharomyces cerevisiae
- 2015
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Ingår i: FEMS Yeast Research. - : Oxford University Press (OUP). - 1567-1356 .- 1567-1364. ; 15:7, s. 10-
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Tidskriftsartikel (refereegranskat)abstract
- Oxygen is important for normal aerobic metabolism, as well as for protein production where it is needed for oxidative protein folding. However, several studies have reported that anaerobic conditions seem to be more favorable in terms of recombinant protein production. We were interested in increasing recombinant protein production under aerobic conditions so we focused on Rox1p regulation. Rox1p is a transcriptional regulator, which in oxidative conditions represses genes induced in hypoxia. We deleted ROX1 and studied the effects on the production of recombinant proteins in Saccharomyces cerevisiae. Intriguingly, we found a 100% increase in the recombinant fungal alpha-amylase yield, as well as productivity. Varied levels of improvements were also observed for the productions of the human insulin precursor and the yeast endogenous enzyme invertase. Based on the genome-wide transcriptional response, we specifically focused on the effect of UPC2 upregulation on protein production and suggested a possible mechanistic explanation.
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| 11. |
- Martinez Ruiz, Jose Luis, 1981, et al.
(författare)
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Engineering the Oxygen Sensing Regulation Results in an Enhanced Recombinant Human Hemoglobin Production by Saccharomyces cerevisiae
- 2015
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Ingår i: Biotechnology and Bioengineering. - : Wiley. - 0006-3592 .- 1097-0290. ; 112:1, s. 181-188
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Tidskriftsartikel (refereegranskat)abstract
- Efficient production of appropriate oxygen carriers for transfusions (blood substitutes or artificial blood) has been pursued for many decades, and to date several strategies have been used, from synthetic polymers to cell-free hemoglobin carriers. The recent advances in the field of metabolic engineering also allowed the generation of different genetically modified organisms for the production of recombinant human hemoglobin. Several studies have showed very promising results using the bacterium Escherichia coli as a production platform, reporting hemoglobin titers above 5% of the total cell protein content. However, there are still certain limitations regarding the protein stability and functionality of the recombinant hemoglobin produced in bacterial systems. In order to overcome these limitations, yeast systems have been proposed as the eukaryal alternative. We recently reported the generation of a set of plasmids to produce functional human hemoglobin in Saccharomyces cerevisiae, with final titers of active hemoglobin exceeding 4% of the total cell protein. In this study, we propose a strategy for further engineering S. cerevisiae by altering the oxygen sensing pathway by deleting the transcription factor HAP1, which resulted in an increase of the final recombinant active hemoglobin titer exceeding 7% of the total cellular protein.
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| 12. |
- Martinez Ruiz, Jose Luis, 1981, et al.
(författare)
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Heme metabolism in stress regulation and protein production: From Cinderella to a key player.
- 2016
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Ingår i: Bioengineered. - : Informa UK Limited. - 2165-5987 .- 2165-5979. ; 7:2, s. 1-4
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Heme biosynthesis is a highly conserved pathway which is present in all kingdoms, from Archaea to higher organisms such as plants and mammals. The heme molecule acts as a prosthetic group for different proteins and enzymes involved in energy metabolism and reactions involved in electron transfer. Based on our recent findings and other recent reports, we here illustrate that heme is more than a co-factor. We also discuss the necessity to gain more insight into the heme biosynthesis pathway regulation, as this interacts closely with overall stress control. Understanding heme biosynthesis and its regulation could impact our ability to develop more efficient yeast cell factories for heterologous protein production.
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| 13. |
- Muñoz Arellano, Ana Joyce, 1983, et al.
(författare)
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Different expression levels of human mutant ubiquitin B+1 (UBB+1) can modify chronological lifespan or stress resistance of saccharomyces cerevisiae
- 2018
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Ingår i: Frontiers in Molecular Neuroscience. - : Frontiers Media SA. - 1662-5099. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- The ubiquitin-proteasome system (UPS) is the main pathway responsible for the degradation of misfolded proteins, and its dysregulation has been implicated in several neurodegenerative diseases, including Alzheimer’s disease (AD). UBB+1, a mutant variant of ubiquitin B, was found to accumulate in neurons of AD patients and it has been linked to UPS dysfunction and neuronal death. Using the yeast Saccharomyces cerevisiae as a model system, we constitutively expressed UBB+1to evaluate its effects on proteasome function and cell death, particularly under conditions of chronological aging. We showed that the expression of UBB+1caused inhibition of the three proteasomal proteolytic activities (caspase-like (β1), trypsin-like (β2) and chymotrypsin-like (β5) activities) in yeast. Interestingly, this inhibition did not alter cell viability of growing cells. Moreover, we showed that cells expressing UBB+1at lower level displayed an increased capacity to degrade induced misfolded proteins. When we evaluated cells during chronological aging, UBB+1expression at lower level, prevented cells to accumulate reactive oxygen species (ROS) and avert apoptosis, dramatically increasing yeast life span. Since proteasome inhibition by UBB+1has previously been shown to induce chaperone expression and thus protect against stress, we evaluated our UBB+1model under heat shock and oxidative stress. Higher expression of UBB+1caused thermotolerance in yeast due to induction of chaperones, which occurred to a lesser extent at lower expression level of UBB+1(where we observed the phenotype of extended life span). Altering UPS capacity by differential expression of UBB+1protects cells against several stresses during chronological aging. This system can be valuable to study the effects of UBB+1on misfolded proteins involved in neurodegeneration and aging.
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| 14. |
- Wang, Guokun, 1988, et al.
(författare)
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RNAi expression tuning, microfluidic screening, and genome recombineering for improved protein production in Saccharomyces cerevisiae
- 2019
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 116:19, s. 9324-9332
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Tidskriftsartikel (refereegranskat)abstract
- The cellular machinery that supports protein synthesis and secretion lies at the foundation of cell factory-centered protein production. Due to the complexity of such cellular machinery, the challenge in generating a superior cell factory is to fully exploit the production potential by finding beneficial targets for optimized strains, which ideally could be used for improved secretion of other proteins. We focused on an approach in the yeast Saccharomyces cerevisiae that allows for attenuation of gene expression, using RNAi combined with high-throughput microfluidic single-cell screening for cells with improved protein secretion. Using direct experimental validation or enrichment analysis-assisted characterization of systematically introduced RNAi perturbations, we could identify targets that improve protein secretion. We found that genes with functions in cellular metabolism (YDC1, AAD4, ADE8, and SDH1), protein modification and degradation (VPS73, KTR2, CNL1, and SSA1), and cell cycle (CDC39), can all impact recombinant protein production when expressed at differentially down-regulated levels. By establishing a workflow that incorporates Cas9-mediated recombineering, we demonstrated how we could tune the expression of the identified gene targets for further improved protein production for specific proteins. Our findings offer a high throughput and semirational platform design, which will improve not only the production of a desired protein but even more importantly, shed additional light on connections between protein production and other cellular processes.
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| 15. |
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| 16. |
- Chen, Xin, 1980, et al.
(författare)
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Amyloid-beta peptide-induced cytotoxicity and mitochondrial dysfunction in yeast
- 2015
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Ingår i: FEMS Yeast Research. - : Oxford University Press (OUP). - 1567-1356 .- 1567-1364. ; 15:6
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Tidskriftsartikel (refereegranskat)abstract
- Alzheimer's disease (AD) is the most common neurodegenerative disease, characterized by deposits of amyloid-beta(A beta) peptides. However, the underlying molecular mechanisms of neuron cell dysfunction and cell death in AD still remain poorly understood. Yeast Saccharomyces cerevisiae shares many conserved biological processes with all eukaryotic cells, including human neurons. Thanks to relatively simple and quick genetic and environmental manipulations, the large knowledge base and data collections, this organism has become a valuable tool to unravel fundamental intracellular mechanisms underlying neurodegeneration. In this study, we have used yeast as a model system to study the effects of intracellular A beta peptides and we found that cells constitutively producing native A beta directed to the secretory pathway exhibited a lower growth rate, lower biomass yield, lower respiratory rate, increased oxidative stress, hallmarks of mitochondrial dysfunction and ubiquitin-proteasome system dysfunction. These findings are relevant for better understanding the role of A beta in cell stress and cell damage.
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| 17. |
- Chen, Xin, 1980, et al.
(författare)
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Interplay of Energetics and ER Stress Exacerbates Alzheimer's Amyloid-beta (A beta) Toxicity in Yeast
- 2017
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Ingår i: Frontiers in Molecular Neuroscience. - : Frontiers Media SA. - 1662-5099. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Alzheimer's disease (AD) is a progressive neurodegeneration. Oligomers of amyloid-beta peptides (A beta) are thought to play a pivotal role in AD pathogenesis, yet the mechanisms involved remain unclear. Two major isoforms of A beta associated with AD are A beta 40 and A beta 42, the latter being more toxic and prone to form oligomers. Here, we took a systems biology approach to study two humanized yeast AD models which expressed either A beta 40 or A beta 42 in bioreactor cultures. Strict control of oxygen availability and culture pH, strongly affected chronological lifespan and reduced variations during cell growth. Reduced growth rates and biomass yields were observed upon A beta 42 expression, indicating a redirection of energy from growth to maintenance. Quantitative physiology analyses furthermore revealed reduced mitochondria' functionality and ATP generation in A beta 42 expressing cells, which matched with observed aberrant mitochondria' structures. Genome-wide expression level analysis showed that A beta 42 expression triggered strong ER stress and unfolded protein responses. Equivalent expression of A beta 40, however, induced only mild ER stress, which resulted in hardly affected physiology. Using AD yeast models in well controlled cultures strengthened our understanding on how cells translate different A beta toxicity signals into particular cell fate programs, and further enhance their potential as a discovery platform to identify possible therapies.
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| 18. |
- Chen, Xin, 1980, et al.
(författare)
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Role of frameshift ubiquitin B protein in Alzheimer's disease
- 2016
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Ingår i: Wiley Interdisciplinary Reviews: Systems Biology and Medicine. - : Wiley. - 1939-5094 .- 1939-005X. ; 8:4, s. 300-313
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Forskningsöversikt (refereegranskat)abstract
- Alzheimer's disease (AD) is the most common neurodegenerative disease and is characterized by accumulation of misfolded and aggregated proteins. Since the ubiquitin-proteasome system (UPS) is the major intracellular protein quality control (PQC) system in eukaryotic cells, it is likely involved in the etiology of AD. The frameshift form of ubiquitin (Ubb+1) accumulates in the neuritic plaques and neurofibrillary tangles in patients with AD. Ubb+1 accumulates in an age-dependent manner as a result of RNA-polymerase mediated molecular misreading during transcription, which allows the formation of mutant proteins in the absence of gene mutations. The accumulation of the Ubb+1 protein may act as an endogenous reporter for proteasome dysfunction and a growing number of studies have shown that Ubb+1 may play more important pathogenic roles in AD etiology than previously hypothesized. The yeast Saccharomyces cerevisiae shares many conserved biological processes with all eukaryotic cells, including human neurons. This organism has been regarded as a model system for investigating the fundamental intracellular mechanisms, including those underlying neurodegeneration. We propose here that yeast systems biology approaches, combined with cell and molecular biology approaches will increase the relevant knowledge needed for advancement and elucidation of mechanisms and complex traits, which could provide new targets for therapeutic intervention in AD. WIREs Syst Biol Med 2016, 8:300–313. doi: 10.1002/wsbm.1340. For further resources related to this article, please visit the WIREs website.
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| 19. |
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| 20. |
- Ishchuk, Olena, 1980, et al.
(författare)
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Improving the Production of Cofactor-Containing Proteins: Production of Human Hemoglobin in Yeast
- 2019
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Ingår i: Methods in Molecular Biology. - New York, NY : Springer New York. - 1940-6029 .- 1064-3745. ; 1923, s. 243-264
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Human hemoglobin is an essential protein, whose main function as an oxygen carrier is indispensable for life. Hemoglobin is a cofactor-containing protein with heme as prosthetic group. Same as in humans, heme is synthesized in many organisms in a complex pathway involving two cellular compartments (mitochondria and cytosol), which is tightly regulated. Red blood cells (erythrocytes) are specialized and adapted for production and transport of the hemoglobin molecules. In addition to oxygen binding, hemoglobin can participate in a variety of chemical reactions by its iron and heme and may become toxic when released from erythrocytes. Hemoglobin is a major target for the development of blood substitutes/oxygen carriers, and therefore its microbial production is attractive, as it may provide a cheap and reliable source of human hemoglobin. Significant efforts have been dedicated to this task for the last three decades. Moreover since the first generation of cell-free blood substitutes based on unmodified hemoglobin failed human trials, mutant forms became of great interest.In this chapter we summarize the existing knowledge about human hemoglobin, challenges of its microbial production, and its improvement, with a particular focus upon yeast as production host.
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| 21. |
- Johansson, Magnus, 1983, et al.
(författare)
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PUFA-induced cell death is mediated by Yca1p-dependent and -independent pathways, and is reduced by vitamin C in yeast
- 2016
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Ingår i: FEMS Yeast Research. - : Oxford University Press (OUP). - 1567-1356 .- 1567-1364. ; 16:2
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Tidskriftsartikel (refereegranskat)abstract
- Polyunsaturated fatty acids (PUFA) such as linoleic acid (LA, n-6, C18:2) and gamma-linolenic acid (GLA, n-6, C18: 3) are essential and must be obtained from the diet. There has been a growing interest in establishing a bio-sustainable production of PUFA in several microorganisms, e.g. in yeast Saccharomyces cerevisiae. However, PUFAs can also be toxic to cells because of their susceptibility to peroxidation. Here we investigated the negative effects of LA and GLA production on S. cerevisiae by characterizing a strain expressing active Delta 6 and Delta 12 desaturases from the fungus Mucor rouxii. Previously, we showed that the PUFA-producing strain has low viability, down-regulated genes for oxidative stress response, and decreased proteasome activity. Here we show that the PUFA strain accumulates high levels of reactive oxygen species (ROS) and lipid peroxides, and accumulates damaged proteins. The PUFA strain also showed great increase in metacaspase Yca1p activity, suggesting cells could die by caspase-mediated cell death. When treated with antioxidant vitamin C, ROS, lipid peroxidation and protein carbonylation were greatly reduced, and the activity of the metacaspase was significantly decreased too, ultimately doubling the lifespan of the PUFA strain. When deleting YCA1, the caspase-like activity and the oxidative stress decreased and although the lifespan was slightly prolonged, the phenotype could not be fully reversed, pointing that Yca1p was not the main executor of cell death.
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| 22. |
- Ponnandai Schanmugavel, Kumaravel, 1991, et al.
(författare)
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Probing functional roles of Wilson disease protein (ATP7B) copper-binding domains in yeast
- 2017
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Ingår i: Metallomics. - : Oxford University Press (OUP). - 1756-5901 .- 1756-591X. ; 9:7, s. 981-988
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Tidskriftsartikel (refereegranskat)abstract
- After Ctr1-mediated uptake into human cells, copper (Cu) ions are transported by the cytoplasmic Cu chaperone Atox1 to the Wilson disease protein (ATP7B) in the Golgi network. Cu transfer occurs via direct protein-protein interactions and leads to incorporation of Cu into Cu-dependent enzymes. ATP7B is a large multi-domain membrane-spanning protein which, in contrast to homologs, has six cytoplasmic metal-binding domains (MBDs). The reason for multiple MBDs is proposed to be indirect modulation of activity but mechanistic studies of full-length ATP7B are limited. We here developed a system that probes Cu flow through human Atox1 and ATP7B proteins when expressed in yeast. Using this assay, we assessed the roles of the different MBDs in ATP7B and found that the presence of the most N-terminal MBD increased, whereas the third MBD decreased, overall ATP7B-mediated Cu transport activity. Upon removal of all MBDs in ATP7B, the ability to transport Cu disappeared. The designed system can be expanded to include other yeast viability parameters and will be a useful tool for further mechanistic insights on human Cu transport as well as diseases involving Cu imbalance.
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| 23. |
- Tang, Hongting, et al.
(författare)
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Efficient yeast surface-display of novel complex synthetic cellulosomes
- 2018
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Ingår i: Microbial Cell Factories. - : Springer Science and Business Media LLC. - 1475-2859. ; 17:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: The self-assembly of cellulosomes on the surface of yeast is a promising strategy for consolidated bioprocessing to convert cellulose into ethanol in one step. Results: In this study, we developed a novel synthetic cellulosome that anchors to the endogenous yeast cell wall protein a-agglutinin through disulfide bonds. A synthetic scaffoldin ScafAGA3 was constructed using the repeated N-terminus of Aga1p and displayed on the yeast cell surface. Secreted cellulases were then fused with Aga2p to assemble the cellulosome. The display efficiency of the synthetic scaffoldin and the assembly efficiency of each enzyme were much higher than those of the most frequently constructed cellulosome using scaffoldin ScafCipA3 from Clostridium thermocellum. A complex cellulosome with two scaffoldins was also constructed using interactions between the displayed anchoring scaffoldin ScafAGA3 and scaffoldin I ScafCipA3 through disulfide bonds, and the assembly of secreted cellulases to ScafCipA3. The newly designed cellulosomes enabled yeast to directly ferment cellulose into ethanol. Conclusions: This is the first report on the development of complex multiple-component assembly system through disulfide bonds. This strategy could facilitate the construction of yeast cell factories to express synergistic enzymes for use in biotechnology.
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| 24. |
- Wanichthanarak, Kwanjeera, 1981, et al.
(författare)
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Genome-wide expression analyses of the stationary phase model of ageing in yeast
- 2015
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Ingår i: Mechanisms of Ageing and Development. - : Elsevier BV. - 0047-6374 .- 1872-6216. ; 149, s. 65-74
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Tidskriftsartikel (refereegranskat)abstract
- Ageing processes involved in replicative lifespan (RLS) and chronological lifespan (CLS) have been found to be conserved among many organisms, including in unicellular Eukarya such as yeast Saccharomyces cerevisiae. Here we performed an integrated approach of genome wide expression profiles of yeast at different time points, during growth and starvation. The aim of the study was to identify transcriptional changes in those conditions by using several different computational analyses in order to propose transcription factors, biological networks and metabolic pathways that seem to be relevant during the process of chronological ageing in yeast. Specifically, we performed differential gene expression analysis, gene-set enrichment analysis and network-based analysis, and we identified pathways affected in the stationary phase and specific transcription factors driving transcriptional adaptations. The results indicate signal propagation from G protein-coupled receptors through signaling pathway components and other stress and nutrient-induced transcription factors resulting in adaptation of yeast cells to the lack of nutrients by activating metabolism associated with aerobic metabolism of carbon sources such as ethanol, glycerol and fatty acids. In addition, we found STE12, XBP1 and TOS8 as highly connected nodes in the subnetworks of ageing yeast.
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