Objectives: To genetically engineer Saccharomyces cerevisiae for improved ethanol productivity from glucose/xylose mixtures.
Results: An endogenous gene cassette composed of aldose reductase (GRE3), sorbitol dehydrogenase (SOR1) and xylulose kinase (XKS1) with a PGK1 promoter and a terminator was introduced into two S. cerevisiae strains, a laboratory strain (CEN.PK2-1C) and an industrial strain (Kyokai No. 7). The engineered Kyokai No. 7 strain (K7-XYL) exhibited a higher sugar consumption rate (1.03 g l(-1) h(-1)) and ethanol yield (63.8 %) from a glucose and xylose mixture compared to the engineered CEN.PK2-1C strain. Furthermore, K7-XYL produced a larger amount of ethanol (39.6 g l(-1)) compared to K7-SsXYL (32 g l(-1)) with integrated xylose reductase and xylitol dehydrogenase from a xylose-assimilating yeast Scheffersomyces stipitis instead of GRE3 and SOR1.
Conclusion: The created S. cerevisiae strain showed sufficient xylose-fermenting ability to be used for efficient ethanol production from glucose/xylose.
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http://dx.doi.org/10.1007/s10529-015-1840-2 | DOI Listing |
BBA Adv
October 2024
Department of Biochemistry, Panjab University, Chandigarh 160014, India.
Hal5 gene is involved in halo-tolerance of during high salt stress. Ethanol stress and high salt stress have similarities, as both decrease the availability of water for cells and strain the osmotic homeostasis across the cell membrane. The Hal5 over-expression strain of yeast has more ethanol tolerance, but the Hal5 null mutant strain also has more ethanol tolerance than the wild-type strain.
View Article and Find Full Text PDFNonsense-mediated decay (NMD) is a eukaryotic surveillance pathway that controls degradation of cytoplasmic transcripts with aberrant features. NMD-controlled RNA degradation acts to regulate a large fraction of the mRNA population. It has been implicated in cellular responses to infections and environmental stress, as well as in deregulation of tumor-promoting genes.
View Article and Find Full Text PDFJ Biol Chem
January 2025
Department of Biological Sciences, St. John's University, Queens, New York, USA. Electronic address:
One of the key events in DNA damage response (DDR) is activation of checkpoint kinases leading to activation of ribonucleotide reductase (RNR) and increased synthesis of deoxyribonucleotide triphosphates (dNTPs), required for DNA repair. Among other mechanisms, the activation of dNTP synthesis is driven by derepression of genes encoding RNR subunits RNR2, RNR3, and RNR4, following checkpoint activation and checkpoint kinase Dun1p-mediated phosphorylation and inactivation of transcriptional repressor Crt1p. We report here that in the absence of genotoxic stress during respiratory growth on nonfermentable carbon source acetate, inactivation of checkpoint kinases results in significant growth defect and alters transcriptional regulation of RNR2-4 genes and genes encoding enzymes of the tricarboxylic acid (TCA) and glyoxylate cycles and gluconeogenesis.
View Article and Find Full Text PDFmBio
January 2025
Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York, USA.
Unlabelled: Pathogenic strains cause cholera using different mechanisms. O1 and O139 serogroup strains use the toxin-co-regulated pilus (TCP) and cholera toxin (CT) for intestinal colonization and to promote secretory diarrhea, while non-O1/non-O139 serogroup strains are typically non-toxigenic and use alternate virulence factors to cause a clinically similar disease. An O39 serogroup, TCP/CT-negative strain, named AM-19226, uses a type III secretion system (T3SS) to translocate more than 10 effector proteins into the host cell cytosol.
View Article and Find Full Text PDFNucleic Acids Res
January 2025
Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China.
Achieving targeted hypermutation of specific genomic sequences without affecting other regions remains a key challenge in continuous evolution. To address this, we evolved a T7 RNA polymerase (RNAP) mutant that synthesizes single-stranded DNA (ssDNA) instead of RNA in vivo, while still exclusively recognizing the T7 promoter. By increasing the error rate of the T7 RNAP mutant, it generates mutated ssDNA that recombines with homologous sequences in the genome, leading to targeted genomic hypermutation.
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