Search results for "MUTATION"
showing 10 items of 2830 documents
Molecular response of Saccharomyces cerevisiae wine and laboratory strains to high sugar stress conditions.
2010
One of the stress conditions that can affect Saccharomyces cerevisiae cells during their growth is osmotic stress. Under particular environments (for instance, during the production of alcoholic beverages) yeasts have to cope with osmotic stress caused by high sugar concentrations. Although the molecular changes and pathways involved in the response to saline or sorbitol stress are widely understood, less is known about how cells respond to high sugar concentrations. In this work we present a comprehensive study of the response to this form of stress which indicates important transcriptomic changes, especially in terms of the genes involved in both stress response and respiration, and the i…
The C-terminal region of the Hot1 transcription factor binds GGGACAAA-related sequences in the promoter of its target genes
2015
Response to hyperosmotic stress in the yeast Saccharomyces cerevisiae involves the participation of the general stress response mediated by Msn2/4 transcription factors and the HOG pathway. One of the transcription factors activated through this pathway is Hot1, which contributes to the control of the expression of several genes involved in glycerol synthesis and flux, or in other functions related to adaptation to adverse conditions. This work provides new data about the interaction mechanism of this transcription factor with DNA. By means of one-hybrid and electrophoretic mobility assays, we demonstrate that the C-terminal region, which corresponds to amino acids 610-719, is the DNA-bindi…
Genetic analysis of maintenance and expression of L and M double-stranded RNAs from yeast killer virus K28
1992
The killer phenotype expressed by Saccharomyces cerevisiae strain 28 differs from that of the more extensively studied K1 and K2 killers with respect to immunity, mode of toxin action and cell wall primary toxin receptor. We previously demonstrated that the M28 and L28 dsRNAs found in strain 28 are present in virus-like particles (VLPs) and that transfection with these VLPs is sufficient to confer the complete K28 phenotype on a dsRNA-free recipient cell. We also demonstrated that L28, like the L-A-H species in K1 killers, has [HOK] activity required for maintenance of M1-dsRNA, and predicted that M28 would share with M1 dependence on L-A for replication. We now confirm this prediction by g…
The ATC1 gene encodes a cell wall-linked acid trehalase required for growth on trehalose in Candida albicans.
2004
After screening a Candida albicans genome data base, the product of an open reading frame (IPF 19760/CA2574) with 41% identity to Saccharomyces cerevisiae vacuolar acid trehalase (Ath1p) was identified and named Atc1p. The deduced amino acid sequence shows that Atc1p contains an N-terminal hydrophobic signal peptide and 20 potential sites for N-glycosylation. C. albicans homozygous mutants that lack acid trehalase activity were constructed by gene disruption at the two ATC chromosomal alleles. Analysis of these null mutants shows that Atc1p is localized in the cell wall and is required for growth on trehalose as a carbon source. An Atc1p endowed with acid trehalase activity was obtained by …
Ubiquitin ligase Rsp5p is involved in the gene expression changes during nutrient limitation inSaccharomyces cerevisiae
2009
Rsp5p is an essential ubiquitin ligase involved in many different cellular events, including amino acid transporters degradation, transcription initiation and mRNA export. It plays important role in both stress resistance and adaptation to the change of nutrients. We have found that ubiquitination machinery is necessary for the correct induction of the stress response SPI1 gene at the entry of the stationary phase. SPI1 is a gene whose expression is regulated by the nutritional status of the cell and whose deletion causes hypersensitivity to various stresses, such as heat shock, alkaline stress and oxidative stress. Its regulation is mastered by Rsp5p, as mutations in this gene lead to a lo…
Saccharomyces cerevisiae Glutaredoxin 5-deficient Cells Subjected to Continuous Oxidizing Conditions Are Affected in the Expression of Specific Sets …
2004
The Saccharomyces cerevisiae GRX5 gene codes for a mitochondrial glutaredoxin involved in the synthesis of iron/sulfur clusters. Its absence prevents respiratory growth and causes the accumulation of iron inside cells and constitutive oxidation of proteins. Null ⌬grx5 mu- tants were used as an example of continuously oxidized cells, as opposed to situations in which oxidative stress is instantaneously caused by addition of external oxi- dants. Whole transcriptome analysis was carried out in the mutant cells. The set of genes whose expression was affected by the absence of Grx5 does not significantly overlap with the set of genes affected in respiratory petite mutants. Many Aft1-dependent ge…
Specific Defects in Different Transcription Complexes Compensate for the Requirement of the Negative Cofactor 2 Repressor in Saccharomyces cerevisiae
2007
Abstract Negative cofactor 2 (NC2) has been described as an essential and evolutionarily conserved transcriptional repressor, although in vitro and in vivo experiments suggest that it can function as both a positive and a negative effector of transcription. NC2 operates by interacting with the core promoter and components of the basal transcription machinery, like the TATA-binding protein (TBP). In this work, we have isolated mutants that suppress the growth defect caused by the depletion of NC2. We have identified mutations affecting components of three different complexes involved in the control of basal transcription: the mediator, TFIIH, and RNA pol II itself. Mutations in RNA pol II in…
The distribution of active RNA polymerase II along the transcribed region is gene-specific and controlled by elongation factors.
2010
In order to study the intragenic profiles of active transcription, we determined the relative levels of active RNA polymerase II present at the 3'- and 5'-ends of 261 yeast genes by run-on. The results obtained indicate that the 3'/5' run-on ratio varies among the genes studied by over 12 log(2) units. This ratio seems to be an intrinsic characteristic of each transcriptional unit and does not significantly correlate with gene length, G + C content or level of expression. The correlation between the 3'/5' RNA polymerase II ratios measured by run-on and those obtained by chromatin immunoprecipitation is poor, although the genes encoding ribosomal proteins present exceptionally low ratios in …
Acid excreting mutants of yeast Saccharomyces cerevisiae.
2004
Saccharomyces cerevisiae mutants acidifying glucose medium containing bromocresol purple were shown to excrete protons when placed in unbuffered water in the absence of any external carbon source. The mutants belong to 16 different complementation groups. Most of them do not grow on glycerol and the excreted protons are associated to particular sets of organic anions such as citrate, aconitate, succinate, fumarate or malate. These novel types of respiratory mutations seem to be located in genes operating in the Krebs or glyoxylate cycle.
Diagonalization of indefinite saddle point forms
2020
We obtain sufficient conditions that ensure block diagonalization (by a direct rotation) of sign-indefinite symmetric sesquilinear forms as well as the associated operators that are semi-bounded neither from below nor from above. In the semi-bounded case, we refine the obtained results and, as an example, revisit the block Stokes operator from fluid dynamics.