Search results for "Mutant"
showing 10 items of 670 documents
Citrate permease gene expression inLactococcus lactissubsp.lactisstrains IL1403 and MG1363
1996
Citrate permease gene expression in the plasmid-free Lactococcus lactis strains IL1403 and MG1363 was studied. The ability to transport citrate results in diacetyl and acetoin production in IL1403 but not in MG1363. Citrate lyase, α-acetolactate decarboxylase, diacetyl and acetoin reductase were detected in IL1403. These data show that L. lactis ssp. lactis strain IL1403 is a citrate permease mutant of the biovar. diacetylactis. Immunological analysis revealed the α-and β-subunits of citrate lyase not only in IL1403 but also in MG1363 where no citrate lyase activity was found.
Changes in the Pi uptake and polyP accumulation in Saccharomyces cerevisiae strains deficient in the synthesis of trehalose and/or glycerol
2007
Abstract The intracellular level of free inorganic orthophosphate (P i ) in yeast cells generally depends on the P i uptake capacity, energy state of the cells in respect to the activity of the membrane-associated ATPases and on the activity of metabolic pathways involved in the production of glycerol and trehalose. Batch fermentation was performed to investigate the carbon substrate consumption, the P i uptake capacity and product formation by four Saccharomyces cerevisiae strains differing in their ability to produce glycerol and/or trehalose. The consumption of P i in mutant strains with a lack of the synthesis of the trehalose and/or glycerol exceeded the level for a wild type strain ab…
Active site conformation in the αH87G mutant hemoglobin: An optical absorption and FTIR study
2000
We have studied the active site conformation in the carbonmonoxy derivative of the αH87G mutant hemoglobin by means of optical absorption and FTIR spectroscopies. A red shift (≈30 cm−1) of the Soret band peak frequency, together with a concomitant red shift (≈2 cm−1) of the bound CO stretching frequency has been observed for the mutant protein. This indicates an altered electrostatic environment of the heme group in the mutated subunits. In view of the FTIR data showing that the bound CO molecule experiences an increased positive electrostatic field, we attribute the observed effects to a closer interaction of the CO ligand with the partially positively charged imidazole side chain of the p…
Dysfunction of Torr causes a Harlequin-type ichthyosis-like phenotype in Drosophila melanogaster
2019
AbstractPrevention of desiccation is a constant challenge for terrestrial organisms. Land insects have an extracellular coat, the cuticle, that plays a major role in protection against exaggerated water loss. Here, we report that the ABC transporter Torr - a human ABCA12 paralog - contributes to the waterproof barrier function of the cuticle in the fruit fly Drosophila melanogaster. We show that the reduction or elimination of Torr function provokes rapid desiccation. Torr is also involved in defining the inward barrier against xenobiotics penetration. Consistently, the amounts of cuticular hydrocarbons that are involved in cuticle impermeability decrease markedly when Torr activity is redu…
Glucose uptake in germinating Aspergillus nidulans conidia: involvement of the creA and sorA genes
2003
d-Glucose uptake in germinating wild-typeAspergillus nidulansconidia is an energy-requiring process mediated by at least two transport systems of differing affinities for glucose: a low-affinity system (Km∼1·4 mM) and a high-affinity system (Km∼16 μM). The low-affinity system is inducible by glucose; the high-affinity system is subject to glucose repression effected by the carbon catabolite repressor CreA and is absent insorA3mutant conidia, which exhibit resistance tol-sorbose toxicity. An intermediate-affinity system (Km∼400 μM) is present insorA3conidia germinating in derepressing conditions.creAderepressed mutants show enhanced sensitivity tol-sorbose. The high-affinity uptake system ap…
Isolation and characterization of yeast monomorphic mutants of Candida albicans.
1994
A method was devised for the isolation of yeast monomorphic (LEV) mutants of Candida albicans. By this procedure, about 20 stable yeast-like mutants were isolated after mutagenesis with ethyl methane sulfonate. The growth rate of the mutants in different carbon sources, both fermentable and not, was indistinguishable from that of the parental strain, but they were unable to grow as mycelial forms after application of any of the common effective inducers, i.e., heat shock, pH alterations, proline addition, or use of GlcNAc as the carbon source. Studies performed with one selected strain demonstrated that it had severe alterations in the chemical composition of the cell wall, mainly in the le…
Characterization of aSchizosaccharomyces pombemorphological mutant altered in the galactomannan content
1991
In a search for Schizosaccharomyces pombe mutants resistant to the antifungal agent papulacandin B, a morphological mutant was isolated. The mutant is round shaped in contrast to the rod shaped parental strain. This morphological defect segregated as a recessive Mendelian character and was not observed in other papulacandin B resistant mutants belonging to the same complementation group. The mutation mapped in the right arm of S. pombe chromosome III very close to pap1 marker. Mutant cell walls were more susceptible to alkali extraction and Novozyme degradation than those from the wild-type. A specific reduction in the cell wall galactomannan fraction was the only significant difference det…
The intracellular Arabidopsis COPT5 transport protein is required for photosynthetic electron transport under severe copper deficiency
2011
Copper is an essential micronutrient that functions as a redox cofactor in multiple plant processes, including photosynthesis. Arabidopsis thaliana possesses a conserved family of CTR-like high-affinity copper transport proteins denoted as COPT1-5. COPT1, the only family member that is functionally characterized, participates in plant copper acquisition. However, little is known about the function of the other Arabidopsis COPT proteins in the transport and distribution of copper. Here, we show that a functional fusion of COPT5 to the green fluorescent protein localizes in Arabidopsis cells to the prevacuolar compartment. Plants defective in COPT5 do not exhibit any significant phenotype und…
Increased Auxin Content and Altered Auxin Response in Barley Necrotic Mutant nec1
2012
The role of hormone crosstalk in plant immunity is lately emerging as significant topic of plant physiology. Although crosstalk between salicylic acid and auxin affects plant disease resistance, molecular mechanisms of this process have not yet been uncovered in details. Mutations disrupting cyclic nucleotide-gated ion channel 4 (CNGC4) affect SA-mediated disease resistance in barley Hordeum vulgare and in A. thaliana. Significantly, decreased stomatal apertures of barley CNGC4 mutant nec1 and dwarfed stature of A. thaliana CNGC4 mutant dnd2 suggest that nonfunctional CNGC4 might be affecting also auxin signaling. Excised coleoptile elongation, stomatal conductance, and cell size measuremen…
Large-scale analysis of SARS-CoV-2 spike-glycoprotein mutants demonstrates the need for continuous screening of virus isolates
2021
AbstractDue to the widespread of the COVID-19 pandemic, the SARS-CoV-2 genome is evolving in diverse human populations. Several studies already reported different strains and an increase in the mutation rate. Particularly, mutations in SARS-CoV-2 spike-glycoprotein are of great interest as it mediates infection in human and recently approved mRNA vaccines are designed to induce immune responses against it.We analyzed 146,917 SARS-CoV-2 genome assemblies and 2,393 NGS datasets from GISAID, NCBI Virus and NCBI SRA archives focusing on non-synonymous mutations in the spike protein.Only around 13.8% of the samples contained the wild-type spike protein with no variation from the reference. Among…