Search results for "mutant"
showing 10 items of 670 documents
Isolation and characterization of anavirulent Candida albicansyeast monomorphic mutant
2003
Mutagenesis of Candida albicans strain ATCC 26555 with N-methyl-nitro-N-nitrosoguanidine followed by plating on solid yeast nitrogen base-N-acetylglucosamine medium at 37 degrees C yielded colony morphology variants that were characterized as forming smooth colonies, in contrast to the rough colonies formed by the parental strain. One yeast monomorphic mutant, CAL4, was studied in detail. Strain CAL4 is defective in filamentous growth, unable to form hyphae or pseudohyphae in vivo and in vitro. These filamentous structures are not elicited by commonly used external stimuli such as serum. The mutant had no obvious alterations in its mannan, glucan or chitin content. The total quantity of non…
Mitochondrial localization and temporal expression of the Drosophila melanogaster DnaJ homologous tumor suppressor Tid50
1998
The Drosophila melanogaster tumor suppressor gene lethal(2)tumorous imaginal discs (tid) was identified as a homolog of all dnaJ-like genes known to date which have been well preserved in evolution. Homozygous D. melanogaster l(2)tid mutants l(2)tid1, l(2)tid2 and l(2)tid3 are characterized by neoplastic transformation of the adult integumental primordia, the imaginal discs, and the death at the time of puparium formation. The first part of this study is concerned with the identification and subcellular localization of the l(2)tid-encoded protein, Tid50. The second part examines its tissue specific expression during wild-type development and in tumorous imaginal discs. To specify the functi…
T helper 17 lineage differentiation is programmed by orphan nuclear receptors ROR alpha and ROR gamma.
2007
T cell functional differentiation is mediated by lineage-specific transcription factors. T helper 17 (Th17) has been recently identified as a distinct Th lineage mediating tissue inflammation. Retinoic acid receptor-related orphan receptor gamma (ROR gamma) was shown to regulate Th17 differentiation; ROR gamma deficiency, however, did not completely abolish Th17 cytokine expression. Here, we report Th17 cells highly expressed another related nuclear receptor, ROR alpha, induced by transforming growth factor-beta and interleukin-6 (IL-6), which is dependent on signal transducer and activator of transcription 3. Overexpression of ROR alpha promoted Th17 differentiation, possibly through the c…
A membrane-destabilizing peptide in capsid protein L2 is required for egress of papillomavirus genomes from endosomes
2005
ABSTRACT Papillomaviruses are internalized via clathrin-dependent endocytosis. However, the mechanism by which viral genomes pass endosomal membranes has not been elucidated. In this report we show that the minor capsid protein L2 is required for egress of viral genomes from endosomes but not for initial uptake and uncoating and that a 23-amino-acid peptide at the C terminus of L2 is necessary for this function. Pseudogenomes encapsidated by L1 and L2 lacking this peptide accumulated in vesicular compartments similar to that observed with L1-only viral particles, and these mutant pseudoviruses were noninfectious. This L2 peptide displayed strong membrane-disrupting activity, induced cytolys…
Mutant Plasticity Related Gene 1 (PRG1) acts as a potential modifier in SCN1A related epilepsy
2018
ABSTRACTPlasticity related gene 1 encodes a cerebral neuron-specific synaptic transmembrane protein that modulates hippocampal excitatory transmission on glutamatergic neurons. In mice, homozygous Prg1-deficiency results in juvenile epilepsy. Screening a cohort of 18 patients with infantile spasms (West syndrome), we identified one patient with a heterozygous mutation in the highly conserved third extracellular phosphatase domain (p.T299S). The functional relevance of this mutation was verified by in-utero electroporation of a mutant Prg1 construct into neurons of Prg1-knockout embryos, and the subsequent inability of hippocampal neurons to rescue the knockout phenotype on the single cell l…
Binding of Escherichia coli hemolysin and activation of the target cells is not receptor-dependent.
2005
Abstract Production of a single cysteine substitution mutant, S177C, allowed Escherichia coli hemolysin (HlyA) to be radioactively labeled with tritiated N-ethylmaleimide without affecting biological activity. It thus became possible to study the binding characteristics of HlyA as well as of toxin mutants in which one or both acylation sites were deleted. All toxins bound to erythrocytes and granulocytes in a nonsaturable manner. Only wild-type toxin and the lytic monoacylated mutant stimulated production of superoxide anions in granulocytes. An oxidative burst coincided with elevation of intracellular Ca2+, which was likely because of passive influx of Ca2+ through the toxin pores. Competi…
Crucial role of aspartic acid at position 265 in the CH2 domain for murine IgG2a and IgG2b Fc-associated effector functions.
2008
Abstract Replacement of aspartic acid by alanine at position 265 (D265A) in mouse IgG1 results in a complete loss of interaction between this isotype and low-affinity IgG Fc receptors (FcγRIIB and FcγRIII). However, it has not yet been defined whether the D265A substitution could exhibit similar effects on the interaction with two other FcγR (FcγRI and FcγRIV) and on the activation of complement. To address this question, 34-3C anti-RBC IgG2a and IgG2b switch variants bearing the D265A mutation were generated, and their effector functions and in vivo pathogenicity were compared with those of the respective wild-type Abs. The introduction of the D265A mutation almost completely abolished the…
Photobacterium damselae subsp. damselae Major Virulence Factors Dly, Plasmid-Encoded HlyA, and Chromosome-Encoded HlyA Are Secreted via the Type II S…
2015
ABSTRACT Photobacterium damselae subsp. damselae is a marine bacterium that causes septicemia in marine animals and in humans. Previously, we had determined a major role of pPHDD1 plasmid-encoded Dly (damselysin) and HlyA (HlyA pl ) and the chromosome-encoded HlyA (HlyA ch ) hemolysins in virulence. However, the mechanisms by which these toxins are secreted remain unknown. In this study, we found that a mini-Tn 10 transposon mutant in a plasmidless strain showing an impaired hemolytic phenotype contained an insertion in epsL , a component of a type II secretion system (T2SS). Reconstruction of the mutant by allelic exchange confirmed the specific involvement of epsL in HlyA ch secretion. In…
Die Bildung höherer Alkohole bei Aminosäuremangelmutanten von Saccharomyces cerevisiae III. Höhere Alkohole als Nebenprodukte der Aminosäuresynthese
1975
Summary The formation of higher alcohols as byproducts of the synthesis of threonine, isoleucine and valine was investigated using isogenic haploid and diploid mutant strains of Saccharomyces cerevisiae . Genetic markers were ade 2, leu 1. The growth rate, the formation of ethanol, the amino acid metabolism and the formation of higher alcohols were determined during fermentations in a synthetic medium. n-Propanol-1, 2-methylbutanol-l and isobutanol were synthesized parallel to ethanol formation during exponential and stationary growth phase. However, the formation of 3-methylbutanol-l from leucine was restricted to the exponential phase. A comparison of haploid and diploid strains revealed,…
Regulation of cuticular hydrocarbon profile maturation by Drosophila tanning hormone, bursicon, and its interaction with desaturase activity
2016
International audience; Shortly after emergence the exoskeleton (cuticle) of adult insects is rapidly expanded, hardened (sclerotized), and pigmented (melanized). In parallel with this process, the oenocytes, which are large polyploid cells located below the abdominal epidermis, secrete onto the cuticle a cocktail of cuticular hydrocarbons (CHs) and waxes. These improve the waterproofing of the cuticle, and also provide important chemosensory and pheromonal cues linked with gender, age, and species differentiation. The hardening and pigmentation of the new cuticle are controlled by the neurohormone, bursicon, and its receptor, encoded by the DLGR2 receptor, rickets (rk); by contrast, little…