Search results for "Nucleases"
showing 10 items of 147 documents
Determinants of intracellular RNA pharmacokinetics: Implications for RNA-based immunotherapeutics
2011
RNAs with optimized properties are increasingly investigated as a tool to deliver the genetic information of complete antigens into professional antigen-presenting dendritic cells for HLA haplotype-independent antigen-specific vaccination against cancer. As the dose of the antigen and duration of its presentation are critical factors for generating strong and sustained antigen-specific immune responses, improvement of the immunobioavailability of RNA-based vaccines has been a recurrent subject of research. Substantial increase of the amount of antigen produced from RNA can be achieved by optimizing RNA stability and translational efficiency. Both features are determined by cis-acting elemen…
The mitochondrial genome of Schizosaccharomyces pombe. Stimulation of intra-chromosomal recombination in Escherichia coli by the gene product of the …
1991
The open reading frame of the first intron of the mitochondrial cox1 gene (cox1I1) was expressed in Escherichia coli. The putative intron-encoded protein stimulated the formation of intra-chromosomal lac +-recombinants about threefold. No stimulation was found when the reading frame was inserted in the opposite direction, or when it was interrupted by a deletion. The intronic open reading frame did not complement recA − or recB − mutants of E. coli. In S. pombe, elimination of this intron did not abolish homologous recombination in mitochondria. A possible role of the recombinase activity in yeast mitochondria will be discussed.
New sulfonamide complexes with essential metal ions [Cu (II), Co (II), Ni (II) and Zn (II)]. Effect of the geometry and the metal ion on DNA binding …
2019
Abstract Mixed divalent Cu, Co, Ni and Zn complexes containing the new sulfonamide ligand N–(2–(pyridin–2–yl)ethyl)quinoline–8–sulfonamide (HQSEP) were prepared and characterized by physico-chemical techniques. The tetracoordinate [Cu(QSEP)X] [X = Br (1), Cl (2)] compounds present a seesaw geometry (τ4 = 0.56 (1) and 0.50 (2)). The Cu(II) in the [Cu(QSEP)(NO3)(MeOH)] (3) complex is five coordinate with a slightly distorted SP geometry (τ = 0.11). The [M(QSEP)(benz)] [M = Cu(II) (4), Ni(II) (5), Co(II) (6) and Zn(II) (7); benz = benzoate] compounds are configurationally isotypic. The coordination geometries of the M(II) ions can be best described as distorted SP (τ = 0.29, 0.15, 0.34 and 0.1…
Messenger RNA degradation is initiated at the 5′ end and follows sequence- and condition-dependent modes in chloroplasts
2011
Using reporter gene constructs, consisting of the bacterial uidA (GUS) coding region flanked by the 5' and 3' regions of the Chlamydomonas rbcL and psaB genes, respectively, we studied the degradation of mRNAs in the chloroplast of Chlamydomonas reinhardtii in vivo. Extending the 5' terminus of transcripts of the reporter gene by more than 6 nucleotides triggered rapid degradation. Placing a poly(G) tract, known to pause exoribonucleases, in various positions downstream of the 5' terminus blocked rapid degradation of the transcripts. In all these cases the 5' ends of the accumulating GUS transcripts were found to be trimmed to the 5' end of the poly(G) tracts indicating that a 5' → 3' exori…
The mRNA degradation factor Xrn1 regulates transcription elongation in parallel to Ccr4
2019
Abstract Co-transcriptional imprinting of mRNA by Rpb4 and Rpb7 subunits of RNA polymerase II (RNAPII) and by the Ccr4–Not complex conditions its post-transcriptional fate. In turn, mRNA degradation factors like Xrn1 are able to influence RNAPII-dependent transcription, making a feedback loop that contributes to mRNA homeostasis. In this work, we have used repressible yeast GAL genes to perform accurate measurements of transcription and mRNA degradation in a set of mutants. This genetic analysis uncovered a link from mRNA decay to transcription elongation. We combined this experimental approach with computational multi-agent modelling and tested different possibilities of Xrn1 and Ccr4 acti…
Expression of yeast but not human apurinic/apyrimidinic endonuclease renders Chinese hamster cells more resistant to DNA damaging agents.
1997
Abasic sites represent ubiquitous DNA lesions that arise spontaneously or are induced by DNA-damaging agents. They block DNA replication and are considered to be cytotoxic and mutagenic. The key enzymes involved in the repair of abasic sites are apurinic/apyrimidinic (AP) endonucleases which process these lesions in an error-free mechanism. To analyze the role of AP endonuclease in the protection of mammalian cells against DNA damaging agents, we have transfected both the human (APE) and the yeast (APN1) AP endonuclease in Chinese hamster cells and compared the effects of expression of these genes in stable transfectants as to survival of cells and formation of chromosomal aberrations. Alth…
Recruitment of Xrn1 to stress-induced genes allows efficient transcription by controlling RNA polymerase II backtracking
2020
A new paradigm has emerged proposing that the crosstalk between nuclear transcription and cytoplasmic mRNA stability keeps robust mRNA levels in cells under steady-state conditions. A key piece in this crosstalk is the highly conserved 5′–3′ RNA exonuclease Xrn1, which degrades most cytoplasmic mRNAs but also associates with nuclear chromatin to activate transcription by not well-understood mechanisms. Here, we investigated the role of Xrn1 in the transcriptional response of Saccharomyces cerevisiae cells to osmotic stress. We show that a lack of Xrn1 results in much lower transcriptional induction of the upregulated genes but in similar high levels of their transcripts because of parallel …
A natural A/T-rich sequence from the yeast FBP1 gene exists as a cruciform in Escherichia coli cells.
1993
Abstract Palindromic or semipalindromic sequences can adopt cruciform structures in DNA in vitro. It has been demonstrated in some cases that A/T-rich cruciforms exist also in vivo in Escherichia coli. The biological function of those structures is not understood although putative cruciforms have been found in interesting locations on replication origins, operators, or transcriptional termination regions. Here we show by means of the use of structure-dependent nucleases that the 3′ end of the yeast FBP1 gene contains a stable cruciform both in vitro and in E. coli cells and that in both cases, its extrusion depends on the DNA supercoiling state.
Centromeric heterochromatin and satellite DNA in the Chironomus plumosus species group
1994
Species of the Chironomus plumosus group display significant differences in their amount of centromeric heterochromatin. A tandem-repetitive satellite-like DNA has been isolated from C. plumosus. This DNA accounts for a major part of the centromeric heterochromatin. The DNA element has a Sau3AI restriction site ("Sau elements") and a monomer length of 165 or 166 bp. It is A-T rich (73%) and reveals a moderate DNA curvature, as shown by gel migration and computer analysis. The chromosomal localization and genomic organization of Sau elements were studied in 24 Chironomus species by in situ hybridization and (or) Southern analysis. The DNA is predominantly located in the centromeric regions …
Compromised nuclear envelope integrity drives TREX1-dependent DNA damage and tumor cell invasion
2021
Although mutations leading to a compromised nuclear envelope cause diseases such as muscular dystrophies or accelerated aging, the consequences of mechanically induced nuclear envelope ruptures are less known. Here, we show that nuclear envelope ruptures induce DNA damage that promotes senescence in non-transformed cells and induces an invasive phenotype in human breast cancer cells. We find that the endoplasmic reticulum (ER)-associated exonuclease TREX1 translocates into the nucleus after nuclear envelope rupture and is required to induce DNA damage. Inside the mammary duct, cellular crowding leads to nuclear envelope ruptures that generate TREX1-dependent DNA damage, thereby driving the …