19 research outputs found
The dual control of TFIIB recruitment by NC2 is gene specific
Get PDFNegative co-factor 2 (NC2) is a conserved eukaryotic complex composed of two subunits, NC2α (Drap1) and NC2ÎČ (Dr1) that associate through a histone-fold motif. In this work, we generated mutants of NC2, characterized target genes for these mutants and studied the assembly of NC2 and general transcription factors on target promoters. We determined that the two NC2 subunits mostly function together to be recruited to DNA and regulate gene expression. We found that NC2 strongly controls promoter association of TFIIB, both negatively and positively. We could attribute the gene-specific repressor effect of NC2 on TFIIB to the C-terminal domain of NC2ÎČ, and define that it requires ORF sequences of the target gene. In contrast, the positive function of NC2 on TFIIB targets is more general and requires adequate levels of the NC2 histone-fold heterodimer on promoters. Finally, we determined that NC2 becomes limiting for TATA-binding protein (TBP) association with a heat inducible promoter under heat stress. This study demonstrates an important positive role of NC2 for formation of the pre-initiation complex on promoters, under normal conditions through control of TFIIB, or upon activation by stress via control of TBP
Alternatives for sustained disaster risk reduction
Get PDFThe daily media is filled with images of catastrophic events which seem increasingly frequent and violent In parallel there are a large range of scientific studies debates in the policy arena, and a growing number of international institutions focused on disaster reduction. But a paradox remains that despite advances in technology, disasters continue to increase, affecting many individuals in rich as well as poor countries
The NC2 alpha and beta subunits play different roles in vivo
No full textNC2 is a heterodimeric regulator of transcription that plays both positive and negative roles in vivo. Here we show that the alpha and beta subunits of yeast NC2 are not always associated in a tight complex. Rather, their association is regulated, in particular by glucose depletion. Indeed, stable NC2 alpha/beta complexes can only be purified from cells after the diauxic shift when glucose has been depleted from the growth medium. In vivo, the presence of NC2 alpha, but not NC2 beta, at promoters generally correlates with the presence of TBP and transcriptional activity. In contrast, increased presence of NC2 beta relative to TBP correlates with transcriptional repression. NC2 is regulated by phosphorylation. We found that mutation of genes encoding casein kinase II (CKII) subunits as well as potential CKII phosphorylation sites in NC2 alpha and beta affected gene repression. Interestingly, NC2-dependent repression in the phosphorylation site mutants was only perturbed in high glucose when NC2 beta and NC2 alpha are not associated, but not after the diauxic shift when NC2 alpha and beta form stable complexes. Thus, the separation of NC2 alpha and beta function indicated by these mutants also supports the existence of multiple NC2 complexes with different functions in transcription
Supramolecular Chemistry for Pressure Sensitive Adhesives ?
No full textInternational audiencePressure Sensitive Adhesives (PSA) are soft polymer materials which instantly stick on almost any surface. The adhesives properties of these materials are mainly based on their rheological behavior and, thus on the chemical architecture of the polymer chains. Commercial PSAs are usually composed of lightly crosslinked and highly entangled polymer chains, the molecular structure of which is adjusted to get a good peeling and shear resistance (Creton, C. MRS Bulletin, 2003). The specificity of my project is to investigate the rheological and adhesive properties of short polymer chains functionalized by urea groups. The strong hydrogen bonding interactions between these urea moieties increase strongly the dissipative properties upon deformation, while keeping a low viscosity in non polar solvents (Courtois, J. et al, Adv. Funct. Mater., 2010).The viscoelastic and adhesive properties of linear poly(butylacrylate) chains center-functionalized by bis- or tri-urea stickers were systematically studied. The molecular mechanisms, which govern the rheological behavior at small and large deformation, were identified by modifying the chemical structure of the polymer chains in a systematic way. Based on these results, more complex molecular architectures were then synthesized in order to improve the adhesive properties. The promising results from these new systems highlight the high potential of the supramolecular chemistry for the elaboration of new PSAs
