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DNA Binding Region (dna + binding_region)
Selected AbstractsLigand-induced heterodimerization between the ligand binding domains of the Drosophila ecdysteroid receptor and ultraspiracleFEBS JOURNAL, Issue 13 2002Markus Lezzi The insect ecdysteroid receptor consists of a heterodimer between EcR and the RXR-orthologue, USP. We addressed the question of whether this heterodimer, like all other RXR heterodimers, may be formed in the absence of ligand and whether ligand promotes dimerization. We found that C-terminal protein fragments that comprised the ligand binding, but not the DNA binding domain of EcR and USP and which were equipped with the activation or DNA binding region of GAL4, respectively, exhibit a weak ability to interact spontaneously with each other. Moreover, the heterodimer formation is greatly enhanced upon administration of active ecdysteroids in a dose-dependent manner. This was shown in vivo by a yeast two-hybrid system and in vitro by a modified electromobility shift assay. Furthermore, the EcR fragment expressed in yeast was functional and bound radioactively labelled ecdysteroid specifically. Ligand binding was greatly enhanced by the presence of a USP ligand binding domain. Therefore, ecdysteroids are capable of inducing heterodimer formation between EcR and USP, even when the binding of these receptor proteins to cognate DNA response elements does not occur. This capability may be a regulated aspect of ecdysteroid action during insect development. [source] MIDA1 is a sequence specific DNA binding protein with novel DNA binding propertiesGENES TO CELLS, Issue 9 2000Toshiaki Inoue Background Id proteins not only regulate cell differentiation negatively, but they also promote growth and apoptosis. To know the mechanism of how Id regulates cell fate, we previously isolated an Id-associating protein, MIDA1, which positively regulates cell growth. Its predicted amino acid sequence contains tryptophan-mediated repeats (Tryp-med repeats) similar to the DNA binding region of the c-Myb oncoprotein. We determined whether MIDA1 can bind to DNA in a sequence specific manner by PCR-assisted binding site selection. Results We identified a 7-base sequence (GTCAAGC) surrounded by a 1,3 bp palindromic sequence as the DNA sequence recognized by the Tryp-med repeats of MIDA1. This motif is located within the 5,-flanking sequence of several growth regulating genes. Gel shift assays revealed that this sequence and a certain length of flanking DNA are necessary for MIDA1 to bind DNA in a stable manner. Methylation interference and DNase I footprint analysis suggested that the DNA binding of MIDA1 is resistant to DNA methylation and that MIDA1 does not specifically localize on this particular motif. Conclusions We concluded that MIDA1 is a novel sequence-specific DNA binding protein with some different properties from the usual transcription factors and that MIDA1 may act as a mediator of Id-mediated growth-promoting function through its DNA binding activity. [source] Role and regulation of human XRCC4-like factor/cernunnos,JOURNAL OF CELLULAR BIOCHEMISTRY, Issue 5 2008Kirsten Dahm Abstract In mammalian cells, non-homologous end joining (NHEJ) is the major double strand break (DSB) repair mechanism during the G1 phase of the cell cycle. It also contributes to DSB repair during the S and G2 phases. Ku heterodimer, DNA PKcs, XRCC4 and DNA Ligase IV constitute the core NHEJ machinery, which joins directly ligatable ends. XRCC4-like factor/Cernunnos (XLF/Cer) is a recently discovered interaction partner of XRCC4. Current evidence suggests the following model for the role of XLF/Cer in NHEJ: after DSB induction, the XRCC4-DNA Ligase IV complex promotes efficient accumulation of XLF/Cer at DNA damage sites via constitutive interaction of the XRCC4 and XLF/Cer head domains and dependent on components of the DNA PK complex. Ku alone can stabilise the association of XLF/Cer with DNA ends. XLF/Cer stimulates ligation of complementary and non-complementary DNA ends by XRCC4-DNA Ligase IV. This activity involves the carboxy-terminal DNA binding region of XLF/Cer and could occur via different, non-exclusive modes: (i) enhancement of the stability of the XRCC4-DNA Ligase IV complex on DNA ends by XLF/Cer, (ii) modulation of the efficiency and/or specificity of DNA Ligase IV by binding of XLF/Cer to the XRCC4-DNA Ligase IV complex, (iii) promotion of the alignment of blunt or other non-complementary DNA ends by XLF/Cer for ligation. XLF/Cer promotes the preservation of 3, overhangs, restricts nucleotide loss and thereby promotes accuracy of DSB joining by XRCC4-DNA Ligase IV during NHEJ and V(D)J recombination. J. Cell. Biochem. 104: 1534,1540, 2008. © 2008 Wiley-Liss, Inc. [source] Rapid Identification of a Putative Interaction between ,2 -Adrenoreceptor Agonists and ATF4 using a Chemical Genomics ApproachCHEMMEDCHEM, Issue 5 2008Sweta Chemical genomics. We have uncovered a specific interaction between the ,2 -adrenoreceptor agonist salbutamol and the DNA binding region of transcription factor ATF4 in a chemical genomics approach using phage display combined with photoimmobilisation. [source] | |||||||||||||