Transcription activators in eukaryotes

The main contents of this chapter include all of the following: Categories of activators, structures of the DNA-Binding motifs of activators, independence of the domains of activators, functions of activators, interaction among activators, regulation of transcription factors.

53p tangtuy05 30-03-2016 63 4   Download

Chapter 11 - general transcription factors in eukaryotes. Eukaryotic RNA polymerases, unlike their bacterial counterparts, are incapable of binding by themselves to their respective promoters. Instead, they rely on proteins called transcription factors to show them the way. Such factors are grouped into two classes: general transcription factors and gene-specifi c transcription factors (activators). In this chapter we will survey the general transcription factors that interact with all three RNA polymerases and their promoters.

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HIC1(hypermethylated in cancer 1) is a transcriptional repressor containing fiveKru¨ppel-likeC2H2zinc fingers and an N-terminal dimerization and autonomous repression domain called BTB/POZ. Here, we demonstrate that full-length HIC1 proteins are modified both in vivo andin vitro with O-linkedN-acetylglucosamine (O-GlcNAc). This is a highly dynamic glycosylation found within the cytosolic and the nuclear compartments of eukaryotes. Analysis of [ 3 H]Gal-labeled tryptic peptides indicates that HIC1 has three major sites forO-GlcNAc glycosylation....

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NA helicases are ubiquitous molecular motor proteins which harness the chemical free energy of ATPhydrolysis to catalyze the unwinding of energetically stable duplex DNA, and thus play important roles in nearly all aspects of nucleic acid metabolism, including replication, repair, recombina-tion, and transcription. They break the hydrogen bonds between the duplex helix and move unidirectionally along the bound strand. All helicases are also translocases and DNA-dependentATPases.Most contain conserved helicase motifs that act as an engine to power DNA unwinding. ...

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Eukaryotic chromosomal DNA is densely packaged in the nucleus and organized into discrete domains of active and inactive chromatin. Gene loci that are activated during the process of cell differentiation undergo changes that result in modifications of specific histone tail residues and in loosening of chromatin structure. Theb-globin genes are expressed exclusively in eryth-roid cells.

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To identify artificial DNA segments that can stably express transgenes in the genome of host cells, we built a series of curved DNA segments that mimic a left-handed superhelical structure. Curved DNA segments of 288 bp (T32) and 180 bp (T20) were able to activate transcription from the herpes simplex virus thymidine kinase (tk) promoter by approximately 150-fold and 70-fold, respectively, compared to a control in a transient transfection assay in COS-7 cells.

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DNA polymeraseeco-operates with polymerasesaanddin the replicative DNA synthesis of eukaryotic cells. We describe here a specific physical interaction between DNA polymerase eand RNA polymerase II, evidenced by reciprocal immunoprecipitation experiments. The interacting RNA polymerase II was the hyperphosphorylated IIO form implicated in tran-

15p inspiron33 23-03-2013 44 3   Download