Article Abstract:
Histone deacetylase activity of Rpd3, part of a multiprotein complex of eukaryotic organisms, as is Sin3, seems to be important, but may not be required, for transcriptional repression in vivo. Four Rpd3 mutants described do not have detectable histone deacetylase activity in vitro but behave normally with Sin3 in vivo. In yeast cells the noncatalytic mutants cannot repress transcription. It appears, since they keep some Rpd3 function in vivo, that repression by the Sin3-Rpd3 complex may not come only from intrinsic histone deacetylase activity. A human Rpd3 homolog can interact with yeast Sin3 and repress transcription when artificially brought to a promoter.
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Article Abstract:
Ume6, an upstream repression sequence-binding protein (URS1), represses the gene involved in meiosis by requiring the presence of Sin3 and Rpd3. This was indicated through the use of deletion analysis and affinity chromatography. Furthermore, Ume6 effects repression by targeted histone deacetylation as evidenced by a correlation of inaccessible chromatin and decreased transcriptional acivity with decreased histone acetylation. Targeted Rpd3 histone deacetylation mediates repression by rendering repressed chromatins which inhibit the accessibility of transcriptional activators.
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Article Abstract:
There are three specific types of specific DNA sequences that are fundamental to gene regulation in the cellular level. These are, the promoters, exclusively recognized by RNA polymerase, the operator sequences, recognized by repressor proteins, and the positive control elements, recognized by activator proteins. Transcriptional ground state has been found to be useful in understanding the workings of gene regulation at the organism level.
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