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Nucleosomes are the basic packing unit of genomic DNA built from histone proteins around which DNA is coiled. They serve as a scaffold for formation of higher order chromatin structure as well as for a layer of regulatory control of gene expression. Nucleosomes are quickly assembled onto newly synthesized DNA behind the replication fork.
Ribonucleoprotein particles are distinct intracellular foci for post-transcriptional regulation. These particles play an important role in influenza A virus replication. [27] The influenza viral genome is composed of eight ribonucleoprotein particles formed by a complex of negative-sense RNA bound to a viral nucleoprotein.
This opens up the usually tightly packed nucleosome and allows transcription machinery to come into contact with the DNA template, leading to gene transcription. [1]: 242 Repression of gene transcription is achieved by the reverse of this mechanism. The acetyl group is removed by one of the HDAC enzymes during deacetylation, allowing histones ...
ADPr is an important mechanism in gene regulation that affects chromatin organization, the binding of transcription factors, and mRNA processing through poly-ADP ribose polymerase (PARP) enzymes. There are multiple types of PARP proteins, but the subclass of DNA-dependent PARP proteins including PARP-1, PARP-2, and PARP-3 interact with the ...
Basic units of chromatin structure. Histone H2B is a structural protein that helps organize eukaryotic DNA. [5] It plays an important role in the biology of the nucleus where it is involved in the packaging and maintaining of chromosomes, [5] regulation of transcription, and replication and repair of DNA. [2]
Chromatin remodeling enzymes: These enzymes are responsible for promoting euchromatin or heterochromatin formation by a number of processes, particularly modifying histone tails or physically moving the nucleosomes. This in turn, helps regulate gene expression, replication, and how the chromatin interacts with architectural factors. [16]
The level of nucleosomal packaging can have profound consequences on all DNA-mediated processes including gene regulation. Euchromatin (loose or open chromatin) structure is permissible for transcription whereas heterochromatin (tight or closed chromatin) is more compact and refractory to factors that need to gain access to the DNA template.
Histone gene transcription is controlled by multiple gene regulatory proteins such as transcription factors which bind to histone promoter regions. In budding yeast, the candidate gene for activation of histone gene expression is SBF. SBF is a transcription factor that is activated in late G1 phase, when it dissociates from its repressor Whi5.