What happens in chromatin remodeling?
Chromatin remodeling is the dynamic modification of chromatin architecture to allow access of condensed genomic DNA to the regulatory transcription machinery proteins, and thereby control gene expression.
How can chromatin be modified?
The principal epigenetic mechanisms by which tissue-specific gene-expression patterns and global gene silencing are established and maintained are chromatin modification — including processes such as DNA methylation, histone modification (acetylation, phosphorylation, methylation and ubiquitylation) — and chromatin …
How does chromatin open?
Histone modification can open chromatin, thus permitting selective binding of transcription factors that, in turn, recruit RNA polymerase II (Turner, 2005). Varying levels and types of histone modifications have been shown to correlate with levels of chromatin activation.
Is chromatin remodeling epigenetic?
Chromatin remodeling is highly implicated in epigenetics. Epigenetic modifications to histone proteins such as methylation/demethylation and acetylation/deacetylation can alter the structure of chromatin resulting in transcriptional activation or repression.
What are the three ways in which chromatin remodeling might happen to allow for transcription?
The basic mechanism of chromatin remodeling depends on the three dynamic properties of nucleosomes: reconstruction, enzyme-induced covalent modification, and repositioning.
How do chromatin remodelers change the structure of the chromatin?
Chromatin remodelers have two types of effects on chromatin dynamics: 1) they package genomic DNA, and incorporate histones into the nucleosome, or 2) release DNA from the histones. After DNA replication, chromatin remodelers pack genomic DNA into nucleosomes.
How is chromatin remodeling measured?
Chromatin remodeling is measured using an ATP-dependent nucleosome sliding assay, which monitors the movement of a nucleosome on a DNA molecule using an electrophoretic mobility shift assay (EMSA)-based method.
How is chromatin regulated?
Chromatin is not an inert structure, but rather an instructive DNA scaffold that can respond to external cues to regulate the many uses of DNA. A principle component of chromatin that plays a key role in this regulation is the modification of histones.
Is chromatin remodeling reversible?
Like all biochemical reactions they are, in principle, reversible and the outcome of remodeling reactions—be it the disruption of histone–DNA interactions or their formation, the sliding of a histone octamer on or off a particular DNA sequence, or alteration of the histone variant composition of a nucleosome—are …
What are chromatin remodeling factors?
Chromatin remodeling factors are key components involved in this process and include histone chaperones, histone modifying enzymes and ATP-dependent chromatin remodeling complexes. Several of these factors interact directly with components of the replication machinery.
How are histones removed?
By acting together, the ATP-dependent nucleosome remodelers and histone chaperones facilitate the removal of histones from the DNA and their assembly onto the DNA.
How do you silence genes?
The genes can be silenced by siRNA molecules that cause the endonucleatic cleavage of the target mRNA molecules or by miRNA molecules that suppress translation of the mRNA molecule. With the cleavage or translational repression of the mRNA molecules, the genes that form them are rendered essentially inactive.