What are nucleosome-free regions?

Nucleosome-free regions (NFRs) at the 5′ and 3′ ends of genes are general sites of transcription initiation for mRNA and noncoding RNA (ncRNA). To date, multiple factors are known to facilitate transcription initiation by positively regulating the formation and/or size of NFRs in vivo.

Why are nucleosome-free regions important?

Nucleosome-free gaps are highly enriched in active chromatin, particularly in DNA regions that support transcription factor binding (51,52). The presence of nucleosome-free gaps facilitates formation of more dynamic chromatin (11), making the fiber more flexible and potentially a better device to support efficient EPC.

What is nucleosome occupancy?

(B) Nucleosome occupancy along every basepair in the genome is defined as the fraction of cells from the population in which the basepair is occupied by any histone octamer.

What is the nucleosome positioning sequence?

Nucleosome positioning DNA sequence patterns (NPS)—usually distributions of particular dinucleotides or other sequence elements in nucleosomal DNA—at least partially determine chromatin structure and arrangements of nucleosomes that in turn affect gene expression.

What is nucleosome depletion?

Nucleosome-depleted regions (NDRs) (also called nucleosome-free regions or NFRs) are often found in the promoter regions of many yeast genes, and are formed by multiple mechanisms, including the binding of activators and enhancers, the actions of chromatin remodeling complexes, and the specific DNA sequences themselves …

What is nucleosome and its function?

A nucleosome is a section of DNA that is wrapped around a core of proteins. Inside the nucleus, DNA forms a complex with proteins called chromatin, which allows the DNA to be condensed into a smaller volume. The nucleosome is the fundamental subunit of chromatin.

What is a nucleosome discuss its significance?

How do nucleosomes affect gene expression?

Nucleosomes can slide along DNA. When nucleosomes are spaced closely together (top), transcription factors cannot bind and gene expression is turned off. When the nucleosomes are spaced far apart (bottom), the DNA is exposed. Transcription factors can bind, allowing gene expression to occur.

How nucleosome positioning or spacing can interfere with DNA accessibility?

The positioning of nucleosomes relative to DNA and their neighboring nucleosomes represents a fundamental layer of chromatin organization. Changes in nucleosome positioning and spacing affect the accessibility of DNA to regulatory factors and the formation of higher order chromatin structures.

Why are nucleosomes important to eukaryotic cells?

Nucleosomal chromatin is a hallmark of all eukaryotic genomes [1]. Nucleosomes serve three primary functions as components of chromosomes. First, they provide some measure of packaging and stabilize the negative supercoiling of genomic DNA in vivo [2, 3].