binucleosome

A binucleosome is a fundamental unit of chromatin structure. It consists of two nucleosomes positioned adjacent to each other. Nucleosomes themselves are the basic repeating units of eukaryotic DNA packaging, formed by approximately 147 base pairs of DNA wrapped around a histone octamer. The binucleosome represents a slightly larger assembly, comprising about 294 base pairs of DNA and two histone octamers.

The concept of the binucleosome is important for understanding how DNA is further compacted within the nucleus. While a single nucleosome is the primary structural motif, the arrangement of multiple nucleosomes in a linear or slightly offset fashion, as seen in a binucleosome, contributes to the formation of higher-order chromatin structures. These higher-order structures are essential for fitting the vast length of genomic DNA into the confines of the cell nucleus and for regulating gene expression.

Studies of binucleosomes have provided insights into the dynamics of chromatin. The linker DNA between adjacent nucleosomes plays a critical role in maintaining the spacing and flexibility of the chromatin fiber. The precise arrangement and interactions between binucleosomes can influence the accessibility of DNA to transcription factors and other regulatory proteins. Therefore, understanding binucleosome structure and organization is key to comprehending gene regulation and DNA accessibility in eukaryotes.