Insights into the role of brdt in chromatin remodeling during rat spermiogenesis

Abstract

Chromatin is a complex of DNA and proteins that was named so by Walther Flemming in 1882 as a substance that could be visualized by staining. It is a highly ordered structure made up of arrays of nucleosomes that forms the genetic material within a eukaryotic cell [1]. The details of the composition of the nucleosome came with solving of the crystal structure at 2.8 Ao resolution by Luger et al [2]. Nucleosome is the repeating unit of chromatin that consists of 146 bp of DNA wrapped in about 1.67 turns around an octamer of core histones [3, 4]. X-ray crystallographic studies also revealed that the histone octamer has a disc-like shape with a thickness of 6 nm and diameter of 6.5 nm [5]. The core histones that form the octamer are H2A, H2B, H3 and H4 each present as two copies within the nucleosome. Core histones are basic proteins rich in lysine and arginine residues and it is this basic nature of histones that allows them to be wrapped by the negatively charged DNA.