Core component of nucleosome. Nucleosomes wrap and compact DNA into chromatin, limiting DNA accessibility to the cellular machineries which require DNA as a template. Histones thereby play a central role in transcription regulation, DNA repair, DNA replication and chromosomal stability. DNA accessibility is regulated via a complex set of post-translational modifications of histones, also called histone code, and nucleosome remodeling. Hipposin shows strong antimicrobial activity against several Gram-positive and Gram-negative bacteria. The nucleosome is a histone octamer containing two molecules each of H2A, H2B, H3 and H4 assembled in one H3-H4 heterotetramer and two H2A-H2B heterodimers. The octamer wraps approximately 147 bp of DNA. Acetylation is not necessary for the antibacterial activity. Monoubiquitination in C-terminus gives a specific tag for epigenetic transcriptional repression. Following DNA double-strand breaks (DSBs), it is ubiquitinated through 'Lys-63' linkage of ubiquitin moieties, leading to the recruitment of repair proteins to sites of DNA damage. H2AK119Ub and ionizing radiation-induced 'Lys-63'-linked ubiquitination are distinct events (By similarity). Phosphorylation on Ser-2 is enhanced during mitosis. Phosphorylation on Ser-2 directly represses transcription (By similarity). Belongs to the histone H2A family.