Editing Histone fold (section)

== Evolution ==

The histone fold is thought to have evolved from ancestral [[peptide]] sets that formed helix-strand-helix motifs. These peptides are believed to have originated from ancient fragments, which may be precursors to the modern H3-H4 tetramer found in eukaryotes. Notably, archaeal single-chain histones, similar to eukaryotic histones, are found in the bacterium [[Aquifex aeolicus]], suggesting a shared ancestry between eukaryotes and archaea, with possible lateral gene transfers to bacteria.<ref name = "Alva_2007" />

Studies on species like [[Drosophila]] have revealed variations in the histone fold motif, particularly in the subunits of transcription initiation factors. These proteins contain histone-like structures, which show that the histone fold motif can also be found in non-histone proteins involved in protein-protein and protein-DNA interactions.<ref name=pmid7479959/>