8BDK

Structure of a non-canonical histone from archaea

8BDK の概要

• エントリーDOI: 10.2210/pdb8bdk/pdb
• 分子名称: DNA-binding protein HmvA (2 entities in total)
• 機能のキーワード: histone, dimerisation, transcription, dna binding protein
• 由来する生物種: Methanocaldococcus jannaschii
• タンパク質・核酸の鎖数: 4
• 化学式量合計: 44884.90

構造登録者

Ofer, S.,Werner, F. (登録日: 2022-10-19, 公開日: 2023-07-12, 最終更新日: 2024-02-07)

主引用文献

Ofer, S.,Blombach, F.,Erkelens, A.M.,Barker, D.,Soloviev, Z.,Schwab, S.,Smollett, K.,Matelska, D.,Fouqueau, T.,van der Vis, N.,Kent, N.A.,Thalassinos, K.,Dame, R.T.,Werner, F.
DNA-bridging by an archaeal histone variant via a unique tetramerisation interface.
Commun Biol, 6:968-968, 2023

PubMed Abstract: In eukaryotes, histone paralogues form obligate heterodimers such as H3/H4 and H2A/H2B that assemble into octameric nucleosome particles. Archaeal histones are dimeric and assemble on DNA into 'hypernucleosome' particles of varying sizes with each dimer wrapping 30 bp of DNA. These are composed of canonical and variant histone paralogues, but the function of these variants is poorly understood. Here, we characterise the structure and function of the histone paralogue MJ1647 from Methanocaldococcus jannaschii that has a unique C-terminal extension enabling homotetramerisation. The 1.9 Å X-ray structure of a dimeric MJ1647 species, structural modelling of the tetramer, and site-directed mutagenesis reveal that the C-terminal tetramerization module consists of two alpha helices in a handshake arrangement. Unlike canonical histones, MJ1647 tetramers can bridge two DNA molecules in vitro. Using single-molecule tethered particle motion and DNA binding assays, we show that MJ1647 tetramers bind ~60 bp DNA and compact DNA in a highly cooperative manner. We furthermore show that MJ1647 effectively competes with the transcription machinery to block access to the promoter in vitro. To the best of our knowledge, MJ1647 is the first histone shown to have DNA bridging properties, which has important implications for genome structure and gene expression in archaea.

PubMed: 37740023
DOI: 10.1038/s42003-023-05348-2

実験手法

X-RAY DIFFRACTION (1.88 Å)