title: Chromatin is an ancient innovation conserved between Archaea and Eukarya.
abstract: The eukaryotic nucleosome is the fundamental unit of chromatin, comprising a protein octamer that wraps ∼147 bp of DNA and has essential roles in DNA compaction, replication and gene expression. Nucleosomes and chromatin have historically been considered to be unique to eukaryotes, yet studies of select archaea have identified homologs of histone proteins that assemble into tetrameric nucleosomes. Here we report the first archaeal genome-wide nucleosome occupancy map, as observed in the halophile Haloferax volcanii. Nucleosome occupancy was compared with gene expression by compiling a comprehensive transcriptome of Hfx. volcanii. We found that archaeal transcripts possess hallmarks of eukaryotic chromatin structure: nucleosome-depleted regions at transcriptional start sites and conserved -1 and +1 promoter nucleosomes. Our observations demonstrate that histones and chromatin architecture evolved before the divergence of Archaea and Eukarya, suggesting that the fundamental role of chromatin in the regulation of gene expression is ancient.DOI:http://dx.doi.org/10.7554/eLife.00078.001.
authors.affiliation: Department of Molecular Genetics ,  University of Toronto ,  Toronto ,  Canada ; Donnelly Centre ,  University of Toronto ,  Toronto ,  Canada.
authors.forename: Ron
authors.initials: R
authors.lastname: Ammar
authors.forename: Dax
authors.initials: D
authors.lastname: Torti
authors.forename: Kyle
authors.initials: K
authors.lastname: Tsui
authors.forename: Marinella
authors.initials: M
authors.lastname: Gebbia
authors.forename: Tanja
authors.initials: T
authors.lastname: Durbic
authors.forename: Gary D
authors.initials: GD
authors.lastname: Bader
authors.forename: Guri
authors.initials: G
authors.lastname: Giaever
authors.forename: Corey
authors.initials: C
authors.lastname: Nislow
mesh_terms: D005075:Biological Evolution; D042002:Chromatin Assembly and Disassembly; D004261:DNA Replication; D005057:Eukaryotic Cells / Q000166:cytology / Q000378:metabolism; D020869:Gene Expression Profiling; D019848:Gene Expression Regulation, Archaeal; D020745:Genome, Archaeal; D019622:Haloferax volcanii / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D006657:Histones / Q000235:genetics* / Q000378:metabolism; D058977:Molecular Sequence Annotation; D009707:Nucleosomes / Q000737:chemistry* / Q000378:metabolism; D011401:Promoter Regions, Genetic; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D024363:Transcription Initiation Site; D014158:Transcription, Genetic
chemical_list: D006657:Histones; D009707:Nucleosomes; D014157:Transcription Factors