H3.1 is predominantly expressed and therefore incorporated during DNA replication, while H3.3 is deposited throughout the cell cycle вЂ“. In addition to the centromeric variant CENH3, the variants H3.1 and H3.3 are highly similar in their amino acid composition, yet they are incorporated into the chromatin through different pathways. Histones H3 can be subdivided into several classes. They are targets of chromatin modifiers that deposit covalent modifications on histone tails and thereby influence chromatin properties and affect transcriptional and translational activities. Histones are not static scaffolding proteins but dynamic actors involved in many aspects of chromatin related functions. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.ДЇunding: This work was funded by Temasek LifeSciences Laboratory ( and Genome Institute of Singapore ( The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Д¬ompeting interests: The authors have declared that no competing interests exist. Received: NovemAccepted: MaPublished: May 3, 2012Д¬opyright: В© 2012 Wollmann et al. PLoS Genet 8(5):Д®ditor: Tetsuji Kakutani, National Institute of Genetics, Japan We anticipate that the dynamic link between H3.3 variants and transcription enables remodeling of histone modifications that contribute to developmental transitions.Д¬itation: Wollmann H, Holec S, Alden K, Clarke ND, Jacques P-Г‰, Berger F (2012) Dynamic Deposition of Histone Variant H3.3 Accompanies Developmental Remodeling of the Arabidopsis Transcriptome. In contrast with H3.1, H3.3 incorporation is dynamic and accompanies global changes of gene activity at major developmental transitions. Our study indicates that these core properties include the high enrichment of H3.3 at active genes and a relative low deposition of H3.3 over regions deprived of genes or with inactive genes. Hence, H3 variants' properties shared by plants and animals would reflect core functions that have been selected during evolution. H3 variants evolved independently in plants and animals. Studies in animals have shown that the deposition of two different histone H3 variants, H3.1 and H3.3, requires distinct pathways and results in distinct profiles throughout the genome. Beyond their role as DNA scaffold, histones participate in the regulation of gene activity. Histone proteins are assembled into nucleosomes to build the skeleton of chromosomes. Our study suggests that H3 variants properties likely result from functionally convergent evolution. We propose that H3.3 dynamics are linked to transcription and are involved in resetting covalent histone marks at a genomic scale during plant development. We report that, in planta, dynamic changes in H3.3 profiles are associated with the extensive remodeling of the transcriptome that occurs during cell differentiation. In contrast with H3.1, heterochromatic regions are mostly depleted of H3.3. We find H3.3 enrichment to positively correlate with gene expression and to be biased towards the transcription termination site. Here we present genome-wide maps of H3.3 and H3.1 enrichment and the dynamic changes of their profiles upon cell division arrest. We studied Arabidopsis H3 variants in order to find core properties of this class of histones. Histone H3 variants evolved independently in plants and animals, and it is unclear whether different replication-independent H3.3 variants developed similar properties in both phyla. Furthermore, H3.3 is specifically incorporated upon gene activation. H3.3 variants are enriched at active genes and their promoters. In animals, replication-coupled histone H3.1 can be distinguished from replication-independent histone H3.3.

Histone h3