{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\n The variant histone H2A.Bbd (also referred to as H2A.Bbd or H2A.Bbd‐like, sometimes denoted H2AB2) is emerging as a key modulator of chromatin structure and function. Unlike canonical H2A, incorporation of H2A.Bbd into nucleosomes produces particles that are less stable and more “open,” as evidenced by a reduced DNA protection footprint (≈118 bp versus 147 bp) and increased nucleosome dynamics. These altered particles display a relaxed chromatin organization that mimics features of transcriptionally active and acetylated chromatin, thereby facilitating access of transcription factors and other regulatory proteins."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "1", "end_ref": "4"}]}, {"type": "t", "text": ""}]}, {"type": "t", "text": "\n \n "}, {"type": "p", "children": [{"type": "t", "text": "\n In addition, the unique structural features of H2A.Bbd nucleosomes influence their interaction with chromatin remodeling complexes. For example, although certain ATP‐dependent remodelers like SWI/SNF can still enhance DNA accessibility in these contexts, remodeling of H2A.Bbd‐containing nucleosomes proceeds with distinct kinetics and may require alternative mechanisms as they are generally more resistant to certain remodeling activities."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "5"}]}, {"type": "t", "text": " Furthermore, evidence suggests that in the context of DNA repair—such as base excision repair—the presence of H2A.Bbd alters the efficiency of lesion processing, potentially by modulating how remodeling complexes interact with the nucleosome to expose damaged DNA."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "6"}]}, {"type": "t", "text": ""}]}, {"type": "t", "text": "\n \n "}, {"type": "p", "children": [{"type": "t", "text": "\n Together, these findings indicate that H2A.Bbd functions as a dynamic “replacement” histone that promotes a chromatin environment more conducive to transcriptional activation and may also influence DNA repair processes through its distinctive nucleosomal properties. Its rapid evolution and unique biochemical behavior underscore its potential role as an epigenetic marker that re‐programs local chromatin structure in active genomic regions.\n "}]}, {"type": "rg", "children": [{"type": "r", "ref": 1, "children": [{"type": "t", "text": "Yunhe Bao, Kasey Konesky, Young-Jun Park, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Nucleosomes containing the histone variant H2A.Bbd organize only 118 base pairs of DNA."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "EMBO J (2004)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1038/sj.emboj.7600316"}], "href": "https://doi.org/10.1038/sj.emboj.7600316"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "15257289"}], "href": "https://pubmed.ncbi.nlm.nih.gov/15257289"}]}, {"type": "r", "ref": 2, "children": [{"type": "t", "text": "Thierry Gautier, D Wade Abbott, Annie Molla, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Histone variant H2ABbd confers lower stability to the nucleosome."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "EMBO Rep (2004)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1038/sj.embor.7400182"}], "href": "https://doi.org/10.1038/sj.embor.7400182"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "15192699"}], "href": "https://pubmed.ncbi.nlm.nih.gov/15192699"}]}, {"type": "r", "ref": 3, "children": [{"type": "t", "text": "José María Eirín-López, Toyotaka Ishibashi, Juan Ausió "}, {"type": "b", "children": [{"type": "t", "text": "H2A.Bbd: a quickly evolving hypervariable mammalian histone that destabilizes nucleosomes in an acetylation-independent way."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "FASEB J (2008)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1096/fj.07-9255com"}], "href": "https://doi.org/10.1096/fj.07-9255com"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "17726088"}], "href": "https://pubmed.ncbi.nlm.nih.gov/17726088"}]}, {"type": "r", "ref": 4, "children": [{"type": "t", "text": "Michael Y Tolstorukov, Joseph A Goldman, Cristele Gilbert, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Histone variant H2A.Bbd is associated with active transcription and mRNA processing in human cells."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Mol Cell (2012)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1016/j.molcel.2012.06.011"}], "href": "https://doi.org/10.1016/j.molcel.2012.06.011"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "22795134"}], "href": "https://pubmed.ncbi.nlm.nih.gov/22795134"}]}, {"type": "r", "ref": 5, "children": [{"type": "t", "text": "Dimitar Angelov, André Verdel, Woojin An, et al. "}, {"type": "b", "children": [{"type": "t", "text": "SWI/SNF remodeling and p300-dependent transcription of histone variant H2ABbd nucleosomal arrays."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "EMBO J (2004)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1038/sj.emboj.7600400"}], "href": "https://doi.org/10.1038/sj.emboj.7600400"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "15372075"}], "href": "https://pubmed.ncbi.nlm.nih.gov/15372075"}]}, {"type": "r", "ref": 6, "children": [{"type": "t", "text": "Hervé Menoni, Didier Gasparutto, Ali Hamiche, et al. "}, {"type": "b", "children": [{"type": "t", "text": "ATP-dependent chromatin remodeling is required for base excision repair in conventional but not in variant H2A.Bbd nucleosomes."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Mol Cell Biol (2007)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1128/MCB.00376-07"}], "href": "https://doi.org/10.1128/MCB.00376-07"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "17591702"}], "href": "https://pubmed.ncbi.nlm.nih.gov/17591702"}]}]}]}