Research over the past decade has greatly expanded our understanding of the nucleosome's role as a dynamic hub that is specifically recognized by many regulatory proteins involved in transcription, silencing, replication, repair, and chromosome segregation. While many of these nucleosome interactions are mediated by post-translational modifications in the disordered histone tails, it is becoming increasingly apparent that structured regions of the nucleosome, including the histone fold domains, are also recognized by numerous regulatory proteins. This review will focus on the recognition of structured domains in the histone H2A-H2B dimer, including the acidic patch, the H2A docking domain, the H2B α3-αC helices, and the HAR/HBR domains, and will survey the known biological functions of histone residues within these domains. Novel post-translational modifications and trans-histone regulatory pathways involving structured regions of the H2A-H2B dimer will be highlighted, along with the role of intrinsic disorder in the recognition of structured nucleosome regions.
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http://dx.doi.org/10.1016/j.bbagrm.2012.04.001 | DOI Listing |
Nucleic Acids Res
December 2024
Department of Epigenetics and Molecular Carcinogenesis, UT MD Anderson Cancer Center, 1901 East Rd., Houston, TX 77054, USA.
The INO80 chromatin remodeler is a versatile enzyme capable of several functions, including spacing nucleosomes equal distances apart, precise positioning of nucleosomes based on DNA shape/sequence and exchanging histone dimers. Within INO80, the Arp5 subunit plays a central role in INO80 remodeling, evidenced by its interactions with the histone octamer, nucleosomal and extranucleosomal DNA, and its necessity in linking INO80's ATPase activity to nucleosome movement. We find two distinct regions of Arp5 binding near the acidic pocket of nucleosomes.
View Article and Find Full Text PDFScience
December 2024
Department of Cell Biology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA.
During transcription, RNA polymerase II traverses through chromatin, and post-translational modifications including histone methylations mark regions of active transcription. Histone protein H3 lysine 36 trimethylation (H3K36me3), which is established by the histone methyltransferase SETD2, suppresses cryptic transcription, regulates splicing, and serves as a binding site for transcription elongation factors. The mechanism by which the transcription machinery coordinates the deposition of H3K36me3 is not well understood.
View Article and Find Full Text PDFJ Cell Biol
January 2025
Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX, USA.
Core histones, synthesized and processed in the cytoplasm, must be chaperoned as they are transported into the nucleus for nucleosome assembly. The importin Kap114 transports H2A-H2B into the yeast nucleus, where RanGTP facilitates histone release. Kap114 and H2A-H2B also bind the histone chaperone Nap1, but how Nap1 and Kap114 cooperate in transport and nucleosome assembly remains unclear.
View Article and Find Full Text PDFMol Diagn Ther
November 2024
Department of Stem Cell Biology and Transplantology, Research Institute of the Medical University of Varna, Varna, Bulgaria.
Background: Diffuse midline glioma, H3 K27-altered (DMG) is a fatal tumour that arises in the midline structures of the brain. When located in the pons, it is more commonly referred to as diffuse intrinsic pontine glioma (DIPG). DMG/DIPG is usually diagnosed when children are < 10 years, and it has a median overall survival of < 12 months after diagnosis.
View Article and Find Full Text PDFNature
December 2024
Single Molecule Biophysics Group, MRC Laboratory of Medical Sciences, London, UK.
The yeast SWR1 complex catalyses the exchange of histone H2A-H2B dimers in nucleosomes, with Htz1-H2B dimers. Here we used single-molecule analysis to demonstrate two-step double exchange of the two H2A-H2B dimers in a canonical yeast nucleosome with Htz1-H2B dimers, and showed that double exchange can be processive without release of the nucleosome from the SWR1 complex. Further analysis showed that bound nucleosomes flip between two states, with each presenting a different face, and hence histone dimer, to SWR1.
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