title: Internal modifications in the CENP-A nucleosome modulate centromeric dynamics.
abstract: Posttranslational modifications of core histones are correlated with changes in transcriptional status, chromatin fiber folding, and nucleosome dynamics. However, within the centromere-specific histone H3 variant CENP-A, few modifications have been reported, and their functions remain largely unexplored. In this multidisciplinary report, we utilize in silico computational and in vivo approaches to dissect lysine 124 of human CENP-A, which was previously reported to be acetylated in advance of replication.
  
  
  
  Computational modeling demonstrates that acetylation of K124 causes tightening of the histone core and hinders accessibility to its C-terminus, which in turn diminishes CENP-C binding. Additionally, CENP-A K124ac/H4 K79ac containing nucleosomes are prone to DNA sliding. In vivo experiments using a CENP-A acetyl or unacetylatable mimic (K124Q and K124A, respectively) reveal alterations in CENP-C levels and a modest increase in mitotic errors. Furthermore, mutation of K124 results in alterations in centromeric replication timing. Purification of native CENP-A proteins followed by mass spectrometry analysis reveals that while CENP-A K124 is acetylated at G1/S, it switches to monomethylation during early S and mid-S phases. Finally, we provide evidence implicating the histone acetyltransferase (HAT) p300 in this cycle.
  
  
  
  Taken together, our data suggest that cyclical modifications within the CENP-A nucleosome contribute to the binding of key kinetochore proteins, the integrity of mitosis, and centromeric replication. These data support the paradigm that modifications in histone variants can influence key biological processes.
authors.affiliation: Chromatin Structure and Epigenetic Mechanisms Unit, Laboratory of Receptor Biology and Gene Expression, CCR, NCI, NIH, Bethesda, MD 20892 USA.
authors.forename: Minh
authors.initials: M
authors.lastname: Bui
authors.affiliation: Chromatin Structure and Epigenetic Mechanisms Unit, Laboratory of Receptor Biology and Gene Expression, CCR, NCI, NIH, Bethesda, MD 20892 USA.|Department of Biophysics, University of Maryland, College Park, MD USA.
authors.forename: Mary
authors.initials: M
authors.lastname: Pitman
authors.affiliation: Cellular Networks Proteomics Unit, Laboratory of Systems Biology, NIAID, NIH, Bethesda, MD 20892 USA.
authors.forename: Arthur
authors.initials: A
authors.lastname: Nuccio
authors.affiliation: Chromatin Structure and Epigenetic Mechanisms Unit, Laboratory of Receptor Biology and Gene Expression, CCR, NCI, NIH, Bethesda, MD 20892 USA.
authors.forename: Serene
authors.initials: S
authors.lastname: Roque
authors.affiliation: Chromatin Structure and Epigenetic Mechanisms Unit, Laboratory of Receptor Biology and Gene Expression, CCR, NCI, NIH, Bethesda, MD 20892 USA.|Department of Cell Biology, Emory University, Atlanta, GA USA.
authors.forename: Paul Gregory
authors.initials: PG
authors.lastname: Donlin-Asp
authors.affiliation: Cellular Networks Proteomics Unit, Laboratory of Systems Biology, NIAID, NIH, Bethesda, MD 20892 USA.
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Nita-Lazar
authors.affiliation: Department of Biophysics, University of Maryland, College Park, MD USA.
authors.forename: Garegin A
authors.initials: GA
authors.lastname: Papoian
authors.affiliation: Chromatin Structure and Epigenetic Mechanisms Unit, Laboratory of Receptor Biology and Gene Expression, CCR, NCI, NIH, Bethesda, MD 20892 USA.
authors.forename: Yamini
authors.identifier: 0000-0002-7655-6182
authors.initials: Y
authors.lastname: Dalal
mesh_terms: D000107:Acetylation; D002503:Centromere / Q000378:metabolism; D000076247:Centromere Protein A / Q000737:chemistry / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism; D004261:DNA Replication; D016193:G1 Phase; D006367:HeLa Cells; D006657:Histones / Q000737:chemistry; D006801:Humans; D008856:Microscopy, Fluorescence; D056004:Molecular Dynamics Simulation; D009707:Nucleosomes / Q000378:metabolism*; D010455:Peptides / Q000032:analysis; D011485:Protein Binding; D016196:S Phase; D053719:Tandem Mass Spectrometry; D050880:p300-CBP Transcription Factors / Q000378:metabolism; D000099224:p300-CBP-Associated Factor
chemical_list: D000076247:Centromere Protein A; D002868:Chromosomal Proteins, Non-Histone; D006657:Histones; D009707:Nucleosomes; D010455:Peptides; D050880:p300-CBP Transcription Factors; D000099224:p300-CBP-Associated Factor; C060905:centromere protein C