title: Biotinylation of lysine 16 in histone H4 contributes toward nucleosome condensation.
abstract: Holocarboxylase synthetase (HLCS) is part of a multiprotein gene repression complex and catalyzes the covalent binding of biotin to lysines (K) in histones H3 and H4, thereby creating rare gene repression marks such as K16-biotinylated histone H4 (H4K16bio). We tested the hypothesis that H4K16bio contributes toward nucleosome condensation and gene repression by HLCS. We used recombinant histone H4 in which K16 was mutated to a cysteine (H4K16C) for subsequent chemical biotinylation of the sulfhydryl group to create H4K16Cbio. Nucleosomes were assembled by using H4K16Cbio and the 'Widom 601' nucleosomal DNA position sequence; biotin-free histone H4 and H4K16C were used as controls. Nucleosomal compaction was analyzed using atomic force microscopy (AFM). The length of DNA per nucleosome was ∼30% greater in H4K16Cbio-containing histone octamers (61.14±10.92nm) compared with native H4 (46.89±12.6nm) and H4K16C (47.26±10.32nm), suggesting biotin-dependent chromatin condensation (P<0.001). Likewise, the number of DNA turns around histone core octamers was ∼17.2% greater in in H4K16Cbio-containing octamers (1.78±0.16) compared with native H4 (1.52±0.21) and H4K16C (1.52±0.17), judged by the rotation angle (P<0.001; N=150). We conclude that biotinylation of K16 in histone H4 contributes toward chromatin condensation.
authors.affiliation: Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, NE 68583-0806, USA.
authors.forename: Mahendra P
authors.initials: MP
authors.lastname: Singh
authors.forename: Subhashinee S K
authors.initials: SS
authors.lastname: Wijeratne
authors.forename: Janos
authors.initials: J
authors.lastname: Zempleni
mesh_terms: D019921:Biotinylation / Q000379:methods*; D006657:Histones / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008239:Lysine / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D009707:Nucleosomes / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D015202:Protein Engineering / Q000379:methods
chemical_list: D006657:Histones; D009707:Nucleosomes; D008239:Lysine