Submitted to: Journal of Nutritional Biochemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/6/2005
Publication Date: 3/23/2006
Citation: Chew, Y., Camporeale, G., Kothapalli, N., Sarath, G., Zempleni, J. 2006. Lysine residues in n- and c- terminal regions of human histone h2a are targets for biointylation by biotinidase. Journal of Nutritional Biochemistry 17: 225-233. Interpretive Summary: In this study we have used biochemical and immunological tools to understand modification of histone H2 A by biotinylation. Specific lysine residues were biotinylated and biotinylating enzymes were localized to the nucleus. These data provide more evidence for the importance of histone-biotinylation in potentially regulating important cellular processes in eukaryotic cells.
Technical Abstract: In eukaryotic cell nuclei, DNA associates with the core histones H2A, H2B, H3, and H4 to form nuclosomal core particles. DNA binding to histones is regulated by posttranslational modifications of N-terminal tails, e.g., acetylation and methylation of histones. These modifications play important roles in the epigenetic control of chromatin structure. Recently, evidence has been provided that biotinidase and holocarboxylase synthetase catalyze the covalent binding of biotin to histones. Primary aim of this study was to identify biotinylation sites in histone H2A and its variant H2A.X. Secondary aims were to determine whether acetylation and methylation of histone H2A affect subsequent biotinylation, and to determine whether biotinidase and holocarboxylase synthetase localize to the nucleus in human cells. Biotinylation sites were identified using synthetic peptides as substrates for biotinidase. These studies provided evidence that K9 and K13 in the N-terminus of human histone H2A and H2A.X are targets for biotinylation, and that K125, K127, and K129 in the C-terminus of histone H2A are targets for biotinylation. Biotinylation of lysine residues was decreased by acetylation of adjacent lysines, but was increased by dimethylation of adjacent arginines. The existence of biotinylated histone H2A in vivo was confirmed by using modification-specific antibodies. Antibodies to biotinidase and holocarboxylase synthetase localized primarily to the nuclear compartment, consistent with a role for these enzymes in regulating chromatin structure. Collectively, these studies have identified five novel biotinylation sites in human histones; histone H2A is unique among histones in that biotinylation sites include amino acid residues from the C-terminus.