title: N-formylation of lysine in histone proteins as a secondary modification arising from oxidative DNA damage.
abstract: The posttranslational modification of histone and other chromatin proteins has a well recognized but poorly defined role in the physiology of gene expression. With implications for interfering with these epigenetic mechanisms, we now report the existence of a relatively abundant secondary modification of chromatin proteins, the N(6)-formylation of lysine that appears to be uniquely associated with histone and other nuclear proteins. Using both radiolabeling and sensitive bioanalytical methods, we demonstrate that the formyl moiety of 3'-formylphosphate residues arising from 5'-oxidation of deoxyribose in DNA, caused by the enediyne neocarzinostatin, for example, acylate the N(6)-amino groups of lysine side chains. A liquid chromatography (LC)-tandem mass spectrometry (MS) method was developed to quantify the resulting N(6)-formyl-lysine residues, which were observed to be present in unperturbed cells and all sources of histone proteins to the extent of 0.04-0.1% of all lysines in acid-soluble chromatin proteins including histones. Cells treated with neocarzinostatin showed a clear dose-response relationship for the formation of N(6)-formyl-lysine, with this nucleosome linker-selective DNA-cleaving agent causing selective N(6)-formylation of the linker histone H1. The N(6)-formyl-lysine residue appears to represent an endogenous histone secondary modification, one that bears chemical similarity to lysine N(6)-acetylation recognized as an important determinant of gene expression in mammalian cells. The N(6)-formyl modification of lysine may interfere with the signaling functions of lysine acetylation and methylation and thus contribute to the pathophysiology of oxidative and nitrosative stress.
authors.affiliation: Biological Engineering Division and Center for Environmental Health Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
authors.forename: Tao
authors.initials: T
authors.lastname: Jiang
authors.forename: Xinfeng
authors.initials: X
authors.lastname: Zhou
authors.forename: Koli
authors.initials: K
authors.lastname: Taghizadeh
authors.forename: Min
authors.initials: M
authors.lastname: Dong
authors.forename: Peter C
authors.initials: PC
authors.lastname: Dedon
mesh_terms: D000107:Acetylation; D002478:Cells, Cultured; D002853:Chromatography, Liquid; D004249:DNA Damage; D003855:Deoxyribose / Q000378:metabolism; D006657:Histones / Q000378:metabolism*; D006801:Humans; D008239:Lysine / Q000378:metabolism*; D010084:Oxidation-Reduction; D053719:Tandem Mass Spectrometry
chemical_list: D006657:Histones; D003855:Deoxyribose; D008239:Lysine