Rapid Histone-Catalyzed DNA Lesion Excision and Accompanying Protein Modification in Nucleosomes and Nucleosome Core Particles.
C5'-Hydrogen atoms are frequently abstracted during DNA oxidation. The oxidized abasic lesion 5'-(2-phosphoryl-1,4-dioxobutane) (DOB) is an electrophilic product of the C5'-radical. DOB is a potent irreversible inhibitor of DNA polymerase β, and forms interstrand cross-links in free DNA. We examined the reactivity of DOB within nucleosomes and nucleosome core particles (NCPs), the monomeric component of chromatin. Depending upon the position at which DOB is generated within a NCP, it is excised from nucleosomal DNA at a rate 275-1500-fold faster than that in free DNA. The half-life of DOB (7.0-16.8 min) in NCPs is shorter than any other abasic lesion. DOB's lifetime in NCPs is also significantly shorter than the estimated lifetime of an abasic site within a cell, suggesting that the observed chemistry would occur intracellularly. Histones also catalyze DOB excision when the lesion is present in the DNA linker region of a nucleosome. Schiff-base formation between DOB and histone proteins is detected in nucleosomes and NCPs, resulting in pyrrolone formation at the lysine residues. The lysines modified by DOB are often post-translationally modified. Consequently, the histone modifications described herein could affect the regulation of gene expression and may provide a chemical basis for the cytotoxicity of the DNA damaging agents that produce this lesion.
Department of Chemistry, Johns Hopkins University , 3400 North Charles Street, Baltimore, Maryland 21218, United States.
Liwei
L
Weng
Department of Chemistry, Johns Hopkins University , 3400 North Charles Street, Baltimore, Maryland 21218, United States.
Marc M
MM
Greenberg
D002074:Butanones / Q000737:chemistry / Q000494:pharmacology*; D019951:DNA Polymerase beta / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D021881:DNA, Catalytic / Q000737:chemistry*; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D006657:Histones / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D009707:Nucleosomes / Q000737:chemistry*
C546811:5'-(2-phosphoryl-1,4-dioxobutane); D002074:Butanones; D021881:DNA, Catalytic; D004791:Enzyme Inhibitors; D006657:Histones; D009707:Nucleosomes; D019951:DNA Polymerase beta