Attenuation of DNA charge transport by compaction into a nucleosome core particle.
The nucleosome core particle (NCP) is the fundamental building block of chromatin which compacts approximately 146 bp of DNA around a core histone protein octamer. The effects of NCP packaging on long-range DNA charge transport reactions have not been adequately assessed to date. Here we study DNA hole transport reactions in a 157 bp DNA duplex (AQ-157TG) incorporating multiple repeats of the DNA TG-motif, a strong NCP positioning sequence and a covalently attached Anthraquinone photooxidant. Following a thorough biophysical characterization of the structure of AQ-157TG NCPs by Exonuclease III and hydroxyl radical footprinting, we compared the dynamics of DNA charge transport in ultraviolet-irradiated free and NCP-incorporated AQ-157TG. Compaction into a NCP changes the charge transport dynamics in AQ-157TG drastically. Not only is the overall yield of oxidative lesions decreased in the NCPs, but the preferred sites of oxidative damage change as well. This NCP-dependent attenuation of DNA charge transport is attributed to DNA-protein interactions involving the folded histone core since removal of the histone tails did not perturb the charge transport dynamics in AQ-157TG NCPs.
Bjorklund
Chad C
CC
School of Molecular Biosciences, Fulmer Hall 275, Washington State University, Pullman, WA 99164-4660, USA.
Davis
William B
WB
D004247:DNA / Q000737:chemistry* / Q000528:radiation effects; D004249:DNA Damage; D018983:DNA Footprinting; D042003:DNA Packaging; D004583:Electrons; D006657:Histones / Q000737:chemistry; D009707:Nucleosomes / Q000737:chemistry*; D018384:Oxidative Stress; D014466:Ultraviolet Rays
C509907:AQ 157TG; D006657:Histones; D009707:Nucleosomes; D004247:DNA