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Title: Nucleosome-like, Single-stranded DNA (ssDNA)-Histone Octamer Complexes and the Implication for DNA Double Strand Break Repair.

Authors: Adkins, Nicholas L; Swygert, Sarah G; Kaur, Parminder; Niu, Hengyao; Grigoryev, Sergei A; Sung, Patrick; Wang, Hong; Peterson, Craig L

Published In J Biol Chem, (2017 Mar 31)

Abstract: Repair of DNA double strand breaks (DSBs) is key for maintenance of genome integrity. When DSBs are repaired by homologous recombination, DNA ends can undergo extensive processing, producing long stretches of single-stranded DNA (ssDNA). In vivo, DSB processing occurs in the context of chromatin, and studies indicate that histones may remain associated with processed DSBs. Here we demonstrate that histones are not evicted from ssDNA after in vitro chromatin resection. In addition, we reconstitute histone-ssDNA complexes (termed ssNucs) with ssDNA and recombinant histones and analyze these particles by a combination of native gel electrophoresis, sedimentation velocity, electron microscopy, and a recently developed electrostatic force microscopy technique, DREEM (dual-resonance frequency-enhanced electrostatic force microscopy). The reconstituted ssNucs are homogenous and relatively stable, and DREEM reveals ssDNA wrapping around histones. We also find that histone octamers are easily transferred in trans from ssNucs to either double-stranded DNA or ssDNA. Furthermore, the Fun30 remodeling enzyme, which has been implicated in DNA repair, binds ssNucs preferentially over nucleosomes, and ssNucs are effective at activating Fun30 ATPase activity. Our results indicate that ssNucs may be a hallmark of processes that generate ssDNA, and that posttranslational modification of ssNucs may generate novel signaling platforms involved in genome stability.

PubMed ID: 28202543 Exiting the NIEHS site

MeSH Terms: Chromatin Assembly and Disassembly/genetics; DNA Breaks, Double-Stranded; DNA Repair/genetics*; DNA, Single-Stranded/metabolism*; Genomic Instability; Histones/metabolism*; Nucleosomes/metabolism*; Protein Processing, Post-Translational; Saccharomyces cerevisiae Proteins/metabolism; Saccharomyces cerevisiae/genetics*; Transcription Factors/metabolism

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