PARENT SESSION

Chromatin Remodeling and DNA Repair

(SY051) Chromatin remodeling during DSB repair.

Osley, Mary Ann¹, ¹ University of New Mexico, Albuquerque, NM, USA

ABSTRACT- Chromatin structure influences all processes that occur on DNA and must be altered to allow binding of factors that regulate transcription, replication, and DNA repair. In response to a DNA double strand break(DSB), phosphorylation of histone H2A (gamma-H2A) occurs rapidly and spreads over a large domain surrounding the break. Using budding yeast, we have found that gamma-H2A is followed by displacement of nucleosomes near a DSB, and have identified the INO80 nucleosome-remodeling factor as important for histone eviction. Gamma-H2A and INO80-regulated nucleosome displacement are independent events, although both forms of chromatin remodeling are ultimately controlled by MRX (Mre11-Rad50-Xrs2), one of the earliest factors to be recruited to DSBs. Nucleosome displacement plays an important role in DNA repair by homologous recombination (HR) and is required for efficient recruitment of HR proteins to DSBs. In contrast, gamma-H2A is required for stable association of DNA repair factors with DSBs.

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