Abstract
Histone H3 acetylation is induced by UV damage in yeast and may play an important role in regulating the repair of UV photolesions in nucleosome-loaded genomic loci. However, it remains elusive how H3 acetylation facilitates repair. We generated a strongly positioned nucleosome containing homogeneously acetylated H3 at Lys-14 (H3K14ac) and investigated possible mechanisms by which H3K14 acetylation modulates repair. We show that H3K14ac does not alter nucleosome unfolding dynamics or enhance the repair of UV-induced cyclobutane pyrimidine dimers by UV photolyase. Importantly, however, nucleosomes with H3K14ac have a higher affinity for purified chromatin remodeling complex RSC (Remodels the Structure of Chromatin) and show greater cyclobutane pyrimidine dimer repair compared with unacetylated nucleosomes. Our study indicates that, by anchoring RSC, H3K14 acetylation plays an important role in the unfolding of strongly positioned nucleosomes during repair of UV damage.
Highlights
Histone H3K14 acetylation is induced by UV damage
Nucleosomes with H3K14ac have a higher affinity for purified chromatin remodeling complex RSC (Remodels the Structure of Chromatin) and show greater cyclobutane pyrimidine dimer repair compared with unacetylated nucleosomes
H3K14 Acetylation Does Not Affect Nucleosome Unwrapping Dynamics and Salt Stability—To investigate the role of H3K14 acetylation, a modification that is induced by UV irradiation and is important for nucleotide excision repair (NER) [6], we prepared both unmodified histone octamers [35] and histone octamers homogenously acetylated at H3K14
Summary
Histone H3K14 acetylation is induced by UV damage. Results: Nucleosomes with acetylated H3K14 show greater CPD repair than unacetylated nucleosomes in the presence of the chromatin remodeling complex RSC. Histone H3 acetylation is induced by UV damage in yeast and may play an important role in regulating the repair of UV photolesions in nucleosome-loaded genomic loci. It remains elusive how H3 acetylation facilitates repair. The access step in UV damage repair is regulated by several different mechanisms, including histone posttranslational modification and chromatin remodeling by ATP-dependent remodeling complexes [3, 4]. Nucleosomes are not static particles but exist in a dynamic equilibrium in which the DNA unwraps and rewraps from the histone octamer spontaneously (10 –12) This transient DNA site exposure may result in increased accessibility to repair proteins. There is no direct evidence showing that chromatin remodeling complexes and histone acetylation act in a coordinated manner to facilitate repair following UV damage
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