Nucleotide excision repair (NER) is critical for maintaining genome integrity. How chromatin dynamics are regulated to facilitate this process in chromatin is still under exploration. Htz1 (H2A.Z), a highly conserved histone H2A variant, is incorporated into the nucleosomes around the promoters of many genes in S. cerevisiae. Htz1 is involved in the maintenance of genome stability, DNA transcription activation, DNA replication and DNA repair. In this study, I employed Saccharomyces cerevisiae, as a model organism. In this thesis, I examined the role of histone Htz1 in the response to UV light at specific regions using a high resolution approach and throughout the entire yeast genome using chromatin-immunoprecipitation coupled to microarrays. htz1Δ and its deposition related mutants are more sensitive to UV and CPD removal was impaired in total DNA from both htz1Δ and swr1Δ strains. Acetylation of Htz1 at K3, 8, 10, 14 does not contribute to UV sensitivity or CPD removal from total DNA. CPD removal experiments at the MFA2 promoter and the HMRa1 coding region have showed that Htz1 has a role in NER and it likely only affects repair at local nucleosomes containing Htz1. My ChIP experiments at MFA2 and HMRa1 indicate that Htz1 enhances the binding of the HAT Gcn5 to Htz1 containing chromatin and this promotes histone H3 hyperacetylation in Htz1 nucleosomes in the MFA2 promoter after UV irradiation. As a result of this optimal level of histone H3 acetylation occur and the binding of Rad14 to damaged DNA is also enhanced at this region. My genome-wide study shows that UV does not influence the localization of Htz1 as it still resides at the pre-UV sites. Htz1 and H3 K9K14 acetylation is found to be associated with each other genome-wide. This is believed to be via the interaction between Htz1 and Gcn5. These results show that there is a positive role of Htz1 in promoting efficient GG-NER.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:585332 |
| Date | January 2013 |
| Creators | Deng, Yanbo |
| Publisher | Cardiff University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://orca.cf.ac.uk/53919/ |
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