Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.641743
Title: Analysis of long-range chromatin domains in yeast
Author: Boa, C.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2007
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Abstract:
In yeast the average nucleosome repeat length is only 165bp compared to the 180-200bp linker length seen in higher eukaryotes. Therefore, the majority of the yeast genome does not have sufficient linker length between nucleosomes to enable the binding of ‘linker’ histones and only areas with increased repeat length will be able to bind these specialised proteins. The FLO1 gene locus includes a potentially gene-free 6kb upstream region that exhibits antagonistic chromatin remodelling effects by two ATP-dependent nucleosome remodelling factors: Swi-Snf and Tup1-Ssn6. These complexes modulate nucleosome binding by altering the histone-DNA interactions and are pivotal to FLO1 gene regulation. Interestingly, the nucleosome array in this region is most regularly spaced when the Tup1p co-repressor is present. Thus, it constitutes a region of chromatin in the yeast genome that could accommodate linker histones and / or the Tup1p repressor complex, leading to an area of higher-order chromatin compaction. The causal relationship between Hholp (yeast ‘linker’ histone) and Tup1p-Ssn6p binding was investigated in wild-type, hho1, snf2, ssn6 and tup1 mutant cells by chromatin immuno-precipitation in the FLO1 upstream region. Hholp flanks regions of Tup1p deposition, but does not seem to recruit Tup1p-Ssn6p. Importantly, Hho1p can restrict Tup1p deposition by binding in regions of increased nucleosomal spacing. In addition, Tup1p deposition is altered significantly in snf2 strains, suggesting that a change in the higher-order chromatin structure alters the ability of chromatin remodelling factors to access the DNA. The 3D proximity of the two Tup1p peaks was investigated using chromatin capture analyses, which showed that the Tup1p sites are closely aligned, except in snf2 strains. The change in the conformation of DNA may be influenced by changes in the acetylation of the core histones which alter the fluidity of the chromatin fibre.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.641743  DOI: Not available
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