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Title: The study of chromodomain protein interactions
Author: Callaghan, J. M.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2005
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The packaging of DNA into chromatin is not merely a means by which DNA is confined within the cell, moreover, it also provides a mechanism by which gene expression is regulated. How eukaryotic genomes are manipulated within the chromatin environment is a fundamental biological issue in which the histone proteins and the proteins that interact with them, play a key role. This thesis describes the biochemical and biophysical characterisation of four chromodomain proteins, the chromodomain and the shadow chromodomain of Heterochromatin Protein 1 (HP1) and the chromodomains of the Polycomb proteins Pc and M33. The ability of the HP1, Pc and M33 chromodomains to function as histone recognition modules was investigated, with the results showing that both families of chromodomain interact with methylated lysine residues of histone H3 in a very similar manner. However, the HP1 chromodomain interacts with a greater affinity with methylated K9 of H3, than those of Pc and M33 which bind preferentially to methylated K27 of H3. The latter class of chromodomain exhibits a weaker affinity for its target than that shown by the HP1 chromodomain and possesses a longer peptide binding site. Binding studies of HP1 chromodomain mutants are described, which show that residues within the methyl binding pocket are essential for methyllysine recognition. The importance of other residues in the recognition of the H3 sequence was also investigated and highlighted the significant contribution made by A7 of H3. The influence of other histone modifications, namely, phosphorylation and acetylation upon the ability of the HP1 chromodomain to bind methylated K9 of H3 was also investigated. The acetylation of K14 was not found to interfere with methyllysine 9 binding by HP1, whereas S10 phosphorylation reduces the affinity and the simultaneous presence of all three modifications abrogates binding.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available