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Title: Molecular analysis of the subunits of DNA-dependent protein kinase
Author: Gell, D.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 1999
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The work contained within this thesis is concerned with understanding the protein interactions between the subunits of DNA-PK, and how these interactions contribute to the correct functioning of the enzyme. The first part of this thesis investigates interactions between the subunits of Ku. The Ku heterodimer is composed of ~69 and ~83 kDa subunits, termed ku70 and Ku80 respectively. I have determined regions of both ku70 and Ku80 that mediate contact between the Ku subunits. Strikingly, these regions show amino acid sequence similarity, and further analysis has revealed that sequence similarities between Ku70 and Ku80 exist at many positions throughout the full lengths of these proteins. From these studies I propose that the structures of Ku70 and Ku80 are similar and that they associate by a pseudo-homodimerisation mechanism. A second part of this work investigates interactions between Ku and DNA-PKcs. I have shown that a major contribution to this interaction occurs through the extreme C-terminus of Ku80. Whilst it has been reported recently that DNA-PKcs can be activated by DNA-ends in the absence of Ku, my data suggests that, under cellular conditions, Ku is required to achieve efficient activation of DNA-PK. Understanding how the interaction between Ku and DNA-PKcs is modulated is, therefore, central to understanding DNA-PK activation. Data presented in this thesis suggests that the C-terminal region of Ku80, containing the DNA-PKcs interaction region, is more accessible to the solute after Ku is bound to DNA. A conformational change is Ku80 upon Ku binding to DNA could expose the DNA-PKcs interaction domain and lead to formation of the active DNA-PK complex.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available