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Title: Structural basis of centrosome assembly in flies
Author: Haensele, Andreas Florian Matthias
ISNI:       0000 0004 9351 3322
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 2020
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Centrosomes are the main microtubule-organising centres in many animal cells. They consist of a pair of centrioles surrounded by a dense mass of protein known as the pericentriolar material. As the cell enters mitosis, this pericentriolar material expands dramatically in a process called centrosome maturation. In flies, the protein Centrosomin (Cnn) assembles into a network that acts as a scaffold for the recruitment of the hundreds of other proteins making up a mature centrosome. Cnn network formation is known to depend on phosphorylation of a central region within Cnn. However, it is unclear how Cnn assembles into a network and how this process is controlled. In this thesis it is shown that Cnn network formation in vitro depends on an interaction between the conserved C-terminus of Cnn and the phospho-regulated central region. The crystal structure of part of this central region is solved, revealing that it forms a dimer of α-helical hairpins that are sterically incompatible with binding of the Cnn C-terminus. The structure is therefore proposed to constitute an “inactive” state. Furthermore, the structure suggests a mechanism wherein phosphorylation acts by disrupting the hairpin fold, thereby exposing the Cnn C-terminus binding site and hence allowing formation of an “assembly-competent” state where the Cnn C-terminus is bound. In addition, the calcium-binding protein Calmodulin is shown to crosslink the Cnn C-terminus in crystallo. However, Calmodulin inhibits network assembly of Cnn constructs in solution, possibly by preventing the assembly-competent state from forming a network. Taken together, this thesis draws on structural and functional data to provide important atomic-level insights into the mechanism of mitotic centrosome assembly in flies.
Supervisor: Raff, Jordan ; Lea, Susan Sponsor: Clarendon Fund ; Sir William Dunn School of Pathology ; Santander
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Mitosis ; Drosophila melanogaster ; X-ray crystallography