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dc.contributor.authorCan, Geylani
dc.date.accessioned2017-11-10T16:26:20Z
dc.date.available2017-11-10T16:26:20Z
dc.date.issued2017-10-12
dc.identifier.urihttps://www.repository.cam.ac.uk/handle/1810/268506
dc.description.abstractDNA damage or replication stress during S-phase can activate the S-phase checkpoint which executes a variety of responses, such as the inhibition of origin firing and replication fork stabilisation. Deregulation of the S-phase checkpoint leads to genomic instability, which has been implicated in diseases such as cancer. In this thesis, I aimed to address whether the S-phase checkpoint is regulated outside of S-phase, and how the S-phase checkpoint targets its substrates in budding yeast. Although this checkpoint has thus far been associated exclusively with S-phase, it remains unknown whether its responses such as inhibition of origin firing can also occur in other phases of the cell cycle. To investigate this, the targets of the S-phase checkpoint for the inhibition of origin firing were analysed outside of S-phase upon DNA damage. Interestingly, I showed that the S-phase checkpoint effector kinase Rad53 phosphorylates its targets to inhibit origin firing outside of S-phase upon DNA damage when there is no replication. I then set out to test whether inhibition of origin firing by Rad53 outside of S-phase might be important for faithful DNA replication. Having shown that the checkpoint response is not specific for any cell cycle phases, I then tested how the specificity of Rad53 for its substrates might be determined. After demonstrating that the essential replication protein Cdc45 is required for Rad53 to phosphorylate the initiation factor Sld3, the key residues of Cdc45 necessary for Rad53 interaction were identified. A Cdc45 allele was produced by mutating the identified residues. This allele of Cdc45 is a separation-of-function mutant which prevents Sld3 phosphorylation upon DNA damage, but retains its function in DNA replication. Because Cdc45 travels with the replication fork, it is possible that Cdc45 also targets Rad53 to the replication fork to stabilise it upon replication stress. Overall, this thesis provides evidence that the S-phase checkpoint can function throughout the cell cycle and that Cdc45 targets Rad53 to some of its substrates, and possibly plays a role in replication fork stabilisation.
dc.description.sponsorshipRepublic of Turkey Ministry of national education, the Raymond and Beverly Sackler Scholarships
dc.language.isoen
dc.rightsNo Creative Commons licence (All rights reserved)
dc.rightsAll Rights Reserveden
dc.rights.urihttps://www.rioxx.net/licenses/all-rights-reserved/en
dc.subjectCell cycle
dc.subjectDNA replication
dc.subjectDNA damage
dc.subjectRad53
dc.subjectCdc45
dc.subjectreplication fork stabilisation
dc.titleS-phase checkpoint activity and function throughout the cell cycle
dc.typeThesis
dc.type.qualificationlevelDoctoral
dc.type.qualificationnameDoctor of Philosophy (PhD)
dc.publisher.institutionUniversity of Cambridge
dc.publisher.departmentZoology
dc.date.updated2017-11-10T13:18:04Z
dc.identifier.doi10.17863/CAM.14717
dc.contributor.orcidCan, Geylani [0000-0002-1716-7830]
dc.publisher.collegeSidney Sussex
dc.type.qualificationtitlePhD in Zoology
cam.supervisorZegerman, Philip
rioxxterms.freetoread.startdate2018-11-10


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