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Title: The regulation of pre-replicative complex formation in the budding yeast cell cycle
Author: Noton, Elizabeth Anne
ISNI:       0000 0001 3449 916X
Awarding Body: University of London
Current Institution: University College London (University of London)
Date of Award: 2000
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DNA replication must occur once and only once in every cell cycle to ensure that mitosis produces two daughter cells with the same complement of genomic DNA. Initiation of DNA replication depends upon pre-replicative complex (pre-RC) assembly at origins during Gl. The pre-RC includes a six-subunit origin recognition complex (ORC) and Cdc6p which together load a complex of the Mcm2-7p family of putative helicases onto chromatin. Only one ORC subunit, Orc6p, is not required for binding of the others to origins in vitro. Using a temperature sensitive orc6 mutant we have shown in vivo that although Orc6p is dispensable for binding of other ORC subunits to chromatin, it is essential for pre-RC formation and may function as an "adapter" between ORC and other pre-RC components. The activity of cyclin dependent kinases (CDKs) regulates pre-RC formation in the cell cycle. CDKs inhibit the formation of pre-RCs during S phase, G2 and M phase, suggesting that inactivation of CDKs at the end of mitosis is essential for pre- RC formation in Gl. Other mitotic events may also be important for pre-RC formation. In particular, the anaphase promoting complex (APC/C), which targets mitotic proteins for proteolysis and the mitotic exit network which activates a mitotic phosphatase, Cdcl4p, have been implicated in pre-RC formation. We have found that inactivation of CDKs during mitosis bypasses the requirement for the APC/C and the mitotic exit network in DNA replication. This suggests that the only essential role for these proteins for pre-RC formation is to bring about CDK inactivation at the end of mitosis.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: DNA replication; Cyclin dependent kinases