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Dissertation
Investigation into synaptic and post-synaptic events of RAD51 mediated homologous recombination
Doctor of Philosophy (Ph.D.), Drexel University
May 2018
DOI:
https://doi.org/10.17918/D8TQ1G
Abstract
Homologous Recombination (HR) is the only means by which the deadliest form of DNA damage (Double Strand Break) can be repaired without error. Thus, I set out to better understand HR. Specifically, I wanted to address two holes in the field which were: (1) how are the template DNA strands found (synapsis) during HR; and (2) what happens afterwards. To address these two questions, I purified the main mammalian recombinase (RAD51) and other key proteins involved in HR to study in vitro. Through my studies, I have found that synapsis occurs through RAD51-nucleoprotein complexes which we term Homology-Search-Networks. This network has the following characteristics: (1) it consists of ssDNA, dsDNA, and RAD51; (2) it is essential to strand-exchange; (3) it is organized ; and (4) it is based upon multiple weak contacts. Furthermore, I found that in the post-synaptic phase, RAD51 dissociates D-Loops by unwinding dsDNA. Moreover, this process can be controlled by BRCA2 through BRC4 interaction. The result is a fine-tuning mechanism at the site of DNA damage to control strand-exchange and thereby HR. The implication is that the old notions of co-aggregates during synapsis can be updated and the current findings fit nicely with new single-molecule studies by Kowalczykowski, Ha, and Greene. Furthermore, my post-synaptic findings provide a solid molecular mechanism of the RAD51-BRCA2 homeostasis that controls Homologous Recombination. Together, my work will impact the fields of DNA repair, cancer biology, and genetic engineering.
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Details
- Title
- Investigation into synaptic and post-synaptic events of RAD51 mediated homologous recombination
- Creators
- Charles X. Wang - DU
- Contributors
- Alexander V. Mazin (Advisor) - Drexel University (1970-)Jane Clifford (Advisor) - Drexel University (1970-)
- Awarding Institution
- Drexel University
- Degree Awarded
- Doctor of Philosophy (Ph.D.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Number of pages
- ix, 114 pages
- Resource Type
- Dissertation
- Language
- English
- Academic Unit
- Biochemistry and Molecular Biology; College of Medicine; Drexel University
- Other Identifier
- 8113; 991014632573004721