Mechanism and Genetics of Polymerase Theta-Mediated End Joining
Public Deposited- Creator
-
Carvajal Garcia, Juan
- School of Medicine, Curriculum in Genetics and Molecular Biology
-
Carvajal Garcia, Juan
- Abstract
- DNA stores the information that cells need to function, grow, and divide. However, DNA is constantly being damaged. Therefore, cells need to efficiently recognize and repair damage in their DNA to survive. Chromosome double strand breaks are a particularly toxic form of DNA damage that cells repair in one of three ways: non-homologous end joining, homologous recombination, and polymerase theta-mediated end joining. This dissertation is dedicated to improving our understanding of polymerase theta-mediated end joining, an error-prone chromosome break repair pathway that is rarely used in normal cells, but that many cancer cells rely on for survival. Mechanistically, polymerase theta-mediated end joining takes advantage of microhomologies, small patches of identical sequences present at both side of a chromosome break. First, I show how polymerase theta finds these microhomologies, in a way that minimizes the amount of lost DNA, and also how, when microhomologies are not present, polymerase theta is able to create them. Then, I systematically test which substrates polymerase theta is able to use in the repair of chromosome breaks, which helps characterize the beginning of the pathway. The versatility I observe makes polymerase theta-mediated end joining an ideal pathway for the repair of breaks with end structures that are not amenable to non-homologous end joining and homologous recombination. I also describe the last two steps of the pathway, which involve nucleolysis and DNA synthesis.Finally, I characterize the genetic interaction between polymerase theta and the Holliday junction resolvases, proteins involved in a potentially mutagenic form of homologous recombination, and determine that polymerase theta protects against this detrimental form of repair. Throughout the dissertation, I describe multiple circumstances in which, even though the use of polymerase theta-mediated end joining guarantees a small loss of DNA, it also protects against more pathogenic forms of repair. This helps explain the paradoxical observation that this error-prone repair pathway is present in almost all eukaryotic organisms.
- Date of publication
- 2021
- Keyword
- DOI
- Resource type
- Rights statement
- In Copyright - Educational Use Permitted
- Advisor
- Ramsden, Dale A
- Sekelsky, Jeff
- Duronio, Robert J
- Gupta, Gaorav P
- Kunkel, Thomas A
- Degree
- Doctor of Philosophy
- Degree granting institution
- University of North Carolina at Chapel Hill Graduate School
- Graduation year
- 2021
- Language
Relations
- Parents:
This work has no parents.
Items
| Thumbnail | Title | Date Uploaded | Visibility | Actions |
|---|---|---|---|---|
|
|
CarvajalGarcia_unc_0153D_20122.pdf | 2021-06-21 | Public | Download |