Title

Functional consequences of physical interactions between PriA and PriB in DNA replication restart pathways in Neisseria Gonorrhoeae

Author

Cui Feng

Date of Award

2011

Degree Name

M.S. in Chemistry

Department

Department of Chemistry

Advisor/Chair

Advisor: Matthew E. Lopper

Abstract

DNA replication restart pathways enable bacterial cells to reinitiate DNA replication when replication has been disrupted due to encounters with DNA damage, thereby allowing complete and faithful duplication of the cell's genetic information. Neisseria gonorrhoeae is a bacterium that is highly adapted to survive oxidative damage to its DNA incurred by attack from immune cells in infected individuals, suggesting that DNA replication restart pathways might play a critical role in N. gonorrhoeae pathogenicity. The bacterial helicase, PriA, is a key primosome protein that plays essential roles in DNA replication restart pathways. However, little is known of the mechanism by which PriA performs these roles in N. gonorrhoeae. I performed equilibrium DNA binding assays and DNA unwinding assays to provide insight into the mechanisms by which PriA functions in DNA replication restart pathways. I report that DNA binding by PriA is strongly dependent on the structure of the DNA. DNA substrates that resemble a DNA replication fork with a three-way branch are bound with higher affinity than partial duplex structures or single-stranded DNA. PriA-catalyzed DNA unwinding is also DNA structure-specific, and PriA-catalyzed unwinding decreases upon increasing the length of the duplex DNA, indicating that PriA is a low-processivity helicase. Another primosome protein, PriB, strongly stimulates the helicase activity of PriA, and this activity might facilitate reloading of the replication machinery by PriA at repaired replication forks. Stimulation of PriA by PriB appears to occur through a mechanism that is distinct from that used by the well-studied E. coli primosome proteins.

Keywords

DNA helicases Research, Neisseria gonorrhoeae Research, Bacterial genetics Research, DNA repair Research

Rights Statement

Copyright 2011, author

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