Role of Orc9 in DNA damage response in Haloferax volcanii
Publication Date
December 11, 2020
Creator
Abstract
Archaeal species encode numerous copies of the DNA replication initiator protein Orc1. Haloferax volcanii contains 16 orc1 genes, however only two of these are conserved throughout species: one is always linked to a replication origin (Hvo-orc1) while the other is never linked to a replication origin (Hvo-orc9). Unlike Orc1, Orc9 has been shown to play no role in replication, with preliminary data showing strains lacking Orc9 have an acute sensitivity to DNA damaging agents such as UV radiation. This suggests a role for Orc9 in the DNA damage response.
Here, we investigate the potential function of Orc9 as a DNA damage response factor in Haloferax volcanii through analysis of transcription profiles of wild type and ∆orc9 strains in response to treatment with mitomycin-C (MMC). Cell killing assays using several DNA damaging agents such as MMS, phleomycin, hydrogen peroxide and gamma radiation were performed and results showed that the Δorc9 was hypersensitive to all these mutagens except hydrogen peroxide. Standard growth assays showed that in the presence of sub-lethal doses of MMC, ∆orc9 strains have slower growth compared to wild type strains. These growth assays will inform the ideal concentration at which each DNA damaging agent induces a DNA damage response large enough to influence the cell’s transcriptome profile and that also gives some cell viability. The correct concentrations of each DNA damaging agent were used to treat both the wild type and the ∆orc9 cells prior to RNA extraction for downstream sequencing. The RNA-sequencing data revealed that Orc9 has an influence on the global genome expression of H. volcanii.
Overall, this study has provided insights into the role of Orc9 in DNA damage response (DDR). Orc9 is likely to be a key regulator that orchestrates a network of events that lead to repair of DNA damage. If this is the case, this means that DDR is conserved in all domains of life including Archaea.
Item Type
ethesis
Thesis Type
MRes
Supervisors
Subjects (LC)
Associated Schools / Departments
School of Life Sciences
eprints ID
60072
UoN Repository URI
Except where otherwise noted, this item's license is described as
File(s)![Thumbnail Image]()
Name
Çağla Tosun 4337684 - Post corrections.pdf
Size
4.46 MB
Format
Adobe PDF
Checksum (MD5)
72e38ee1f33ba4f34334a1716896bcc9