Master of Science in Biology

in the

School of Biological Sciences

Yixun Tan

Will defend his thesis

“Role of RNase H1 in RNA-mediated End Joining Repair”

12 JANUARY 2026

14:30

https://gatech.zoom.us/j/91594268291?pwd=Lv4EbpeocuTRDSbmb6ZIjWXssDS0Sz.1

Thesis Advisor:

Dr. Francesca Storici

School of Biological Sciences

Georgia Institute of Technology

Committee Members:

Dr. Yury O. Chernoff

School of Biological Sciences

Georgia Institute of Technology

 Dr. Andrew McShan

School of Chemistry & Biochemistry

Georgia Institute of Technology

Abstract: RNA has increasingly been recognized as an active participant in the repair of DNA double-strand breaks (DSBs), extending the classical DNA-centric view,In multiple organisms, transcript RNA and RNA–DNA hybrids have been shown to influence repair efficiency and pathway choice, yet the regulatory mechanisms governing RNA-mediated end joining at chromosomal breaks remain incompletely understood. RNase H1, a conserved enzyme that selectively degrades the RNA strand of RNA–DNA hybrids, represents a key factor linking RNA metabolism to genome maintenance.

This thesis investigates the role of RNase H1 in RNA-mediated end-joining repair using a chromosomal reporter system in Saccharomyces cerevisiae. Antisense and branchΔ intron-containing constructs were integrated into the yeast genome to generate spliced and non-spliced RNA species in a defined chromosomal context. These constructs were analyzed in parallel wild-type and rnh1Δ backgrounds, allowing direct assessment of how RNase H1 status influences RNA processing and repair outcomes. A genetically controlled strain panel was generated through targeted deletion and restoration of the endogenous RNH1 locus using the delitto perfetto strategy.