| 研究実績の概要 |
Homologous recombination (HR) is a major pathway for the repair of DNA double-strand breaks (DSBs), a severe form of DNA damage. During HR, genetic information from an intact region of the genome is used as a template to recover lost genetic information, leading to the precise repair of a DSB. The Rad51 protein is essential for HR, but several auxiliary factors promote the activity of Rad51, including the Swi5-Sfr1 and Rad55-Rad57 complexes. We employed an interdisciplinary approach to characterize the interactions between these proteins.
Through a combination of NMR-based protein-protein interaction analysis and in vivo proximity crosslinking, I identified two sites within the N-terminal half of Sfr1 that physically interact with Rad51. Mutations in each site reduced the interaction with Rad51, whereas mutations in both sites completely ablated the interaction. Consistently, while the single-site mutants were mildly defective for the stimulation of Rad51 in vitro, the double-site mutant was severely defective. Surprisingly, I found that cells containing mutations in both sites were nevertheless completely proficient in DNA repair. However, this was because the Rad55-Rad57 complex, which was thought to comprise an independent sub-pathway of HR, was rescuing the defect of the (Swi5-Sfr1)-Rad51 interaction mutants. Consistently, Swi5-Sfr1 and Rad55-Rad57 were found to interact with each other. These results provided mechanistic insights into the activation of Rad51 by Swi5-Sfr1 and uncovered a functional interplay between Swi5-Sfr1 and Rad55-Rad57.
|
