Functional analysis of Rad51 activation by Rad55-Rad57 and Swi5-Sfr1

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K15061
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Molecular biology
• Research Institution: Tokyo Institute of Technology
• Principal Investigator: Argunhan Bilge 東京工業大学, 科学技術創成研究院, 特任助教 (30792759)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: DNA repair / Genome stability / Double-strand break / Homologous recombination / Rad51 / Swi5-Sfr1 / fiision yeast

Outline of Final Research Achievements

DNA damage is an unavoidable consequence of life. DNA double stranded breaks are the most severe form of DNA damage, and their repair by homologous recombination (HR) is critical for maintaining genome stability. The central protein in HR is Rad51, but Rad51 requires several auxiliary factors to promote HR, including Swi5-Sfr1. We characterized the physical and functional interaction of Swi5-Sfr1 with Rad51 by employing an interdisciplinary approach. Our experiments demonstrated that the N-terminal half of Sfr1 contains two regions that bind Rad51. Biochemical analysis demonstrated that the stimulation of Rad51 activity by Swi5-Sfr1 is substantially diminished when both sites are mutated. However, cells expressing the mutated form of Sfr1 were not sensitive to DNA damage. We discovered that Rad55-Rad57, an independent auxiliary factor complex, was suppressing the defect in the Swi5-Sfr1 to Rad51 interaction. These results revealed novel insights into the molecular mechanisms of HR.

Free Research Field

分子生物学

Academic Significance and Societal Importance of the Research Achievements

相同組換えは、哺乳類の腫瘍形成を防ぐために重要であるゲノムの安定性を維持するための不可欠な生体機構であり、また、減数分裂時の配偶子の生成に重要な役割を果たす。 したがって、相同組換えは、細胞増殖と生殖という2つの生命の中心的な特徴で重要な役割を果たしている。 重要なことは、相同組換の分子メカニズムが酵母からヒトまで高度に保存されていることである。したがって、酵母細胞に関する我々の発見は、ヒト細胞におけるDNA修復プロセスの理解に繋がり、そのため、がんや老化、不妊といった人類にとって極めて重要な現象の詳細な分子メカニズムの解明の基盤知識として貢献する。