Mechanobiology Institute, Singapore (NUS)
PhD Oral Defence

Investigation of key steps involved in DNA Homologous Recombination Repair at single molecular level

Speaker           :   CHEN Jin (Graduate Student, MBI, NUS)
Date                 :   19 Oct 2017, Thursday
Time                :    10am
Venue              :   T-Lab, MBI, level 5 seminar rooms
Supervisor(s)  :   Prof YAN Jie

Abstract: Homologous recombination (HR) repairs DNA double strand break through genetic exchange with identical chromosome under the regulation of a variety of repair proteins. Single-stranded DNA binding proteins such as prokaryotic SSB and its eukaryotic homolog RPA are important factors involved in HR. In this study, activity of a group of E.coli SSB and human RPA on a single ssDNA molecule binding is investigated. In addition, a label-free single molecule platform is developed to detect real-time annealing events between a mechanically extended ssDNA and short complementary ssDNA oligos. SSB and RPA showed different extent of inhibitory effect on annealing between ssDNA through retarding the nucleation process. Moreover, a spontaneous homology specific interaction between ssDNA and dsDNA is observed, indicating formation of a parallel DNA triplex structure. The parallel triplex has similar stability compared to B-form dsDNA. The triplex structure provides clue for the actual role of DNA recombinase in homologous search and pairing. In sum, results in this study provide molecular insights for the key steps involved in HR.

ALL EXCEPT PANEL ARE EXCUSED FOR CLOSE DOOR EXAMINATION