The 5′-segment of Rad51 nucleoprotein filament is preferentially used for successful strand exchange process
Date Issued
2012
Date
2012
Author(s)
Chu, Chia-Chieh
Abstract
Rad51 recombinases in eukaryotes and RecA recombinases in prokaryotes play an essential role in repairing damaged DNA by the homologous recombinational repair pathway. Once assembled on single-stranded (ss) DNA, Rad51 nucleoprotein filaments mediate the pairing and strand exchange with the homologous sequence. Single-molecule tethered particle motion (TPM) experiments monitor the DNA length and topology change during biochemical processes, and allow us to study the mechanistic details of DNA recombination processes. In the Rad51 invading strand experiments, beads were labeled on the invading ssDNA with sequence homologous to the surface-anchored duplex DNA. When bead-labeled Rad51 nucleoprotein filaments first interacted with the surface-anchored DNA, the initial Brownian motion (BM) amplitude which was resulted from the combined length contribution of the Rad51 nucleoprotein filament and surface anchored duplex DNA can be detected. The initial Brownian motion provides information on the initial contact point of the Rad51 nucleoprotein filament as well as its polarity preference for the stable synapses formation. A sum of two-segment model successfully describes the distribution of initial BM values. For transient events, the synaptic complex formation initiated at random position with no end preference. For events that drive successfully into the final strand exchange product, 5′-end segment of Rad51 nucleoprotein filament was preferentially used. Our studies suggest that Rad51 nucleoprotein filaments carry out initial strand exchange in the 5′-to-3′ direction.
Subjects
Rad51 recombinases
RecA recombinases
strand exchange
TPM
homologous recombination
Type
thesis
File(s)![Thumbnail Image]()
Loading...
Name
ntu-101-R99223207-1.pdf
Size
23.32 KB
Format
Adobe PDF
Checksum
(MD5):972d0c8b459cd4aa2c80878a53a36e7a