From strand exchange to branch migration; bypassing of non-homologous sequences by human Rad51 and Rad54.
Rad51 and Rad54 play crucial roles during homologous recombination. The biochemical activities of human Rad51 (hRad51) and human Rad54 (hRad54) and their interactions with each other are well documented. However, it is not known how these two proteins work together to bypass heterologous sequences; i.e. mismatched base pairs, during homologous recombination. In this study, we used a fluorescence resonance energy transfer assay to monitor homologous recombination processes in real time so that the interactions between hRad54 and hRad51 during DNA strand exchange and branch migration, which are two core steps of homologous recombination, could be characterized. Our results indicate that hRad54 can facilitate hRad51-promoted strand exchange through various degrees of mismatching. We propose that the main roles of hRad51 in homologous recombination is to initiate the homology recognition and strand-exchange steps and those of hRad54 are to promote efficient branch migration, bypass potential mismatches and facilitate long-range strand exchanges through branch migration of Holliday junctions.
Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA.
Damian E
DE
Urena
Zhaoqing
Z
Zhang
Yu-Cheng
YC
Tsai
Yu-Zhen
YZ
Wang
Junghuei
J
Chen
D020137:Base Pair Mismatch; D004247:DNA / Q000378:metabolism*; D004265:DNA Helicases; D045566:DNA, Cruciform; D004268:DNA-Binding Proteins; D031541:Fluorescence Resonance Energy Transfer; D006801:Humans; D009687:Nuclear Proteins / Q000378:metabolism*; D011485:Protein Binding; D051135:Rad51 Recombinase / Q000378:metabolism*; D011995:Recombination, Genetic; D013194:Staining and Labeling / Q000379:methods
D045566:DNA, Cruciform; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D004247:DNA; C495153:RAD51 protein, human; D051135:Rad51 Recombinase; D004265:DNA Helicases; C103532:RAD54L protein, human