Heterology tolerance and recognition of mismatched base pairs by human Rad51 protein.
Human Rad51 (hRad51) promoted homology recognition and subsequent strand exchange are the key steps in human homologous recombination mediated repair of DNA double-strand breaks. However, it is still not clear how hRad51 deals with sequence heterology between the two homologous chromosomes in eukaryotic cells, which would lead to mismatched base pairs after strand exchange. Excessive tolerance of sequence heterology may compromise the fidelity of repair of DNA double-strand breaks. In this study, fluorescence resonance energy transfer (FRET) was used to monitor the heterology tolerance of human Rad51 mediated strand exchange reactions, in real time, by introducing either G-T or I-C mismatched base pairs between the two homologous DNA strands. The strand exchange reactions were much more sensitive to G-T than to I-C base pairs. These results imply that the recognition of homology and the tolerance of heterology by hRad51 may depend on the local structural motif adopted by the base pairs participating in strand exchange. AnhRad51 mutant protein (hRad51K133R), deficient in ATP hydrolysis, showed greater heterology tolerance to both types of mismatch base pairing, suggesting that ATPase activity may be important for maintenance of high fidelity homologous recombination DNA repair.
Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA.
Yu-Cheng
YC
Tsai
Yuzhen
Y
Wang
Damian E
DE
Urena
Sandip
S
Kumar
Junghuei
J
Chen
D000255:Adenosine Triphosphate / Q000378:metabolism; D020137:Base Pair Mismatch / Q000235:genetics*; D004277:DNA, Single-Stranded / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D031541:Fluorescence Resonance Energy Transfer; D006801:Humans; D006868:Hydrolysis; D009154:Mutation; D051135:Rad51 Recombinase / Q000235:genetics / Q000378:metabolism*; D011995:Recombination, Genetic
D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; D000255:Adenosine Triphosphate; D051135:Rad51 Recombinase