- 作者: Chien-Der Lee; Ting-Fang Wang
- 作者服務機構: Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan, R.O.C.
- 中文摘要: --
- 英文摘要:
Escherichia coli RecA mediates homologous recombination, a process essential to
maintaining genome integrity. In the presence of ATP, RecA proteins bind a singlestranded
DNA (ssDNA) to form a RecA-ssDNA presynaptic nucleoprotein filament that
captures donor double-stranded DNA (dsDNA), searches for homology, and then
catalyzes the strand exchange between ssDNA and dsDNA to produce a new
heteroduplex DNA. Based upon a recently reported crystal structure of the RecA-ssDNA
nucleoprotein filament, we carried out structural and functional studies of the N-terminal
domain (NTD) of the RecA protein. The RecA NTD was thought to be required for
monomer-monomer interaction. Here we report that it has two other distinct roles in
promoting homologous recombination. It first facilitates the formation of a RecA-ssDNA
presynaptic nucleoprotein filament by converting ATP to an ADP-Pi intermediate. Then,
once the RecA-ssDNA presynaptic nucleoprotein filament is stably assembled in the
presence of ATPγS, the NTD is required to capture donor dsDNA. Our results also
suggest that the second function of NTD may be similar to that of Arg243 and Lys245,
which were implicated earlier as binding sites of donor dsDNA. A two-step model is
proposed to explain how a RecA-ssDNA presynaptic nucleoprotein filament interacts
with donor dsDNA. - 中文關鍵字: --
- 英文關鍵字: --