The Rad51/RadA N-Terminal Domain Activates Nucleoprotein Filament ATPase Activity

Department of Biochemistry and Molecular Genetics, University of Virginia, Box 800733, Charlottesville, Virginia 22908, USA.
Structure (Impact Factor: 5.62). 07/2006; 14(6):983-92. DOI: 10.1016/j.str.2006.04.001
Source: PubMed


Proteins in the RecA/RadA/Rad51 family form helical filaments on DNA that function in homologous recombination. While these proteins all have the same highly conserved ATP binding core, the RadA/Rad51 proteins have an N-terminal domain that shows no homology with the C-terminal domain found in RecA. Both the Rad51 N-terminal and RecA C-terminal domains have been shown to bind DNA, but no role for these domains has been established. We show that RadA filaments can be trapped in either an inactive or active conformation with respect to the ATPase and that activation involves a large rotation of the subunit aided by the N-terminal domain. The G103E mutation within the yeast Rad51 N-terminal domain inactivates the filament by failing to make proper contacts between the N-terminal domain and the core. These results show that the N-terminal domains play a regulatory role in filament activation and highlight the modular architecture of the recombination proteins.

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    • "We incubated KaiC1mer (20 μM) in reaction buffer containing 6 mM ADP, 30 mM MgCl2, 2.5 mM NaF, and 2.5 mM AlCl3 at 25 °C for 2 h to form KaiC6mer (ADP-AlFX) [31]. We then mixed the reacion mixtures with an equal volume of 0 or 60 μM KaiB1-94 in the same buffer and incubated them further at 25 °C for 6 h. "
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