Abstract
The Swi5-Sfr1 heterodimer protein stimulates the Rad51-promoted DNA strand exchange reaction, a crucial step in homologous recombination. To clarify how this accessory protein acts on the strand exchange reaction, we have analyzed how the structure of the primary reaction intermediate, the Rad51/single-stranded DNA (ssDNA) complex filament formed in the presence of ATP, is affected by Swi5-Sfr1. Using flow linear dichroism spectroscopy, we observe that the nucleobases of the ssDNA are more perpendicularly aligned to the filament axis in the presence of Swi5-Sfr1, whereas the bases are more randomly oriented in the absence of Swi5-Sfr1. When using a modified version of the natural protein where the N-terminal part of Sfr1 is deleted, which has no affinity for DNA but maintained ability to stimulate the strand exchange reaction, we still observe the improved perpendicular DNA base orientation. This indicates that Swi5-Sfr1 exerts its activating effect through interaction with the Rad51 filament mainly and not with the DNA. We propose that the role of a coplanar alignment of nucleobases induced by Swi5-Sfr1 in the presynaptic Rad51/ssDNA complex is to facilitate the critical matching with an invading double-stranded DNA, hence stimulating the strand exchange reaction.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 2358-2365 |
| Number of pages | 8 |
| Journal | Nucleic Acids Research |
| Volume | 42 |
| Issue number | 4 |
| DOIs | |
| State | Published - Dec 3 2013 |
| Externally published | Yes |
Bibliographical note
KAUST Repository Item: Exported on 2020-10-01Acknowledged KAUST grant number(s): KUK-11-008-23
Acknowledgements: King Abdullah University of Science and Technology Grant [KUK-11-008-23 to L.F.]; the Agence Nationale de la Recherche Grant [ANR-2010-BLAN-1013 DynRec to A.R-C. and M.T.]; the European Research Council [ERC-2008-AdG 227700 to B.N.]; Ministry of Education, Culture, Sports, Science and Technology (MEXT) Japan [22125003 to H.I.]; and Japan Society for the Promotion of Science (JSPS) KAKENHI Grant [23770105 to N.K.]; The visit of M.T. to Japan was supported by JSPS Short-term Fellowship and that of N.K. to France by JSPS Institutional Program for Young Researcher Overseas Visits. Funding for open access charge: The Agence Nationale de la Recherche [ANR-2010-BLAN-1013].
This publication acknowledges KAUST support, but has no KAUST affiliated authors.