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Swi5-Sfr1 protein stimulates Rad51-mediated DNA strand exchange reaction through organization of DNA bases in the presynaptic filament

Louise Fornander (Institutionen för kemi- och bioteknik, Fysikalisk kemi) ; A. Renodon-Corniere ; N. Kuwabara ; K. Ito ; Y. Tsutsui ; T. Shimizu ; H. Iwasaki ; Bengt Nordén (Institutionen för kemi- och bioteknik, Fysikalisk kemi) ; M. Takahashi
Nucleic Acids Research (0305-1048). Vol. 42 (2014), 4, p. 2358-2365.
[Artikel, refereegranskad vetenskaplig]

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.



Denna post skapades 2014-04-10. Senast ändrad 2014-08-19.
CPL Pubid: 196551

 

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Institutioner (Chalmers)

Institutionen för kemi- och bioteknik, Fysikalisk kemi (2005-2014)

Ämnesområden

Fysikalisk kemi

Chalmers infrastruktur

Relaterade publikationer

Denna publikation ingår i:


Biophysical studies of DNA binding – by the large filament-forming protein Rad51 and the small minor-groove binder Hoechst 33258


 


Projekt

Denna publikation är ett resultat av följande projekt:


Supramolecular motive power (SUMO) (EC/FP7/227700)