Biochemical and Structural Study of RuvC and YqgF from Deinococcus radiodurans

Deinococcus radiodurans possesses robust DNA damage response and repair abilities, and this is mainly due to its efficient homologous recombination repair system, which incorporates an uncharacterized Holliday junction (HJ) resolution process. D. radiodurans encodes two putative HJ resolvase (HJR) homologs: RuvC (DrRuvC) and YqgF (DrYqgF). Here, both DrRuvC and DrYqgF were identified as essential proteins for the survival of D. radiodurans. The crystal structures and the biochemical properties of DrRuvC and DrYqgF were also studied. DrRuvC crystallized as a homodimer, while DrYqgF crystallized as a monomer. DrRuvC could preferentially cleave HJ at the consensus 5′-(G/C)TC↓(G/C)-3′ sequence and could prefer using Mn(2+) for catalysis in vitro, which would be different from the preferences of the other previously characterized RuvCs. On the other hand, DrYqgF was identified as a Mn(2+)-dependent RNA 5′–3′ exo/endonuclease with a sequence preference for poly(A) and without any HJR activity.