The zinc-binding motif of human RECQ5β suppresses the intrinsic strand annealing activity of its DExH helicase domain and is essential for the helicase activity of the enzyme

Hua Ren , Shuo-Xing Dou , Xing-Dong Zhang , Peng-Ye Wang , Radhakrishnan Kanagaraj , Pavel Janscak , Jin-Shan Hu , Xu Guang Xi (1)

1 Section de recherche

RecQ family helicases, functioning as caretakers of genomic integrity, contain a zinc-binding motif which is highly conserved among these helicases, but does not have a substantial structural similarity with any other known zinc-finger folds. Here, we show that a truncated variant of the human RECQ5β helicase comprised of the conserved helicase domain only, a splice variant named RECQ5b possesses neither ATPase nor DNA unwinding activities, but surprisingly displays a strong strand-annealing activity. In contrast, a fragment of RECQ5β including the intact zinc-binding motif, which is located immediately downstream of the helicase domain, does not exhibit any strand-annealing activity and is proficient in DNA unwinding. Quantitative measurements indicate that the regulatory role of the zinc-binding motif is achieved by enhancing the DNA binding affinity of the enzyme. The novel intra-molecular modulation of RECQ5β catalytic activity mediated by the zinc-binding motif may represent a universal regulation mode for all RecQ family helicases.

Mots clés: Life Sciences

Hua Ren, Shuo-Xing Dou, Xing-Dong Zhang, Peng-Ye Wang, Radhakrishnan Kanagaraj, et al.. The zinc-binding motif of human RECQ5β suppresses the intrinsic strand annealing activity of its DExH helicase domain and is essential for the helicase activity of the enzyme. Biochemical Journal, 2008, 412 (3), pp.425-433. ⟨10.1042/BJ20071150⟩. ⟨hal-00478878⟩