期刊
BIOCHEMICAL JOURNAL
卷 412, 期 -, 页码 425-433出版社
PORTLAND PRESS LTD
DOI: 10.1042/BJ20071150
关键词
DNA annealing; DNA unwinding; intramolecular regulation; RecQ helicase; zinc-finger motif
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. In the present study, we show that a truncated variant of the human RECQ5 beta helicase comprised of the conserved helicase domain only, a splice variant named RECQ5 alpha, possesses neither ATPase nor DNA-unwinding activities, but surprisingly displays a strong strand-annealing activity. In contrast, fragments of RECQ5 beta including the intact zinc-binding motif, which is located immediately downstream of the helicase domain, exhibit much reduced strand-annealing activity but are 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 intramolecular modulation of RECQ5 catalytic activity mediated by the zinc-binding motif may represent a universal regulation mode for all RecQ family helicases.
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