期刊
JOURNAL OF BIOLOGICAL CHEMISTRY
卷 290, 期 40, 页码 24036-24050出版社
AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
DOI: 10.1074/jbc.M115.680900
关键词
-
资金
- National Institutes of Health
Artemis is a member of the metallo-beta-lactamase protein family of nucleases. It is essential in vertebrates because, during V(D)J recombination, the RAG complex generates hairpins when it creates the double strand breaks at V, D, and J segments, and Artemis is required to open the hairpins so that they can be joined. Artemis is a diverse endo-and exonuclease, and creating a unified model for its wide range of nuclease properties has been challenging. Here we show that Artemis resects iteratively into blunt DNA ends with an efficiency that reflects the AT-richness of the DNA end. GC-rich ends are not cut by Artemis alone because of a requirement for DNA end breathing (and confirmed using fixed pseudo-Y structures). All DNA ends are cut when both the DNA-dependent protein kinase catalytic subunit and Ku accompany Artemis but not when Ku is omitted. These are the first biochemical data demonstrating a Ku dependence of Artemis action on DNA ends of any configuration. The action of Artemis at blunt DNA ends is slower than at overhangs, consistent with a requirement for a slow DNA end breathing step preceding the cut. The AT sequence dependence, the order of strand cutting, the length of the cuts, and the Ku-dependence of Artemis action at blunt ends can be reconciled with the other nucleolytic properties of both Artemis and Artemis DNA-PKcs in a model incorporating DNA end breathing of blunt ends to form transient single to double strand boundaries that have structural similarities to hairpins and fixed 5' and 3' overhangs.
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