Details

Autor(en) / Beteiligte

• Meek, Katheryn

Titel

Activation of DNA-PK by hairpinned DNA ends reveals a stepwise mechanism of kinase activation

Ist Teil von

• Nucleic acids research, 2020-09, Vol.48 (16), p.9098

Ort / Verlag

England

Erscheinungsjahr

2020

Quelle

MEDLINE

Beschreibungen/Notizen

• As its name implies, the DNA dependent protein kinase (DNA-PK) requires DNA double-stranded ends for enzymatic activation. Here, I demonstrate that hairpinned DNA ends are ineffective for activating the kinase toward many of its well-studied substrates (p53, XRCC4, XLF, HSP90). However, hairpinned DNA ends robustly stimulate certain DNA-PK autophosphorylations. Specifically, autophosphorylation sites within the ABCDE cluster are robustly phosphorylated when DNA-PK is activated by hairpinned DNA ends. Of note, phosphorylation of the ABCDE sites is requisite for activation of the Artemis nuclease that associates with DNA-PK to mediate hairpin opening. This finding suggests a multi-step mechanism of kinase activation. Finally, I find that all non-homologous end joining (NHEJ) defective cells (whether deficient in components of the DNA-PK complex or components of the ligase complex) are similarly deficient in joining DNA double-stranded breaks (DSBs) with hairpinned termini.