S. Soubeyrand et al., Activation and autoregulation of DNA-PK from structured single-stranded DNA and coding end hairpins, P NAS US, 98(17), 2001, pp. 9605-9610
Citations number
36
Categorie Soggetti
Multidisciplinary
Journal title
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
DNA-dependent protein kinase (DNA-PK) acts through an essential relationshi
p with DNA to participate in the regulation of multiple cellular processes.
Yet the role of DNA as a cofactor in kinase activity remains to be complet
ely elucidated. For example, although DNA-PK activity appears to be require
d for the resolution of hairpin coding ends in variable diversity joining r
ecombination, kinase activity remains to be demonstrated from hairpin ends
or other DNA structures. In the present study we report that DNA-PK is stro
ngly activated from hairpin ends and structured single-stranded DNA, but th
at the phosphorylation of many heterologous substrates is blocked efficient
ly by inactivation of the kinase through autophosphorylation. However, subs
trates that bound efficiently to single-stranded DNA such as p53 and replic
ation protein A were efficiently phosphorylated by DNA-PK from structured D
NA. DNA-PK also was found to be active toward heterologous substrates from
hairpin ends on double-stranded DNA under conditions where autophosphorylat
ion was minimized. These results suggest that the role of DNA-PK in resolvi
ng coding end hairpins is likely to be enzymatic rather than structural, ex
pand understanding of how DNA-PK binding to structured DNA relates to enzym
e activity, and suggest a mechanism for autoregulatory control of its kinas
e activity in the cell.