The DNA-dependent protein kinase is inactivated by autophosphorylation of the catalytic subunit.
The DNA-dependent protein kinase (DNA-PK) requires for activity free ends or other discontinuities in the structure of double strand DNA. In vitro, DNA-PK phosphorylates several transcription factors and other DNA-binding proteins and is thought to function in DNA damage recognition or repair and/or transcription. Here we show that in vitro DNA-PK undergoes autophosphorylation of all three protein subunits (DNA-PKcs, Ku p70 and Ku p80) and that phosphorylation correlates with inactivation of the serine/threonine kinase activity of DNA-PK. Significantly, activity is restored by the addition of purified native DNA-PKcs but not Ku, suggesting that inactivation is due to autophosphorylation of DNA-PKcs. Our data also suggest that autophosphorylation results in dissociation of DNA-PKcs from the Ku-DNA complex. We suggest that autophosphorylation is an important mechanism for the regulation of DNA-PK activity.
Chan
D W
DW
Department of Biological Sciences, University of Calgary, 2500 University Drive, N.W., Calgary, Alberta, T2N 1N4, Canada.
Lees-Miller
S P
SP
D000255:Adenosine Triphosphate / Q000378:metabolism; D034961:Antigens, Nuclear; D001483:Base Sequence; D004247:DNA / Q000378:metabolism; D004265:DNA Helicases; D051747:DNA-Activated Protein Kinase; D004268:DNA-Binding Proteins / Q000378:metabolism; D004789:Enzyme Activation; D006801:Humans; D000072200:Ku Autoantigen; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism; D010455:Peptides / Q000737:chemistry; D010766:Phosphorylation; D010920:Placenta / Q000201:enzymology; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*
D034961:Antigens, Nuclear; D004268:DNA-Binding Proteins; D046911:Macromolecular Substances; D009687:Nuclear Proteins; D010455:Peptides; D000255:Adenosine Triphosphate; D004247:DNA; D051747:DNA-Activated Protein Kinase; C497263:PRKDC protein, human; D017346:Protein Serine-Threonine Kinases; D004265:DNA Helicases; C106893:XRCC5 protein, human; C000606509:Xrcc6 protein, human; D000072200:Ku Autoantigen