The checkpoint clamp, Rad9-Rad1-Hus1 complex, preferentially stimulates the activity of apurinic/apyrimidinic endonuclease 1 and DNA polymerase beta in long patch base excision repair.
Growing evidence suggests that the Rad9-Rad1-Hus1 complex (the 9-1-1 complex), besides its functions in DNA damage sensing and signaling pathways, plays also a direct role in various DNA repair processes. Recent studies have demonstrated that the 9-1-1 complex physically and functionally interacts with several components of the base excision repair (BER) machinery namely DNA polymerase beta (Pol beta), flap endonuclease 1 (Fen 1), DNA ligase I (Lig I) and the MutY homologue of Schizosaccharomyces pombe. In this work, we found for the first time that the 9-1-1 complex interacts in vitro and in vivo with the apurinic/apyrimidinic endonuclease 1 (APE 1), an early component of BER, and can stimulate its AP-endonuclease activity. Moreover, we show that the 9-1-1 complex possesses a stimulatory effect on long patch base excision repair (LP-BER) reconstituted in vitro. The enhancement of LP-BER activity is due to the specific stimulation of the two early components of the repair machinery, namely APE 1 and Pol beta, suggesting a hierarchy of interactions between the 9-1-1 complex and the BER proteins acting in the repairosome. Overall, our results indicate that the 9-1-1 complex is directly involved in LP-BER, thus providing a possible link between DNA damage checkpoints and BER.
Gembka
Agnieszka
A
Institute of Veterinary Biochemistry and Molecular Biology, University of Zürich-Irchel, Winterthurerstrasse 190, CH-8057, Zürich, Switzerland.
Toueille
Magali
M
Smirnova
Ekaterina
E
Poltz
Rainer
R
Ferrari
Elena
E
Villani
Giuseppe
G
Hübscher
Ulrich
U
D018797:Cell Cycle Proteins / Q000378:metabolism*; D002460:Cell Line; D004247:DNA / Q000378:metabolism; D000072481:DNA Ligase ATP; D011088:DNA Ligases / Q000378:metabolism; D019951:DNA Polymerase beta / Q000378:metabolism*; D004260:DNA Repair; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase / Q000378:metabolism*; D004789:Enzyme Activation; D005092:Exonucleases / Q000378:metabolism*; D045585:Flap Endonucleases / Q000378:metabolism; D006801:Humans
D018797:Cell Cycle Proteins; C549605:HUS1 protein, human; C462949:HUS1B protein, human; C000607892:LIG1 protein, human; C069930:rad9 protein; D004247:DNA; D019951:DNA Polymerase beta; D005092:Exonucleases; D045585:Flap Endonucleases; C468317:FEN1 protein, human; C113574:Rad1 protein, human; C085108:APEX1 protein, human; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D011088:DNA Ligases; D000072481:DNA Ligase ATP