The ataxia-oculomotor apraxia 1 gene product has a role distinct from ATM and interacts with the DNA strand break repair proteins XRCC1 and XRCC4.
Ataxia-oculomotor apraxia 1 (AOA1) is an autosomal recessive neurodegenerative disease that is reminiscent of ataxia-telangiectasia (A-T). AOA1 is caused by mutations in the gene encoding aprataxin, a protein whose physiological function is currently unknown. We report here that, in contrast to A-T, AOA1 cell lines exhibit neither radioresistant DNA synthesis nor a reduced ability to phosphorylate downstream targets of ATM following DNA damage, suggesting that AOA1 lacks the cell cycle checkpoint defects that are characteristic of A-T. In addition, AOA1 primary fibroblasts exhibit only mild sensitivity to ionising radiation, hydrogen peroxide, and methyl methanesulphonate (MMS). Strikingly, however, aprataxin physically interacts in vitro and in vivo with the DNA strand break repair proteins XRCC1 and XRCC4. Aprataxin possesses a divergent forkhead associated (FHA) domain that closely resembles the FHA domain present in polynucleotide kinase, and appears to mediate the interactions with CK2-phosphorylated XRCC1 and XRCC4 through this domain. Aprataxin is therefore physically associated with both the DNA single-strand and double-strand break repair machinery, raising the possibility that AOA1 is a novel DNA damage response-defective disease.
Clements
Paula M
PM
Genome Damage and Stability Centre, University of Sussex, Falmer, Brighton BN19RQ, UK.
Breslin
Claire
C
Deeks
Emma D
ED
Byrd
Philip J
PJ
Ju
Limei
L
Bieganowski
Pawel
P
Brenner
Charles
C
Moreira
Maria-Céu
MC
Taylor
A Malcolm R
AM
Caldecott
Keith W
KW
D001072:Apraxias / Q000235:genetics* / Q000378:metabolism*; D001259:Ataxia / Q000235:genetics* / Q000378:metabolism*; D001260:Ataxia Telangiectasia / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D004249:DNA Damage; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D015840:Oculomotor Nerve Diseases / Q000235:genetics / Q000378:metabolism; D011836:Radiation Tolerance; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D020798:Two-Hybrid System Techniques; D000076105:X-ray Repair Cross Complementing Protein 1
C438188:APTX protein, human; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D011994:Recombinant Proteins; D000076105:X-ray Repair Cross Complementing Protein 1; C000619371:XRCC1 protein, human; C101467:XRCC4 protein, human