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8-OxoG retards the activity of the ligase III/XRCC1 complex during the repair of a single-strand break, when present within a clustered DNA damage site.

Abstract:
Ionising radiation produces clustered DNA damage. Recent studies have established that the efficiency of excision of a lesion within clustered damage sites is reduced. This study presents evidence that the repair of clustered DNA damage is compromised, relative to that of the isolated lesions, since the lifetime of both lesions is extended by up to eight fold. Simple clustered damage sites, comprised of a single-strand break, one or five bases 3' or 5' to 8-oxoG on the opposite strand, were synthesised in oligonucleotides and repair carried out in XRS5 nuclear extracts. The rate of repair of the single-strand break within these clustered damage sites is reduced, mainly due to inhibition of the DNA ligase III/XRCC1 complex. The single-strand break, present as an isolated lesion, is repaired by short-patch base excision repair, however the mechanism of repair of the single-strand break within the clustered damage site is asymmetric. When the lesions are 5' to each other, the single-strand break is rejoined by short-patch repair whereas the rejoining of the single-strand break occurs by long-patch type repair when the lesions are 3' to one another. The retardation of DNA ligase III/XRCC1 complex, following addition of one base, is responsible for the initiation of long-patch base excision repair when the lesions are 3' to each other. The lesions within the cluster are processed sequentially, the single-strand break being repaired before excision of 8-oxoG, limiting the formation of double-strand breaks to <2%. Stalled processing of clustered DNA damage is suggested to have implications for mutation induction by radiation.
Publication status:
Published

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Publisher copy:
10.1016/j.dnarep.2003.11.006

Authors

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Institution:
University of Oxford
Division:
MSD
Department:
Oncology
Role:
Author


Journal:
DNA repair More from this journal
Volume:
3
Issue:
3
Pages:
289-299
Publication date:
2004-03-01
DOI:
EISSN:
1568-7856
ISSN:
1568-7864


Language:
English
Keywords:
Pubs id:
pubs:131126
UUID:
uuid:1061ed85-7ed7-469d-bf93-77b9322d53ad
Local pid:
pubs:131126
Source identifiers:
131126
Deposit date:
2012-12-19
ARK identifier:

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