In Vitro Replication and Repair of DNA Containing a C2'-Oxidized Abasic Site
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- 作者：Marc M. Greenberg ; Yvonne N. Weledji ; Kelly M. Kroeger ; and Jaeseung Kim
- 刊名：Biochemistry
- 出版年：2004
- 出版时间：December 7, 2004
- 年：2004
- 卷：43
- 期：48
- 页码：15217 - 15222
- 全文大小：118K
- 年卷期：v.43,no.48(December 7, 2004)
- ISSN：1520-4995
文摘
Abasic lesions are unable to form Watson-Crick hydrogen bonds with nucleotides. Nonetheless,polymerase and repair enzymes distinguish between various oxidized abasic lesions, as well as fromnonoxidized abasic sites (AP). The C2-AP lesion is produced when DNA is exposed to 
-radiolysis. Itseffects on polymerases and repair enzymes are unknown. A recently reported method for the chemicalsynthesis of oligonucleotides containing C2-AP at a defined site was utilized for studying the activity ofKlenow exo- and repair enzymes on templates containing the lesion. The C2-AP lesion has a similareffect on Klenow exo- as do AP and C4-AP sites. Deoxyadenosine is preferentially incorporated oppositeC2-AP, but extension of the primer past the lesion is strongly blocked. C2-AP is incised less efficientlyby exonuclease III and endonuclease IV than are other abasic lesions. Furthermore, although a Schiffbase between C2-AP and endonuclease III can be chemically trapped, the location of the 3'-phosphate 
with respect to the aldehyde prevents 
-elimination associated with the lyase activity of type I base excisionrepair enzymes. The interactions of the C2'-oxidized abasic site with Klenow exo- and repair enzymessuggest that the lesion will be mutagenic and that it will be removed by strand displacement synthesisand flap endonuclease processing via a long patch repair mechanism.
-radiolysis. Itseffects on polymerases and repair enzymes are unknown. A recently reported method for the chemicalsynthesis of oligonucleotides containing C2-AP at a defined site was utilized for studying the activity ofKlenow exo- and repair enzymes on templates containing the lesion. The C2-AP lesion has a similareffect on Klenow exo- as do AP and C4-AP sites. Deoxyadenosine is preferentially incorporated oppositeC2-AP, but extension of the primer past the lesion is strongly blocked. C2-AP is incised less efficientlyby exonuclease III and endonuclease IV than are other abasic lesions. Furthermore, although a Schiffbase between C2-AP and endonuclease III can be chemically trapped, the location of the 3'-phosphate with respect to the aldehyde prevents -elimination associated with the lyase activity of type I base excisionrepair enzymes. The interactions of the C2'-oxidized abasic site with Klenow exo- and repair enzymessuggest that the lesion will be mutagenic and that it will be removed by strand displacement synthesisand flap endonuclease processing via a long patch repair mechanism.