Recognition and processing of a new repertoire of DNA substrates by human 3-methyladenine DNA glycosylase (AAG).
Recognition and processing of a new repertoire of DNA substrates by human 3-methyladenine DNA glycosylase (AAG).
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DOI：
10.1021/bi8018898
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发表时间：
2009-03-10
期刊：
影响因子：
2.9
通讯作者：
Samson, Leona D.
中科院分区：
文献类型：
--
作者：
Lee, Chun-Yue I.;Delaney, James C.;Kartalou, Maria;Lingaraju, Gondichatnahalli M.;Maor-Shoshani, Ayelet;Essigmann, John M.;Samson, Leona D.
人 3-甲基腺嘌呤 DNA 糖基化酶 (AAG) 可识别并切除因烷基化和氧化损伤而受损的多种嘌呤，包括 3-甲基腺嘌呤、7-甲基鸟嘌呤、次黄嘌呤 (Hx) 和 1,N6-乙烯腺嘌呤 (εA)。与 εA 结合的 AAG 的晶体结构为了解底物识别、碱基切除以及从其底物识别口袋中排除正常嘌呤和嘧啶的结构基础提供了见解。在本研究中，我们探索了全长和截短的 Δ80AAG 在包含结构不同碱基修饰的寡核苷酸文库上的底物特异性。检查了 AAG 与 13 种受损寡核苷酸的底物结合和碱基切除动力学。我们发现 AAG 与多种嘌呤和嘧啶病变结合，但只切除了其中的少数。单周转切除动力学表明，除了众所周知的 εA 和 Hx 底物外，AAG 也能有效切除 1-甲基鸟嘌呤 (m1G)。因此，与 εA 和乙腺嘌呤 (EA) 一样，m1G 是 AAG 和直接修复蛋白 AlkB 之间共享的另一种底物。此外，我们发现全长和截短的 AAG 都从双链 DNA 中切除了 1,N2-乙烯基鸟嘌呤 (1,N2-εG)，尽管效果很弱。尿嘧啶从单链和双链 DNA 中被切除，但仅被全长 AAG 切除，表明 AAG 的 N 末端可能影响某些底物的糖基化酶活性。虽然AAG主要被证明作用于双链DNA，但AAG从单链DNA中切除了εA和Hx，这表明修复复制和转录过程中短暂产生的单链DNA中这些常见损伤的可能意义。
The human 3-methyladenine DNA glycosylase (AAG) recognizes and excises a broad range of purines damaged by alkylation and oxidative damage, including 3-methyladenine, 7-methylguanine, hypoxanthine (Hx), and 1,N6-ethenoadenine (εA). The crystal structures of AAG bound to εA have provided insights into the structural basis for substrate recognition, base excision, and exclusion of normal purines and pyrimidines from its substrate recognition pocket. In the present study, we explored the substrate specificity of full-length and truncated Δ80AAG on a library of oligonucleotides containing structurally diverse base modifications. Substrate binding and base excision kinetics of AAG with 13 damaged oligonucleotides were examined. We found that AAG bound to a wide variety of purine and pyrimidine lesions, but excised only few of them. Single-turnover excision kinetics showed that in addition to the well-known εA and Hx substrates, 1-methylguanine (m1G) was also excised efficiently by AAG. Thus, along with εA and ethanoadenine (EA), m1G is another substrate that is shared between AAG and the direct repair protein AlkB. In addition, we found that both the full-length and truncated AAG excised 1,N2-ethenoguanine (1,N2-εG), albeit weakly, from duplex DNA. Uracil was excised from both single- and double-stranded DNA, but only by the full-length AAG, indicating that the N-terminus of AAG may influence glycosylase activity for some substrates. Although AAG has been primarily shown to act on double-stranded DNA, AAG excised both εA and Hx from single-stranded DNA, suggesting the possible significance of repair of these frequent lesions in single-stranded DNA transiently generated during replication and transcription.
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影响因子：
2.9
作者：
KUSMIEREK, JT;SINGER, B
通讯作者：
SINGER, B
影响因子：
3.5
作者：
Bjelland, S;Seeberg, E
通讯作者：
Seeberg, E
影响因子：
4.1
作者：
Goodenough, AK;Kozekov, ID;Rizzo, CJ
通讯作者：
Rizzo, CJ
DOI：
10.1073/pnas.94.24.12869
发表时间：
1997-11-25
影响因子：
11.1
作者：
Hang, B;Singer, B;Elder, RH
通讯作者：
Elder, RH
DOI：
10.1073/pnas.0403489101
发表时间：
2004-09-28
影响因子：
11.1
作者：
Delaney, JC;Essigmann, JM
通讯作者：
Essigmann, JM