Inhibition of O6-methylguanine-DNA methyltransferase by an alkyltransferase-like protein from Escherichia coli.
Inhibition of O6-methylguanine-DNA methyltransferase by an alkyltransferase-like protein from Escherichia coli.
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通过大肠杆菌的烷基转移酶样蛋白抑制O6-甲基鸟嘌呤-DNA甲基转移酶。
DOI：
10.1093/nar/gki696
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发表时间：
2005
影响因子：
14.9
通讯作者：
Margison, GP
中科院分区：
文献类型：
--
作者：
Pearson, SJ;Ferguson, J;Santibanez-Koref, M;Margison, GP
烷基转移酶样（ATL）蛋白含有与DNA修复O 6-烷基鸟嘌呤-DNA烷基转移酶蛋白相似的一级序列基序。然而，在ATL蛋白的推定活性位点中，色氨酸（W83）残基取代了烷基转移酶的已知活性位点处的半胱氨酸。大肠杆菌atl基因作为融合蛋白表达和纯化。ATL、C83或A83突变体均不将[3 H]从[3 H]-甲基化DNA转移到自身，底物DNA中的O 6-甲基鸟嘌呤（O 6-meG）水平不受ATL影响。然而，ATL抑制甲基转移到人烷基转移酶（MGMT）。在MGMT存在下通过延长孵育降低抑制，再次表明底物中的O 6-meG不被ATL改变。凝胶位移分析表明，ATL结合短的单链或双链寡核苷酸含有O 6-meG，但不含8-氧代鸟嘌呤，乙烯腺嘌呤，5-羟基胞嘧啶或O 4-甲基胸腺嘧啶的寡核苷酸。没有证据表明O 6-meG或糖基化酶或核酸内切酶活性的去甲基化。ATL在大肠杆菌中的过表达分别增加或不影响N-甲基-N′-硝基-N-亚硝基胍在烷基转移酶活性良好和缺陷菌株中的毒性。这些结果表明，ATL可能作为一个损伤传感器，标志O 6-meG和其他可能的O 6-烷基化病变处理其他修复途径。
The alkyltransferase-like (ATL) proteins contain primary sequence motifs resembling those found in DNA repair O6-alkylguanine-DNA alkyltransferase proteins. However, in the putative active site of ATL proteins, a tryptophan (W83) residue replaces the cysteine at the known active site of alkyltransferases. The Escherichia coli atl gene was expressed as a fusion protein and purified. Neither ATL nor C83 or A83 mutants transferred [3H] from [3H]-methylated DNA to themselves, and the levels of O6-methyl guanine (O6-meG) in substrate DNA were not affected by ATL. However, ATL inhibited the transfer of methyl groups to human alkyltransferase (MGMT). Inhibition was reduced by prolonged incubation in the presence of MGMT, again suggesting that O6-meG in the substrate is not changed by ATL. Gel-shift assays show that ATL binds to short single- or double-stranded oligonucleotides containing O6-meG, but not to oligonucleotides containing 8-oxoguanine, ethenoadenine, 5-hydroxycytosine or O4-methylthymine. There was no evidence of demethylation of O6-meG or of glycosylase or endonuclease activity. Overexpression of ATL in E.coli increased, or did not affect, the toxicity of N-methyl-N′-nitro-N-nitrosoguanidine in an alklyltransferase-proficient and -deficient strain, respectively. These results suggest that ATL may act as a damage sensor that flags O6-meG and possibly other O6-alkylation lesions for processing by other repair pathways.
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DOI：
10.1073/pnas.82.9.2688
发表时间：
1985-01-01
影响因子：
11.1
作者：
DEMPLE, B;SEDGWICK, B;LINDAHL, T
通讯作者：
LINDAHL, T
影响因子：
16.8
作者：
Daniels, DS;Woo, TT;Tainer, JA
通讯作者：
Tainer, JA
DOI：
10.1073/pnas.87.2.686
发表时间：
1990-01-01
影响因子：
11.1
作者：
TANO, K;SHIOTA, S;MITRA, S
通讯作者：
MITRA, S
影响因子：
2.7
作者：
Margison, GP;Koref, MFS;Povey, AC
通讯作者：
Povey, AC
影响因子：
64.8
作者：
SAMSON, L;CAIRNS, J
通讯作者：
CAIRNS, J