THE ESCHERICHIA-COLI ALKB PROTEIN PROTECTS HUMAN-CELLS AGAINST ALKYLATION-INDUCED TOXICITY
THE ESCHERICHIA-COLI ALKB PROTEIN PROTECTS HUMAN-CELLS AGAINST ALKYLATION-INDUCED TOXICITY
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DOI：
10.1128/jb.176.20.6255-6261.1994
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发表时间：
1994-10-01
影响因子：
3.2
通讯作者：
SAMSON, L
中科院分区：
文献类型：
--
作者：
CHEN, BRJ;CARROLL, P;SAMSON, L
大肠杆菌可以通过阻止DNA烷基化或修复DNA烷基化损伤来减轻烷化剂的毒性作用。对E. coli alkB突变体标志着alkB途径是对抗SN 2烷化剂而非SN 1烷化剂的细胞毒性作用的极其有效的防御机制。虽然很明显，AlkB有助于细胞更好地处理烷基化DNA，但没有DNA烷基化修复功能可以分配给纯化的AlkB蛋白，这表明AlkB要么作为复合物的一部分，要么调节其他基因的表达，这些基因的产物直接负责烷基化抗性。然而，在这里，我们提出的证据表明，提供烷基化抗性是一个内在的功能的AlkB蛋白每集。coli AlkB蛋白在两个人细胞系中的表达，发现它在这种外源环境中赋予与在大肠杆菌中相同的抗烷基化表型。杆菌AlkB表达使人细胞对SN 2而不是SN 1烷化剂的细胞杀伤具有极强的抗性，但不影响硫酸二甲酯（SN 2试剂）使基因组烷基化的能力。我们推断SN2试剂产生一类DNA损伤，而SN1试剂不能有效地产生这种损伤，AlkB以某种方式阻止这种损伤杀死细胞。
Escherichia coli can ameliorate the toxic effects of alkylating agents either by preventing DNA alkylation or by repairing DNA alkylation damage. The alkylation-sensitive phenotype of E. coli alkB mutants marks the alkB pathway as bn extremely effective defense mechanism against the cytotoxic effects of the SN2, but not the SN1, alkylating agents. Although it is clear that AlkB helps cells to better handle alkylated DNA, no DNA alkylation repair function could be assigned to the purified AlkB protein, suggesting that AlkB either acts as part of a complex or acts to regulate the expression of other genes whose products are directly responsible for alkylation resistance. However, here we present evidence that the provision of alkylation resistance is an intrinsic function of the AlkB protein per set We expressed the E. coli AlkB protein in two human cell lines and found that it confers the same characteristic alkylation-resistant phenotype in this foreign environment as it does in E. coli. AlkB expression rendered human cells extremely resistant to cell killing by the SN2 but not the SN1 alkylating agents but did not affect the ability of dimethyl sulfate (an SN2 agent) to alkylate the genome. We infer that SN2 agents produce a class of DNA damage that is not efficiently produced by SN1 agents and that AlkB somehow prevents this damage from killing the cell.