DNA (Cytosine-C5) methyltransferase inhibition by oligodeoxyribonucleotides containing 2-(1H)-pyrimidinone (zebularine aglycon) at the enzymatic target site.
DNA (Cytosine-C5) methyltransferase inhibition by oligodeoxyribonucleotides containing 2-(1H)-pyrimidinone (zebularine aglycon) at the enzymatic target site.
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DNA（胞嘧啶-C5）甲基转移酶通过酶靶位点含有 2-(1H)-嘧啶酮（zebularine 苷元）的寡脱氧核糖核苷酸抑制。
DOI：
10.1016/j.bcp.2009.05.017
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发表时间：
2009
影响因子：
5.8
通讯作者：
Christman,JudithK
中科院分区：
文献类型：
--
作者：
vanBemmel,DanaM;Brank,AdamS;Eritja,Ramon;Marquez,VictorE;Christman,JudithK
启动子区域的异常胞嘧啶甲基化导致与癌症进展相关的基因沉默。已知许多DNA甲基转移酶抑制剂可以重新激活沉默的基因，包括5-氮杂胞苷和2-（1H）-嘧啶酮核苷（zebularine）。与5-氮杂胞苷相比，Zebularine是一种更稳定、细胞毒性更小的抑制剂。为了确定这种差异的机制基础，我们进行了一个详细的比较纯化的DNA甲基转移酶和寡脱氧核糖核苷酸（ODNs）含有5-氮杂胞嘧啶或2-（1H）-嘧啶酮取代胞嘧啶甲基化靶向之间的相互作用。当掺入小ODN中时，两种核苷对C5 DNA甲基转移酶的抑制率基本相同。然而，酶复合物的稳定性和可逆性在辅因子的存在和不存在下不同。5-当5-氮杂胞嘧啶环完整时，氮杂胞嘧啶ODN与C5 DNA甲基转移酶形成不可逆的复合物。在酶靶位点含有2-（1H）-嘧啶酮的ODN是原核和哺乳动物DNA C5甲基转移酶的竞争性抑制剂。我们确定，酶，2-（1H）-嘧啶酮抑制剂和辅因子S-腺苷甲硫氨酸之间的三元复合物通过形成可逆的共价相互作用来维持。共价键的不同稳定性和可逆性可能部分解释了zebularine和5-氮杂胞苷抑制剂之间观察到的细胞毒性差异。
Aberrant cytosine methylation in promoter regions leads to gene silencing associated with cancer progression. A number of DNA methyltransferase inhibitors are known to reactivate silenced genes; including 5-azacytidine and 2-(1H)-pyrimidinone riboside (zebularine). Zebularine is a more stable, less cytotoxic inhibitor compared to 5-azacytidine. To determine the mechanistic basis for this difference, we carried out a detailed comparisons of the interaction between purified DNA methyltransferases and oligodeoxyribonucleotides (ODNs) containing either 5-azacytosine or 2-(1H)-pyrimidinone in place of the cytosine targeted for methylation. When incorporated into small ODNs, the rate of C5 DNA methyltransferase inhibition by both nucleosides is essentially identical. However, the stability and reversibility of the enzyme complex in the absence and presence of cofactor differs. 5-Azacytosine ODNs form complexes with C5 DNA methyltransferases that are irreversible when the 5-azacytosine ring is intact. ODNs containing 2-(1H)-pyrimidinone at the enzymatic target site are competitive inhibitors of both prokaryotic and mammalian DNA C5 methyltransferases. We determined that the ternary complexes between the enzymes, 2-(1H)-pyrimidinone inhibitor, and the cofactor S-adenosyl methionine are maintained through the formation of a reversible covalent interaction. The differing stability and reversibility of the covalent bonds may partially account for the observed differences in cytotoxicity between zebularine and 5-azacytidine inhibitors.