Mechanism of allosteric regulation of Dnmt1's processivity.
Mechanism of allosteric regulation of Dnmt1's processivity.
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DOI：
10.1021/bi050988f
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发表时间：
2005-11
期刊：
影响因子：
2.9
通讯作者：
Ž. Svedružić;N. Reich
中科院分区：
文献类型：
--
作者：
Ž. Svedružić;N. Reich
分析了DNA甲基转移酶1（Dnmt 1）的变构调节与加工催化的关系。持续合成能力定量描述的周转率，DNA解离速率，和持续合成概率。我们的研究结果进一步证明了Dnmt 1上的活性位点和变构位点可以独立地与DNA结合。当变构位点结合未甲基化DNA时，Dnmt 1对未甲基化DNA的进行性催化被部分抑制，而当变构位点结合单链寡核苷酸抑制剂时，Dnmt 1对未甲基化DNA的进行性催化被完全抑制。未甲基化DNA的部分抑制是由周转率的降低和底物DNA解离速率的增加引起的。如果变构位点暴露于预甲基化DNA，则预甲基化DNA的过程催化不受影响，但如果变构位点结合未甲基化DNA或聚（dA-dT），则完全抑制。总之，别构位点的占据调节酶对催化的承诺，这反映了底物和结合在别构位点的DNA的性质。我们在体外的结果是一致的可能性，即Dnmt 1的进行性行动可能在体内受到特定的调节核酸，如DNA，RNA，或聚（ADP-核糖）。
We have analyzed the relationship between the allosteric regulation and processive catalysis of DNA methyltransferase 1 (Dnmt1). Processivity is described quantitatively in terms of turnover rate, DNA dissociation rate, and processivity probability. Our results provide further evidence that the active site and the allosteric sites on Dnmt1 can bind DNA independently. Dnmt1's processive catalysis on unmethylated DNA is partially inhibited when the allosteric site binds unmethylated DNA and fully inhibited when the allosteric site binds a single-stranded oligonucleotide inhibitor. The partial inhibition by unmethylated DNA is caused by a decrease in the turnover rate and an increase in the substrate DNA dissociation rate. Processive catalysis with premethylated DNA is not affected if the allosteric site is exposed to premethylated DNA but is fully inhibited if the allosteric site binds unmethylated DNA or poly(dA-dT). In sum, the occupancy of the allosteric site modulates the enzyme's commitment to catalysis, which reflects the nature of the substrate and the DNA bound at the allosteric site. Our in vitro results are consistent with the possibility that the processive action of Dnmt1 may be regulated in vivo by specific regulatory nucleic acids such as DNA, RNA, or poly(ADP-ribose).