Lin I G, Hsieh C L
Department of Urology, University of Southern California, Norris Cancer Center, Los Angeles 90033, USA.
EMBO Rep. 2001 Feb;2(2):108-12. doi: 10.1093/embo-reports/kve023.
In the present study, we utilize the well-characterized Escherichia coli lac repressor/operator system to demonstrate that protein binding can lead to demethylation at the binding sites in the chromosome. Similar to the findings using the episome, we found that the presence of LacI in the cells can lead to demethylation of methylated lacO in the chromosome and the LacI inhibitor, isopropyl-beta-D-thiogalactopyranoside (IPTG), can prevent demethylation of the methylated lacO. The lacO sites become progressively more demethylated over time with the presence of LacI, supporting the role of protein occupancy in demethylation targeting. These results validate our earlier conclusions using a stable episomal system, and establish for the first time that protein binding can specify sites of demethylation in the chromosome.
在本研究中，我们利用特征明确的大肠杆菌乳糖阻遏物/操纵子系统来证明蛋白质结合可导致染色体上结合位点的去甲基化。与使用附加体的研究结果相似，我们发现细胞中LacI的存在可导致染色体上甲基化的lacO去甲基化，而LacI抑制剂异丙基-β-D-硫代半乳糖苷（IPTG）可阻止甲基化的lacO去甲基化。随着时间的推移，在LacI存在的情况下，lacO位点的去甲基化程度逐渐增加，这支持了蛋白质占据在去甲基化靶向中的作用。这些结果证实了我们早期使用稳定附加体系统得出的结论，并首次证明蛋白质结合可确定染色体上去甲基化的位点。
