Critical DNA binding interactions of the insulator protein CTCF - A small number of zinc fingers mediate strong binding, and a single finger-DNA interaction controls binding at imprinted loci
Critical DNA binding interactions of the insulator protein CTCF - A small number of zinc fingers mediate strong binding, and a single finger-DNA interaction controls binding at imprinted loci
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DOI：
10.1074/jbc.m706213200
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发表时间：
2007-11-16
影响因子：
4.8
通讯作者：
Pedone, Paolo V.
中科院分区：
文献类型：
--
作者：
Renda, Mario;Baglivo, Ilaria;Pedone, Paolo V.
DNA结合蛋白CTCF（CCCTC结合因子）在整个基因组的位点介导增强子阻断绝缘作用，并在调节Igf2/H19基因座及其他印记基因座的等位基因特异性表达中起重要作用。也有越来越多的证据表明CTCF参与基因组染色质的大规模组织。尽管CTCF有11个锌指结构，但我们在此表明其中只有4个对强结合至关重要，并且它们识别大多数CTCF位点共有的一个核心12bp DNA序列。通过缺失单个锌指结构并突变单个位点，我们确定了结合的方向。此外，我们能够确定当印记的Igf2/H19基因座中的CpG残基甲基化时，导致CTCF结合丧失的特定锌指及其与DNA相互作用的位点。这种单一的相互作用似乎对CTCF的等位基因特异性结合和绝缘作用至关重要。
The DNA-binding protein CTCF (CCCTC binding factor) mediates enhancer blocking insulation at sites throughout the genome and plays an important role in regulating allele-specific expression at the Igf2/H19 locus and at other imprinted loci. Evidence is also accumulating that CTCF is involved in large scale organization of genomic chromatin. Although CTCF has 11 zinc fingers, we show here that only 4 of these are essential to strong binding and that they recognize a core 12-bp DNA sequence common to most CTCF sites. By deleting individual fingers and mutating individual sites, we determined the orientation of binding. Furthermore, we were able to identify the specific finger and its point of DNA interaction that are responsible for the loss of CTCF binding when CpG residues are methylated in the imprinted Igf2/H19 locus. This single interaction appears to be critical for allele-specific binding and insulation by CTCF.