线粒体 DNA 中 CpG 序列的胞嘧啶甲基化影响转录因子 A 的 DNA 结合和转录。

Cytosine methylation of mitochondrial DNA at CpG sequences impacts transcription factor A DNA binding and transcription.

机构信息

Program in Structural Biology and Biochemistry, University of Colorado School of Medicine, Aurora, CO 80045, USA.

Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO 80045, USA; Program in Structural Biology and Biochemistry, University of Colorado School of Medicine, Aurora, CO 80045, USA.

出版信息

Biochim Biophys Acta Gene Regul Mech. 2019 May;1862(5):598-607. doi: 10.1016/j.bbagrm.2019.01.006. Epub 2019 Feb 23.

Abstract

In eukaryotes, cytosine methylation of nuclear DNA at CpG sequences (CpG) regulates epigenetic inheritance through alterations in chromatin structure. However, mitochondria lack nucleosomal chromatin, therefore the molecular mechanisms by which CpG influences mitochondria must be different and are as yet unknown. Mitochondrial Transcription Factor A (TFAM) is both the primary DNA-compacting protein in the mitochondrial DNA (mtDNA) nucleoid and a transcription-initiation factor. TFAM must encounter hundreds of CpGs in mtDNA, so the occurrence of CpG has the potential to impact TFAM-DNA recognition. We used biophysical approaches to determine whether CpG alters any TFAM-dependent activities. CpG in the heavy strand promoter (HSP1) increased the binding affinity of TFAM and induced TFAM multimerization with increased cooperativity compared to nonmethylated DNA. However, CpG had no apparent effect on TFAM-dependent DNA compaction. Additionally, CpG had a clear and context-dependent effect on transcription initiating from the three mitochondrial promoters. Taken together, our findings demonstrate that CpG in the mitochondrial promoter region does impact TFAM-dependent activities in vitro.

摘要

在真核生物中,CpG 序列(CpG)处的核 DNA 胞嘧啶甲基化通过改变染色质结构来调节表观遗传遗传。然而,线粒体缺乏核小体染色质,因此 CpG 影响线粒体的分子机制必须不同,目前尚不清楚。线粒体转录因子 A(TFAM)既是线粒体 DNA(mtDNA)核小体的主要 DNA 压缩蛋白,也是转录起始因子。TFAM 必须在 mtDNA 中遇到数百个 CpG,因此 CpG 的发生有可能影响 TFAM-DNA 识别。我们使用生物物理方法来确定 CpG 是否改变了任何依赖 TFAM 的活性。与非甲基化 DNA 相比,重链启动子(HSP1)中的 CpG 增加了 TFAM 的结合亲和力,并增加了协同作用诱导 TFAM 多聚化。然而,CpG 对 TFAM 依赖性 DNA 紧缩似乎没有明显影响。此外,CpG 对来自三个线粒体启动子的转录起始有明显且上下文相关的影响。总之,我们的研究结果表明,线粒体启动子区域的 CpG 确实会影响体外依赖 TFAM 的活性。

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