In Vitro-Reconstituted Nucleoids Can Block Mitochondrial DNA Replication and Transcription
In Vitro-Reconstituted Nucleoids Can Block Mitochondrial DNA Replication and Transcription
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DOI：
10.1016/j.celrep.2014.05.046
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发表时间：
2014-07-10
期刊：
影响因子：
8.8
通讯作者：
Falkenberg, Maria
中科院分区：
文献类型：
--
作者：
Farge, Geraldine;Mehmedovic, Majda;Falkenberg, Maria
调节mtDNA活性拷贝数的机制尚不清楚。一个哺乳动物细胞通常含有1，000 - 10，000个mtDNA拷贝，它们被包装成称为类核的核蛋白复合物。这些结构的主要蛋白质组分是线粒体转录因子A（TFAM）。在这里，我们在体外重建类核颗粒，并证明TFAM水平的微小变化显着影响可用于转录和DNA复制的DNA分子的分数。TFAM的压实是高度合作的，并且在TFAM与DNA的生理比率下，压实存在很大的变化，从完全压实的类核到裸DNA。在紧密的类核中，TFAM在DNA上形成稳定的蛋白质丝，阻止DNA的解链并阻止复制和转录机制的进展。基于我们的观察，我们认为TFAM与mtDNA比例的微小变化可能用于调节线粒体基因转录和DNA复制。
The mechanisms regulating the number of active copies of mtDNA are still unclear. A mammalian cell typically contains 1,000-10,000 copies of mtDNA, which are packaged into nucleoprotein complexes termed nucleoids. The main protein component of these structures is mitochondrial transcription factor A (TFAM). Here, we reconstitute nucleoid-like particles in vitro and demonstrate that small changes in TFAM levels dramatically impact the fraction of DNA molecules available for transcription and DNA replication. Compaction by TFAM is highly cooperative, and at physiological ratios of TFAM to DNA, there are large variations in compaction, from fully compacted nucleoids to naked DNA. In compacted nucleoids, TFAMforms stable protein filaments onDNAthat block melting and prevent progression of the replication and transcription machineries. Based on our observations, we suggest that small variations in the TFAM-to-mtDNA ratio may be used to regulate mitochondrial gene transcription and DNA replication.