The PPR domain of mitochondrial RNA polymerase is an exoribonuclease required for mtDNA replication in Drosophila melanogaster,Nature Cell Biology

Mitochondrial DNA (mtDNA) replication and transcription are of paramount importance to cellular energy metabolism. Mitochondrial RNA polymerase is thought to be the primase for mtDNA replication. However, it is unclear how this enzyme, which normally transcribes long polycistronic RNAs, can produce short RNA oligonucleotides to initiate mtDNA replication. We show that the PPR domain of Drosophila mitochondrial RNA polymerase (PolrMT) has 3′-to-5′ exoribonuclease activity, which is indispensable for PolrMT to synthesize short RNA oligonucleotides and prime DNA replication in vitro. An exoribonuclease-deficient mutant, PolrMTE423P, partially restores mitochondrial transcription but fails to support mtDNA replication when expressed in PolrMT-mutant flies, indicating that the exoribonuclease activity is necessary for mtDNA replication. In addition, overexpression of PolrMTE423P in adult flies leads to severe neuromuscular defects and a marked increase in mtDNA transcript errors, suggesting that exoribonuclease activity may contribute to the proofreading of mtDNA transcription.

中文翻译:








线粒体 RNA 聚合酶的 PPR 结构域是黑腹果蝇 mtDNA 复制所需的外切核糖核酸酶


线粒体 DNA (mtDNA) 复制和转录对细胞能量代谢至关重要。线粒体 RNA 聚合酶被认为是 mtDNA 复制的引发酶。然而,目前尚不清楚这种通常转录长多顺反子 RNA 的酶如何产生短 RNA 寡核苷酸以启动 mtDNA 复制。我们表明,果蝇线粒体 RNA 聚合酶 (PolrMT) 的 PPR 结构域具有 3′ 到 5′ 外切核糖核酸酶活性,这对于 PolrMT 合成短 RNA 寡核苷酸和启动 DNA 体外复制是必不可少的。外核糖核酸酶缺陷突变体 PolrMT E423P部分恢复线粒体转录,但在PolrMT中表达时不能支持 mtDNA 复制-突变体苍蝇,表明外切核糖核酸酶活性是mtDNA复制所必需的。此外,成蝇中 PolrMT E423P的过表达导致严重的神经肌肉缺陷和 mtDNA 转录错误的显着增加,这表明外切核糖核酸酶活性可能有助于 mtDNA 转录的校对。








Read more here: Source link