Department of Botany and Plant Pathology, Michigan State University, East Lansing, MI 48824-1312, USA.
Fungal Biol. 2012 Aug;116(8):919-31. doi: 10.1016/j.funbio.2012.06.003. Epub 2012 Jun 28.
The in vivo conformation and replication intermediates of fungal circular mitochondrial plasmids and plasmid-like mitochondrial element (plMEs) were analyzed by two-dimensional gel electrophoresis and electron microscopy. Plasmids with circular restriction maps exist predominantly as circular molecules and were found to replicate by rolling circle mechanisms. However, the reverse transcriptase-encoding Mauriceville plasmid of Neurospora crassa was observed to replicate by two possible mechanisms: one that is consistent with a reverse transcriptase-mediated process and a second one might involve rolling circle DNA replication. Like the mtDNA-derived plasmid-like elements of N. crassa (Hausner et al. 2006a, b), a plasmid-like element of Cryphonectria parasitica (plME-C9), which consists predominantly of a 1.4 kb nucleotide sequence different from mitochondrial DNA, also was found to replicate by a rolling circle mechanism. Although the techniques used in this study were not suited for the establishment of the in vivo conformation and mode of replication of the mtDNAs of Neurospora or Cryphonectria, we surmise that the rolling circle mechanism might be the predominant mode of DNA replication in fungal mitochondria.
通过二维凝胶电泳和电子显微镜分析了真菌环状线粒体质粒和类似质粒的线粒体元件（plMEs）的体内构象和复制中间体。具有圆形限制图谱的质粒主要以环状分子存在，并通过滚环机制进行复制。然而，粗糙脉孢菌的编码逆转录酶的 Mauriceville 质粒被观察到通过两种可能的机制进行复制：一种与逆转录酶介导的过程一致，另一种可能涉及滚环 DNA 复制。与粗糙脉孢菌的 mtDNA 衍生的类似质粒元件（Hausner 等人，2006a，b）一样，Cryphonectria parasitica 的一个类似质粒元件（plME-C9），主要由与线粒体 DNA 不同的 1.4 kb 核苷酸序列组成，也通过滚环机制进行复制。尽管本研究中使用的技术不适合建立粗糙脉孢菌或 Cryphonectria 的 mtDNA 的体内构象和复制方式，但我们推测滚环机制可能是真菌线粒体中 DNA 复制的主要方式。
