Kirshenboim Noa, Hayouka Zvi, Friedler Assaf, Hizi Amnon
Department of Cell and Developmental Biology, Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, 69978, Israel.
Virology. 2007 Sep 30;366(2):263-76. doi: 10.1016/j.virol.2007.04.002. Epub 2007 May 23.
The LTR retrotransposon of Schizosacharomyces pombe, Tf1, has several distinctive properties that can be related to the unique properties of its reverse transcriptase (RT). Consequently, we expressed, purified and studied the recombinant Tf1 RT. This monomeric protein possesses all activities typical to RTs: DNA and RNA-dependent DNA polymerase as well as an inherent ribonuclease H. The DNA polymerase activity shows preference to Mn(+)(2) or Mg(+)(2), depending on the substrate used, whereas the ribonuclease H strongly prefers Mn(+)(2). The most outstanding feature of Tf1 RT is its capacity to add non-templated nucleotides to the 3'-ends of the nascent DNA. This is mainly apparent in the presence of Mn(+)(2), as is the noticeable low fidelity of DNA synthesis. In all, Tf1 RT has a marked infidelity in synthesizing DNA at template ends, a phenomenon that can explain, as discussed herein, some of the features of Tf1 replication in the host cells.
粟酒裂殖酵母的LTR逆转录转座子Tf1具有几个独特的特性，这些特性与其逆转录酶（RT）的独特性质有关。因此，我们表达、纯化并研究了重组Tf1 RT。这种单体蛋白具有RT典型的所有活性：依赖DNA和RNA的DNA聚合酶以及固有的核糖核酸酶H。DNA聚合酶活性根据所使用的底物不同，对Mn(2+)或Mg(2+)表现出偏好，而核糖核酸酶H强烈偏好Mn(2+)。Tf1 RT最突出的特点是其能够在新生DNA的3'末端添加非模板核苷酸。这主要在存在Mn(2+)的情况下明显，DNA合成的显著低保真度也是如此。总之，Tf1 RT在模板末端合成DNA时具有明显的低保真度，如本文所讨论的，这种现象可以解释Tf1在宿主细胞中复制的一些特征。
