Roberti M, Musicco C, Polosa P L, Gadaleta M N, Cantatore P
Department of Biochemistry and Molecular Biology, University of Bari, Italy.
Biochem Biophys Res Commun. 1996 Feb 6;219(1):134-9. doi: 10.1006/bbrc.1996.0194.
As a step toward the characterization of the main components of mitochondrial DNA replication apparatus in sea urchin, we report the identification of a DNA-helicase activity in Paracentrotus lividus mitochondria. The activity was detected in a protein fraction obtained by fractionating on DEAE-Sephacel a lysate of gradient purified mitochondria from paracentrotus lividus eggs. The mitochondrial helicase unwound, in the presence of ATP and Mg++, a 39-base oligonucleotide annealed to single-stranded M13mp18 (+) DNA. Its direction of movement is 3' to 5' with respect to the single stranded portion of the partial duplex DNA substrate. This polarity is similar to that exhibited by the Escherichia coli rep helicase and by the helicase from bovine brain mitochondria. These features suggest that the sea urchin mitochondrial helicase could function in enabling the polymerization of the H-strand during mitochondrial DNA replication.
作为对海胆线粒体DNA复制装置主要成分进行表征的第一步，我们报告了在紫球海胆线粒体中鉴定出一种DNA解旋酶活性。该活性在通过DEAE-葡聚糖凝胶柱层析从紫球海胆卵的梯度纯化线粒体裂解物中获得的蛋白质组分中被检测到。在ATP和Mg++存在的情况下，线粒体解旋酶解开了与单链M13mp18（+）DNA退火的39个碱基的寡核苷酸。其相对于部分双链DNA底物单链部分的移动方向是3'到5'。这种极性与大肠杆菌rep解旋酶和牛脑线粒体解旋酶所表现出的极性相似。这些特征表明，海胆线粒体解旋酶可能在促进线粒体DNA复制过程中H链的聚合中发挥作用。
