Hübscher U, Kuenzle C C, Spadari S
Proc Natl Acad Sci U S A. 1979 May;76(5):2316-20. doi: 10.1073/pnas.76.5.2316.
The physiological functions of DNA polymerases (deoxynucleosidetriphosphate:DNA deoxynucleotidyltransferase, EC 2.7.7.7) beta and gamma were investigated by using neuronal nuclei and synaptosomes isolated from rat brain. UV irradiation of neuronal nuclei from 60-day-old rats resulted in a 7- to 10-fold stimulation of DNA repair synthesis attributable to DNA polymerase beta which, at this developmental stage, is virtually the only DNA polymerase present in the nuclei. No repair synthesis could be elicited by treating the nuclei with N-methyl-N-nitrosourea, but this way probably due to the inability of brain tissues to excise alkylated bases from DNA. The role of DNA polymerase gamma was studied in synaptosomes by using a system mimicking in vivo mitochondrial DNA synthesis. By showing that, under these conditions, DNA replication occurs in mitochondria, and exploiting the fact that DNA polymerase gama is the only DNA polymerase present in mitochondria, evidence was obtained for a role of DNA polymerase gamma in mitochondrial DNA replication. Based on these results and on the wealth of literature on DNA polymerase alpha, we conclude that DNA polymerase alpha is mainly responsible for DNA replication in nuclei, DNA polymerase beta is involved in nuclear DNA repair, and DNA polymerase gamma is the mitochondrial replicating enzyme. However, minor roles for DNA polymerase alpha in DNA repair or for DNA polymerase beta in DNA replication cannot be excluded.
利用从大鼠脑中分离出的神经元细胞核和突触体，对DNA聚合酶（脱氧核苷三磷酸：DNA脱氧核苷酸转移酶，EC 2.7.7.7）β和γ的生理功能进行了研究。对60日龄大鼠的神经元细胞核进行紫外线照射，可使DNA修复合成受到7至10倍的刺激，这归因于DNA聚合酶β，在这个发育阶段，它实际上是细胞核中唯一存在的DNA聚合酶。用N-甲基-N-亚硝基脲处理细胞核不能引发修复合成，但这可能是由于脑组织无法从DNA中切除烷基化碱基。通过使用模拟体内线粒体DNA合成的系统，在突触体中研究了DNA聚合酶γ的作用。通过证明在这些条件下线粒体中发生DNA复制，并利用DNA聚合酶γ是线粒体中唯一存在的DNA聚合酶这一事实，获得了DNA聚合酶γ在线粒体DNA复制中起作用的证据。基于这些结果以及关于DNA聚合酶α的大量文献，我们得出结论：DNA聚合酶α主要负责细胞核中的DNA复制，DNA聚合酶β参与细胞核DNA修复，而DNA聚合酶γ是线粒体复制酶。然而，不能排除DNA聚合酶α在DNA修复中或DNA聚合酶β在DNA复制中起次要作用的可能性。
