Motea Edward A, Berdis Anthony J
Department of Chemistry, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA.
Biochim Biophys Acta. 2010 May;1804(5):1151-66. doi: 10.1016/j.bbapap.2009.06.030. Epub 2009 Jul 29.
Nearly every DNA polymerase characterized to date exclusively catalyzes the incorporation of mononucleotides into a growing primer using a DNA or RNA template as a guide to direct each incorporation event. There is, however, one unique DNA polymerase designated terminal deoxynucleotidyl transferase that performs DNA synthesis using only single-stranded DNA as the nucleic acid substrate. In this chapter, we review the biological role of this enigmatic DNA polymerase and the biochemical mechanism for its ability to perform DNA synthesis in the absence of a templating strand. We compare and contrast the molecular events for template-independent DNA synthesis catalyzed by terminal deoxynucleotidyl transferase with other well-characterized DNA polymerases that perform template-dependent synthesis. This includes a quantitative inspection of how terminal deoxynucleotidyl transferase binds DNA and dNTP substrates, the possible involvement of a conformational change that precedes phosphoryl transfer, and kinetic steps that are associated with the release of products. These enzymatic steps are discussed within the context of the available structures of terminal deoxynucleotidyl transferase in the presence of DNA or nucleotide substrate. In addition, we discuss the ability of proteins involved in replication and recombination to regulate the activity of the terminal deoxynucleotidyl transferase. Finally, the biomedical role of this specialized DNA polymerase is discussed focusing on its involvement in cancer development and its use in biomedical applications such as labeling DNA for detecting apoptosis.
迄今为止，几乎所有已被鉴定的DNA聚合酶都仅以DNA或RNA模板为指导，催化单核苷酸掺入正在延长的引物中，从而指导每次掺入事件。然而，有一种独特的DNA聚合酶称为末端脱氧核苷酸转移酶，它仅使用单链DNA作为核酸底物来进行DNA合成。在本章中，我们将综述这种神秘的DNA聚合酶的生物学作用，以及它在没有模板链的情况下进行DNA合成的生化机制。我们将比较和对比末端脱氧核苷酸转移酶催化的不依赖模板的DNA合成与其他已充分表征的进行依赖模板合成的DNA聚合酶的分子事件。这包括对末端脱氧核苷酸转移酶如何结合DNA和dNTP底物的定量研究，磷酸转移之前可能发生的构象变化，以及与产物释放相关的动力学步骤。这些酶促步骤将在末端脱氧核苷酸转移酶与DNA或核苷酸底物结合时的现有结构背景下进行讨论。此外，我们还将讨论参与复制和重组的蛋白质调节末端脱氧核苷酸转移酶活性的能力。最后，将讨论这种特殊DNA聚合酶的生物医学作用，重点关注其在癌症发展中的作用以及在生物医学应用中的用途，如标记DNA以检测细胞凋亡。
