Genome Damage and Stability Centre, University of Sussex, Brighton, UK.
Cell Cycle. 2010 Feb 1;9(3):588-595. doi: 10.4161/cc.9.3.10598.
Tyrosyl DNA phosphodiesterase (TDP1) is a DNA 3'-end processing enzyme that preferentially hydrolyses the bond between the 3'-end of DNA and stalled DNA topoisomerase 1. the importance of TDP1 is highlighted by its association with the human genetic disease spinocerebellar ataxia with axonal neuropathy. TDP1 comprises of a highly conserved C-terminus phosphodiesterase domain and a less conserved N-terminus tail. the importance of the N-terminus domain was suggested by its interaction with Lig3alpha. Here we show that this interaction is promoted by serine 81 that is located within a putative S/TQ site in the N-terminus domain of TDP1. Although mutation of serine 81 to alanine had no impact on TDP1 activity in vitro and had little impact on the ability of TDP1 to mediate the rapid repair of CPT- or IR-induced DNA breaks in vivo, it led to marked reduction of protein stability. Moreover, it reduced the ability of TDP1 to promote cell survival following genotoxic stress. Together, our findings highlight a novel mechanism for regulating TDP1 function in mammalian cells that is not directly related to its enzymatic activity.
酪氨酰 DNA 磷酸二酯酶（TDP1）是一种 DNA 3'-末端加工酶，它优先水解 DNA 3'-末端与停滞的 DNA 拓扑异构酶 1 之间的键。TDP1 与人类遗传性疾病脊髓小脑共济失调伴轴索神经病有关，这凸显了其重要性。TDP1 由高度保守的 C 端磷酸二酯酶结构域和不太保守的 N 端尾部组成。N 端结构域的重要性是由其与 Lig3alpha 的相互作用所提示的。在这里，我们表明，这种相互作用是由丝氨酸 81 促进的，丝氨酸 81 位于 TDP1 的 N 端结构域内一个假定的 S/TQ 位点。尽管将丝氨酸 81 突变为丙氨酸对 TDP1 的体外活性没有影响，并且对 TDP1 介导 CPT 或 IR 诱导的 DNA 断裂的快速修复能力几乎没有影响，但它导致蛋白质稳定性明显降低。此外，它降低了 TDP1 在遗传毒性应激后促进细胞存活的能力。总之，我们的研究结果强调了一种调节哺乳动物细胞中 TDP1 功能的新机制，该机制与酶活性没有直接关系。
