Yoon Jung Hoon, Sellamuthu Karthi, Prakash Louise, Prakash Satya
Department of Biochemistry and Molecular Biology, University of Texas Medical Branch at Galveston, Galveston, United States.
Elife. 2025 Sep 3;14:RP106934. doi: 10.7554/eLife.106934.
Y-family DNA polymerases (Pols) are intrinsically highly error-prone; yet they conduct predominantly error-free translesion synthesis (TLS) in normal human cells. In response to DNA damage, Y-family Pols assemble and function together with WRN, WRNIP1, and Rev1 in TLS. Among these proteins, WRN possesses a 3'→5' exonuclease activity and an ATPase/3'→5' DNA helicase activity, and WRNIP1 has a DNA-dependent ATPase activity. In a previous study, we identified a role of WRN 3'→5' exonuclease activity in the high in vivo fidelity of TLS by Y-family Pols. Here we provide evidence for a crucial role of WRN and WRNIP1 ATPase activities in raising the fidelity of TLS by these Pols. Defects in WRN and WRNIP1 ATPase activities cause a diversity of nucleotide (nt) misincorporations opposite DNA lesions by Y-family Pols, implicating an unprecedented role of these activities in restraining nt misincorporations, which they could accomplish by tightening the active site of the TLS Pol. Altogether, the combined actions of WRN and WRNIP1 ATPases in preventing nt misincorporations and of WRN exonuclease in removing misinserted nts confer such an enormous rise in the fidelity of Y-family Pols that they perform error-free TLS - essential for genome stability and cellular homeostasis.
Y家族DNA聚合酶（Pols）本质上极易出错；然而，它们在正常人类细胞中主要进行无错误的跨损伤合成（TLS）。响应DNA损伤时，Y家族Pols在TLS过程中与WRN、WRNIP1和Rev1一起组装并发挥作用。在这些蛋白质中，WRN具有3'→5'核酸外切酶活性和ATP酶/3'→5' DNA解旋酶活性，而WRNIP1具有DNA依赖性ATP酶活性。在先前的一项研究中，我们确定了WRN的3'→5'核酸外切酶活性在Y家族Pols的TLS体内高保真度中的作用。在此，我们提供证据表明WRN和WRNIP1的ATP酶活性在提高这些Pols的TLS保真度方面起着关键作用。WRN和WRNIP1的ATP酶活性缺陷会导致Y家族Pols在DNA损伤对面出现多种核苷酸（nt）错配，这表明这些活性在抑制nt错配方面具有前所未有的作用，它们可以通过收紧TLS Pol的活性位点来实现这一点。总之，WRN和WRNIP1的ATP酶在防止nt错配方面的联合作用以及WRN核酸外切酶在去除错误插入的nt方面的作用，使得Y家族Pols的保真度大幅提高，从而能够进行无错误的TLS，这对基因组稳定性和细胞内稳态至关重要。
