Dannenberg Rachel L, Cardina Joseph A, Washington Helen, Gao Shijun, Greenberg Marc M, Hedglin Mark
Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, United States.
Department of Chemistry, Johns Hopkins University, Baltimore, MD 21218, United States.
Nucleic Acids Res. 2025 Jul 8;53(13). doi: 10.1093/nar/gkaf646.
During replication, lagging strand lesions are initially encountered by high-fidelity DNA polymerase (pol) holoenzymes comprised of pol δ and the PCNA sliding clamp. To proceed unhindered, pol δ holoenzymes must bypass lesions without stalling. This entails dNMP incorporation opposite the lesion (insertion) and the 5' template deoxynucleotide (extension). Historically, it was viewed that high-fidelity pol holoenzymes stall upon encountering lesions, activating DNA damage tolerance pathways that are ultimately responsible for lesion bypass. Our recent study of four prominent lesions revealed that human pol δ holoenzymes support insertion and/or bypass for multiple lesions and the extent of these activities depends on the lesion and pol δ proofreading. In the present study, we expand these analyses to other prominent lesions. Collectively, analyses of 10 lesions from both studies reveal that the insertion and bypass efficiencies of pol δ holoenzymes each span a complete range (0%-100%). Consequently, the fates of pol δ holoenzymes upon encountering lesions are quite diverse. Furthermore, pol δ proofreading promoted holoenzyme progression at 7 of the 10 lesions and did not deter progression at any. Altogether, the results significantly alter our understanding of the replicative capacity of high-fidelity pol holoenzymes and their functional role(s) in lesion bypass.
在复制过程中，滞后链损伤最初会被由聚合酶δ和增殖细胞核抗原（PCNA）滑动夹组成的高保真DNA聚合酶（pol）全酶遇到。为了不受阻碍地进行下去，聚合酶δ全酶必须绕过损伤而不停滞。这需要在损伤对面掺入脱氧核苷酸单磷酸（插入）和5'模板脱氧核苷酸（延伸）。从历史上看，人们认为高保真聚合酶全酶在遇到损伤时会停滞，从而激活最终负责绕过损伤的DNA损伤耐受途径。我们最近对四种主要损伤的研究表明，人类聚合酶δ全酶支持多种损伤的插入和/或绕过，并且这些活性的程度取决于损伤和聚合酶δ的校对功能。在本研究中，我们将这些分析扩展到其他主要损伤。两项研究对10种损伤的综合分析表明，聚合酶δ全酶的插入和绕过效率各自涵盖了一个完整的范围（0%-100%）。因此，聚合酶δ全酶在遇到损伤时的命运是多种多样的。此外，聚合酶δ校对功能在10种损伤中的7种促进了全酶的进展，并且在任何一种损伤中都没有阻碍进展。总之，这些结果显著改变了我们对高保真聚合酶全酶复制能力及其在绕过损伤中的功能作用的理解。
