SB RAS Institute of Chemical Biology and Fundamental Medicine, Novosibirsk 630090, Russia.
Institute of Molecular Genetics, National Research Center "Kurchatov Institute", Moscow 123182, Russia.
Int J Mol Sci. 2023 Jun 29;24(13):10877. doi: 10.3390/ijms241310877.
DNA-protein cross-links remain the least-studied type of DNA damage. Recently, their repair was shown to involve proteolysis; however, the fate of the peptide remnant attached to DNA is unclear. Particularly, peptide cross-links could interfere with DNA polymerases. Apurinuic/apyrimidinic (AP) sites, abundant and spontaneously arising DNA lesions, readily form cross-links with proteins. Their degradation products (AP site-peptide cross-links, APPXLs) are non-instructive and should be even more problematic for polymerases. Here, we address the ability of human DNA polymerases involved in DNA repair and translesion synthesis (POLβ, POLλ, POLη, POLκ and PrimPOL) to carry out synthesis on templates containing AP sites cross-linked to the N-terminus of a 10-mer peptide (APPXL-I) or to an internal lysine of a 23-mer peptide (APPXL-Y). Generally, APPXLs strongly blocked processive DNA synthesis. The blocking properties of APPXL-I were comparable with those of an AP site, while APPXL-Y constituted a much stronger obstruction. POLη and POLκ demonstrated the highest bypass ability. DNA polymerases mostly used dNTP-stabilized template misalignment to incorporate nucleotides when encountering an APPXL. We conclude that APPXLs are likely highly cytotoxic and mutagenic intermediates of AP site-protein cross-link repair and must be quickly eliminated before replication.
DNA-蛋白质交联仍然是研究最少的 DNA 损伤类型。最近，已经证明它们的修复涉及蛋白质水解；然而，与 DNA 结合的肽残基的命运尚不清楚。特别是肽交联可能会干扰 DNA 聚合酶。富含且自发产生的 DNA 损伤的无嘌呤/无嘧啶（AP）位点很容易与蛋白质形成交联。它们的降解产物（AP 位点-肽交联，AP-PXLs）是非指令性的，对聚合酶来说应该更成问题。在这里，我们研究了参与 DNA 修复和跨损伤合成的人类 DNA 聚合酶（POLβ、POLλ、POLη、POLκ 和 PrimPOL）在模板上进行合成的能力，该模板包含与 N 端 10 肽交联的 AP 位点（AP-PXL-I）或与 23 肽内部赖氨酸交联的 AP 位点（AP-PXL-Y）。通常，AP-PXLs 强烈阻止了连续的 DNA 合成。AP-PXL-I 的阻断特性与 AP 位点相当，而 AP-PXL-Y 构成了更强的阻碍。POLη 和 POLκ 表现出最高的旁路能力。当遇到 AP-PXL 时，DNA 聚合酶主要使用 dNTP 稳定的模板错配来掺入核苷酸。我们得出结论，AP-PXLs 是 AP 位点-蛋白质交联修复的高度细胞毒性和致突变的中间产物，在复制之前必须迅速消除。
