Histones catalyze DNA strand incision at apurinic/apyrimidinic (AP) sites accompanied by the formation of reversible but long-lived DNA–protein cross-links at 3′-termini (3′-histone-DPCs). However, the chemical structures of 3′-histone-DPCs are not well characterized, and whether they are formed in cells is uncertain. In this study, we developed a liquid chromatography with tandem mass spectrometry workflow to characterize DPCs produced from the reaction of histones with AP sites and wish to report evidence that histones cross-link to incised AP sites via Schiff bases. We also demonstrated for the first time that 3′-histone-DPCs are produced endogenously in human embryonic kidney 293T cells.

中文翻译：

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体外和人体细胞中无碱基位点形成希夫碱 3′-DNA-组蛋白交联的质谱证据

组蛋白在无嘌呤/无嘧啶 (AP) 位点催化 DNA 链切割，同时在 3′ 末端形成可逆但寿命长的 DNA-蛋白质交联 (3′-组蛋白-DPC)。然而，3'-组蛋白-DPCs的化学结构尚未得到很好的表征，并且它们是否在细胞中形成还不确定。在这项研究中，我们开发了一种液相色谱与串联质谱工作流程，以表征组蛋白与 AP 位点反应产生的 DPC，并希望报告组蛋白通过希夫碱与切割的 AP 位点交联的证据。我们还首次证明 3'-组蛋白-DPC 在人胚胎肾 293T 细胞中内源产生。