DNA-PKcs is a DNA damage sensor kinase with established roles in DNA double-strand break repair nonhomologous end joining. Recent studies have revealed additional roles of DNA-PKcs in the regulation of transcription, translation, and DNA replication. However, the substrates through which DNA-PKcs regulates these processes remain largely undefined. Here, we utilized quantitative phosphoproteomics to generate a high coverage map of DNA-PKcs signaling in response to ionizing radiation and mapped its interplay with the ATM kinase. Beyond the detection of the canonical S/T-Q phosphorylation motif, we uncovered a noncanonical mode of DNA-PKcs signaling targeting S/T-ψ-D/E motifs. Sequence and structural analyses of the DNA-PKcs substrate recognition pocket revealed unique features compared to closely related phosphatidylinositol 3-kinase-related kinases that may explain its broader substrate preference. These findings expand the repertoire of DNA-PKcs and ATM substrates while establishing a novel preferential phosphorylation motif for DNA-PKcs.

中文翻译：

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DNA-PKcs 信号传导的深入图谱揭示了其激酶特异性的非典型特征


DNA-PKcs 是一种 DNA 损伤传感器激酶，在 DNA 双链断裂修复非同源末端连接中具有明确的作用。最近的研究揭示了 DNA-PKcs 在转录、翻译和 DNA 复制调节中的其他作用。然而，DNA-PKcs 调节这些过程的底物在很大程度上仍不清楚。在这里，我们利用定量磷酸蛋白质组学生成了响应电离辐射的 DNA-PKcs 信号传导的高覆盖图谱，并绘制了其与 ATM 激酶的相互作用。除了检测典型的 S/TQ 磷酸化基序之外，我们还发现了针对 S/T-ψ-D/E 基序的 DNA-PKcs 信号传导的非典型模式。 DNA-PKcs 底物识别口袋的序列和结构分析揭示了与密切相关的磷脂酰肌醇 3 激酶相关激酶相比的独特特征，这可能解释其更广泛的底物偏好。这些发现扩展了 DNA-PKcs 和 ATM 底物的库，同时建立了 DNA-PKcs 的新型优先磷酸化基序。