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Chk2 Activation and Phosphorylation-Dependent Oligomerization

机译:Chk2 激活和磷酸化依赖性寡聚化

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The tumor suppressor gene CHK2 encodes a versatile effector serine/threonine kinase involved in responses to DNA damage. Chk2 has an amino-terminal SQ/TQ cluster domain (SCD), followed by a forkhead-associated (FHA) domain and a carboxyl-terminal kinase catalytic domain. Mutations in the SCD or FHA domain impair Chk2 checkpoint function. We show here that autophosphorylation of Chk2 produced in a cell-free system requires trans phosphorylation by a wortmannin-sensitive kinase, probably ATM or ATR. Both SQ/TQ sites and non-SQW/TQ sites within the Chk2 SCD can be phosphorylated by active Chk2. Amino acid substitutions in the SCD and the FHA domain impair auto- and trans-kinase activities of Chk2. Chk2 forms oligomers that minimally require the FHA domain of one Chk2 molecule and the SCD within another Chk2 molecule. Chk2 oligomerization in vivo increases after DNA damage, and when damage is induced by gamma irradiation, this increase requires ATM. Chk2 oligomerization is phosphorylation dependent and can occur in the absence of other eukaryotic proteins. Chk2 can cross-phosphorylate another Chk2 molecule in an oligomeric complex. Induced oligomerization of a Chk2 chimera in vivo concomitant with limited DNA damage augments Chk2 kinase activity. These results suggest that Chk2 oligomerization regulates Chk2 activation, signal amplification, and transduction in DNA damage checkpoint pathways.
机译:肿瘤抑制基因 CHK2 编码一种多功能效应丝氨酸/苏氨酸激酶,参与对 DNA 损伤的反应。Chk2 具有氨基末端 SQ/TQ 簇结构域 (SCD),其次是叉头相关 (FHA) 结构域和羧基末端激酶催化结构域。SCD 或 FHA 结构域中的突变会损害 Chk2 检查点功能。我们在这里表明,在无细胞系统中产生的 Chk2 的自磷酸化需要通过麦芽甘露蛋白敏感激酶(可能是 ATM 或 ATR)进行反式磷酸化。Chk2 SCD 中的 SQ/TQ 位点和非 SQW/TQ 位点都可以被活性 Chk2 磷酸化。 SCD 和 FHA 结构域中的氨基酸取代会损害 Chk2 的自激酶和反式激酶活性。 Chk2 形成的寡聚物只需要一个 Chk2 分子的 FHA 结构域和另一个 Chk2 分子内的 SCD。DNA损伤后,体内Chk2寡聚化增加,当伽马辐照诱导损伤时,这种增加需要ATM。 Chk2寡聚化是磷酸化依赖性的,可以在没有其他真核蛋白的情况下发生。Chk2 可以交叉磷酸化寡聚复合物中的另一个 Chk2 分子。诱导 Chk2 嵌合体在体内寡聚化,伴有有限的 DNA 损伤,可增强 Chk2 激酶活性。这些结果表明,Chk2寡聚化调节DNA损伤检查点通路中的Chk2激活、信号扩增和转导。

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