ROLE OF CALF THYMUS DNA-TOPOISOMERASE-I PHOSPHORYLATION ON RELAXATION ACTIVITY EXPRESSION AND ON DNA-PROTEIN INTERACTION - ROLE OF DNA-TOPOISOMERASE-I PHOSPHORYLATION
ROLE OF CALF THYMUS DNA-TOPOISOMERASE-I PHOSPHORYLATION ON RELAXATION ACTIVITY EXPRESSION AND ON DNA-PROTEIN INTERACTION - ROLE OF DNA-TOPOISOMERASE-I PHOSPHORYLATION
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DOI：
10.1007/bf00422713
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发表时间：
1990-02-01
影响因子：
2.8
通讯作者：
GIANFRANCESCHI, GL
中科院分区：
文献类型：
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作者：
CODERONI, S;PAPARELLI, M;GIANFRANCESCHI, GL
研究发现，小牛胸腺 DNA 拓扑异构酶 I 的活性因磷酸化的改变而改变：碱性磷酸酶去磷酸化后，它被完全抑制，但与 N II 蛋白激酶和 ATP 一起孵育，可将松弛活性恢复到高于去磷酸化前观察到的水平。由喜树碱诱导的小牛胸腺拓扑异构酶 I 介导的 DNA 裂解也被证明受到去磷酸化的抑制，这显然稳定了最初的酶-底物复合物。我们的结论是：天然蛋白质是部分磷酸化的，磷酸化，磷酸化参与对于活性表达以及DNA-蛋白质相互作用是必需的，磷酸化程度的变化可能参与DNA加工的调节；这唤起了染色质肽模型的一些特性，该模型仅在磷酸化时结合 DNA，并导致假设它们代表 N II 蛋白激酶的最小功能底物。
Calf thymus DNA-Topoisomerase I activity was found to be altered by changing in phosphorylation: it was completely inhibited upon dephosphorylation by alkaline phosphatase, but incubation with N II protein kinase and ATP restored the relaxation activity to a level higher than that observed prior to dephosphorylation. The calf thymus Topoisomerase I-mediated DNA cleavage, induced by camptothecin, also proved to be inhibited by dephoshorylation, which, apparently, stabilizes the initial enzyme-substrate complex. We conclude that: the native protein is partially phosphorylated, the phosphorylated, the phosphorylation involvement is essential for the activity expression and also for DNA-protein interaction, changes in the degree of phosphorylation might be involved in the regulation of DNA processing; that evokes some properties of chromatinic peptide models, which bind DNA only when phosphorylated and leads to the assumption that they represent the minimum functional substrate for N II protein kinase.