PROTEIN-KINASE-C MODULATES THE CATALYTIC ACTIVITY OF TOPOISOMERASE-II BY ENHANCING THE RATE OF ATP HYDROLYSIS - EVIDENCE FOR A COMMON MECHANISM OF REGULATION BY PHOSPHORYLATION
PROTEIN-KINASE-C MODULATES THE CATALYTIC ACTIVITY OF TOPOISOMERASE-II BY ENHANCING THE RATE OF ATP HYDROLYSIS - EVIDENCE FOR A COMMON MECHANISM OF REGULATION BY PHOSPHORYLATION
复制标题
DOI：
10.1021/bi00059a029
复制
发表时间：
1993-03-02
期刊：
影响因子：
2.9
通讯作者：
OSHEROFF, N
中科院分区：
文献类型：
--
作者：
CORBETT, AH;FERNALD, AW;OSHEROFF, N
拓扑异构酶II的催化活性在酪蛋白激酶II或蛋白激酶C磷酸化后被刺激约2-3倍。先前的研究[Corbett，A. H、德沃尔河F.、& Osheroff，N.（1992）J.Biol.Chem.267，20513-20518]证明酪蛋白激酶II通过特异性增强酶水解其ATP辅因子的能力来调节拓扑异构酶II的活性。为了确定其他蛋白激酶是否使用类似的机制来激活酶，评估了蛋白激酶C介导的磷酸化对拓扑异构酶II催化循环的各个步骤的影响。修饰刺激酶介导的ATP水解速率约2.7倍，但对此步骤之前的任何反应没有影响，包括酶。DNA结合，前或后链通过DNA切割/再连接，或双链DNA链通过事件。此外，ATP水解的激活逆转后，磷酸化的拓扑异构酶II与碱性磷酸酶的治疗。如通过部分蛋白水解作图所确定的，蛋白激酶C修饰的位点定位于拓扑异构酶II的350个氨基酸的C-末端调节结构域，在被酪蛋白激酶II磷酸化的位点的大约50个氨基酸内。最后，虽然蛋白激酶C和酪蛋白激酶II能够修改的酶同时，双修饰的拓扑异构酶II的ATP水解率是可比的，观察到的酶磷酸化后，由任何个别激酶。在这些研究结果的基础上，它的结论是，蛋白激酶C和酪蛋白激酶II调节拓扑异构酶II的催化功能的一个共同的机制和酶的催化循环的ATP水解步骤是控制点激活拓扑异构酶II由这两个不同的蛋白激酶。
The catalytic activity of topoisomerase II is stimulated approximately 2-3-fold following phosphorylation by either casein kinase Il or protein kinase C. A previous study [Corbett, A. H., DeVore, R. F., & Osheroff, N. (1992) J. Biol. Chem. 267, 20513-20518] demonstrated that casein kinase II regulates the activity of topoisomerase II by specifically enhancing the ability of the enzyme to hydrolyze its ATP cofactor. To determine whether other protein kinases use a similar mechanism to activate the enzyme, the effects of protein kinase C mediated phosphorylation on the individual steps of the topoisomerase II catalytic cycle were assessed. Modification stimulated rates of enzyme-mediated ATP hydrolysis approximately 2.7-fold, but had no effect on any reaction that preceded this step, including enzyme.DNA binding, pre- or poststrand passage DNA cleavage/religation, or the double-stranded DNA strand passage event. Furthermore, the activation of ATP hydrolysis was reversed following treatment of phosphorylated topoisomerase II with alkaline phosphatase. As determined by partial proteolytic mapping, the site(s) of protein kinase C modification was (were) localized to the 350 amino acid C-terminal regulatory domain of topoisomerase II within approximately 50 amino acids of the site(s) phosphorylated by casein kinase II. Finally, while protein kinase C and casein kinase II were able to modify the enzyme simultaneously, rates of ATP hydrolysis for doubly-modified topoisomerase II were comparable to those observed for the enzyme following phosphorylation by either individual kinase. On the basis of these findings, it is concluded that protein kinase C and casein kinase II regulate the catalytic function of topoisomerase II by a common mechanism and that the ATP hydrolysis step of the enzyme's catalytic cycle is the control point for activation of topoisomerase II by these two disparate protein kinases.