Aoufouchi S, Shall S
Department of Molecular Medicine, King's College School of Medicine and Dentistry, The Rayne Institute, 123 Coldharbour Lane, London SE5 9NU, U.K.
Biochem J. 1997 Jul 15;325 ( Pt 2)(Pt 2):543-51. doi: 10.1042/bj3250543.
Poly(ADP-ribose) polymerase (PARP) is an abundant nuclear enzyme that is dependent on DNA breaks and nicks for its enzyme activity. These DNA nicks and breaks function as allosteric effectors of the enzyme activity. This reaction is important for efficient DNA base excision repair, although it is not a component of the elementary repair pathway itself. The physiological relevance of this reaction might be to ensure correct and efficient DNA repair. We have examined the enzyme activity of PARP in oocytes and eggs of Xenopus laevis. Although both oocytes and eggs contain approximately the same amounts of enzyme protein, there is no detectable enzyme activity in the oocytes, whereas in the eggs the enzyme is active. Enzyme activity appears during oocyte maturation, approx. 4 h after induction by progesterone. This enzyme activation coincides with the appearance of active maturation-promoting factor. Enzyme activation is accompanied by a shift in the electrophoretic mobility of the polypeptide, from an apparent molecular mass of 116 kDa to 125 kDa. Treatment with either bacterial or potato phosphatase reverses the mobility shift and abolishes enzyme activity. Incubation of maturing X. laevis eggs with radioactive inorganic phosphate and subsequent immunoprecipitation demonstrate that the PARP protein is phosphorylated in vivo. We show that maturation-promoting factor (Cyclin B/cdc2) cannot itself be responsible for the phosphorylation and activation of PARP in maturing X. laevis eggs. Together, these results demonstrate that the enzyme activity of PARP in X. laevis oocytes and eggs is regulated by post-translational, covalent phosphorylation.
聚（ADP - 核糖）聚合酶（PARP）是一种丰富的核酶，其酶活性依赖于DNA断裂和切口。这些DNA切口和断裂作为酶活性的别构效应物发挥作用。尽管该反应不是基本修复途径本身的组成部分，但对于有效的DNA碱基切除修复很重要。该反应的生理相关性可能是确保正确和高效的DNA修复。我们研究了非洲爪蟾卵母细胞和卵中PARP的酶活性。尽管卵母细胞和卵中所含的酶蛋白量大致相同，但卵母细胞中未检测到酶活性，而卵中的酶是有活性的。酶活性在卵母细胞成熟过程中出现，大约在孕酮诱导后4小时。这种酶的激活与活性成熟促进因子的出现同时发生。酶的激活伴随着多肽电泳迁移率的变化，从表观分子量116 kDa变为125 kDa。用细菌或马铃薯磷酸酶处理可逆转迁移率变化并消除酶活性。用放射性无机磷酸盐孵育成熟的非洲爪蟾卵，随后进行免疫沉淀，结果表明PARP蛋白在体内被磷酸化。我们表明，成熟促进因子（细胞周期蛋白B/细胞分裂周期蛋白2）本身不能负责成熟的非洲爪蟾卵中PARP的磷酸化和激活。总之，这些结果表明，非洲爪蟾卵母细胞和卵中PARP的酶活性受翻译后共价磷酸化的调节。
