Self-incompatibility in Papaver targets soluble inorganic pyrophosphatases in pollen
Self-incompatibility in Papaver targets soluble inorganic pyrophosphatases in pollen
复制标题
DOI：
10.1038/nature05311
复制
发表时间：
2006-11-23
期刊：
影响因子：
64.8
通讯作者：
Franklin-Tong, Vernonica E.
中科院分区：
文献类型：
--
作者：
de Graaf, Barend H. J.;Rudd, Jason J.;Franklin-Tong, Vernonica E.
在高等植物中，有性生殖涉及花粉和雌蕊之间的相互作用。防止近亲繁殖的一个关键机制是通过排斥不相容（“自我”）花粉的自交不亲和性（1）。在虞美人中，柱头编码的S蛋白与不亲和的花粉相互作用，触发Ca 2+依赖性信号网络（2-5），导致花粉管抑制和程序性细胞死亡（6）。在不亲和花粉中鉴定的胞质磷蛋白p26.1在体内表现出快速的、自交不亲和诱导的Ca 2+依赖性过度磷酸化（3）。在这里，我们发现p26. 1包含两个蛋白质，Pr-p26.1a和Pr-p26.1b，这是可溶性无机焦磷酸酶（sPPases）。这些蛋白质具有经典的Mg 2+依赖性sPP酶活性，其被Ca 2+抑制，并且出乎意料地可以在体外磷酸化。我们发现，磷酸化抑制sPPase活性，建立一个以前未知的机制，调节真核sPPases。降低sPPase活性的预测，导致许多生物合成途径的抑制，这表明可能有其他机制的自交不亲和介导的花粉管抑制。我们提供的证据表明，spPPases是生长所必需的，自交不亲和性导致无机焦磷酸盐的增加，这意味着Pr-p26.1的功能作用。
In higher plants, sexual reproduction involves interactions between pollen and pistil. A key mechanism to prevent inbreeding is self-incompatibility through rejection of incompatible ('self') pollen(1). In Papaver rhoeas, S proteins encoded by the stigma interact with incompatible pollen, triggering a Ca2+-dependent signalling network(2-5) resulting in pollen tube inhibition and programmed cell death(6). The cytosolic phosphoprotein p26.1, which has been identified in incompatible pollen, shows rapid, self-incompatibility-induced Ca2+-dependent hyperphosphorylation in vivo(3). Here we show that p26.1 comprises two proteins, Pr-p26.1a and Pr-p26.1b, which are soluble inorganic pyrophosphatases (sPPases). These proteins have classic Mg2+-dependent sPPase activity, which is inhibited by Ca2+, and unexpectedly can be phosphorylated in vitro. We show that phosphorylation inhibits sPPase activity, establishing a previously unknown mechanism for regulating eukaryotic sPPases. Reduced sPPase activity is predicted to result in the inhibition of many biosynthetic pathways, suggesting that there may be additional mechanisms of self-incompatibility-mediated pollen tube inhibition. We provide evidence that sPPases are required for growth and that self-incompatibility results in an increase in inorganic pyrophosphate, implying a functional role for Pr-p26.1.