A plastidic ABC protein involved in intercompartmental communication of light signaling
A plastidic ABC protein involved in intercompartmental communication of light signaling
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DOI：
10.1101/gad.850101
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发表时间：
2001-01-01
影响因子：
10.5
通讯作者：
Chua, NH
中科院分区：
文献类型：
--
作者：
Moller, SG;Kunkel, T;Chua, NH
植物通过专门的光感受器感知光，其中光敏色素（phyA-E），吸收远红光（FR）和红光（R）是最好的理解。几个核和细胞质蛋白质的特点是其缺陷导致光依赖性的形态反应和基因表达的变化。然而，尚未发现质体蛋白在光敏色素信号转导中发挥作用。我们已经分离出一个新的拟南芥突变体，laf（长FR后）6，减少响应优先对连续ER光。laf 6中被破坏的基因编码一种新的植物ATP结合盒（atABC 1）蛋白，该蛋白具有557个氨基酸，与来自低等真核生物的ABC样蛋白具有高度同源性。然而，与低等真核ABC相反，atABC 1含有一个N-末端转运肽，将其靶向叶绿体。Iaf 6中atABC 1缺陷导致叶绿素前体原卟啉IX的积累和PR调节基因表达的减弱。laf 6的长下胚轴表型和原卟啉IX在突变体中的积累可以通过用flumioxazin（一种原卟啉原IX氧化酶（PPO）抑制剂）处理野生型（WT）幼苗来重现。此外，原卟啉IX积累在flumioxazin处理的WT幼苗可以减少过表达atABC 1。与ABC蛋白参与运输的概念相一致，这些观察结果表明，功能atABC 1是运输和正确分布的原卟啉IX，这可能是一个光特异性信号因子参与协调间室质体和细胞核之间的通信所需的。
Plants perceive light via specialized photoreceptors of which the phytochromes (phyA-E), absorbing far-red (FR) and red light (R) are best understood. Several nuclear and cytoplasmic proteins have been characterized whose deficiencies lead to changes in light-dependent morphological responses and gene expression. However, no plastid protein has yet been identified to play a role in phytochrome signal transduction. We have isolated a new Arabidopsis mutant, laf (long after FR) 6, with reduced responsiveness preferentially toward continuous ER light. The disrupted gene in laf6 encodes a novel plant ATP-binding-cassette (atABC1) protein of 557 amino acids with high homology to ABC-like proteins from lower eukaryotes. In contrast to lower eukaryotic ABCs, however, atABC1 contains an N-terminal transit peptide, which targets it to chloroplasts. atABC1 deficiency in Iaf6 results in an accumulation of the chlorophyll precursor protoporphyrin IX and in attenuation of PR-regulated gene expression. The long hypocotyl phenotype of laf6 and the accumulation of protoporphyrin IX in the mutant can be recapitulated by treating wild-type (WT) seedlings with flumioxazin, a protoporphyrinogen IX oxidase (PPO) inhibitor. Moreover, protoporphyrin IX accumulation in flumioxazin-treated WT seedlings can be reduced by overexpression of atABC1. Consistent with the notion that ABC proteins are involved in transport, these observations suggest that functional atABC1 is required for the transport and correct distribution of protoporphyrin IX, which may act as a light-specific signaling factor involved in coordinating intercompartmental communication between plastids and the nucleus.