Characterization of the requirements for localization of phytochrome B to nuclear bodies
Characterization of the requirements for localization of phytochrome B to nuclear bodies
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DOI：
10.1073/pnas.1935989100
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发表时间：
2003-11-25
影响因子：
11.1
通讯作者：
Chory, J
中科院分区：
文献类型：
--
作者：
Chen, M;Schwabb, R;Chory, J
光敏色素是红光和远红光感受器，可检测植物整个生命周期中光的数量、质量和持续时间。光敏色素在黑暗中积聚在细胞质中。作为光照射后最早的反应之一，光敏色素定位于细胞核，在那里它们与离散的核体 (NB) 相关联。在这里，我们描述了拟南芥光敏色素 B (phyB) 定位响应不同光照条件的稳态动态，并定义了四种 phyB 亚核定位模式：弥散核定位、仅小和大量 NB、小和大 NB 以及仅大 NB。我们表明 phyB 核输入不足以形成 phyB NB。相反，NB 中的 phyB 积累主要取决于活跃 phyB 构象异构体中 phyB 蛋白总量的百分比，大的 NB 总是与强烈的 phyB 反应相关。一项旨在鉴定 phyB 亚核定位所需决定因素的遗传筛选产生了几种 phyB 突变体、光敏色素发色团生物合成缺陷的突变体以及至少一个先前未研究的基因座的突变。这项研究为未来的研究奠定了基础，以确定植物光感受器光调节分配到离散亚核域的分子机制。
Phytochromes are red- and far-red-sensing photoreceptors that detect the quantity, quality, and duration of light throughout the entire life cycle of plants. Phytochromes accumulate in the cytoplasm in the dark. As one of the earliest responses after light illumination, phytochromes localize to the nucleus where they become associated with discrete nuclear bodies (NBs). Here, we describe the steady-state dynamics of Arabidopsis phytochrome B (phyB) localization in response to different light conditions and define four phyB subnuclear localization patterns: diffuse nuclear localization, small and numerous NBs only, both small and large NBs, and large NBs only. We show that phyB nuclear import is not sufficient for phyB NB formation. Rather, phyB accumulation in NBs is mainly determined by the percentage of the total amount of phyB protein that is in the active phyB conformer, with large NBs always correlating with strong phyB responses. A genetic screen to identify determinants required for subnuclear localization of phyB resulted in several phyB mutants, mutants deficient in phytochrome chromophore biosynthesis, and mutations in at least one previously uninvestigated locus. This study lays the groundwork for future investigations to identify the molecular mechanisms of light-regulated partitioning of plant photoreceptors to discrete subnuclear domains.