Heterodimerization of type II phytochromes in Arabidopsis
Heterodimerization of type II phytochromes in Arabidopsis
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DOI：
10.1073/pnas.0404286101
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发表时间：
2004-08-03
影响因子：
11.1
通讯作者：
Clack, T
中科院分区：
文献类型：
--
作者：
Sharrock, RA;Clack, T
来自植物提取物的光敏色素红/远红光感受器家族成员的共免疫沉淀已用于分析它们的异聚结合相互作用。 N 末端融合有六个 myc 表位的光敏色素 (phy)B 或 phyD 脱辅基蛋白在拟南芥中表达时具有生物活性。对来自幼苗提取物的这些标记蛋白进行免疫沉淀可共沉淀其他 11 型光敏色素：六种 myc (myc(6))-phyB 共沉淀 phyC-phyE； myc(6)-phyD 共沉淀 phyB 和 phyE。没有检测到表位标记蛋白与 I 型 phyA 的相互作用。凝胶过滤色谱显示所有五种拟南芥光敏色素均以二聚体形式存在于幼苗中，并且异聚型 11 型光敏色素复合物以异二聚体的分子质量特征迁移。在黑暗生长的幼苗的提取物中观察到类似水平的异二聚体形成，其中光敏色素是细胞质的，而在光生长的幼苗的提取物中它们主要是细胞核的。这些发现表明，迄今为止人们认为拟南芥含有五种同二聚体形式的光敏色素，但实际上它含有多种同二聚体和异二聚体光敏色素。光敏色素家族在整个被子植物中的保守性表明，异二聚体红色/远红色受体可能存在于许多开花植物中。
Coimmunoprecipitation of members of the phytochrome red/far-red photoreceptor family from plant extracts has been used to analyze their heteromeric binding interactions. Phytochrome (phy)B or phyD apoproteins with six myc epitopes fused to their N termini are biologically active when expressed in Arabidopsis. Immunoprecipitation of either of these tagged proteins from seedling extracts coprecipitates additional type 11 phytochromes: six myc (myc(6))-phyB coprecipitates phyC-phyE; and myc(6)-phyD coprecipitates phyB and phyE. No interaction of the epitope-tagged proteins with type I phyA was detected. Gel filtration chromatography shows that all five of the Arabidopsis phytochromes are present in seedlings as dimers, and that the heteromeric type 11 phytochrome complexes migrate at molecular masses characteristic of heterodimers. Similar levels of heterodimer formation are observed in extracts of dark-grown seedlings, where the phytochromes are cytosolic, and light-grown seedlings, where they are predominantly nuclear. These findings indicate that Arabidopsis, which until now has been thought to contain five homodimeric forms of phytochrome, in fact contains multiple species of both homodimeric and heterodimeric phytochromes. The conservation of the phytochrome family throughout angiosperms suggests that heterodimeric red/far-red receptors may be present in many flowering plants.