PHYTOCHROME REQUIRES THE 6-KDA N-TERMINAL DOMAIN FOR FULL BIOLOGICAL-ACTIVITY
PHYTOCHROME REQUIRES THE 6-KDA N-TERMINAL DOMAIN FOR FULL BIOLOGICAL-ACTIVITY
复制标题
DOI：
10.1073/pnas.89.11.5039
复制
发表时间：
1992-06-01
影响因子：
11.1
通讯作者：
VIERSTRA, RD
中科院分区：
文献类型：
--
作者：
CHERRY, JR;HONDRED, D;VIERSTRA, RD
光敏色素是一种红色/远红吸收光感受器，控制植物光形态发生的许多方面。由于从 124-kDa 燕麦光敏色素的 N 末端蛋白水解去除几乎等于 6 kDa 会显着改变色素蛋白的许多理化性质，因此有人提出 N 末端是生物活性所必需的。在这里，我们通过比较表达全长燕麦光敏色素 (FL) 的烟草植物与表达缺乏氨基酸 7-69 的 118 kDa 燕麦光敏色素（NA 光敏色素）的植物来检验这一假设。 NA 光敏色素与其 FL 对应物一样，在溶液中以同二聚体形式存在，能够共价结合发色团形成红色/远红光可逆产物，并在光转化为远红光吸收形式后在体内迅速降解。然而，与缺少 N 末端的蛋白水解降解光敏色素一样，NA 光敏色素的红光和远红光吸收形式的吸收最大值相对于 FL 色素蛋白的最大值发生蓝移，并且远红光吸收形式至红光吸收形式的暗回复率显着增加。产生高水平 NA 光敏色素的烟草植物不表现出 FL 光敏色素过度表达的光夸大表型特征。通过比较使用一系列表达不同水平的 FL 或 NA 光敏色素的转基因系产生的光敏色素-剂量-表型-反应曲线，我们证明 NA 光敏色素具有
Phytochrome is a red/far-red-absorbing photoreceptor that controls many aspects of plant photomorphogenesis. Because proteolytic removal of almost-equal-to 6 kDa from the N terminus of 124-kDa oat phytochrome substantially alters many physicochemical properties of the chromoprotein, it has been proposed that the N terminus is required for biological activity. Here we test this hypothesis by comparing tobacco plants expressing full-length oat phytochrome (FL) with plants expressing a 118-kDa oat phytochrome lacking amino acids 7-69 (NA phytochrome). NA phytochrome, like its FL counterpart, exists as a homodimer in solution, is capable of covalently binding chromophore to form a red/far-red-photoreversible product, and is rapidly degraded in vivo after photoconversion to the far-red-absorbing form. However, like proteolytically degraded phytochrome missing the N terminus, the absorption maxima of the red- and far-red-light-absorbing forms of NA phytochrome are blue shifted relative to the maxima of the FL chromoprotein, and the rate of dark reversion of the far-red- to red-light-absorbing form is substantially increased. Tobacco plants producing high levels of NA phytochrome do not exhibit the light-exaggerated phenotype characteristic of FL phytochrome overexpression. By comparison of phytochrome-dose-phenotype-response curves generated by using a series of transgenic lines expressing various levels of FL or NA phytochrome, we demonstrate that NA phytochrome has