Phytochrome requires the 6-kDa N-terminal domain for full biological activity.

作者：Joel R. Cherry, D. Hondred, Joseph M. Walker, Richard David Vierstra · 发表于：Proceedings of the National Academy of Sciences · 年份：1992 · DOI：10.1073/pnas.89.11.5039 · 被引用次数：125 · 研究领域：Light effects on plants、Photosynthetic Processes and Mechanisms、Algal biology and biofuel production

Phytochrome is a red/far-red-absorbing photoreceptor that controls many aspects of plant photomorphogenesis. Because proteolytic removal of approximately 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 less than 1/5th ...