生物谷报道：植物中很多至关重要的发育过程由光和赤霉素共同调控，然而我们对二者之间对话的分子基础还没有充分了解。现在，两个小组在本期《自然》上报告的结果显示了一个信号级联，它有助于光和赤霉素对植物生长进行协调的控制。在没有赤霉素时，DELLA蛋白抑制转录因子PIF3（一种光敏素相互作用蛋白）与基因启动子结合。赤霉素诱导DELLA蛋白的降解，从而允许PIFs与它们的目标启动子结合，并调控基因表达。光通过一个光反应器发挥作用，来使PIF4失去稳定性。所以，DELLA蛋白及PIF家族成员之间的竞争性相互作用，似乎是将光与赤霉素联系在一起的关键因素。（科学时报）
生物谷推荐英文原文：
Nature 451, 475-479 (24 January 2008) | doi:10.1038/nature06448; Received 28 September 2007; Accepted 1 November 2007
Coordinated regulation of Arabidopsisthaliana development by light and gibberellins
Suhua Feng1,2,7, Cristina Martinez1,8, Giuliana Gusmaroli1,8, Yu Wang3,8, Junli Zhou2,8, Feng Wang2, Liying Chen2, Lu Yu2, Juan M. Iglesias-Pedraz4, Stefan Kircher5, Eberhard Schäfer5, Xiangdong Fu6, Liu-Min Fan3 & Xing Wang Deng1,2,3
Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut 06520-8104, USA
National Institute of Biological Sciences, Zhongguancun Life Science Park, Beijing 102206, China
Peking–Yale Joint Center for Plant Molecular Genetics and Agrobiotechnology, and National Laboratory for Protein Engineering and Plant Genetic Engineering, College of Life Sciences, Peking University, Beijing 100871, China
Departamento Genética Molecular de Plantas, Centro Nacional de Biotecnología-CSIC, Campus Universidad Autónoma de Madrid, 28049 Madrid, Spain
Institut für Biologie II/Botanik, Albert Ludwigs Universität, Freiburg D-79104, Germany
Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100080, China
Present address: Howard Hughes Medical Institute, University of California at Los Angeles, Los Angeles, California 90095-1606, USA.
These authors contributed equally to this work.
Correspondence to: Xing Wang Deng1,2,3 Correspondence and requests for materials should be addressed to X.W.D. (Email: xingwang.deng@yale.edu).
Light and gibberellins (GAs) mediate many essential and partially overlapping plant developmental processes. DELLA proteins are GA-signalling repressors that block GA-induced development1. GA induces degradation of DELLA proteins via the ubiquitin/proteasome pathway2, but light promotes accumulation of DELLA proteins by reducing GA levels3. It was proposed that DELLA proteins restrain plant growth largely through their effect on gene expression4, 5. However, the precise mechanism of their function in coordinating GA signalling and gene expression remains unknown. Here we characterize a nuclear protein interaction cascade mediating transduction of GA signals to the activity regulation of a light-responsive transcription factor. In the absence of GA, nuclear-localized DELLA proteins accumulate to higher levels, interact with phytochrome-interacting factor 3 (PIF3, a bHLH-type transcription factor) and prevent PIF3 from binding to its target gene promoters and regulating gene expression, and therefore abrogate PIF3-mediated light control of hypocotyl elongation. In the presence of GA, GID1 proteins (GA receptors) elevate their direct interaction with DELLA proteins in the nucleus, trigger DELLA protein's ubiquitination and proteasome-mediated degradation, and thus release PIF3 from the negative effect of DELLA proteins.
