Staiger D
Institute for Plant Sciences, ETH Zurich, CH-8092 Zurich, Switzerland.
Philos Trans R Soc Lond B Biol Sci. 2001 Nov 29;356(1415):1755-9. doi: 10.1098/rstb.2001.0964.
An Arabidopsis transcript preferentially expressed at the end of the daily light period codes for the RNA-binding protein AtGRP7. A reverse genetic approach in Arabidopsis thaliana has revealed its role in the generation of circadian rhythmicity: AtGRP7 is part of a negative feedback loop through which it influences the oscillations of its own transcript. Biochemical and genetic experiments indicate a mechanism for this autoregulatory circuit: Atgrp7 gene transcription is rhythmically activated by the circadian clock during the day. The AtGPR7 protein accumulates with a certain delay and represses further accumulation of its transcript, presumably at the post-transcriptional level. In this respect, the AtGRP7 feedback loop differs from known circadian oscillators in the fruitfly Drosophila and mammals based on oscillating clock proteins that repress transcription of their own genes with a 24 h rhythm. It is proposed that the AtGRP7 feedback loop may act within an output pathway from the Arabidopsis clock.
一种在每日光照周期结束时优先表达的拟南芥转录本编码RNA结合蛋白AtGRP7。在拟南芥中采用反向遗传学方法揭示了其在昼夜节律产生中的作用：AtGRP7是一个负反馈环的一部分，通过该负反馈环它影响自身转录本的振荡。生化和遗传学实验表明了这种自动调节回路的机制：Atgrp7基因转录在白天被生物钟有节奏地激活。AtGPR7蛋白会有一定延迟地积累，并抑制其转录本的进一步积累，推测是在转录后水平。在这方面，AtGRP7反馈环不同于果蝇和哺乳动物中已知的基于以24小时节律抑制自身基因转录的振荡生物钟蛋白的昼夜振荡器。有人提出，AtGRP7反馈环可能在拟南芥生物钟的输出途径中起作用。
