Bäckström Stefan, Elfving Nils, Nilsson Robert, Wingsle Gunnar, Björklund Stefan
Department of Medical Biochemistry and Biophysics, KBC, Umeå University, SE-901 87 Umeå, Sweden.
Mol Cell. 2007 Jun 8;26(5):717-29. doi: 10.1016/j.molcel.2007.05.007.
Mediator, a central coregulator of transcription, has been identified as a large protein complex in eukaryotes ranging from yeast to man. It is therefore remarkable that Mediator has not yet been identified within the plant kingdom. Here we identify Mediator in a plant, Arabidopsis thaliana. The plant Mediator subunits typically show very low homology to other species, but our biochemical purification identifies 21 conserved and six A. thaliana-specific Mediator subunits. Most notably, we identify the A. thaliana proteins STRUWWELPETER (SWP) and PHYTOCHROME AND FLOWERING TIME 1 (PFT1) as the Med14 and Med25 subunits, respectively. These findings show that specific plant Mediator subunits are linked to the regulation of specialized processes such as the control of cell proliferation and the regulation of flowering time in response to light quality. The identification of the plant Mediator will provide new tools and insights into the regulation of transcription in plants.
中介体是转录的核心共调节因子，已被鉴定为从酵母到人类的真核生物中的一种大型蛋白质复合物。因此，在植物界尚未鉴定出中介体这一点就显得很引人注目了。在此，我们在一种植物拟南芥中鉴定出了中介体。植物中介体亚基通常与其他物种的同源性非常低，但我们的生化纯化鉴定出了21个保守的和6个拟南芥特有的中介体亚基。最值得注意的是，我们分别将拟南芥蛋白STRUWWELPETER（SWP）和光敏色素与开花时间1（PFT1）鉴定为Med14和Med25亚基。这些发现表明，特定的植物中介体亚基与细胞增殖控制和响应光质的开花时间调节等特殊过程的调控有关。植物中介体的鉴定将为植物转录调控提供新的工具和见解。
