本文为2017年7月The Plant Journal文章，原题目为：

CYCLING DOF FACTOR 1 represses transcription through the TOPLESS co-repressor to control photoperiodic flowering in Arabidopsis

CDF1及其同系物在拟南芥中通过抑制开花激活基因（如CO和FT）的表达，从而在成花转变中起重要作用。日长可以特异性的去除CDF1依赖性的开花抑制，这是光周期开花的关键机制。然而，CDF1抑制CO和FT转录的机制仍然难以捉摸。在这里，我们阐明了拟南芥中含有非EAR motif类保守域的CDF蛋白质，其与TPL共阻遏蛋白相互作用实调控开花所需要的。这种与TPL的相互作用赋予了CDF1的抑制功能，因为N-末端TPL结合结构域的突变极大地损害了CDF1蛋白抑制其靶基因的能力。TPL蛋白存在于CO和FT启动子的特定区域上，这些区域正是CDF1在早晨所结合的区域。另外，当CDF1表达升高时，TPL结合增加，表明CDF以时间依赖的方式将TPL募集到这些启动子。此外，通过在韧皮伴侣细胞中表达显性负性版本的TPL（tpl-1），使TPL的活性降低，导致早开花，并且与cdf功能缺失突变体相似，降低了对光周期的敏感性。我们的研究结果表明，CDF1抑制的机制是通过形成CDF-TPL转录复合体，进而在季节性开花的早晨降低CO和FT的表达水平。

CYCLING DOF FACTOR 1 (CDF1) and its homologs play an important role in the floral transition by repressing the expression of floral activator genes such as CONSTANS (CO) and FLOWERING LOCUS T (FT) in Arabidopsis. The day-length-specific removal of CDF1-dependent repression is a critical mechanism in photoperiodic flowering. However, the mechanism by which CDF1 represses CO and FT transcription remained elusive. Here we demonstrate that Arabidopsis CDF proteins contain non-EAR motif-like conserved domains required for interaction with the TOPLESS (TPL) co-repressor protein. This TPL interaction confers a repressive function on CDF1, as mutations of the N-terminal TPL binding domain largely impair the ability of CDF1 protein to repress its targets. TPL proteins are present on specific regions of the CO and FT promoters where CDF1 binds during the morning. In addition, TPL binding increases when CDF1 expression is elevated, suggesting that TPL is recruited to these promoters in a time-dependent fashion by CDFs. Moreover, reduction of TPL activity induced by expressing a dominant negative version of TPL (tpl-1) in phloem companion cells results in early flowering and a decreased sensitivity to photoperiod in a manner similar to a cdf loss-of-function mutant. Our results indicate that the mechanism of CDF1 repression is through the formation of a CDF–TPL transcriptional complex, which reduces the expression levels of CO and FT during the morning for seasonal flowering.

每日一词

removal

英[rɪˈmu:vl]

美[rɪˈmuvəl]

n. 除去; 搬迁; 免职; 移走;

[例句]What they expected to be the removal of a small lump turned out to be major surgery

他们原以为只需切除小肿块的手术最后变成了一次大手术。

[其他] 复数：removals