背景回顾：In angiosperms, flower development requires the combined action of the transcription factor LEAFY (LFY) and the ubiquitin ligase adaptor F-box protein, UNUSUAL FLORAL ORGANS (UFO), but the molecular mechanism underlying this synergy has remained unknown. 

结果1-UFO泛素化功能不必需：Here we show in transient assays and stable transgenic plants that the connection to ubiquitination pathways suggested by the UFO F-box domain is mostly dispensable. 

结果2-UFO-LFY转录激活复合体：On the basis of biochemical and genome-wide studies, we establish that UFO instead acts by forming an active transcriptional complex with LFY at newly discovered regulatory elements. 

结果3-UFO招募LFY至新顺式元件上：Structural characterization of the LFY–UFO–DNA complex by cryo-electron microscopy further demonstrates that UFO performs this function by directly interacting with both LFY and DNA. 

结论：Finally, we propose that this complex might have a deep evolutionary origin, largely predating flowering plants. This work reveals a unique mechanism of an F-box protein directly modulating the DNA binding specificity of a master transcription factor.

在被子植物中，花发育需要转录因子LEAFY和泛素连接酶接头F-box蛋白UFO的组合作用，但是这两个蛋白之间协调作用的分子机制还不清楚。本文中，作者通过瞬时转化和稳定转化发现，UFO参与花发育调控并不依赖于其F-box结构域所介导的泛素化途径。基于生化和基因组范围的研究，作者发现UFO通过与LFY形成一个激活转录复合物，结合到新发现的调控元件上。通过冷冻电镜对LFY–UFO–DNA复合体的结构解析，作者发现UFO通过同时直接与LFY和DNA结合，从而执行该功能。最终，作者提出该复合物可能具有一个比较原始的演化起源，可能要早于有花植物出现的时间。本文的研究结果揭示了一个F-box蛋白直接调控关键转录因子的DNA结合特异性的独特机制。

** François Parcy **