UFO helps LEAFY find new promoter elements

Floral development has been the object of decades of plant research, yet many fundamental questions remain. One of these is the mechanism by which LEAFY (LFY), the master transcription factor of floral development, works with UNUSUAL FLORAL ORGANS (UFO), an F-box protein, to regulate petal and stamen development. In Arabidopsis (Arabidopsis thaliana), LFY and UFO work together to regulate APETALA3 (AP3), and UFO has been thought to be involved in the degradation of LFY. A recent paper by Rieu et al. tackled this question and showed that UFO works as a transcriptional cofactor of LFY to regulate AP3 expression, and that its F-box domain is dispensable for the transcriptional activity of the LFY-UFO complex. UFO allows LFY to bind to new genomic sites that the transcription factor cannot bind on its own, and the cryogenic electron microscopy (cryo-EM) structure of the (ASK1)-UFO-LFY-DNA complex revealed that UFO directly interacts with DNA. If you are wondering whether this mechanism is only found in Arabidopsis, the authors show that several LFY proteins from different species can interact (and induce gene expression) with Arabidopsis UFO. These results suggest that the LFY-UFO interaction may be conserved beyond flowering plants. Interacting with non-transcription factor proteins could be a more widespread mechanism than is currently thought to fine-tune gene regulation and modulate transcription factor activity in different territories. (Summary by Laura Turchi @turchi_l) Nature Plants 10.1038/s41477-022-01336-2