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In flowering plants, the transcription factor (TF) LEAFY (LFY) is key for flower formation. Recent evidence indicates that LFY links transcriptional and epigenetic regulations. Thanks to its two functional domains (a DNA binding domain or DBD and an oligomerization domain), LFY is able to contact closed chromatin regions and recruit the SWI/SNF chromatin remodellers SPLAYED (SYD) and BRAMA (BRM) to the loci of some of its targets. Unpublished results of the Plant & Cell Physiology Laboratory show that the interaction with BRM is mediated by the LFY DBD. However, the molecular and structural basis for this interaction remains elusive. LFY is not only present in flowering plants, but also in more ancestral lineages, such as gymnosperms, ferns, mosses, and even in some green algae. Therefore, the LFY protein and its function must have undergone major evolutionary changes. A recent study of the evolution of the LFY DBD shows that it changed several times during early land plant evolution. Moreover, whereas the LFY DBD has a conserved interface with DNA, the candidate surface to recruit the SWI/SNF chromatin remodellers shows much more variation. This suggests that the LFY DBD - SYD/BRM interaction might have originated at a specific moment in evolution. However, when and how this interaction started is completely unknown. My project aims to use LFY as a model for the cross-talk between transcription and epigenetic regulations, and solve the crystal structure of LFY in complex with remodellers. Despite their central importance in many organisms, no structure of SWI/SNF-TF complex has ever been elucidated. SYD/BRM interact with many TFs (such as ARFs or MADS), and solving such a structure would clear the way for manipulation of the interaction in plants. The other objective is to map the origin of the LFY-SYD/BRM interaction during plant evolution to understand the evolution of such a regulatory complex.
During my PhD, I studied the molecular mechanisms underlying ambient temperature-dependent flowering time regulation in the group of Gerco Angenent in Wageningen, The Netherlands. Besides making interesting advances on the role of alternative splicing in this process, I enjoyed being in an environment with such profound knowledge on flower development and transcription factor functioning. During a summer school at the École de Physique des Houches (France), dealing with integrated structural cell biology, I developed a particular interest in the structural element of transcription factors involved in flowering. I decided to contact François Parcy in Grenoble, France, who has been working on the structural aspects of the transcription LEAFY, a key player in flower development for many years. I propose a project to study the structural changes this protein has undergone throughout the evolution of plants. I was very happy to receive funding from AgreenSkills to start this project in February 2017, and I am really enjoying working in this lab, learning new techniques and gaining more knowledge on structural biology.
Verhage L, Severing EI, Bucher J, Lammers M, BusscherLange J, Bonnema G, et al., 2017. Splicing-related genes are alternatively spliced upon changes in ambient temperatures in plants. PLoS ONE 12(3): e0172950. Doi: 10.1371/journal.pone.0172950.
Pajoro A., Verhage L., Immink RGH, 2016. Plasticity versus Adaptation of Ambient-Temperature Flowering Response. Trends in plant science, 21(1), 6-8.
Verhage L, Angenent CC, Immink RGH, 2014. Research on floral timing by ambient temperature comes into blossom. Trends in plant science, 19 (9), 583-591.
Posé D, Verhage L, Ott F, Yant L, Mathieu J, Angenent GC, Immink RGH, Schmid M. 2013. Temperature-dependent regulation of flowering by antagonistic FLM variants. Nature 503 (7476), 414-417.