Laboratoire Physiologie Cellulaire et Végétale, Université Grenoble Alpes, CNRS, CEA, INRAE, IRIG-DBSCI-LPCV, 17 avenue des martyrs, 38054, Grenoble, France.
Université Paris-Saclay, CNRS, INRAE, Université d'Evry, Institute of Plant Sciences Paris-Saclay (IPS2), 91405, Orsay, France.
Mol Plant. 2021 May 3;14(5):829-837. doi: 10.1016/j.molp.2021.03.004. Epub 2021 Mar 5.
Pioneer transcription factors (TFs) are a special category of TFs with the capacity to bind to closed chromatin regions in which DNA is wrapped around histones and may be highly methylated. Subsequently, pioneer TFs are able to modify the chromatin state to initiate gene expression. In plants, LEAFY (LFY) is a master floral regulator and has been suggested to act as a pioneer TF in Arabidopsis. Here, we demonstrate that LFY is able to bind both methylated and non-methylated DNA using a combination of in vitro genome-wide binding experiments and structural modeling. Comparisons between regions bound by LFY in vivo and chromatin accessibility data suggest that a subset of LFY bound regions is occupied by nucleosomes. We confirm that LFY is able to bind nucleosomal DNA in vitro using reconstituted nucleosomes. Finally, we show that constitutive LFY expression in seedling tissues is sufficient to induce chromatin accessibility in the LFY direct target genes APETALA1 and AGAMOUS. Taken together, our study suggests that LFY possesses key pioneer TF features that contribute to launching the floral gene expression program.
先驱转录因子 (TFs) 是一类特殊的 TFs，它们能够结合到 DNA 缠绕在组蛋白上且可能高度甲基化的闭链染色质区域。随后，先驱 TFs 能够修饰染色质状态以启动基因表达。在植物中，LEAFY (LFY) 是一个主要的花器官调控因子，并且被认为在拟南芥中作为一个先驱 TF 发挥作用。在这里，我们通过体外全基因组结合实验和结构建模的组合，证明了 LFY 能够结合甲基化和非甲基化的 DNA。LFY 在体内结合的区域与染色质可及性数据之间的比较表明，LFY 结合的区域子集被核小体占据。我们使用重建的核小体证实了 LFY 能够在体外结合核小体 DNA。最后，我们表明幼苗组织中组成型 LFY 表达足以诱导 LFY 直接靶基因 APETALA1 和 AGAMOUS 的染色质可及性。总的来说，我们的研究表明，LFY 具有关键的先驱 TF 特征，有助于启动花器官基因表达程序。
