Plant Cellular and Molecular Biology Graduate Program, The Ohio State University, 500 Aronoff Laboratory, Columbus, OH, USA.
Plant J. 2012 Sep;71(5):736-49. doi: 10.1111/j.1365-313X.2012.05026.x. Epub 2012 Jun 12.
The floral meristem identity gene LEAFY (LFY) of Arabidopsis thaliana is essential for the formation of fertile flowers and has roles in the control of several aspects of floral development, which include phyllotaxy and organ number and identity. This gene encodes a land plant-specific transcription factor and regulates expression of a number of genes that include other floral meristem identity genes and floral homeotic genes. Although the LFY DNA-binding domain has a structure that resembles that of helix-turn-helix proteins, LFY and its orthologs represent a novel family of transcription factors that are characterized by a conserved N-terminus domain of unknown function and a C-terminus DNA-binding domain. Many transcription factors act as dimers. These dimers are essential for the biological activity of the proteins. We demonstrate that LFY forms homodimers or oligomers in solution. This association is mediated through the N-terminus conserved region of the LFY protein. Although mutant LFY proteins that cannot dimerize in solution can bind DNA, the binding is weaker than that of wild type LFY protein. LFY-LFY interactions mediated by the N-terminus domain are essential for the biological activity of this protein, as mutations that abolish the ability to self-associate cannot complement an lfy null allele. Our data indicate: (i) that LFY, and probably its orthologs in other plants, must act in complexes that contain at least two LFY molecules; and (ii) that the N-terminus is essential for stabilization of LFY complexes. This situation is integral to the ability of LFY to regulate gene expression.
拟南芥花分生组织特征基因 LEAFY（LFY）对于可育花的形成是必需的，并且在花发育的几个方面起作用，包括叶序和器官数量和身份。该基因编码一种陆地植物特异性转录因子，并调节包括其他花分生组织特征基因和花同源基因在内的许多基因的表达。虽然 LFY DNA 结合域具有与螺旋-转角-螺旋蛋白相似的结构，但 LFY 和其同源物代表了一类新的转录因子家族，其特征是具有未知功能的保守 N 端结构域和 C 端 DNA 结合域。许多转录因子作为二聚体起作用。这些二聚体对于蛋白质的生物活性是必需的。我们证明 LFY 在溶液中形成同源二聚体或寡聚体。这种关联是通过 LFY 蛋白的 N 端保守区介导的。尽管不能在溶液中形成二聚体的突变 LFY 蛋白可以结合 DNA，但结合强度低于野生型 LFY 蛋白。由 N 端结构域介导的 LFY-LFY 相互作用对于该蛋白的生物活性是必需的，因为破坏自组装能力的突变不能互补 lfy 缺失等位基因。我们的数据表明：（i）LFY，以及可能在其他植物中的同源物，必须在至少包含两个 LFY 分子的复合物中起作用；（ii）N 端对于 LFY 复合物的稳定是必需的。这种情况是 LFY 调节基因表达的能力的组成部分。
