Gross Thomas, Broholm Suvi, Becker Annette
Department of Biology, Institute of Botany, Justus Liebig University Giessen, Giessen, Germany.
Biosciences and Environment Research Unit, Academy of Finland, Helsinki, Finland.
Front Plant Sci. 2018 Jun 20;9:835. doi: 10.3389/fpls.2018.00835. eCollection 2018.
One of the crucial steps in the life cycle of angiosperms is the development of carpels. They are the most complex plant organs, harbor the seeds, and, after fertilization, develop into fruits and are thus an important ecological and economic trait. CRABS CLAW (CRC), a YABBY protein and putative transcription factor, is one of the major carpel developmental regulators in that includes a C2C2 zinc finger and a domain with similarities to an HMG box. CRC is involved in the regulation of processes such as carpel fusion and growth, floral meristem termination, and nectary formation. While its genetic interactions with other carpel development regulators are well described, its biochemical properties and molecular way of action remain unclear. We combined Bimolecular Fluorescence Complementation, Yeast Two-Hybrid, and Yeast One-Hybrid analyzes to shed light on the molecular biology of CRC. Our results showed that CRC dimerizes, also with other YABBY proteins, via the YABBY domain, and that its DNA binding is mainly cooperative and is mediated by the YABBY domain. Further, we identified that CRC is involved in floral meristem termination via transcriptional repression while it acts as a transcriptional activator in nectary development and carpel fusion and growth control. This work increases our understanding on how YABBY transcription factors interact with other proteins and how they regulate their targets.
被子植物生命周期中的关键步骤之一是心皮的发育。心皮是最复杂的植物器官，容纳种子，受精后发育成果实，因此是一个重要的生态和经济性状。CRABS CLAW（CRC）是一种YABBY蛋白和假定的转录因子，是心皮发育的主要调节因子之一，其包含一个C2C2锌指和一个与HMG盒相似的结构域。CRC参与心皮融合与生长、花分生组织终止和蜜腺形成等过程的调控。虽然其与其他心皮发育调节因子的遗传相互作用已得到充分描述，但其生化特性和分子作用方式仍不清楚。我们结合了双分子荧光互补、酵母双杂交和酵母单杂交分析，以阐明CRC的分子生物学。我们的结果表明，CRC通过YABBY结构域二聚化，也与其他YABBY蛋白二聚化，并且其DNA结合主要是协同的，由YABBY结构域介导。此外，我们发现CRC通过转录抑制参与花分生组织的终止，而在蜜腺发育以及心皮融合与生长控制中它作为转录激活因子发挥作用。这项工作增进了我们对YABBY转录因子如何与其他蛋白质相互作用以及如何调控其靶标的理解。
