Functional Analysis of B3 Domain Transcription Factors

很可能，植物和动物独立地进化出多细胞结构。植物基因组编码了大量的DNA结合蛋白，而这些蛋白在其他生物中没有明显的同源物。在许多情况下，这些植物特有的调控基因与植物特有的信号通路有关。这意味着，新转录因子的招募在植物发育的独立进化中发挥了重要作用。一个重要的植物特异转录因子家族被鉴定为含有高度保守的B3DNA结合域的蛋白质。在拟南芥基因组中确定了四个主要的B3结构域蛋白亚家族(VP1/ABI3，ARF，RAV和VPL组)。ARF和VP1/ABI3分别参与植物生长素和脱落酸(ABA)激素信号转导途径。RAV和VPL家族的功能尚不清楚。本项目重点分析VP1/ABI3、RAV和VPL家族基因的功能。B3蛋白的一个共同主题是将B3连接到自主蛋白质相互作用域(VP1/ABI3和ARF‘s)或第二个DNA结合域(RAV)的二价结构。一个关键的长期目标是了解VP1蛋白的DNA结合(B3)和蛋白质-蛋白质相互作用(CoAR)结构域的相互作用如何导致VP1/ABI3调控基因表达的异常复杂。拟南芥广泛的遗传学和可利用的资源将被应用于VP1突变体的分析，这些突变体区分B3依赖和B3独立的调节功能。一种方法是创造VP1的突变形式，扰乱B3及其与CoAR的相互作用，并在其他基因中产生专门影响B3调节功能的新突变。第二个目标将解决Coar结构域介导的蛋白质-蛋白质相互作用的贡献。最后，目前的VP1功能模型提出了类似的问题，涉及B3结构域在其他转录因子家族中的作用，包括ARF、RAV和VPL家族。第三个目标是开发用于分析B3转录因子RAV和VPL家族的工具。

0322005McCartyIn all likelihood, plants and animals evolved multicellular structures independently. Plant genomes encode a remarkable number of DNA binding proteins that have no obvious homologs in other organisms. In many cases, these plant specific regulatory genes have been implicated in plant specific signaling pathways. The implication is that recruitment of novel transcription factors has played a major role in the independent evolution of plant development. One important family of plant specific transcription factors are identified as proteins containing the highly conserved B3 DNA binding domain. Four major sub-families of B3 domain proteins are identified in the Arabidopsis genome (VP1/ABI3, ARF, RAV and VPL groups). The ARF and VP1/ABI3 groups have been implicated in auxin and abscisic acid (ABA) hormone signaling pathways of plants, respectively. The functions of the RAV and VPL families are unknown. This project focuses on analyzing the functions of genes in the VP1/ABI3, RAV and VPL families. A common theme among the B3 proteins is a bivalent structure coupling B3 to autonomous protein interaction domains (VP1/ABI3 and ARF's) or to a second DNA binding domain (RAV). A key long term goal is to understand how interactions of DNA binding (B3) and protein-protein interaction (COAR) domains of the VP1 protein give rise to the extraordinary complexity of VP1/ABI3 regulated gene expression observed in the developing seed. The extensive genetics and resources available for Arabidopsis will be applied to analysis of VP1 mutants that discriminate B3 dependent and B3 independent regulatory functions. One approach will be to create mutant forms of VP1 that perturb B3 and its interaction with COAR and new mutations in other genes that specifically affect B3 regulated functions. The second objective will address the contribution of protein-protein interactions mediated by the COAR domain. Finally, the current model for VP1 function raises analogous questions concerning the role of B3 domains in other transcription factor families including the ARF, RAV and VPL families. The third objective focuses on developing tools for analysis of the RAV and VPL families of B3 transcription factors.