RIG: Arabidopsis Receptor for Activayed C Kinase1 (RACK1) Proteins: Role of Protein-Protein Interaction in Environmental Stress Signaling Pathways

信号转导网络非常复杂，由许多相互连接的通路组成。信号整合中的支架蛋白正在成为信号转导机制的主要组成部分。一些证据表明，RACK1(Receptor For Actiated C Kinase)家族蛋白作为支架蛋白在协调不同的信号转导途径中发挥重要作用。尽管对其他生物中的RACK1进行了广泛的研究，但对植物中的RACK1的了解要少得多。RACK1相互作用蛋白的谱系现在包括近50个物理相互作用蛋白，而且还在稳步增长。虽然拟南芥中的RACK1A在环境胁迫相关的信号转导途径中发挥了重要作用，但RACK1A介导的胁迫信号转导的分子机制尚不清楚。关键的初步观察表明，这三个家族成员都能够相互作用，并且RACK1中潜在的苏莫化位点在亚细胞定位的调节中起着重要作用。启动子：：GUS记者研究表明，RACK1基因在保卫细胞中普遍表达，并且这三个基因都在保卫细胞中表达，这一观察结果与在rack1A突变体中观察到的抗水胁迫表型一致。为了更好地了解RACK1A介导的信号转导途径，我们将使用基于裂解泛素的cDNA文库筛选系统来鉴定RACK1的相互作用。此外，还将确定RACK1二聚化事件的生理基础，并确定其亚细胞定位和组织特异性表达模式。由于几乎完全相同的RACK1序列在包括水稻、番茄和烟草在内的多种作物中都是保守的；这项研究将提供一个机会，通过从这项研究中获得的分子知识来提高农业生产力和可持续性。深入了解不同的逆境信号转导途径及其相互联系，将有助于作物改良的工程信号转导机制。此外，这项研究将主要在霍华德大学进行，这是一所面向非裔美国学生的主要大学。该项目旨在确保少数族裔本科生的有效参与，并向他们介绍潜在的科学职业。

Signal transduction networks are very complex and comprised of many interconnecting pathways. Scaffold proteins in signal integration are emerging as dominant components of signal transduction mechanisms. Several lines of evidence indicate that RACK1 (Receptor for Activated C Kinase) family of protein can play a major role in coordinating different signal transduction pathways by acting as a scaffold protein. Though RACK1s in other organisms have been studied extensively, much less is known about RACKs in plants. The repertoire of RACK1 interacting proteins now includes almost 50 physical interactors and is steadily growing. Although RACK1A from Arabidopsis appears to play a major role in environmental stress response related signal transduction pathways, the molecular mechanisms of RACK1A mediated stress signaling responses are not known. Key preliminary observations indicate that all three family members are capable of interacting with each other and the potential sumoylation site within RACK1 play a major role in the regulation of sub-cellular localization. Promoter::GUS reporter studies reveal that RACK1 genes are ubiquitously expressed and all three genes are expressed in the guard cells, an observation consistent with water-stress resistance phenotype observed in rack1A mutants. In order to better understand RACK1A mediated signal transduction pathways, RACK1 interactors will be identified with a split ubiquitin based cDNA library screen system. Also, the physiological basis of RACK1 dimerization events will be characterized and its sub-cellular localization and tissue specific expression pattern will be determined. As almost identical RACK1 sequences are conserved in wide range of crop plants including rice, tomato, and tobacco; the research will offer an opportunity to enhance agricultural productivity and sustainability by the molecular knowledge gained from this research. Deeper understanding of different stress signal transduction pathways and their interconnectedness will be instrumental in engineering signal transduction mechanisms for crop improvement. Moreover, the research will primarily be undertaken at Howard University, a major university for African-American students. The project is structured to ensure effective participation of minority undergraduate students and introduce them to potential careers in science.