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。有证据表明RACK 1（Receptor for Activated C Kinase，活化C激酶受体）蛋白家族作为一种支架蛋白在协调不同的信号转导通路中发挥重要作用。虽然其他生物体中的RACK 1已被广泛研究，但对植物中的RACKs知之甚少。RACK 1相互作用蛋白的库现在包括近50个物理相互作用因子，并且正在稳步增长。RACK 1A在拟南芥逆境胁迫信号转导中起重要作用，但RACK 1A介导逆境胁迫信号转导的分子机制尚不清楚。关键的初步观察表明，所有三个家族成员都能够相互作用，并且RACK 1内的潜在sumoylation位点在亚细胞定位的调节中发挥重要作用。 启动子：：GUS报告基因的研究表明，RACK 1基因的普遍表达和所有三个基因在保卫细胞中表达，观察一致的水胁迫抗性表型中观察到的rack 1A突变体。为了更好地理解RACK 1A介导的信号转导途径，RACK 1相互作用物将用基于分裂泛素的cDNA文库筛选系统鉴定。此外，RACK 1二聚化事件的生理基础将被表征，其亚细胞定位和组织特异性表达模式将被确定。 由于几乎相同的RACK 1序列在包括水稻、番茄和烟草在内的广泛的作物中是保守的;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。深入了解不同的胁迫信号转导途径及其相互联系，将有助于工程信号转导机制，作物改良。 此外，这项研究将主要在霍华德大学进行，这是一所主要的非裔美国学生大学。该项目的结构是为了确保少数民族本科生的有效参与，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.