Control of Storage Protein Biosynthesis by mRNA Targeting

通过 mRNA 靶向控制储存蛋白生物合成

• 批准号: 0235140
• 负责人: Thomas Okita
• 金额: $ 38.7万
• 依托单位: Washington State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-05-15 至 2006-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0235140&HistoricalAwards=false
• 关键词: Control; Storage; Protein; Biosynthesis; mRNA

The major metabolic activities of plant seeds are directed toward the synthesis of carbon (in the form of lipids and starch) and nitrogen (in the form of storage proteins) reserves. Although appearing to be independent processes, carbon and nitrogen metabolism are inter-related as evidenced by the near parallel responses exhibited by defined genetic mutants and transgenic plants altered in gene expression in one of these two processes. The mechanisms responsible for this coordinated expression of carbon and nitrogen reserves are not known. This grant application proposes a series of studies on one aspect of nitrogen metabolism, i.e. the control of storage protein biosynthesis in developing rice endosperm. Rice is an excellent system to study storage protein biosynthesis as it synthesizes and accumulates both major classes of storage proteins, prolamines and glutelins, the latter an 11S globulin. Moreover, rice stores these proteins in different subcellular compartments. Prolamines are deposited directly as protein intracisternal granules within the endoplasmic reticulum (ER) lumen, whereas glutelins are transported through the endomembrane system to a protein storage vacuole. Previous studies from this laboratory have demonstrated that the RNAs encoding these two classes of storage proteins are not localized in a stochastic fashion on the ER. Instead, prolamine mRNAs are highly enriched on the ER membranes that bind the prolamine protein bodies (PBs) whereas glutelin mRNAs are predominant on the cisternal ER. The localization of prolamine mRNAs to the prolamine PBs occurs by directed RNA transport from the nucleus. To better understand this process, studies will be undertaken to identify the nucleotide sequences that direct RNA transport and localization and to identify and characterize proteins, which are responsible for the transport and anchoring of prolamine and glutelin RNAs to the prolamine PBs and cisternal ER, respectively. As RNA transport occurs by the formation and movement of particles, efforts will be made to isolate these RNA transport particles and determine what other RNA species may be co-transported. An integrated approach will be taken to achieve these goals, and will incorporate the use of biochemical, cellular, molecular and ultrastructural techniques. This study will provide new information on how RNAs and, in turn, proteins are sorted in plant cells and how the ER can differentiate into unique domains with specific functions. Moreover, it will lead to new insights into the mechanisms that may control utilization of carbon and nitrogen and their conversion into storage reserves.

植物种子的主要代谢活动是合成碳（以脂质和淀粉的形式）和氮（以储存蛋白质的形式）储备。虽然看起来是独立的过程，但碳和氮代谢是相互关联的，这一点得到了明确的基因突变体和转基因植物在这两个过程中的一个过程中基因表达改变所表现出的近乎平行的反应的证明。负责碳和氮储量协调表达的机制尚不清楚。本资助申请旨在研究水稻胚乳发育过程中氮代谢的一个方面，即对储存蛋白生物合成的控制。水稻是研究储存蛋白生物合成的一个很好的系统，因为它可以合成和积累两类主要的储存蛋白：脯胺和谷氨酸，后者是11S球蛋白。此外，水稻将这些蛋白质储存在不同的亚细胞区室中。脯胺以蛋白质颗粒的形式直接沉积在内质网（ER）腔内，而谷蛋白则通过膜系统转运到蛋白质储存液泡中。该实验室先前的研究表明，编码这两类储存蛋白的rna不是以随机方式定位在内质网上。相反，脯胺mrna在与脯胺蛋白体（PBs）结合的内质网膜上高度富集，而谷蛋白mrna在池内质网上占主导地位。脯胺mrna在脯胺PBs上的定位是通过细胞核的定向RNA转运发生的。为了更好地理解这一过程，将进行研究，以确定指导RNA运输和定位的核苷酸序列，并确定和表征分别负责将脯氨酸和谷蛋白RNA运输和锚定到脯氨酸PBs和池内质网的蛋白质。由于RNA转运是通过颗粒的形成和运动发生的，因此将努力分离这些RNA转运颗粒，并确定哪些其他RNA物种可能被共转运。将采取综合方法来实现这些目标，并将结合使用生化、细胞、分子和超微结构技术。这项研究将提供关于rna和蛋白质如何在植物细胞中分类以及内质网如何分化成具有特定功能的独特结构域的新信息。此外，它将导致对可能控制碳和氮的利用及其转化为储存储量的机制的新见解。