Role of Oligopeptide Transport in Plant Growth and Development

多肽转运是一种广泛的现象，2-6个残基以一种能量依赖和饱和的方式跨质膜转运就是一个例子。多肽转运体分为三个家族：三磷酸腺苷结合盒家族(ABC转运体)、多肽转运体(PTR)家族(转运二肽和三肽)和新近发现的寡肽转运体(OPT)家族。拟南芥基因组的完成表明，这种植物拥有比其他测序生物多10倍的预测多肽转运蛋白。例如，有52个预测的PTR家族成员和9个推测的OPT多肽转运蛋白家族成员。OPT家族成员参与调节四肽和五肽的摄取。最近的结果表明，一个AtOPT3：：T-DNA突变体在发育中的种子中存在胚胎形成缺陷。对OPT3胚胎的检查显示，发育受阻于8-细胞期。综上所述，这些数据强烈表明，多肽转运蛋白在植物生长和发育中扮演着非常重要的、未被探索的角色。这项拟议的研究试图确定每个拟南芥opt多肽转运蛋白的生理作用。这将通过检测在酵母和非洲爪哇卵母细胞中表达的这些蛋白质的肽运输活性来完成。反向遗传学将被用来获得转运蛋白功能缺陷的植物。突变体将根据它们的生长和发育(如胚胎)表型以及它们运输多肽的能力来确定特征。每种蛋白质的细胞定位将通过在转基因植物中表达表位标记的蛋白质来检查。这项研究可能会导致对新的信号途径或营养循环途径的认识，这些途径对植物的正常生长和发育至关重要。广泛的影响：研究和教育将通过本科生、研究生和博士后助理的参与整合到该项目中。通过与密苏里大学校园内成熟的项目相结合，将增加未被充分代表的群体对科学的参与。基础设施将通过购买所需的电生理设备得到改善，这些设备将作为全校范围的资源。分子生物化学和综合植物生物学计划共同为该项目提供资金。

Peptide transport is a widespread phenomenon exemplified by the translocation of peptides 2-6 residues in length across the plasma membrane in an energy-dependent and saturable manner. Peptide transporters fall into three families; the ATP binding cassette family (ABC transporters), the peptide transporter (PTR) family (transporting di- and tripeptides) and the recently described oligopeptide transporter (OPT) family. Completion of the Arabidopsis genome revealed that this plant possesses 10-fold more predicted peptide transporters than other sequenced organisms. For example, there are 52 predicted members of the PTR family and 9 putative members of the OPT family of peptide transporters. The OPT family members mediate the uptake of tetra- and pentapeptides. Recent results indicated that an AtOPT3::T-DNA mutant is defective in embryo formation in the developing seed. Examination of the opt3 embryo showed that development was blocked at the 8-cell stage. Together, these data strongly suggest that peptide transporters play very important, unexplored roles in plant growth and development. The proposed research seeks to define the physiological role for each of the Arabidopsis OPT peptide transporters. This will be done by examining the peptide transport activity of these proteins expressed in yeast and in Xenopus oocytes. Reverse genetics will be used to obtain plants defective in transporter function. Mutants will be characterized with regard to their growth and developmental (e.g., embryo) phenotype, as well as their ability to transport peptides. The cellular localization of each protein will be examined by expressing epitope-tagged proteins in transgenic plants. This research may lead to the recognition of new signaling pathways or avenues of nutrient circulation, which are critical to normal plant growth and development.Broader Impact: Research and education will be integrated in the project by the involvement of undergraduates, graduate students and postdoctoral associates. Participation of under-represented groups in science will be increased by interfacing with well established programs on the University of Missouri campus. Infrastructure will be improved by the purchase of needed electrophysiology equipment, which will serve as a campus-wide resource.The Molecular Biochemistry and Integrative Plant Biology Programs jointly fund this project.