The Role of Prenylation in Meristem Function

枝条分生组织的活动是建立植物整体空中结构的主要决定因素：它的身高，枝、叶和花的数量和位置，成熟的时间，以及花和果实的发育过程。分生组织通过将外部环境信号与遗传线索相结合来确定原基起始事件的数量和位置。这些活动同时与调节分生组织内细胞分裂的信号事件相协调，这确保了分生组织细胞种群的持续维持，同时分生组织将细胞分配给原基和茎生产。朗恩博士设计了一种敏化的拟南芥筛选系统，可以快速识别影响分生组织功能的突变体。在他分离的突变体中，有Multiipetala，它显示出对茎分生组织细胞增殖的逐渐失去控制，以及较矮的身材和额外的花器官。他克隆了Puripetala，并发现它编码由预烯基化酶法尼基转移酶和香叶基香叶基转移酶-I共享的α亚基。预基化是一种脂类翻译后修饰，它促进了靶蛋白的膜定位和结合，特别是参与信号转导的蛋白。与动物和酵母系统中同等的苯丙基化突变体不同，多瓣膜植物是活的和可育的。因此，多瓣突变体植物提供了一个独特的机会来测试蛋白质的预烯基化在体内的功能作用，包括预烯基化对蛋白质亚细胞定位和细胞-细胞运输的影响。此外，使用生物信息学和实验分析鉴定预烯基化靶标将有助于深入了解参与分生组织功能和花发育的信号通路的组成部分。他的具体目标是：(1)研究预烯基化在植物生长和发育中的作用；(2)研究预烯基化复合体的每个组成部分的特定作用及其相互关系；以及(3)确定预烯基化在植物中两个潜在靶蛋白上的功能作用。拟议的活动将提高对植物中预烯基化作用的理解，该作用涉及许多过程，包括分生组织功能、花发育和激素反应。这些方法引起了各种植物科学家的兴趣，并具有潜在的农业应用前景。他对植物发育研究的多学科方法结合了遗传学、分子生物学和细胞生物学技术，将为博士后研究员和学生提供极好的培训机会。此外，他正在为当地高中教师开发一个继续科学教育的暑期研讨会。该计划将包括实验室研究的指导、演示和实践经验，部分将在运行的实验室中进行。还将为课堂教学开发教育资源。最后，他正在开发一个基于网络的资源，用于在植物中传播关于脂类翻译后修饰的信息，包括预烯基化。该数据库包括关于利用生物信息学工具确定假定目标的信息，以及那些已得到实验确认的信息。这项提议中的实验将允许更新和完善这个数据库，我们预计这将对植物科学界的成员非常有用，因为脂质翻译后修饰在大量的过程中发挥作用。

The activities of shoot meristems are the primary determinants for establishing the overall aerial architecture of the plant: its stature, the numbers and positions of branches, leaves, and flowers, the time to maturation, and the course of flower and fruit development. Meristems act by integrating external environmental signals with genetic cues to determine numbers and positions of primordia initiation events. These activities are simultaneously coordinated with signaling events that regulate cell divisions within the meristem, which assures continued maintenance of meristem cell populations while the meristem allocates cells to primordia and stem production. Dr. Running designed a sensitized Arabidopsis screen that allows for rapid identification of mutants that affect meristem function. Among the mutants he isolated was pluripetala, which shows a progressive loss of control of shoot meristem cell proliferation, along with shorter stature and extra floral organs. He cloned PLURIPETALA and found that it encodes the alpha subunit shared between the prenylation enzymes farnesyltransferase and geranylgeranyltransferase-I. Prenylation is a lipid posttranslational modification that facilitates membrane localization and association of target proteins, particularly proteins involved in signal transduction. Unlike equivalent prenylation mutants in animal and yeast systems, pluripetala plants are viable and fertile. Therefore, pluripetala mutant plants provide a unique opportunity for testing the functional role of prenylation of proteins in vivo, including the effects of prenylation on protein subcellular localization and cell-cell trafficking. In addition, identification of prenylation targets using bioinformatics and experimental assays will provide insight into components of signaling pathways involved in meristem function and flower development. His specific aims are to: (1) examine the role of prenylation in plant growth and development; (2) examine the specific roles of each component of the prenylation complex and their relation to each other; and (3) determine the functional role of prenylation on two potential target proteins in plants. The proposed activity will improve understanding of the role of prenylation in plants, which is involved in a number of processes, including meristem function, flower development, and hormone responses. These processes are of interest to a wide variety of plant scientists and have potential applications for agriculture. His multidisciplinary approach to the study of plant development combines genetics, molecular biology, and cellular biology techniques and will provide excellent training opportunities for postdoctoral fellows and students. In addition, he is developing a summer workshop for local high school teachers for continuing science education. This program will involve instruction, demonstration, and hands-on experience in laboratory research, which will be carried out in part in the Running lab. Educational resources will also be developed for classroom instruction. Lastly, he is developing a web-based resource for disseminating information on lipid posttranslational modifications, including prenylation, in plants. This database includes information on the identification of putative targets using bioinformatics tools along with those that have been experimentally confirmed. Experiments in this proposal will allow for updates and refinement to this database, which we expect will be very useful to members of the plant scientific community because of the vast number of processes in which lipid post translational modification plays a role.