Plant Protein Farnesyltransferase: Role in the Cell Cycle Control

蛋白法尼基转移酶（FTase）介导的脂质（即法尼基）片段与蛋白质的附着促进了向质膜的易位，从而激活了信号蛋白如p21ras。因此，FTase在许多信号通路中发挥重要作用。近年来的研究表明，FTase在植物脱落酸信号传导和细胞周期调控中起着至关重要的作用。然而，参与这些植物信号事件的法酰化蛋白尚未被确定。在我们的初步研究中，我们发现拟南芥ras样小gtp结合蛋白（RLP1）在体外被法酰化，并对其全长cDNA进行了测序。这代表了已知的第一个被法酰化的植物信号蛋白，并为ABA信号或细胞周期控制中的法酰化蛋白提供了强有力的候选蛋白。在这个修订的目标中，我们将研究这种g蛋白在植物中的功能。将进行两个具体的实验。1)将RLP1与水母绿色荧光蛋白融合，在烟草BY-2细胞中表达，证明RLP1在体内的法尼化，并确定其亚细胞定位。2) RLP1的显性阴性和组成活性突变形式将通过定点诱变产生，并在by -2细胞中表达，以直接评估其在植物信号通路（如ABA或有丝分裂信号传导）中的作用。这项工作将为法尼基化和法尼基化蛋白在信号转导中的作用提供重要的新见解。本项目将研究植物细胞中参与调节细胞分裂的信号过程。了解植物细胞分裂是如何调控的是一个重要的基础过程，对生物技术和农业具有重要意义。杨博士发现，在细胞分裂过程中，一种可能参与信号传递的蛋白质被脂质附着修饰。脂质的附着和去除可能是信号传递过程中的重要步骤之一。该项目将为该蛋白的脂质修饰与植物细胞分裂调控之间的关系提供详细信息。

9604681 Yang Protein farnesyltransferase (FTase)-mediated attachment of a lipid (i.e., farnesyl) moiety to proteins facilitates translocation to the plasma membrane and thus activation of signaling proteins such as p21ras. As a result, FTase plays an important role in many signaling pathways. Recent studies suggest that FTase plays a critical role in abscisic acid signaling and cell cycle control in plants. However, farnesylated proteins involved in these plant signaling events have not been identified. In our preliminary studies, an Arabidopsis Ras-like small GTP-binding protein (RLP1) was shown to be farnesylated in vitro, and its full-length cDNA was sequenced. This represents the first plant signaling protein known to be farnesylated and provides a strong candidate for a farnesylated protein in ABA signaling or cell cycle control. In this revised objective, we will investigate the function of this G-protein in plants. Two specific experiments will be conducted. 1) RLP1 will be fused to the jellyfish green fluorescence protein and expressed in tobacco BY-2 cells to demonstrate in vivo farnesylation of RLP1 and to determine its subcellular localization. 2) Dominant negative and constitutively active mutant forms of RLP1 will be created by site-directed mutagenesis and expressed in BY-2 cells to directly assess its role in plant signaling pathways such as ABA or mitogenic signaling. This work will provide significant new insight into the role of farnesylation and farnesylated proteins in signal transduction. This project will examine the a signal processes that are involved in regulating cell division in plant cells. Understanding how plant cell division is regulated is an important fundamental process with implications in biotechnology and agriculture. Dr. Yang has discovered that one protein that may be involved in signaling during cell division is modified with the attachment of a lipid. The attachment and removal of the lipid may be one of the essential steps in the signali ng process. This project will provide detailed information on the correlation between lipid modification of the protein and the regulation of plant cell division.