The ACC Synthase Genes and Polypeptides

9316475 Theologis该提案的具体目的是：1）分离和结构表征番茄ACC合酶基因的其余部分。 研究番茄各基因在生长发育过程中的表达特征，并确定诱导其表达的诱导剂类型。研究拟南芥ACS 4和ACS 5基因在吲哚乙酸（IAA）和Li+存在下的表达特征。 确定拟南芥ACS 4基因中IAA诱导的顺式作用元件和ACS 5基因中Li+反应元件。 元件将通过启动子区的ExoIII缺失分析来定义。 将在拟南芥原生质体中瞬时测定具有CAT报告基因的启动子构建体。 元件的功能将通过稳定转换实验来验证。 利用反义OS-ACs 1 RNA抑制水稻在低氧条件下的生长，并确定在低氧条件下表达水稻基因OS-ACS 1和OS-ACS 3的细胞类型。 通过体外诱变和在大肠杆菌中表达的实验，确定ACC合酶酶活性所需的关键残基。 杆菌 在E. coli中的ACC合酶，以确定ACC合酶是否为具有两个活性位点的二聚体。 通过特异性同工酶显性负突变的过度表达抑制乙烯依赖性发育过程。 对拟南芥ACC合酶同工酶进行生化分析，以确定其生化多样性。 乙烯是一种独特的植物信号分子。 碳氢化合物气体，被称为果实成熟激素，控制着植物生长和发育的许多方面，其合成受到高度调控。最近的实验证据表明，乙烯生物合成途径中的关键酶1-氨基环丙烷-1-羧酸（ACC）合成酶在单子叶和双子叶植物中由一个高度分化的多基因家族编码。 每个家族的成员受到不同诱导物和发育阶段的不同调节。 本文拟通过对番茄、水稻和拟南芥ACC合酶基因的结构和调控的研究，深入了解ACC合酶基因受各种激素和胁迫条件调控表达的生化机制及其在植物生长调节中的作用。 此外，在体外诱变研究提出了获得ACC合酶蛋白的结构和功能的基础知识。 ***

9316475 Theologis The specific aims of the proposal are : 1) To isolate and structurally characterize the rest of the tomato ACC synthase genes. To characterize the expression characteristics of each tomato gene during growth and development and to define the type of inducer(s) responsible for their induction. To characterize the expression characteristics of the Arabidopsis ACS4 and ACS5 genes in the presence of indoleacetic acid (IAA) and Li+, respectively. To define the cisacting elements for IAA inducibility of the Arabidopsis ACS4 and Li+ responsive elements of the ACS5 gene. The elements will be defined by ExoIII deletion analysis of the promoter regions. Promoter constructs with the CAT reporter gene will be transiently assayed in Arabidopsis protoplasts. The functionally of the elements will be verified by stable transformation experiments. To inhibit growth of rice under hypoxia using antisense OS-ACs1 RNA and to define the cell types that express two rice genes OS-ACS1 and 3 under low O2 tension. To define the critical residues required for enzymatic activity of ACC synthase by in vitro mutagenesis and expression experiments in E. coli. To perform intermolecular complementation experiments in E. coli for determining whether ACC synthase is a dimer with two active sites. To inhibit ethylene dependent developmental processes by overexpression of dominant negative mutations of specific isoenzymes. To biochemically characterize the Arabidopsis ACC synthase isoenzymesfor defining their biochemical diversity. %%% Ethylene is an unique plant signaling molecule. The hydrocarbon gas, known as the fruit ripening hormone, controls many aspects of plant growth and development, and its synthesis is highly regulated. Recent experimental evidence indicates that the key enzyme in the ethylene biosynthetic pathway, 1-aminocyclopropane-1- carboxylic acid (ACC) synthase is encoded by a highly divergent multigene family in various mono-and dicotyledonous plant s. The members of each family are differentially regulated by various inducers and developmental stages. Studies on the structure and regulation of the ACC synthase genes in tomato (Lycopersicon esculentum), rice (Oryza sativa) and Arabidopsis thaliana are proposed here to gain insight into the details of the biochemical mechanisms that regulate their expression by various hormones and stress conditions as well as their role in regulating plant growth. Furthermore, in vitro mutagenesis studies are proposed to obtain fundamental knowledge about the structure and function of the ACC synthase protein. ***