The ACC Synthase Genes and Polypeptides

乙烯是一种独特的植物信号分子。碳氢化合物气体被称为水果成熟激素，控制着植物生长和发育的许多方面。它是由蛋氨酸通过三步酶法合成的：SAM ACC蛋氨酸SAM ACC C2H4。合酶、合酶、氧化酶的合成受到高度调控。近10年来积累的实验证据表明，乙烯生物合成途径中的关键酶之一1-氨基环丙烷-1-羧酸合成酶(1-氨基环丙烷-1-羧酸合成酶)是由一个高度分化的多基因家族编码的，在各种单子叶和双子叶植物中都是如此。拟南芥基因组序列的完成揭示了10个可能的ACS基因(ACS2，4-12)和两个假基因(ACS1，ACS3)的存在。表达研究表明，该家族成员受不同的诱导剂和发育阶段的不同调控。本文拟对拟南芥中ACS基因的调控进行研究，以深入了解生长素和乙烯对ACS基因调控的信号机制的细节。建议进行进一步的研究，以获得关于ACS同工酶的结构和生化性质的知识。所提出的分子和生化实验方法试图回答以下问题：为什么拟南芥中有10个ACC合成酶同工酶用于合成乙烯前体ACC？虽然它们都具有相同的生化功能，但问题是它们是否具有不同的或多余的生物功能。这些发现有可能使人们从根本上理解多基因家族在植物中的作用，这是拟南芥基因组测序项目的一个标志性发现。

Ethylene is an unique plant signaling molecule. The hydrocarbon gas, known as the fruit ripening hormone, controls many aspects of plant growth and development. It is biosynthesized from methionine via a three-step enzymatic process: SAM ACC ACC Methionine SAM ACC C2H4. Synthase synthase oxidaseIts synthesis is highly regulated. Experimental evidence accumulated over the last 10 years indicates that one of the key enzymes in the ethylene biosynthetic pathway, 1-aminocyclopropane-1-carboxylic acid (ACC) synthase (ACS), is encoded by a highly divergent multigene family in various mono- and dicotyledonous plants. The completion of the Arabidopsis genome sequence reveals the presence of 10 putative ACS genes (ACS2, 4-12) and two pseudogenes (ACS1, ACS3). Expression studies reveal that the family members are differentially regulated by various inducers and developmental stages Studies on the regulation of the ACS genes in Arabidopsis are proposed here to gain insight into the details of the signaling machinery involved primarily in the regulation of the ACS gene by auxin and ethylene. Further studies are proposed to obtain knowledge regarding the structure and the biochemical properties of the ACS isoenzymes. The proposed molecular and biochemical experimental approaches attempt to answer the following question: why are there 10 ACC synthase isoenzymes in Arabidopsis for the synthesis of the ethylene precursor ACC? While all of them have the same biochemical function, the question arises whether they have distinct or redundant biological function. The findings have the potential to allow a fundamental understanding of the role of multigene families in plants, a hallmark finding of the Arabidopsis Genome Sequencing project.