Conjugation of Indole-3-Acetic Acid to Proteins and Peptides

吲哚-3-乙酸以游离和共轭形式存在于植物中。 一种研究较少的结合IAA形式是一类独特的蛋白质，其中IAA是直接连接到蛋白质结构的辅基。 越来越多的证据表明，调节蛋白质的稳定性是重要的生长素功能，从而使这些修饰的蛋白质特别感兴趣。 第一个由IAA共价修饰的蛋白质基因最近从豆类中克隆出来，并发现与其他几种植物物种中存在的蛋白质有关，包括模式植物阿拉伯芥。四条研究路线将进一步表征植物中的这些蛋白质。1)实验将在分子水平上确定菜豆35 kDa蛋白的表达、调节和功能。2)以前的研究集中在豆类，将从克隆各自的基因开始，扩展到更适合遗传操作的物种的相关蛋白质，3）将使用报告基因和免疫学技术在组织和亚细胞水平上分析IAA蛋白基因表达。将使用复杂的液相色谱质谱法分析IAA与蛋白质的连接，该方法将允许快速鉴定这类修饰的蛋白质。这些研究应提供必要的生化，组织和分子信息，以进一步了解这类独特的修饰蛋白质在植物激素调节中的可能作用。

Indole-3-acetic acid is found in plants in both free and conjugated form. One of the less well-studied forms of conjugated IAA are a unique class of proteins where IAA is a prosthetic group attached directly to the protein structure. An increasing body of evidence suggests that regulation of protein stability is important to auxin function, thus making these modified proteins of particular interest. The first gene for a protein covalently modified by IAA was recently cloned from bean and found to be related to proteins present in several other plant species, including the model plant Arabadopsis. Four lines of study will further characterize these proteins in plants. 1) Experiments will define, on the molecular level, the expression, regulation and function of the bean 35 kDa protein. 2) Previous studies which focused on bean will be extended, starting with cloning the respective genes, to related proteins from species more amenable to genetic manipulation, such as Arabadopsis and Medicago.3) IAA-protein gene expression will be analyzed at the tissue and subcellular level using reporter genes and immunological techniques.4) The attachment of IAA to the proteins will be analyzed using complex liquid chromatography mass spectrometry methods that will allow rapid identification of this class of modified proteins. These studies should provide the biochemical, tissue and molecular information necessary to further understand the possible roles of this unique class of modified proteins in relation to phytohormone regulation.