Functional analysis of shikimate pathway gene duplicates

本应用的重点是植物和微生物中莽草酸途径基因复制的功能注释。具体地说，我们将研究植物莽草酸激酶和微生物莽草酸脱氢酶基因副本的功能。我们在植物中发现了两个莽草酸激酶基因的重复序列，分别命名为SKL1和SKL2。编码的蛋白质不具有莽草酸激酶活性，但在植物中进化出了新的生物学功能。SKL1在叶绿体发育中发挥作用，SKL2在种子萌发过程中具有耐盐性。我们将根据它们各自的生物学功能来研究它们所催化的生化反应。SKL1是开发作物新型除草剂的极佳靶标，因为我们已经证明它是植物生长所必需的。同样，SKL2的研究进展将加深我们对作物耐盐性机制的理解。该提案的第二个方面涉及微生物莽草酸脱氢酶。我们在微生物中鉴定了莽草酸脱氢酶的五个不同的官能团，Aroe，YdiB，SDHL，Rif1和Ael1。这些莽草酸脱氢酶基因复制体参与多种生化活动。有趣的是，所有这五个类别只在一些土传生物中发现，包括恶臭假单胞菌。其中一些蛋白质的基因存在于称为操纵子的基因簇中。这些操纵子可能是芳香族化合物分解的代谢途径。因此，我们的研究结果可能会对生物修复过程产生直接影响，特别是在这些芳香族化合物水平较高的地区。

This application focuses on the functional annotation of shikimate pathway gene duplicates in plants and microbes. Specifically, we will investigate the function of plant shikimate kinase and microbial shikimate dehydrogenase gene duplicates. We have identified two shikimate kinase gene duplicates in plants, which we annotated as SKL1 and SKL2. The encoded proteins do not have shikimate kinase activity, but have evolved novel biological functions in plants. SKL1 has evolved a function in plastid development and SKL2 confers salinity tolerance during seed germination. We will investigate the biochemical reaction catalyzed by these proteins in light of their respective biological function. SKL1 is an excellent target for the development of novel herbicides in crops because we have shown that it is absolutely required for plant growth. Similarly, progress on SKL2 will enhance our understanding of the mechanism of salinity tolerance in crop plants. The second aspect of this proposal deals with microbial shikimate dehydrogenases. We identified five distinct functional groups of shikimate dehydrogenses in microbes, AroE, YdiB, SDHL, Rif1, and Ael1. These shikimate dehydrogenase gene duplicates participate in diverse biochemical activities. Interestingly, all five classes are found only in some soil borne organisms, including Pseudomonas putida. The genes for some of these proteins are found in genetic clusters, called operons. These operons may represent metabolic pathways for the breakdown of aromatic compounds. As such findings from our studies may have direct implications on bioremediation processes especially for areas where these aromatic compounds are found in elevated levels.