Role of chromatin-associated HMGA and HMGB proteins in Arabidopsis

在细胞核内，真核生物的基因组DNA被包装成称为染色质的核蛋白复合物。DNA的这种包装对基因表达有严重的影响，并被用作调节基因转录的手段。DNA的可及性受到与染色质相关的各种蛋白质的控制。这些蛋白质中有所谓的高迁移率族（HMG）蛋白。它们包括一个小的和高电荷的蛋白质的异质性家庭，作为建筑因素有助于各种DNA依赖性过程，包括转录。有丰富的生物化学数据，这个蛋白质家族的成员，但他们在体内的作用仍然是不明确的。使用拟南芥植物模型系统，我们打算研究HMG蛋白表达水平改变的后果。与对照植物相比，将检查具有改变的HMG蛋白表达（上调或下调）的植物的可能的表型差异以及它们对环境线索的响应。此外，这些植物的转录谱进行了比较分析，以揭示不同的HMG型蛋白可能的功能专业化。为了鉴定差异表达的基因与所讨论的HMG蛋白之间的直接联系，还检查了HMG蛋白的可能靶基因与相应HMG蛋白的物理关联。总之，这些实验将提供深入了解HMG蛋白的生物学作用，特别是关于它们对植物发育的影响和它们在基因转录中的作用。

Within the cell nucleus, the genomic DNA of eukaryotic organisms is packaged into a nucleoprotein complex termed chromatin. This packaging of the DNA has severe consequences for gene expression, and is used as a means of regulating the transcription of genes. The accessibility of the DNA is under control of a wide variety of proteins that are associated with chromatin. Among these proteins are the so-called high mobility group (HMG) proteins. They comprise a heterogeneous family of small and highly-charged proteins that as architectural factors contribute to various DNA-dependent processes including transcription. There is a wealth of biochemical data on members of this protein family, but their in vivo role is still ill-defined. Using the Arabidopsis plant model system, we intend to study the consequences of altered expression levels of HMG proteins. Plants with altered expression of HMG proteins (up- or down-regulated) will be examined in comparison to control plants for possible phenotypic differences as well as their response to environmental cues. Moreover, the transcript profile of these plants is comparatively analysed to reveal possible functional specialisation of different HMG-type proteins. To identify direct links between differentially expressed genes and the HMG protein in question, possible target genes of HMG proteins are also examined for physical association with the respective HMG protein. In summary, these experiments will provide insight into the biological role of HMG proteins, in particular regarding their influence on plant development and their role in gene transcription.