Analysis of Plant Homeodomain Proteins and the Inhibitor of Growth Family Proteins in Arabidopsis thaliana
MetadataShow full item record
The PHD (Plant HomeoDomain) finger is a structural domain primarily found in nuclear proteins across eukaryotes. This domain specifically recognizes the epigenetic marks H3K4me2 and H3K4me3, which are di- and tri-methylated lysine 4 residues of Histone H3 (Loewith et al., 2000; Kuzmichev et al., 2002; Vieyra et al. 2002; Shiseki et al., 2003; Pedeux et al., 2005, Doyon et al., 2006). It is estimated that there are ~150 proteins that contain the PHD finger in humans (Solimon and Riabowol, 2007). The PHD finger is conserved in yeast and plants, however an analysis of this domain has only been performed done in Arabidopsis thaliana (Lee et al., 2009). The work presented in this report aims to extend the analysis of this domain in plants by identifying the PHD fingers of the crop species Oryza sativa (rice). In addition, a phylogenetic analysis of all PHD fingers in Arabidopsis and rice was undertaken. From these analyses, it was determined that there are 78 PHD fingers in Arabidopsis and 70 in rice. In addition, these domains can be categorized into classes and groups by defining features within the conserved motif.
In a separate study, I investigated the function of two of the PHD finger proteins from Arabidopsis, ING1 (INhibitor of Growth1) and ING2. In humans, these proteins can be found in complexes associated with both open and closed chromatin. They facilitate chromatin remodeling by recruiting histone acetyltransferases and histone deacetylases to chromatin (Doyon et al., 2006, Pena et al., 2006). In addition, these proteins recognize H3K4me2/3 marks and are believed to be â interpretersâ of the histone code (Pena et al., 2006, Shi et al., 2006). To understand the function of ING proteins in plants, I took a reverse genetics approach and characterized ing1 and ing2 mutants. My analysis revealed that these mutants are altered in time of flowering, as well as their response to nutrient and stress conditions. Lastly, I was able to show that ING2 protein interacts in vitro with SnRK1.1, a nutrient/stress sensor (Baena-Gonzalez et al., 2007). These results indicate a novel function for PHD proteins in plant growth, development and stress response.
- Masters Theses