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Interactional And Functional Characteristics On DNA Methyltransferase DNMT2 And Histone Deacetylase HD2 In Arabidopsis Thaliana

Posted on:2011-12-15Degree:DoctorType:Dissertation
Country:ChinaCandidate:Y SongFull Text:PDF
GTID:1100360305965727Subject:Botany
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Epigenetics is the study of heritable changes in gene function that occur without a change in the DNA sequence. DNA methylation and histone dacetylation are common epigenetic modification phenomena. They play important roles in eukaryotic development including the perception and transduction of the changes of internal (hormonal) and environmental signals. DNA methylation is a universal modification phenomenon presentted in the eukaryotic genome. It regulates the expression of corresponding genes through the changes of chromatin structure in plant growth and development. Histone post-translational modifications, especial acetylation and deacetylation, are other important ways of regulating eukaryotic gene expression. They are closely linked to DNA methylation. Plants contain a unique type of histone deacetylase called HD2-type. DNA methytransferase2 (DNMT2) is always deemed to be enigmatic over a long period of time, because it contains highly conserved DNA methyltransferase motifs but lacks the DNA methylation catalytic capability. DNMT2 is also deemed to the ancestor of DNA methyltransferase family because of its structure.In this study AtDNMT2 is localized in nucleus. We have shown that AtDNMT2 can interact with AtHD2 family except AtHD2D both in vivo and in vitro and have mapped the interaction and the repression domains in AtDNMT2. Domains at C-terminal of AtDNMT2 are able to mediate repression of gene expression and the domain close to the N-terminal can interact with AtHD2C. This interaction potentially affects correlative enzyme activity. A decrease in the expression of AtDNMT2 is found in athd2c knock-out line. These results show the evidence for a possible function of AtDNMT2 that involves in histone deacetylation activity. While the activity of DNMTs presents synergistic in 35s::HD2C transgenic plants (COE) and hd2c knock down mutant plants (T99). Microarray analysis was performed to test the cold tolerance of DNA methylation inhibitors (5-aza-2'-deoxycytosine) treated plants and histone deacetylase inhibitor (trichostatin A) treated plants. The different expression of genes were analysed by bioinformatics to find correlative pathways and transcription factor. DNA methylation and histone acetylation are critical pathways on cold reponses. DNA methylation and histone acetylation is not a simple synergistic or antagonistic, to some extent, they form a complementary or balanced system.In summary, DNMT2 can repress gene expression and involves in histone deacetylase HD2s gene family activity. DNMT2 plays important role in plant growth and development. These results have raised the likelihood that the biological roles of DNMT2 might be broader than those have been previously considered. Through exploring the mechanism of epigenetic regulation in plant cold tolerance, we hope our research might provide some promising clues for future applications in crop plants.
Keywords/Search Tags:DNA methyltransferase2 DNMT2, Histone deacetylase HD2 family, Protein interaction, Gene expression, Arabidopsis, Rsponses stress mechanism, Epigenetics
PDF Full Text Request
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