Maintenance and Inheritance of DNA Methylation in Arabidopsis
2016
Online
Elektronische Ressource
DNA methylation is a conserved epigenetic modification, usually of the 5th carbon of cytosine in eukaryotes, and in plants is known to regulate gene expression and silence transposable elements. Posttranslational histone tail modifications are also conserved epigenetic regulators, known in the plant kingdom to interact with DNA methylation and regulate chromatin structure. Both DNA methylation and histone modifications are reversible and, collectively, play an important role in the orchestration of dynamic transcriptional profiles during the entire life cycle of the plant. In plants, DNA methylation is found in the symmetric CG and CHG contexts, and the asymmetric CHH context (where H is A, T or C). Several studies have shown that CG methylation is catalyzed by the mammalian DNMT1 methyltransferase ortholog, MET1, and CHG methylation is maintained by the plant specific chromomethylase 3 (CMT3), through a self-reinforcing loop between CMT3 and the heterochromatic dimethylation of lysine 9 of the histone H3 subunit (H3K9me2). Due to its asymmetry, CHH methylation was thought to be maintained solely by DOMAINS REARRANGED METHYLTRANSFERASE 2 (DRM2, an ortholog of mammalian DNMT3-type methyltransferases) through the plant-specific RNA-directed DNA methylation (RdDM) pathway. However, DRM2-mediated CHH methylation only accounts for about 35% of total CHH methylation in Arabidopsis, suggesting that other proteins contribute to the maintenance of CHH methylation. To identify which proteins are involved in the maintenance of CHH methylation in addition to DRM2, I performed a reverse genetic screen on Arabidopsis mutants to identify genes that can potentially affect plant DNA methylation by performing whole-genome bisulfite sequencing of each individual homozygous mutant seedling. Eventually, I found that CMT2, a homolog of CMT3, is an active methyltransferase that maintains ~70% of total CHH methylation in Arabidopsis, independently of RdDM. Furthermore, I determined that th
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Maintenance and Inheritance of DNA Methylation in Arabidopsis
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Autor/in / Beteiligte Person: | Hsieh, Ping-Hung |
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Veröffentlichung: | 2016 |
Medientyp: | Elektronische Ressource |
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