Substitutions in the amino-terminal tail of neurospora histone H3 have varied effects on DNA methylation
| Autor: | Eric U. Selker, Emanuela Berge, Keyur K. Adhvaryu, Hisashi Tamaru, Michael Freitag |
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| Rok vydání: | 2011 |
| Předmět: |
Cancer Research
lcsh:QH426-470 Genes Recessive Biology DNA methyltransferase Euchromatin Histones 03 medical and health sciences 0302 clinical medicine Epigenetics of physical exercise Heterochromatin Histone methylation Genetics Amino Acids Phosphorylation Molecular Biology RNA-Directed DNA Methylation Genetics (clinical) Ecology Evolution Behavior and Systematics 030304 developmental biology 0303 health sciences Neurospora crassa Lysine EZH2 Acetylation Methylation Histone-Lysine N-Methyltransferase DNA Methylation Molecular biology lcsh:Genetics Amino Acid Substitution Histone methyltransferase DNA methylation Mutation Histone Methyltransferases Genes Lethal 030217 neurology & neurosurgery Research Article |
| Zdroj: | PLoS Genetics PLoS Genetics, Vol 7, Iss 12, p e1002423 (2011) |
| ISSN: | 1553-7404 |
| Popis: | Eukaryotic genomes are partitioned into active and inactive domains called euchromatin and heterochromatin, respectively. In Neurospora crassa, heterochromatin formation requires methylation of histone H3 at lysine 9 (H3K9) by the SET domain protein DIM-5. Heterochromatin protein 1 (HP1) reads this mark and directly recruits the DNA methyltransferase, DIM-2. An ectopic H3 gene carrying a substitution at K9 (hH3K9L or hH3K9R) causes global loss of DNA methylation in the presence of wild-type hH3 (hH3WT). We investigated whether other residues in the N-terminal tail of H3 are important for methylation of DNA and of H3K9. Mutations in the N-terminal tail of H3 were generated and tested for effects in vitro and in vivo, in the presence or absence of the wild-type allele. Substitutions at K4, K9, T11, G12, G13, K14, K27, S28, and K36 were lethal in the absence of a wild-type allele. In contrast, mutants bearing substitutions of R2, A7, R8, S10, A15, P16, R17, K18, and K23 were viable. The effect of substitutions on DNA methylation were variable; some were recessive and others caused a semi-dominant loss of DNA methylation. Substitutions of R2, A7, R8, S10, T11, G12, G13, K14, and P16 caused partial or complete loss of DNA methylation in vivo. Only residues R8-G12 were required for DIM-5 activity in vitro. DIM-5 activity was inhibited by dimethylation of H3K4 and by phosphorylation of H3S10, but not by acetylation of H3K14. We conclude that the H3 tail acts as an integrating platform for signals that influence DNA methylation, in part through methylation of H3K9. Author Summary DNA methylation is a common feature of eukaryotic genomes. Methylation is typically associated with silenced chromosomal domains and is essential for development of plants and animals. Although the control of DNA methylation is not well understood, recent findings with model organisms, including the fungus Neurospora crassa, revealed connections between modifications of histones and DNA. DNA methylation is dispensable in Neurospora, facilitating genetic studies. Isolation of mutants defective in DNA methylation revealed that a histone H3 methyltransferase, DIM-5, is required for DNA methylation. DIM-5 trimethylates H3K9, which is then recognized by Heterochromatin Protein 1 (HP1), which recruits the DNA methyltransferase DIM-2. We investigated the possibility that H3 provides a platform to integrate information relevant to whether the associated DNA should be methylated. Indeed, we found that DIM-5 is sensitive to methylation of H3K4 and phosphorylation of H3S10. Our analyses further revealed that H3K14 is critical in vivo, but not because acetyl-K14 inhibits DIM-5. We also found that H3R2 is essential for DNA methylation in vivo but not important for DIM-5 activity. Interestingly, we found H3 mutants that show recessive defects in DNA methylation and others with dominant effects. We also defined a set of H3 mutations that are lethal. |
| Databáze: | OpenAIRE |
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