Publications

• Molecular characterization of the tobacco SET domain protein NtSET1 unravels its role in histone methylation, chromatin binding, and segregation.

  Yu Y., Dong A., Shen W.-H.

  Plants contain a great number of genes encoding a distinctive class of SET domain proteins which harbor a plant-specific N-terminal part together with a C-terminal part showing highest sequence similarity to the catalytic domain of the yeast CLR4, the human SUV39H1 and G9a histone-methyltransferas ... >> More

  Plants contain a great number of genes encoding a distinctive class of SET domain proteins which harbor a plant-specific N-terminal part together with a C-terminal part showing highest sequence similarity to the catalytic domain of the yeast CLR4, the human SUV39H1 and G9a histone-methyltransferases (HMTases). Here we show that NtSET1, a representative member of this class from tobacco, methylated both K9 and K27 of histone H3 in vitro. Ectopic expression of NtSET1, by an inducible promoter, increased the amount of dimethylated H3K9 and induced chromosome-segregation defects in tobacco BY2 cells. Deletion analyses show that the HMTase activity, the association with specific chromatin regions and with condensed chromosomes, and the cellular effects largely depended on the C-terminal region including the SET domain of the protein. Nevertheless, the N-terminal part of NtSET1 was capable of targeting the green fluorescent protein to interphase chromatin. Finally, we show that NtSET1 bound LHP1, the Arabidopsis homolog of animal heterochromatin protein 1 (HP1), and that LHP1 co-localized with heterochromatin containing high amounts of dimethylated H3K9, suggesting a role for NtSET1 in heterochromatic function. Taken together, our results provide new insights into the molecular and global chromatin-binding activities of this particular class member of plant SET domain proteins. << Less

  Plant J. 40:699-711(2004) [PubMed] [EuropePMC]

• Ectopic expression of the NtSET1 histone methyltransferase inhibits cell expansion, and affects cell division and differentiation in tobacco plants.

  Shen W.-H., Meyer D.

  The tobacco NtSET1 gene encodes a member of the SUV39H family of histone methyltransferases. Ectopic expression of NtSET1 causes an increase in methylated histone H3 lysine 9 and abnormal chromosome segregation in tobacco suspension cells, and inhibits tobacco plant growth. Here we show that the i ... >> More

  The tobacco NtSET1 gene encodes a member of the SUV39H family of histone methyltransferases. Ectopic expression of NtSET1 causes an increase in methylated histone H3 lysine 9 and abnormal chromosome segregation in tobacco suspension cells, and inhibits tobacco plant growth. Here we show that the inhibition of plant growth was caused by reduced cell expansion as well as by abnormal cell division and differentiation. We found that deletion of the C-terminally located catalytic domain of the protein abolished the ectopic effects of NtSET1 on plant growth. Our results indicate that histone H3 lysine 9 methylation is a critical mark of epigenetic control for plant development. << Less

  Plant Cell Physiol. 45:1715-1719(2004) [PubMed] [EuropePMC]

• Pivotal role of AtSUVH2 in heterochromatic histone methylation and gene silencing in Arabidopsis.

  Naumann K., Fischer A., Hofmann I., Krauss V., Phalke S., Irmler K., Hause G., Aurich A.-C., Dorn R., Jenuwein T., Reuter G.

  SU(VAR)3-9 like histone methyltransferases control heterochromatic domains in eukaryotes. In Arabidopsis, 10 SUVH genes encode SU(VAR)3-9 homologues where SUVH1, SUVH2 and SUVH4 (KRYPTONITE) represent distinct subgroups of SUVH genes. Loss of SUVH1 and SUVH4 causes weak reduction of heterochromati ... >> More

  SU(VAR)3-9 like histone methyltransferases control heterochromatic domains in eukaryotes. In Arabidopsis, 10 SUVH genes encode SU(VAR)3-9 homologues where SUVH1, SUVH2 and SUVH4 (KRYPTONITE) represent distinct subgroups of SUVH genes. Loss of SUVH1 and SUVH4 causes weak reduction of heterochromatic histone H3K9 dimethylation, whereas in SUVH2 null plants mono- and dimethyl H3K9, mono- and dimethyl H3K27, and monomethyl H4K20, the histone methylation marks of Arabidopsis heterochromatin are significantly reduced. Like animal SU(VAR)3-9 proteins SUVH2 displays strong dosage-dependent effects. Loss of function suppresses, whereas overexpression enhances, gene silencing, causes ectopic heterochromatization and significant growth defects. Furthermore, modification of transgene silencing by SUVH2 is partially transmitted to the offspring plants. This epigenetic stability correlates with heritable changes in DNA methylation. Mutational dissection of SUVH2 indicates an implication of its N-terminus and YDG domain in directing DNA methylation to target sequences, a prerequisite for consecutive histone methylation. Gene silencing by SUVH2 depends on MET1 and DDM1, but not CMT3. In Arabidopsis, SUVH2 with its histone H3K9 and H4K20 methylation activity has a central role in heterochromatic gene silencing. << Less

  EMBO J. 24:1418-1429(2005) [PubMed] [EuropePMC]

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