Ectopic targeting of CG DNA methylation in Arabidopsis with the bacterial SssI methyltransferase

The ability to target epigenetic marks like DNA methylation to specific loci is important in both basic research and in crop plant engineering. However, heritability of targeted DNA methylation, how it impacts gene expression, and which epigenetic features are required for proper establishment are mostly unknown. Here, we show that targeting the CG-specific methyltransferase M.SssI with an artificial zinc finger protein can establish heritable CG methylation and silencing of a targeted locus in Arabidopsis. In addition, we observe highly heritable widespread ectopic CG methylation mainly over euchromatic regions. This hypermethylation shows little effect on transcription while it triggers a mild but significant reduction in the accumulation of H2A.Z and H3K27me3. Moreover, ectopic methylation occurs preferentially at less open chromatin that lacks positive histone marks. These results outline general principles of the heritability and interaction of CG methylation with other epigenomic features that should help guide future efforts to engineer epigenomes. The ability to target DNA methylation to specific loci is important for both basic and applied research. Here, the authors fuse CG-specific methyltransferase SssI with an artificial zinc finger protein for DNA methylation targeting and show the chromatin features favorable for efficient gain of methylation.

Automated summary

The ability to target DNA methylation to specific loci is crucial in both basic and applied research, and using an artificial zinc finger protein to target the CG-specific methyltransferase SssI for DNA methylation demonstrates the chromatin features that are favorable for efficient methylation gain.