The on-and-off affair in DNA

Researchers have discovered that in thale cresses histone H3 lysine-9 (H3K9) methylation, conventionally thought to be a mark of turning off gene transcription, can also turn on gene expression via the interactions of two other proteins and histone marks. The molecular mechanisms demonstrate that rather than functioning as a simple ‘off switch,’ H3K9 methylation is more like a ‘dimmer switch’ that fine-tunes DNA transcription. The discovery suggests there might be similar mechanisms in other organisms, too.