Shedding light on gene regulation

Experimental systems in which gene expression can be carefully regulated are powerful tools for investigating gene function. In an Advanced Online Publication in Nature Biotechnology, Shimizu-Sato and colleagues describe an ingenious gene expression system that exploits a light-sensitive protein from plants.

The system is binary, like the classical yeast two-hybrid system, and is based on a light-induced interaction between two fusion proteins. One is a fusion between the plant PhyB phytochrome and the DNA-binding domain of the yeast transcriptional activator Gal4, while the other contains the plant Pif3 basic helix-loop-helix protein fused to the Gal4 activation domain. A controlled transgene can be 'turned on' by red light, and 'turned off' again by far-red light. The findings demonstrate that their system works well in yeast, and they predict that it could be used in any light-accessible eukaryotic cell to offer a non-invasive, inexpensive and non-toxic gene induction system.