Experimental systems in which gene expression can be carefully regulated are powerful tools for investigating gene function. In an Advanced Online Publication in
The system is binary, like the classical yeast two-hybrid system, and is based on the light-induced interaction between two fusion proteins. One is a fusion between the plant phyB phytochrome and the DNA binding domain of yeast 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.