Building a circadian clock

To keep in balance with day and night all living organisms need a network of feedback loops known as a circadian clock. A number of components in this clockwork, namely CCA1 and LHY have already been identified in Arabidopsis but Steve A. Kay and his coworkers at University of California San Diego in La Jolla wanted to know if other proteins were able to bind to and potentially regulate them. They used a yeast-based expression system to screen a collection of proteins and identified a transcription factor, CHE, that bind to the CCA1-promoter. The CHE and CCA1 proteins represses the expression of each other and thereby establishes a negative feedback loop.

Source: Pruneda-Paz et al (13 March 2009) Science 323: 1481-1485