Abstract
In the cyanobacterium Synechococcus elongatus PCC 7942, the temporal information from the KaiABC-based circadian oscillator is transmitted to the regulatory machinery of gene expression. A number of mutants that are deficient in circadian gene expression have been identified and analyzed. Among them, rpaA, sasA and labA are shown to play key roles in the output pathways from the circadian oscillator. It was proposed that RpaA acts as a transcriptional factor to regulate the circadian kaiBC expression through the SasA-dependent positive pathway and the LabA-dependent negative pathway. However, the labA/sasA double mutant did show a low-amplitude circadian kaiBC expression, suggesting that there are additional circadian output pathways to regulate the kaiBC expression. We performed further screening to identify those genes that are involved in the additional output pathways.
