シアノバクテリアの翻訳制御によるグローバルな概日遺伝子発現

抄録

Central clock genes, kaiABC, are encoded on a genome of cyanobacterium Synechococcus elongatus PCC 7942. These function as central autonomous oscillatory proteins. Additionally, it was proposed that the transcriptional feedback loop involving kaiABC provides a global circadian expression. As a fact, we have never found non-oscillatory genes from cyanobacteria using luxAB reporter system. In this study, we approach the mechanism for global circadian gene expressions in cyanobacteria. A microarray analysis exhibited that only 30% genes had a possible oscillation in the mRNA accumulation level. These genes showed negative feedback regulation against excess KaiC condition, but the others did not. Thus, the global oscillation was not generated in transcriptional level, suggesting it is conferred in post-transcriptional level. In further molecular analysis, an interaction between translation elongation factor and Kai complex was observed in subjective night. According to these facts, we will propose new model for circadian output cascade in cyanobacteria.