Expression of a gene cluster kaiABC as a circadian feedback process in cyanobacteria
Expression of a gene cluster kaiABC as a circadian feedback process in cyanobacteria
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DOI：
10.1126/science.281.5382.1519
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发表时间：
1998-09-04
期刊：
影响因子：
56.9
通讯作者：
Kondo, T
中科院分区：
文献类型：
--
作者：
Ishiura, M;Kutsuna, S;Kondo, T
蓝藻是已知有生物钟的最简单的生物。从蓝藻聚球藻中克隆了一个昼夜节律性Crok基因簇kaiABC。19个时钟突变被定位到这三个KAI基因上。KaIA和Kaib基因上游的启动子活性表现出昼夜节律的表达，KaIA和KaiBC信使RNA都表现出昼夜循环。任何一个KAI基因的失活都会取消这些节律，并降低KaiBC启动子的活性。持续的KaiC过表达抑制了KaiBC启动子的表达，而KaiA的过表达则增强了KaiBC启动子。短暂性kaiC的过度表达重置了节律的相位。因此，KaiC对kaiC表达的负反馈控制在蓝藻中产生昼夜振荡，Kaia通过增强kaiC表达来维持这种振荡。
Cyanobacteria are the simplest organisms known to have a circadian clock. A circadian crock gene cluster kaiABC was cloned from the cyanobacterium Synechococcus. Nineteen clock mutations were mapped to the three kai genes. Promoter activities upstream of the kaiA and kaiB genes showed circadian rhythms of expression, and both kaiA and kaiBC messenger RNAs displayed circadian cycling. inactivation of any single kai gene abolished these rhythms and reduced kaiBC-promoter activity. Continuous kaiC overexpression repressed the kaiBC promoter, whereas kaiA overexpression enhanced it. Temporal kaiC overexpression reset the phase of the rhythms. Thus, a negative feedback control of kaiC expression by KaiC generates a circadian oscillation in cyanobacteria, and KaiA sustains the oscillation by enhancing kaiC expression.