Global gene repression by KaiC as a master process of prokaryotic circadian system
Global gene repression by KaiC as a master process of prokaryotic circadian system
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DOI：
10.1073/pnas.0307411100
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发表时间：
2004-01-20
影响因子：
11.1
通讯作者：
Kondo, T
中科院分区：
文献类型：
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作者：
Nakahira, Y;Katayama, M;Kondo, T
先前从蓝藻细长聚球藻 PCC 7942 中鉴定出 kaiABC 时钟基因簇，并提出 kai 基因的反馈调节是产生昼夜节律振荡的核心机制。在这项研究中，我们证实基于 Kai 的振荡器是蓝藻中发挥作用的主要昼夜节律振荡器。我们探究了这种调节的本质，发现过量的 KaiC 不仅会抑制 kaiBC，还会抑制基因组中所有基因的节律成分。这一结果强烈表明 KaiC 蛋白主要协调全基因组基因表达，包括其自身的表达。我们还发现，源自大肠杆菌的启动子受到 KaiC 的反馈控制，并在 kaiBC 失活的心律失常突变体中恢复完整的昼夜节律，前提是它能够以适当的水平表达 kaiB 和 kaiC 基因。与真核模型不同，kaiBC 启动子的特异性调节对于蓝藻昼夜节律振荡并不是必需的。
A kaiABC clock gene cluster was previously identified from cyanobacterium Synechococcus elongatus PCC 7942, and the feedback regulation of kai genes was proposed as the core mechanism generating circadian oscillation. In this study, we confirmed that the Kai-based oscillator is the dominant circadian oscillator functioning in cyanobacteria. We probed the nature of this regulation and found that excess KaiC represses not only kaiBC but also the rhythmic components of all genes in the genome. This result strongly suggests that the KaiC protein primarily coordinates genomewide gene expression, including its own expression. We also found that a promoter derived from E. coli is feedback controlled by KaiC and restores the complete circadian rhythm in kaiBC-inactivated arrhythmic mutants, provided it can express kaiB and kaiC genes at an appropriate level. Unlike eukaryotic models, specific regulation of the kaiBC promoter is not essential for cyanobacterial circadian oscillations.