KaiB functions as an attenuator of KaiC phosphorylation in the cyanobacterial circadian clock system
KaiB functions as an attenuator of KaiC phosphorylation in the cyanobacterial circadian clock system
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DOI：
10.1093/emboj/cdg212
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发表时间：
2003-05-01
期刊：
影响因子：
11.4
通讯作者：
Kondo, T
中科院分区：
文献类型：
--
作者：
Kitayama, Y;Iwasaki, H;Kondo, T
在蓝藻细长聚球藻 PCC 7942 中，KaiA、KaiB 和 KaiC 蛋白对于昼夜节律的产生至关重要。我们定量分析了这些蛋白质的细胞内动态，发现 KaiB 的膜/胞质定位存在昼夜节律，因此 KaiB 在主观深夜与 KaiA-KaiC 复合物相互作用。 KaiB-KaiC 结合伴随着 KaiC 磷酸化的急剧减少，随后是时钟蛋白复合物的解离。 KaiB 在体外和体内均减弱了 KaiA 增强的磷酸化作用。基于这些结果，我们提出 KaiB 在蓝藻时钟系统中亚细胞定位、蛋白质-蛋白质相互作用和 Kai 蛋白质翻译后修饰之间的调节联系中发挥新作用。
In the cyanobacterium Synechococcus elongatus PCC 7942, the KaiA, KaiB and KaiC proteins are essential for generation of circadian rhythms. We quantitatively analyzed the intracellular dynamics of these proteins and found a circadian rhythm in the membrane/cytosolic localization of KaiB, such that KaiB interacts with a KaiA-KaiC complex during the late subjective night. KaiB-KaiC binding is accompanied by a dramatic reduction in KaiC phosphorylation and followed by dissociation of the clock protein complex(es). KaiB attenuated KaiA-enhanced phosphorylation both in vitro and in vivo. Based on these results, we propose a novel role for KaiB in a regulatory link among subcellular localization, protein-protein interactions and post-translational modification of Kai proteins in the cyanobacterial clock system.