KaiA-stimulated KaiC phosphorylation in circadian timing loops in cyanobacteria
KaiA-stimulated KaiC phosphorylation in circadian timing loops in cyanobacteria
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DOI：
10.1073/pnas.222467299
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发表时间：
2002-11-26
影响因子：
11.1
通讯作者：
Kondo, T
中科院分区：
文献类型：
--
作者：
Iwasaki, H;Nishiwaki, T;Kondo, T
蓝藻时钟蛋白 KaiA 和 KaiC 被认为分别作为自动调节昼夜节律 kaiBC 表达的正调节因子和负调节因子。在这里，我们表明 kaiA 激活 kaiBC 表达需要 KaiC，这表明蓝藻发条系统中存在正反馈控制。我们发现 KaiC 具有强大的昼夜磷酸化作用。 KaiA 对于体内 KaiC 磷酸化和激活体外 KaiC 自磷酸化至关重要。 KaiA2 长周期突变减弱了 KaiA 的这些作用。该突变体中的长周期表型和异常的 KaiC 磷酸化均被先前未记录的 kaiC 突变所抑制。我们认为 KaiA 刺激的昼夜节律 KaiC 磷酸化对于昼夜节律计时很重要。
Cyanobacterial clock proteins KaiA and KaiC are proposed as positive and negative regulators in the autoregulatory circadian kaiBC expression, respectively. Here, we show that activation of kaiBC expression by kaiA requires KaiC, suggesting a positive feedback control in the cyanobacterial clockwork. We found that robust circadian phosphorylation of KaiC. KaiA was essential for in vivo KaiC phosphorylation and activated in vitro KaiC autophosphorylation. These effects of KaiA were attenuated by the kaiA2 long period mutation. Both the long period phenotype and the abnormal KaiC phosphorylation in this mutant were suppressed by a previously undocumented kaiC mutation. We propose that KaiA-stimulated circadian KaiC phosphorylation is important for circadian timing.