A novel mutation in kaiC affects resetting of the cyanobacterial circadian clock
A novel mutation in kaiC affects resetting of the cyanobacterial circadian clock
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DOI：
10.1128/jb.187.8.2559-2564.2005
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发表时间：
2005-04-01
影响因子：
3.2
通讯作者：
Kondo, T
中科院分区：
文献类型：
--
作者：
Kiyohara, YB;Katayama, M;Kondo, T
光是控制昼夜循环系统的最重要因素。为了更好地了解光对长聚球菌PCC 7942昼夜节律的调节，我们筛选了在暗脉冲下相移缺陷的突变体。使用5小时暗脉冲方案，我们在kaiC中发现了一个突变，我们将其命名为pr1。在pr1突变体中，5小时的暗脉冲未能改变昼夜节律的相位，而在野生型细胞中，相同的脉冲导致10小时的相移。在pr1突变体中，KaiC积累的节律性被取消，KaiC磷酸化的节律性降低。此外，pr1突变体在介导kaiBC的反馈抑制方面存在缺陷。最后，与野生型KaiC相比，突变型KaiC的过表达导致相移减少。因此，除了在昼夜节律的反馈调节中有记载的作用外，KaiC似乎还在重置细胞时钟中发挥作用。
Light is the most important factor controlling circadian systems in response to day-night cycles. In order to better understand the regulation of circadian rhythms by light in Synechococcus elongatus PCC 7942, we screened for mutants with defective phase shifting in response to dark pulses. Using a 5-h dark-pulse protocol, we identified a mutation in kaiC that we termed pr1 for phase response 1. In the pr1 mutant, a 5-h dark pulse failed to shift the phase of the circadian rhythm, while the same pulse caused a 10-h phase shift in wild-type cells. The rhythm in accumulation of KaiC was abolished in the pr1 mutant, and the rhythmicity of KaiC phosphorylation was reduced. Additionally, the pr1 mutant was defective in mediating the feedback inhibition of kaiBC. Finally, overexpression of mutant KaiC led to a reduced phase shift compared to that for wild-type KaiC. Thus, KaiC appears to play a role in resetting the cellular clock in addition to its documented role in the feedback regulation of circadian rhythms.