RpaB, Another Response Regulator Operating Circadian Clock-dependent Transcriptional Regulation in Synechococcus elongatus PCC 7942
RpaB, Another Response Regulator Operating Circadian Clock-dependent Transcriptional Regulation in Synechococcus elongatus PCC 7942
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DOI：
10.1074/jbc.m111.338251
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发表时间：
2012-07-27
影响因子：
4.8
通讯作者：
Tanaka, Kan
中科院分区：
文献类型：
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作者：
Hanaoka, Mitsumasa;Takai, Naoki;Tanaka, Kan
蓝藻的生物钟由KaiA、KaiB和KaiC蛋白组成，SasA-RpaA双组分系统参与了生物钟输出途径之一的调控。在这项研究中，我们发现了另一种对生存能力至关重要的反应调节因子，RpaA类似物RpaB，在时钟调节基因的转录振荡中起着核心作用。体内和体外分析显示，RpaB和非RpaA可以特异性结合kaiBC启动子，可能在主观夜间抑制转录。这表明RpaA可能在主观白天终止结合以激活基因转录。此外，我们发现分别编码rna聚合酶2组和3组sigma因子的rpoD6和sigF2也是RpaAB系统的靶标，这表明一组特定的sigma因子可以传播全基因组转录振荡。因此，我们的研究结果揭示了一种由两个平行反应调节因子介导的昼夜节律输出途径的新机制。
The circadian clock of cyanobacteria is composed of KaiA, KaiB, and KaiC proteins, and the SasA-RpaA two-component system has been implicated in the regulation of one of the output pathways of the clock. In this study, we show that another response regulator that is essential for viability, the RpaA paralog, RpaB, plays a central role in the transcriptional oscillation of clock-regulated genes. In vivo and in vitro analyses revealed that RpaB and not RpaA could specifically bind to the kaiBC promoter, possibly repressing transcription during subjective night. This suggested that binding may be terminated by RpaA to activate gene transcription during subjective day. Moreover, we found that rpoD6 and sigF2, which encode group-2 and group-3 sigma factors forRNApolymerase, respectively, were also targets of the RpaAB system, suggesting that a specific group of sigma factors can propagate genome-wide transcriptional oscillation. Our findings thus reveal a novel mechanism for a circadian output pathway that is mediated by two paralogous response regulators.