Cross-talk and regulatory interactions between the essential response regulator RpaB and cyanobacterial circadian clock output
Cross-talk and regulatory interactions between the essential response regulator RpaB and cyanobacterial circadian clock output
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DOI：
10.1073/pnas.1424632112
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发表时间：
2015-02-17
影响因子：
11.1
通讯作者：
Contreras, Asuncion
中科院分区：
文献类型：
--
作者：
Espinosa, Javier;Boyd, Joseph S.;Contreras, Asuncion
响应调节剂Rpa B（藻胆体相关B调节剂），一个重要的双组分系统的一部分，在蓝藻中保守的响应多种环境信号，最近已牵连在控制细胞尺寸和基因表达的昼夜节律的模式蓝藻细长聚球藻PCC 7942。然而，很少有人知道的RpaB功能的分子机制。在这项研究中，我们表明，RpaB的表型的调节与RpaA（藻胆体相关A的调节器），昼夜节律转录模式的主调节器的活性密切相关。RpaB通过控制基因表达（需要完整效应结构域的功能）和改变RpaA磷酸化（通过RpaB的N-末端受体结构域介导的功能）影响RpaA活性。因此，磷酸化串扰和靶基因的共调节在RpaA和RpaB途径之间的遗传相互作用中发挥作用。此外，类似于P水平的RpaB似乎是在光暗循环下生存的关键，在这种条件下，RpaB磷酸化是环境驱动的，不受昼夜节律钟的影响。我们认为，必需且对环境敏感的NblS-RpaB系统和SasA-RpaA时钟输出系统之间复杂的调节相互作用将相关的细胞外和细胞内信号整合到昼夜节律时钟中。
The response regulator RpaB (regulator of phycobilisome associated B), part of an essential two-component system conserved in cyanobacteria that responds to multiple environmental signals, has recently been implicated in the control of cell dimensions and of circadian rhythms of gene expression in the model cyanobacterium Synechococcus elongatus PCC 7942. However, little is known of the molecular mechanisms that underlie RpaB functions. In this study we show that the regulation of phenotypes by RpaB is intimately connected with the activity of RpaA (regulator of phycobilisome associated A), the master regulator of circadian transcription patterns. RpaB affects RpaA activity both through control of gene expression, a function requiring an intact effector domain, and via altering RpaA phosphorylation, a function mediated through the N-terminal receiver domain of RpaB. Thus, both phosphorylation cross-talk and coregulation of target genes play a role in the genetic interactions between the RpaA and RpaB pathways. In addition, RpaB similar to P levels appear critical for survival under light: dark cycles, conditions in which RpaB phosphorylation is environmentally driven independent of the circadian clock. We propose that the complex regulatory interactions between the essential and environmentally sensitive NblS-RpaB system and the SasA-RpaA clock output system integrate relevant extra- and intracellular signals to the circadian clock.