Cyanobacterial daily life with Kai-based circadian and diurnal genome-wide transcriptional control in Synechococcus elongatus
Cyanobacterial daily life with Kai-based circadian and diurnal genome-wide transcriptional control in Synechococcus elongatus
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DOI：
10.1073/pnas.0902587106
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发表时间：
2009-08-18
影响因子：
11.1
通讯作者：
Iwasaki, Hideo
中科院分区：
文献类型：
--
作者：
Ito, Hiroshi;Mutsuda, Michinori;Iwasaki, Hideo
在单细胞蓝细菌细长聚球藻PCC 7942中，基本上所有的启动子活性在连续光（LL）条件下都在生物钟的控制下。在这里，我们使用高密度寡核苷酸阵列，以探索全基因组聚球藻基因表达的野生型，kaiABC-无效，和kaiC-过表达菌株在LL和连续黑暗（DD）条件下的综合概况。在野生型菌株中，> 30%的转录物以昼夜节律的方式显著振荡，在主观的黎明和黄昏达到峰值。这种昼夜节律控制在kaiABC无效菌株中严重减弱。虽然已经提出KaiC在全球范围内抑制基因表达，但我们的分析显示，黎明表达的基因被KaiC过表达上调，使得时钟在主观黎明时被逮捕。将细胞从LL转移到DD条件立即抑制了大多数基因的表达，而在没有转录反馈的情况下，时钟保持均匀的时间。因此，聚球藻基因组似乎主要受光/暗周期的调节，并通过基于蛋白质的昼夜节律振荡器进行显着修改。
In the unicellular cyanobacterium Synechococcus elongatus PCC 7942, essentially all promoter activities are under the control of the circadian clock under continuous light (LL) conditions. Here, we used high-density oligonucleotide arrays to explore comprehensive profiles of genome-wide Synechococcus gene expression in wild-type, kaiABC-null, and kaiC-overexpressor strains under LL and continuous dark (DD) conditions. In the wild-type strains, > 30% of transcripts oscillated significantly in a circadian fashion, peaking at subjective dawn and dusk. Such circadian control was severely attenuated in kaiABC-null strains. Although it has been proposed that KaiC globally represses gene expression, our analysis revealed that dawn-expressed genes were up-regulated by kaiC-overexpression so that the clock was arrested at subjective dawn. Transfer of cells to DD conditions from LL immediately suppressed expression of most of the genes, while the clock kept even time in the absence of transcriptional feedback. Thus, the Synechococcus genome seems to be primarily regulated by light/dark cycles and is dramatically modified by the protein-based circadian oscillator.