Analysis of the fine-tuning of cyanobacterial circadian phase by monochromatic light and long day conditions.
Analysis of the fine-tuning of cyanobacterial circadian phase by monochromatic light and long day conditions.
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单色光和长日照条件对蓝藻昼夜节律相位的微调分析。
DOI：
10.1093/pcp/pcv177
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发表时间：
2016
期刊：
影响因子：
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通讯作者：
Kutsuna S.
中科院分区：
文献类型：
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作者：
Kobayashi T;Obana Y;Kuboi N;Kitayama Y;Hayashi S;Oka M;Wada N;Arita K;Shimizu T;Sato M;Kanaly RA;Kutsuna S.
蓝藻昼夜节律相关蛋白Pex在昼夜光暗循环的黑暗期积累。昼夜循环后，约3小时的推进阶段的昼夜生物发光节律观察inpex缺陷型突变体，与野生型相比。然而，目前还不清楚是什么类型的光敏机制调节的积累和相变。在单色光照射实验中，在蓝光条件下强烈抑制Pex积累;然而，在红光或绿色光条件下仅观察到Pex积累的小幅减少。在12 h白色荧光和12 h蓝光的日周期后，比12 h红光（或绿色）光周期更能抑制细胞的相位提前。在16 h光照/8 h黑暗周期（长日照周期）后也发生了相位提前，但在8 h光照/16 h黑暗周期（短日照周期）后没有发生相位提前。虽然Pex是一种独特的具有二级结构（α0和α4螺旋）的翼状螺旋转录因子，但这些结构的重要性尚不清楚。在α0螺旋定点突变的体内实验中，所获得的突变体，其中Pex在第28或32个氨基酸残基处缺失疏水侧链，在光/暗循环后没有表现出相位延迟。在体外DNA结合试验中，突变蛋白没有表现出结合的启动子区的时钟genekaiA.From这些结果，我们提出了一个分子模型，描述了在蓝藻的相位延迟。
The cyanobacterial circadian-related protein, Pex, accumulates in the dark period of the diurnal light–dark cycle. After the diurnal cycle, an approximately 3 h advance in the phase of the circadian bioluminescence rhythm is observed inpex-deficient mutants, as compared with the wild type. However, it is unclear what type of photosensing mechanism regulates the accumulation and the phase change. In monochromatic light irradiation experiments, Pex accumulation was strongly repressed under blue light conditions; however, only small reductions in Pex accumulation were observed under red or green light conditions. After the diurnal cycle of 12 h of white fluorescent light and 12 h of blue light, the phase advance was repressed more than that of the cycle of 12 h red (or green) light. The phase advance also occurred after 16 h light/8 h dark cycles (long-day cycles) but did not occur after 8 h light/16 h dark cycles (short-day cycles). While Pex is a unique winged helix transcription factor harboring secondary structures (α0 and α4 helices), the importance of the structures is not understood. In in vivo experiments with site-directed mutations in the α0 helix, the obtained mutants, in which Pex was missing the hydrophobic side chain at the 28th or 32nd amino acid residue, exhibited no phase delay after the light/dark cycle. In in vitro DNA binding assays, the mutant proteins showed no binding to the promoter region of the clock genekaiA.From these results, we propose a molecular model which describes the phase delay in cyanobacteria.