Biochemical Evidence for a Timing Mechanism in Prochlorococcus
Biochemical Evidence for a Timing Mechanism in Prochlorococcus
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DOI：
10.1128/jb.00419-09
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发表时间：
2009-09-01
影响因子：
3.2
通讯作者：
Wilde, Annegret
中科院分区：
文献类型：
--
作者：
Axmann, Ilka M.;Duehring, Ulf;Wilde, Annegret
生物体利用内部生物钟协调生物活动，形成每日循环。昼夜节律振荡器蛋白KaiA、KaiB和KaiC被广泛认为是蓝藻中基因表达24小时振荡的基础。然而，一组非常丰富的蓝藻，即海洋原绿球藻物种，在进化过程中失去了第三个振荡器成分KaiA。我们在这里证明，尽管在这个系统中KaiC默认是过度磷酸化的，但剩余的Kai蛋白履行其已知的生化功能。这些数据为观察到的原绿球藻时钟位点的进化减少提供了生化支持，并与一个模型相一致，该模型认为，在原绿球藻所居住的非常稳定的环境中，一个不如聚球菌的KaiABC蛋白时钟强大的机制足以进行生物计时。
Organisms coordinate biological activities into daily cycles using an internal circadian clock. The circadian oscillator proteins KaiA, KaiB, and KaiC are widely believed to underlie 24-h oscillations of gene expression in cyanobacteria. However, a group of very abundant cyanobacteria, namely, marine Prochlorococcus species, lost the third oscillator component, KaiA, during evolution. We demonstrate here that the remaining Kai proteins fulfill their known biochemical functions, although KaiC is hyperphosphorylated by default in this system. These data provide biochemical support for the observed evolutionary reduction of the clock locus in Prochlorococcus and are consistent with a model in which a mechanism that is less robust than the well-characterized KaiABC protein clock of Synechococcus is sufficient for biological timing in the very stable environment that Prochlorococcus inhabits.