Synechocystis KaiC3 Displays Temperature- and KaiB-Dependent ATPase Activity and Is Important for Growth in Darkness
Synechocystis KaiC3 Displays Temperature- and KaiB-Dependent ATPase Activity and Is Important for Growth in Darkness
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集胞藻 KaiC3 显示温度和 KaiB 依赖性 ATP 酶活性，对黑暗中的生长很重要
DOI：
10.1128/jb.00478-19
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发表时间：
2020
影响因子：
3.2
通讯作者：
Axmann IM
中科院分区：
文献类型：
--
作者：
Wiegard A;Köbler C;Oyama K;Dörrich AK;Azai C;Terauchi K;Wilde A;Axmann IM
蓝细菌形成了一个异质的细菌群体，具有不同的生活方式，适应策略和生物钟蛋白的差异。在细长聚球藻PCC 7942中，独特的翻译后KaiABC振荡器驱动昼夜节律。KaiC的ATP酶活性与生物钟的周期相关，并介导温度补偿。菌株PCC 6803表达另外的Kai蛋白，其中KaiB3和KaiC3蛋白被建议用于微调标准KaiAB1C1振荡器。因此，在本研究中，我们表征了KaiC3作为非标准KaiC同系物体外代表的酶活性。KaiC3的ATP酶活性低于细长聚球藻PCC 7942 KaiC蛋白。ATP水解是温度依赖性的。因此，KaiC3缺少模型蓝藻昼夜节律振荡器的定义特征。酵母双杂交分析表明KaiC3与KaiB3、KaiC1和KaiB1相互作用。此外，KaiB3和KaiB1在体外减少KaiC3的ATP水解。斑点试验表明，在恒定黑暗中的化能异养生长在Δ kaiAB1C1缺失后完全消失，在kaiC3缺失时减少。因此，我们建议KaiC3适应黑暗的作用，以及KaiC1和KaiC3为基础的systems.IMPORTANCEThe生物钟影响蓝藻代谢，更深入地了解其调节代谢优化的背景下，工业应用之间的串扰。由于蓝藻的异质性，除了昼夜节律模型细长聚球藻PCC 7942外，还需要生物钟系统的表征。菌株PCC 6803代表主要的蓝细菌模式生物，并且具有在遗传学上分歧的时钟蛋白的同源物，其存在于各种其它非蓝细菌原核生物中。通过我们的体外研究，我们解开了多个集胞藻Kai蛋白的相互作用，并表征了非标准时钟同源物KaiC3的酶活性。我们发现，kaiC3的缺失影响在恒定的黑暗中的生长，这表明它参与了非光合代谢途径的调节。
Cyanobacteria form a heterogeneous bacterial group with diverse lifestyles, acclimation strategies, and differences in the presence of circadian clock proteins. In Synechococcus elongatus PCC 7942, a unique posttranslational KaiABC oscillator drives circadian rhythms. ATPase activity of KaiC correlates with the period of the clock and mediates temperature compensation.Synechocystissp. strain PCC 6803 expresses additional Kai proteins, of which KaiB3 and KaiC3 proteins were suggested to fine-tune the standard KaiAB1C1 oscillator. In the present study, we therefore characterized the enzymatic activity of KaiC3 as a representative of nonstandard KaiC homologsin vitro. KaiC3 displayed ATPase activity lower than that of the Synechococcus elongatus PCC 7942 KaiC protein. ATP hydrolysis was temperature dependent. Hence, KaiC3 is missing a defining feature of the model cyanobacterial circadian oscillator. Yeast two-hybrid analysis showed that KaiC3 interacts with KaiB3, KaiC1, and KaiB1. Further, KaiB3 and KaiB1 reducedin vitroATP hydrolysis by KaiC3. Spot assays showed that chemoheterotrophic growth in constant darkness is completely abolished after deletion of ΔkaiAB1C1and reduced in the absence ofkaiC3. We therefore suggest a role for adaptation to darkness for KaiC3 as well as a cross talk between the KaiC1- and KaiC3-based systems.IMPORTANCEThe circadian clock influences the cyanobacterial metabolism, and deeper understanding of its regulation will be important for metabolic optimizations in the context of industrial applications. Due to the heterogeneity of cyanobacteria, characterization of clock systems in organisms apart from the circadian model Synechococcus elongatus PCC 7942 is required.Synechocystissp. strain PCC 6803 represents a major cyanobacterial model organism and harbors phylogenetically diverged homologs of the clock proteins, which are present in various other noncyanobacterial prokaryotes. By ourin vitrostudies we unravel the interplay of the multipleSynechocystisKai proteins and characterize enzymatic activities of the nonstandard clock homolog KaiC3. We show that the deletion ofkaiC3affects growth in constant darkness, suggesting its involvement in the regulation of nonphotosynthetic metabolic pathways.