Physiological Studies of Glutamine Synthetases I and III from Synechococcus sp. WH7803 Reveal Differential Regulation.
Physiological Studies of Glutamine Synthetases I and III from Synechococcus sp. WH7803 Reveal Differential Regulation.
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DOI：
10.3389/fmicb.2016.00969
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发表时间：
2016
影响因子：
5.2
通讯作者：
García-Fernández JM
中科院分区：
文献类型：
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作者：
Domínguez-Martín MA;Díez J;García-Fernández JM
海洋微蓝杆菌聚球藻属（Synechococcus sp.）WH 7803具有两种谷氨酰胺合成酶（GS; EC 6.3.1.2），GSI由glnA编码，GSIII由glnN编码。这是第一次工作解决这两种酶的生理调节海洋蓝藻菌株。氮饥饿后GS活性的增加与其他模式蓝藻相似。然而，当细胞在黑暗中生长时，发现了一种不寻常的反应：GS活性不受影响，反映了它们对生长环境的适应。另一方面，我们发现，GSIII没有响应氮的可用性，与观察到的结果形成鲜明对比，这种酶在其他蓝藻迄今研究。这些功能表明，GS活动在聚球藻WH 7803代表了一个中间步骤，在进化的蓝藻，在一个过程中的监管精简GSI失去了光的调节，而GSIII失去了对氮的反应。这与Synechococcus sp.WH7803在海洋蓝藻辐射背景下的繁殖过程是一致的。
The marine picocyanobacterium Synechococcus sp. WH7803 possesses two glutamine synthetases (GSs; EC 6.3.1.2), GSI encoded by glnA and GSIII encoded by glnN. This is the first work addressing the physiological regulation of both enzymes in a marine cyanobacterial strain. The increase of GS activity upon nitrogen starvation was similar to that found in other model cyanobacteria. However, an unusual response was found when cells were grown under darkness: the GS activity was unaffected, reflecting adaptation to the environment where they thrive. On the other hand, we found that GSIII did not respond to nitrogen availability, in sharp contrast with the results observed for this enzyme in other cyanobacteria thus far studied. These features suggest that GS activities in Synechococcus sp. WH7803 represent an intermediate step in the evolution of cyanobacteria, in a process of regulatory streamlining where GSI lost the regulation by light, while GSIII lost its responsiveness to nitrogen. This is in good agreement with the phylogeny of Synechococcus sp. WH7803 in the context of the marine cyanobacterial radiation.