Biological Faculty, Saint-Petersburg State University, Universitetskaya nab. 7/9, Saint-Petersburg, 199034, Russia.
Interfaculty Institute of Microbiology and Infection Medicine/Organismic Interactions Department, Eberhard-Karls-Universität Tübingen, Auf der Morgenstelle 28, 72076, Tübingen, Germany.
Sci Rep. 2018 Jan 15;8(1):790. doi: 10.1038/s41598-017-19046-7.
PII superfamily consists of widespread signal transduction proteins found in all domains of life. Whereas they are well-studied in Archaea, Bacteria and Chloroplastida, no PII homolog has been analyzed in Rhodophyta (red algae), where PII is encoded by a chloroplast localized glnB gene. Here, we characterized relevant sensory properties of PII from the red alga Porphyra purpurea (PpPII) in comparison to PII proteins from different phyla of oxygenic phototrophs (cyanobacteria, Chlamydomonas and Physcomitrella) to assess evolutionary conservation versus adaptive properties. Like its cyanobacterial counterparts, PpPII binds ATP/ADP and 2-oxoglutarate in synergy with ATP. However, green algae and land plant PII proteins lost the ability to bind ADP. In contrast to PII proteins from green algae and land plants, PpPII enhances the activity of N-acetyl-L-glutamate kinase (NAGK) and relieves it from feedback inhibition by arginine in a glutamine-independent manner. Like PII from Chloroplastida, PpPII is not able to interact with the cyanobacterial transcriptional co-activator PipX. These data emphasize the conserved role of NAGK as a major PII-interactor throughout the evolution of oxygenic phototrophs, and confirms the specific role of PipX for cyanobacteria. Our results highlight the PII signaling system in red algae as an evolutionary intermediate between Cyanobacteria and Chlorophyta.
PII 超家族由广泛存在于所有生命领域的信号转导蛋白组成。虽然它们在古菌、细菌和叶绿体中得到了很好的研究，但在红藻（红藻）中，尚未分析过 PII 同源物，而 PII 是由叶绿体定位的 glnB 基因编码的。在这里，我们比较了来自红藻紫菜（Porphyra purpurea）的 PII 与来自不同产氧光合生物门（蓝藻、衣藻和Physcomitrella）的 PII 蛋白的相关感觉特性，以评估进化保守性与适应性特性。与蓝藻中的对应物一样，PpPII 与 ATP 协同结合 ADP/ADP 和 2-氧戊二酸。然而，绿藻和陆地植物的 PII 蛋白失去了结合 ADP 的能力。与绿藻和陆地植物的 PII 蛋白不同，PpPII 以谷氨酰胺独立的方式增强 N-乙酰-L-谷氨酸激酶（NAGK）的活性并解除其对精氨酸的反馈抑制。与叶绿体的 PII 蛋白一样，PpPII 不能与蓝细菌转录共激活因子 PipX 相互作用。这些数据强调了 NAGK 作为主要 PII 相互作用物在产氧光合生物进化中的保守作用，并证实了 PipX 对蓝细菌的特定作用。我们的研究结果突出了红藻中的 PII 信号系统作为蓝细菌和绿藻之间的进化中间体。
