Regulatory Switching by Concerted Motions on the Microsecond Time Scale of the Oxygen Sensor Protein FixL
Regulatory Switching by Concerted Motions on the Microsecond Time Scale of the Oxygen Sensor Protein FixL
复制标题
氧传感器蛋白 FixL 在微秒时间尺度上通过协同运动进行调节切换
DOI：
10.1021/acs.jpcb.1c01885
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Mizutani Yasuhisa
中科院分区：
文献类型：
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作者：
Yamawaki Takeo;Mizuno Misao;Ishikawa Haruto;Takemura Kazuhiro;Kitao Akio;Shiro Yoshitsugu;Mizutani Yasuhisa
信号转导蛋白在其传感器模块中感知外部刺激并调节效应器模块的生物活性，从而允许细胞适应环境变化。FixL是一种二聚体血红素蛋白激酶，其感测植物根瘤中的氧水平以通过其同源转录激活因子的磷酸化来调节固氮基因的转录。氧从血红素中解离诱导蛋白质的构象变化，将其从磷酸化的非活性形式转化为活性形式。然而，如何FixL经历构象变化，以调节激酶活性后，氧解离仍然知之甚少。在这里，我们报告的时间分辨紫外共振拉曼光谱显示构象变化的苜蓿中华根瘤菌FixL。我们观察到的光谱变化的时间常数约为3 μs，这是氧特异性的。此外，我们发现，在传感器和激酶结构域的构象变化耦合，使变构控制激酶活性。我们的研究结果表明，一致的结构变化微秒的时间尺度作为调节开关在FixL。
Signal transduction proteins perceive external stimuli in their sensor module and regulate the biological activities of the effector module, allowing cellular adaptation in response to environmental changes. FixL is a dimeric heme protein kinase that senses the oxygen level in plant root nodules to regulate the transcription of nitrogen fixation genes via the phosphorylation of its cognate transcriptional activator. Dissociation of oxygen from the heme induces conformational changes in the protein, converting it from the inactive form for phosphorylation to the active form. However, how FixL undergoes conformational change to regulate kinase activity upon oxygen dissociation remains poorly understood. Here we report time-resolved ultraviolet resonance Raman spectra showing conformational changes for FixL fromSinorhizobium meliloti. We observed spectral changes with a time constant of about 3 μs, which were oxygen-specific. Furthermore, we found that the conformational changes in the sensor and kinase domains are coupled, enabling allosteric control of kinase activity. Our results demonstrate that concerted structural changes on the microsecond time scale serve as the regulatory switch in FixL.