Adenylate Charge Regulates Sensor Kinase CheS3 To Control Cyst Formation in Rhodospirillum centenum.
Adenylate Charge Regulates Sensor Kinase CheS3 To Control Cyst Formation in Rhodospirillum centenum.
复制标题
DOI：
10.1128/mbio.00546-15
复制
发表时间：
2015-05-05
期刊：
影响因子：
6.4
通讯作者：
Bauer CE
中科院分区：
文献类型：
--
作者：
He K;Dragnea V;Bauer CE
百蕊杜鹃在干燥或营养缺乏等不利生长条件下形成代谢休眠孢囊。囊肿的发育受到严格的调控，并涉及一种称为Che 3信号级联的囊肿抑制趋化性样信号转导途径。Che 3级联由甲基化学受体（MCP 3）、受体甲基化/去甲基化蛋白CheB 3和CheR 3、两个CheW 3接头蛋白、CheA 3-CheY杂合组氨酸激酶和单结构域反应调节因子CheY 3组成。除了Che样组分外，Che 3级联还含有第二个杂合组氨酸激酶CheS 3。最近的生物化学和遗传学研究表明，CheA 3并不作为CheY 3的磷供体;相反，CheA 3通过磷酸化CheS 3的抑制性受体结构域来抑制CheS 3 → CheY 3双组分系统。在这项研究中，我们表明，除了磷酸化的CheA 3，磷酸化状态的CheS 3也受到细胞能量水平的ATP/（ATP + ADP）的摩尔比定量。在体内，当营养素降低时，细胞能量减少35%，导致囊肿形成。当这种能量下降在体外复制时，CheS 3的磷酸化水平降低约75%。最后，我们还表明，ADP介导的CheS 3磷酸化的减少是ADP增强CheS 3自身去磷酸化的结果。在饥饿时，百蕊杜鹃经历形成代谢休眠孢囊的发育过程，其经受干燥和营养限制。本研究探讨了细胞能量状态的作用，作为衡量的ATP ADP的比例作为一个重要的调节器的孢囊形成在Rhodocellum centenum。我们表明，R. centenum细胞的经验，在囊肿形成过程中，ATP/（ATP + ADP）作为测量ATP显着减少。当在体外模拟这种体内水平的能量饥饿时，CheS 3磷酸化降低了75%。CheS 3自磷酸化的这种显著降低与响应于ATP/（ATP + ADP）的类似下移的CheA 3磷酸化的低得多的25%的降低形成对比。我们认为，即使腺苷酸能量在一定程度上影响所有ATP依赖性酶，增强的抑制CheS 3活性响应于ATP/（ATP + ADP）比值的降低可能作为一个重要的输入信号，以调节囊肿的发展。
Rhodospirillum centenum forms metabolically dormant cysts under unfavorable growth conditions such as desiccation or nutrient starvation. The development of cysts is tightly regulated and involves a cyst-repressing chemotaxis-like signal transduction pathway called the Che3 signaling cascade. The Che3 cascade is comprised of a methyl chemoreceptor (MCP3), receptor-methylating/demethylating proteins CheB3 and CheR3, two CheW3 linker proteins, a CheA3-CheY hybrid histidine kinase, and a single-domain response regulator, CheY3. In addition to Che-like components, the Che3 cascade also contains a second hybrid histidine kinase, CheS3. Recent biochemical and genetic studies show that CheA3 does not serve as a phosphor donor for CheY3; instead, CheA3 inhibits a CheS3→CheY3 two-component system by phosphorylating an inhibitory receiver domain of CheS3. In this study, we show that in addition to phosphorylation by CheA3, the phosphorylation state of CheS3 is also regulated by the cellular energy level as quantified by the molar ratio of ATP/(ATP + ADP). A 35% decrease in cellular energy is shown to occur in vivo upon a nutrient downshift that gives rise to cyst formation. When this energy decline is replicated in vitro, the phosphorylation level of CheS3 is reduced by ~75%. Finally, we also show that ADP-mediated reduction of CheS3 phosphorylation is a consequence of ADP enhancing autodephosphorylation of CheS3. Upon starvation, Rhodospirillum centenum undergoes a developmental process that forms metabolically dormant cysts, which withstand desiccation and nutritional limitation. This study explores the role of the cellular energy state as measured by the ratio of ATP to ADP as an important regulator of cyst formation in Rhodospirillum centenum. We show that R. centenum cells experience a significant reduction in ATP during cyst formation using ATP/(ATP + ADP) as a measurement. When this in vivo level of energy starvation is simulated in vitro, CheS3 phosphorylation is reduced by 75%. This profound reduction in CheS3 autophosphorylation is contrasted with a much lower 25% decrease in CheA3 phosphorylation in response to a similar downward shift in ATP/(ATP + ADP). We argue that even though adenylate energy affects all ATP-dependent enzymes to an extent, the enhanced inhibition of CheS3 activity in response to a reduction in the ATP/(ATP + ADP) ratio likely functions as an important input signal to regulate cyst development.