Heme-Edge Residues Modulate Signal Transduction within a Bifunctional Homo-Dimeric Sensor Protein
Heme-Edge Residues Modulate Signal Transduction within a Bifunctional Homo-Dimeric Sensor Protein
复制标题
血红素边缘残基调节双功能同源二聚体传感器蛋白内的信号转导
DOI：
10.1021/acs.biochem.1c00581
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发表时间：
2021
期刊：
影响因子：
2.9
通讯作者：
Weinert, Emily E.
中科院分区：
文献类型：
--
作者：
Patterson, Dayna C.;Liu, Yilin;Das, Sayan;Yennawar, Neela H.;Armache, Jean-Paul;Kincaid, James R.;Weinert, Emily E.
双功能酶包含两个具有相反酶活性的结构域，广泛分布于细菌中，但对防止无效循环的调节机制仍知之甚少。最近描述的双功能酶，DcpG，表现出不寻常的血红素特性，并令人惊讶地能够差异调节其两个环状二聚鸟苷一磷酸（c-di-GMP）代谢结构域，以响应血红素气体配体。血红素边缘残基的突变被用来探测血红素口袋，导致O2解离动力学降低，确定这些残基在调节DcpG气体传感的作用。此外，DcpG野生型和血红素边缘突变体的共振拉曼光谱显示，突变改变血红素静电环境，乙烯基构象和自旋态人口。使用小角X射线散射和负染电子显微镜，血红素边缘突变被证明会导致蛋白质构象的变化，从而导致信号转导和酶动力学的改变。这些发现为调节DcpG气体传感的分子相互作用以及控制多结构域细菌信号蛋白的机制提供了见解。
Bifunctional enzymes, which contain two domains with opposing enzymatic activities, are widely distributed in bacteria, but the regulatory mechanism(s) that prevent futile cycling are still poorly understood. The recently described bifunctional enzyme, DcpG, exhibits unusual heme properties and is surprisingly able to differentially regulate its two cyclic dimeric guanosine monophosphate (c-di-GMP) metabolic domains in response to heme gaseous ligands. Mutagenesis of heme-edge residues was used to probe the heme pocket and resulted in decreased O2dissociation kinetics, identifying roles for these residues in modulating DcpG gas sensing. In addition, the resonance Raman spectra of the DcpG wild type and heme-edge mutants revealed that the mutations alter the heme electrostatic environment, vinyl group conformations, and spin state population. Using small-angle X-ray scattering and negative stain electron microscopy, the heme-edge mutations were demonstrated to cause changes to the protein conformation, which resulted in altered signaling transduction and enzyme kinetics. These findings provide insights into molecular interactions that regulate DcpG gas sensing as well as mechanisms that have evolved to control multidomain bacterial signaling proteins.