Structural Basis for Polyamine Binding at the dCACHE Domain of the McpU Chemoreceptor from Pseudomonas putida
Structural Basis for Polyamine Binding at the dCACHE Domain of the McpU Chemoreceptor from Pseudomonas putida
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DOI：
10.1016/j.jmb.2018.05.008
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发表时间：
2018-06-22
影响因子：
5.6
通讯作者：
Krell, Tino
中科院分区：
文献类型：
--
作者：
Antonio Gavira, Jose;Ortega, Alvaro;Krell, Tino
许多细菌可以在化学上移动到各种化合物，化学受体配体结合域(LBD)对化学效应分子的识别决定了反应的特异性。许多化学受体被发现识别不同的氨基酸和有机酸，但恶臭假单胞菌的McpU化学受体被鉴定为第一个与多胺特异结合的化学受体。本文报道了McpU-LBD在腐胺络合物中的三维结构，其分辨率为2.4埃，与小角X射线散射产生的溶液结构很好地吻合。腐胺结合到McpU-LBD膜远端模块中带负电荷的口袋上。腐胺与McpU-LBD和牛磺酸与霍乱弧菌MIp37化学受体LBD的结合具有相似性。在这两种结构中，各自配体的伯氨基是由两个天冬氨酸和一个酪氨酸侧链建立的氢键识别的。这一特征可以用来预测未知功能的化学受体的配体。分析超速离心法发现McpU-LBD在溶液中是单体，配体结合不会改变这种低聚状态。因此，这种传感模式不同于特征良好的四螺旋束域的模式，在四螺旋束域中，配体与LBD二聚体界面的两个位点结合。虽然似乎有不同的感觉模式，但结果是在数据的背景下讨论的，表明化学感受器使用相同的跨膜信号机制。这项工作加深了我们对缓存区的理解，缓存区是细菌化学感受器和传感器激酶中含量最丰富的感应域。(C)2018爱思唯尔有限公司。保留所有权利。
Many bacteria can move chemotactically to a variety of compounds and the recognition of chemoeffectors by the chemoreceptor ligand binding domain (LBD) defines the specificity of response. Many chemoreceptors were found to recognize different amino and organic acids, but the McpU chemoreceptor from Pseudomonas putida was identified as the first chemoreceptor that bound specifically polyamines. We report here the three-dimensional structure of McpU-LBD in complex with putrescine at a resolution of 2.4 angstrom, which fitted well a solution structure generated by small-angle X-ray scattering. Putrescine bound to a negatively charged pocket in the membrane distal module of McpU-LBD. Similarities exist in the binding of putrescine to McpU-LBD and taurine to the LBD of the MIp37 chemoreceptor of Vibrio cholerae. In both structures, the primary amino group of the respective ligand is recognized by hydrogen bonds established by two aspartate and a tyrosine side chain. This feature may be used to predict the ligands of chemoreceptors with unknown function. Analytical ultracentrifugation revealed that McpU-LBD is monomeric in solution and that ligand binding does not alter this oligomeric state. This sensing mode thus differs from that of the well-characterised four-helix bundle domains where ligands bind to two sites at the LBD dimer interface. Although there appear to be different sensing modes, results are discussed in the context of data, indicating that chemoreceptors employ the same mechanism of transmembrane signaling. This work enhances our understanding of CACHE domains, which are the most abundant sensor domains in bacterial chemoreceptors and sensor kinases. (C) 2018 Elsevier Ltd. All rights reserved.