Specificity of the BvgAS and EvgAS phosphorelay is mediated by the C-terminal HPt domains of the sensor proteins
Specificity of the BvgAS and EvgAS phosphorelay is mediated by the C-terminal HPt domains of the sensor proteins
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DOI：
10.1046/j.1365-2958.1998.00716.x
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发表时间：
1998-03-01
影响因子：
3.6
通讯作者：
Gross, R
中科院分区：
文献类型：
--
作者：
Perraud, AL;Kimmel, B;Gross, R
尽管存在高度保守的信令模块，但很少观察到不同的双分量系统之间的显著交叉通信。结构域交换和释放的信号模块的表征使我们能够在体外表征介导特异性的蛋白质结构域，并导致非正统的BVG和EVG双组分系统的磷光传递的高保真。在等摩尔条件下，纯化的BvgA和EVGA蛋白仅通过其组氨酸激酶BvgS和EvgS在体外获得显著的磷酸化。一种由BvgS传递域和HPT结构域以及EvgS受体结构域(BvgS-to-EvgS-R)组成的杂合组氨酸激酶能够磷酸化BvgA，但不能磷酸化EVGA。相反，由BvgS递质、EvgS受体和HPT结构域组成的杂合蛋白(BvgS-T-EvgS-RO)不能磷酸化BvgA，但能有效地磷酸化EVGA。这些结果表明，传感器蛋白的C-末端HPT结构域赋予非常规的双组分系统对相应的调节蛋白具有高度的特异性。在反应调节子的情况下，接收域而不是输出域参与了与组氨酸激酶的特异性相互作用，因为由EVGA接收域和BvgA输出域组成的杂交蛋白只能被EvgS蛋白磷酸化。
Despite the presence of highly conserved signalling modules, significant cross-communication between different two-component systems has only rarely been observed. Domain swapping and the characterization of liberated signalling modules enabled us to characterize in vitro the protein domains that mediate specificity and are responsible for the high fidelity in the phosphorelay of the unorthodox Bvg and Evg two-component systems. Under equimolar conditions, significant in vitro phosphorylation of purified BvgA and EvgA proteins was only obtained by their histidine kinases, BvgS and EvgS respectively. One hybrid histidine kinase consisting of the BvgS transmitter and HPt domains and of the EvgS receiver domain (BvgS-TO-EvgS-R) was able to phosphorylate BvgA but not EvgA. In contrast, the hybrid protein consisting of the BvgS transmitter and the EvgS receiver and HPt domains (BvgS-T-EvgS-RO) was unable to phosphorylate BvgA but efficiently phosphorylated EvgA. These results demonstrate that the C-terminal HPt domains of the sensor proteins endow the unorthodox two-component systems with a high specificity for the corresponding regulator protein. In the case of the response regulators, the receiver but not the output domains contribute to the specific interaction with the histidine kinases, because a hybrid protein consisting of the EvgA receiver and the BvgA output domain could only be phosphorylated by the EvgS protein.