Insights into signal transduction revealed by the low resolution structure of the FixJ response regulator
Insights into signal transduction revealed by the low resolution structure of the FixJ response regulator
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DOI：
10.1016/s0022-2836(02)00651-4
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发表时间：
2002-08-16
影响因子：
5.6
通讯作者：
Samama, JP
中科院分区：
文献类型：
--
作者：
Birck, C;Malfois, M;Samama, JP
双组分调节系统介导大多数细菌细胞对各种信号的反应。在苜蓿中华根瘤菌中，FixL-FixJ对通过两个结构域的反应调节因子FixJ与fixK和nifA启动子的结合来控制固氮基因的表达。N-末端调节结构域的磷酸化激活蛋白质并释放在未磷酸化蛋白质中发生的C-末端DNA结合结构域的抑制。本研究报告的非磷酸化反应调节因子的结构提供了从非活性形式到活性形式转变的见解。从小角X射线散射（SAXS）数据恢复的分子包络的N和C-末端域的相对位置和取向被定义。生物化学研究支持调控结构域的α 4-β 5-α 5表面、接头区和DNA结合结构域的C-末端螺旋参与未磷酸化FixJ的结构域间界面。这些结果，与以前报道的研究磷酸化的调节域的FixJ，强调的作用，α 4-β 5-α 5表面介导的信息流在这个响应调节。这第一次研究SAXS的蛋白质从两个组件系统表明，该方法可以成功地应用于这个家庭的其他成员，并可能适合于研究多结构域蛋白质和蛋白质-蛋白质复合物通过分子界面在低微摩尔范围内调节。(C)2002爱思唯尔科技有限公司版权所有。
Two-component regulatory systems mediate most of the bacterial cells responses to a variety of signals. In Sinorhizobium meliloti, the FixL-FixJ couple controls the expression of the nitrogen fixation genes through the binding of the two-domains response regulator FixJ to the fixK and nifA promoters. Phosphorylation of the N-terminal regulatory domain activates the protein and releases the inhibition of the C-terminal DNA-binding domain that occurs in the unphosphorylated protein. Insights into the transition from the inactive to the active form are provided by the architecture of the unphosphorylated response regulator reported in this study. The relative position and orientation of the N and C-terminal domains were defined from the molecular envelope restored from small-angle X-ray scattering (SAXS) data. The involvement of the alpha4-beta5-alpha5 surface of the regulatory domain, the linker region and the C-terminal helix of the DNA-binding domain in the interdomain interface of unphosphorylated FixJ was supported by biochemical investigations. These results, together with the previously reported studies on the phosphorylated regulatory domain of FixJ, emphasize the role of the alpha4-beta5-alpha5 surface in mediating a flow of information in this response regulator. This first study by SAXS of proteins from two-component systems suggests that the method could be successfully applied to other members of this family and could be suitable for the study of multidomain proteins and protein-protein complexes regulated through molecular interfaces in the low micromolar range. (C) 2002 Elsevier Science Ltd. All rights reserved.