Allosteric mechanism of signal transduction in the two-component system histidine kinase PhoQ.
Allosteric mechanism of signal transduction in the two-component system histidine kinase PhoQ.
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DOI：
10.7554/elife.73336
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发表时间：
2021-12-14
期刊：
影响因子：
7.7
通讯作者：
DeGrado WF
中科院分区：
文献类型：
--
作者：
Mensa B;Polizzi NF;Molnar KS;Natale AM;Lemmin T;DeGrado WF
跨膜信号蛋白偶联胞外传感器的胞质效应。在这里，我们研究如何结合Mg 2+的传感器域的E。coli双组分组氨酸激酶（HK），PhoQ，调节其胞质激酶结构域。我们使用半胱氨酸交联和荧光素酶基因测定，同时和独立的探测信号状态的PhoQ的传感器和自激酶结构域在一组超过30个突变体。引人注目的是，远离传感器或催化位点的保守单位点突变强烈影响PhoQ的配体敏感性以及信号的大小和方向。来自35个突变体的数据解释了一个半经验的三域模型，其中传感器，干预HAMP，和催化结构域可以采用激酶促进或抑制构象，在变构通信。催化和传感器结构域本质上有利于组成型“激酶上”构象，而HAMP结构域有利于“关闭”状态;当耦合时，它们创建响应于生理浓度的Mg 2+的酶系统。突变通过局部调节结构域内在平衡常数和结构域间耦合来改变信号传导。我们的模型表明，通过域间变构信号传输，而不是一个单一的协同构象变化的传播，解释了在个别HK域中观察到的信号结构转变的多样性。
Transmembrane signaling proteins couple extracytosolic sensors to cytosolic effectors. Here, we examine how binding of Mg2+ to the sensor domain of an E. coli two component histidine kinase (HK), PhoQ, modulates its cytoplasmic kinase domain. We use cysteine-crosslinking and reporter-gene assays to simultaneously and independently probe the signaling state of PhoQ’s sensor and autokinase domains in a set of over 30 mutants. Strikingly, conservative single-site mutations distant from the sensor or catalytic site strongly influence PhoQ’s ligand-sensitivity as well as the magnitude and direction of the signal. Data from 35 mutants are explained by a semi-empirical three-domain model in which the sensor, intervening HAMP, and catalytic domains can adopt kinase-promoting or inhibiting conformations that are in allosteric communication. The catalytic and sensor domains intrinsically favor a constitutively ‘kinase-on’ conformation, while the HAMP domain favors the ‘off’ state; when coupled, they create a bistable system responsive to physiological concentrations of Mg2+. Mutations alter signaling by locally modulating domain intrinsic equilibrium constants and interdomain couplings. Our model suggests signals transmit via interdomain allostery rather than propagation of a single concerted conformational change, explaining the diversity of signaling structural transitions observed in individual HK domains.
影响因子：
5.6
作者：
Yusuf R;Draheim RR
通讯作者：
Draheim RR