Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, Illinois.
Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, Illinois.
Biophys J. 2012 Aug 8;103(3):L23-L25. doi: 10.1016/j.bpj.2012.06.030.
The Ciona intestinalis voltage-sensitive phosphatase (Ci-VSP) represents the first discovered member of enzymes regulated by a voltage-sensor domain (VSD) related to the VSD found in voltage-gated ion channels. Although the VSD operation in Ci-VSP exhibits original voltage dependence and kinetics compared to ion channels, it has been poorly investigated. Here, we show that the kinetics and voltage dependence of VSD movement in Ci-VSP can be tuned over 2 orders of magnitude and shifted over 120 mV, respectively, by the size of a conserved isoleucine (I126) in the S1 segment, thus indicating the importance of this residue in Ci-VSP activation. Mutations of the conserved Phe in the S2 segment (F161) do not significantly perturb the voltage dependence of the VSD movement, suggesting a unique voltage sensing mechanism in Ci-VSP.
秀丽隐杆线虫电压敏感磷酸酶（Ci-VSP）是第一个被发现的受电压传感器域（VSD）调控的酶，该 VSD 与电压门控离子通道中的 VSD 有关。尽管 Ci-VSP 中的 VSD 与离子通道相比，其工作方式具有独特的电压依赖性和动力学特征，但尚未得到充分研究。在这里，我们表明，S1 片段中保守的异亮氨酸（I126）的大小可以使 Ci-VSP 中的 VSD 运动的动力学和电压依赖性分别在 2 个数量级内进行调节，并向超过 120 mV 移动，这表明该残基对 Ci-VSP 的激活很重要。S2 片段中保守的苯丙氨酸（F161）的突变不会显著改变 VSD 运动的电压依赖性，这表明 Ci-VSP 具有独特的电压感应机制。
