Creation of a Reactive Oxygen Species-Insensitive Kcv Channel

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• 作者：Indra Schroeder ; Sabrina Gazzarrini ; Giuseppina Ferrara ; Gerhard Thiel ; Ulf-Peter Hansen ; Anna Moroni
• 刊名：Biochemistry
• 出版年：2013
• 出版时间：May 7, 2013
• 年：2013
• 卷：52
• 期：18
• 页码：3130-3137
• 全文大小：394K
• 年卷期：v.52,no.18(May 7, 2013)
• ISSN：1520-4995

文摘

The current of the minimal viral K⁺ channel Kcv_PCBV-1 heterologously expressed in Xenopus oocytes is strongly inhibited by reactive oxygen species (ROS) like H₂O₂. Possible targets for the ROS effect are two cysteines (C53 and C79) and four methionines (M1, M15, M23, and M26). The C53A/C79A and M23L/M26L double mutations maintained the same ROS sensitivity as the wild type. However, M15L as a single mutant or in combination with C53A/C79A and/or M23L/M26L caused a complete loss of sensitivity to H₂O₂. These results indicate a prominent role of M15 at the cytosolic end of the outer transmembrane helix for gating of Kcv_PCBV-1. Furthermore, even though the channel lacks a canonical voltage sensor, it exhibits a weak voltage sensitivity, resulting in a slight activation in the millisecond range after a voltage step to negative potentials. The M15L mutation inverts this kinetics into an inactivation, underlining the critical role of this residue for gating. The negative slope of the I鈥?i>V curves of M15L is the same as in the wild type, indicating that the selectivity filter is not involved.