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在CNGA1通道门控过程中天然C505的运动。

Movements of native C505 during channel gating in CNGA1 channels.

作者信息

Nair Anil V, Anselmi Claudio, Mazzolini Monica

机构信息

SISSA, International School for Advanced Studies, Neurobiology Sector, Area Science Park, Edificio Q1, SS 14 Km 163,5, 34012, Basovizza (TS), Italy.

出版信息

Eur Biophys J. 2009 Apr;38(4):465-78. doi: 10.1007/s00249-008-0396-7. Epub 2009 Jan 9.

Abstract

We investigated conformational changes occurring in the C-linker and cyclic nucleotide-binding (CNB) domain of CNGA1 channels by analyzing the inhibition induced by thiol-specific reagents in mutant channels Q409C and A414C in the open and closed state. Cd(2+) (200 microM) inhibited irreversibly mutant channels Q409C and A414C in the closed but not in the open state. Cd(2+) inhibition was abolished in the mutant A414C(cys-free), in the double mutant A414C + C505T and in the tandem construct A414C + C505T/CNGA1, but it was present in the construct A414C + C505(cys-free). The cross-linker reagent M-2-M inhibited mutant channel Q409C in the open state. M-2-M inhibition in the open state was abolished in the double mutant Q409C + C505T and in the tandem construct Q409C + C505T/CNGA1. These results show that C(alpha) of C505 in the closed state is located at a distance between 4 and 10.5 A from the C(alpha) of A414 of the same subunit, but in the open state C505 moves towards Q409 of the same subunit at a distance that ranges from 10.5 to 12.3 A from C(alpha) of this residue. These results are not consistent with a 3-D structure of the CNGA1 channel homologous to the structure of HCN2 channels either in the open or in the closed state.

摘要

我们通过分析巯基特异性试剂对处于开放和关闭状态的突变通道Q409C和A414C的抑制作用,研究了CNGA1通道的C连接子和环核苷酸结合(CNB)结构域中发生的构象变化。Cd(2+)(200 microM)不可逆地抑制处于关闭状态而非开放状态的突变通道Q409C和A414C。在突变体A414C(无半胱氨酸)、双突变体A414C + C505T以及串联构建体A414C + C505T/CNGA1中,Cd(2+)的抑制作用消失,但在构建体A414C + C505(无半胱氨酸)中仍存在。交联剂试剂M-2-M抑制处于开放状态的突变通道Q409C。在双突变体Q409C + C505T和串联构建体Q409C + C505T/CNGA1中,开放状态下的M-2-M抑制作用消失。这些结果表明,在关闭状态下,C505的Cα与同一亚基的A414的Cα之间的距离在4至10.5埃之间,但在开放状态下,C505向同一亚基的Q409移动,与该残基的Cα的距离在10.5至12.3埃之间。这些结果与开放或关闭状态下与HCN2通道结构同源的CNGA1通道的三维结构均不一致。

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