European Biophysics Journal

, 38:465

Movements of native C505 during channel gating in CNGA1 channels

Original Paper

DOI: 10.1007/s00249-008-0396-7

Cite this article as:
Nair, A.V., Anselmi, C. & Mazzolini, M. Eur Biophys J (2009) 38: 465. doi:10.1007/s00249-008-0396-7

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. Cd2+ (200 μM) inhibited irreversibly mutant channels Q409C and A414C in the closed but not in the open state. Cd2+ inhibition was abolished in the mutant A414Ccys-free, in the double mutant A414C + C505T and in the tandem construct A414C + C505T/CNGA1, but it was present in the construct A414C + C505cys-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 Cα of C505 in the closed state is located at a distance between 4 and 10.5 Å from the Cα 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 Å from Cα 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.

Keywords

GatingIonic channelsCNGA1 channelsCd2+ inhibitionS6 domain

Abbreviations

CNG

Cyclic nucleotide-gated

CNBD

Cyclic nucleotide-binding domain

CSM

Cysteine scanning mutagenesis

MTS

Methanethiosulfonate

M-2-M

1,2-Ethanediyl bismethanethiosulfonate

M-4-M

1,4-Butanediyl bismethanethiosulfonate

DTT

Dithiothreitol

Copyright information

© European Biophysical Societies' Association 2008

Authors and Affiliations

  • Anil V. Nair
    • 1
    • 3
  • Claudio Anselmi
    • 1
    • 2
  • Monica Mazzolini
    • 1
  1. 1.SISSA, International School for Advanced StudiesBasovizza (TS)Italy
  2. 2.SISSA and CNR-INFM-DEMOCRITOS Modeling Center for Research in Atomistic SimulationTriesteItaly
  3. 3.Department of Physiology, Nijmegen Centre for Molecular Life SciencesRadboud University, Nijmegen Medical CentreNijmegenThe Netherlands