European Biophysics Journal

, Volume 38, Issue 7, pp 993–1002

Conformational rearrangements in the S6 domain and C-linker during gating in CNGA1 channels

  • Anil V. Nair
  • Chuong H. H. Nguyen
  • Monica Mazzolini
Original Paper

DOI: 10.1007/s00249-009-0491-4

Cite this article as:
Nair, A.V., Nguyen, C.H.H. & Mazzolini, M. Eur Biophys J (2009) 38: 993. doi:10.1007/s00249-009-0491-4

Abstract

This work completes previous findings and, using cysteine scanning mutagenesis (CSM) and biochemical methods, provides detailed analysis of conformational changes of the S6 domain and C-linker during gating of CNGA1 channels. Specific residues between Phe375 and Val424 were mutated to a cysteine in the CNGA1 and CNGA1cys-free background and the effect of intracellular Cd2+ or cross-linkers of different length in the open and closed state was studied. In the closed state, Cd2+ ions inhibited mutant channels A406C and Q409C and the longer cross-linker reagent M-4-M inhibited mutant channels A406Ccys-free and Q409Ccys-free. Cd2+ ions inhibited mutant channels D413C and Y418C in the open state, both constructed in a CNGA1 and CNGA1cys-free background. Our results suggest that, in the closed state, residues from Phe375 to approximately Ala406 form a helical bundle with a three-dimensional (3D) structure similar to those of the KcsA; furthermore, in the open state, residues from Ser399 to Gln409 in homologous subunits move far apart, as expected from the gating in K+ channels; in contrast, residues from Asp413 to Tyr418 in homologous subunits become closer in the open state.

Keywords

GatingCNGA1 channelsCd2+ inhibitionPoreS6 domain, C-linker

Abbreviations

CNG

Cyclic nucleotide-gated

CNBD

Cyclic nucleotide-binding domain

CSM

Cysteine scanning mutagenesis

MTS

Methanethiosulfonate

MTSET

2-(Trimethylammonium)ethyl] methanethiosulfonate bromide

MTSPT

3-(Trimethylammonium)propyl methanethiosulfonate bromide

MTS-PtrEA

3-(Triethylammonium)propyl methanthiosulfonate bromide

M-2-M

1,2-Ethanediyl bismethanethiosulfonate

M-4-M

1,4-Butanediyl bismethanethiosulfonate

M-6-M

1,6-Hexanediyl bismethanethiosulfonate

Supplementary material

249_2009_491_MOESM1_ESM.doc (88 kb)
Supplementary material 1 (DOC 88 kb)

Copyright information

© European Biophysical Societies' Association 2009

Authors and Affiliations

  • Anil V. Nair
    • 1
    • 2
  • Chuong H. H. Nguyen
    • 1
  • Monica Mazzolini
    • 1
    • 3
  1. 1.International School for Advanced StudiesTriesteItaly
  2. 2.Department of PhysiologyNijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical CentreNijmegenThe Netherlands
  3. 3.International School for Advanced StudiesTriesteItaly