Chimeric constructs endow the human CFTR Cl(-)channel with the gating behavior of murine CFTR

Toby S. Scott-Ward, Zhiwei Cai, Elizabeth S. Dawson, Ann Doherty, Ana Carina Da Paula, Heather Davidson, David J. Porteous, Brandon J. Wainwright, Margarida D. Amaral, David N. Sheppard*, A. Christopher Boyd

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

36 Citations (Scopus)

Abstract

The cystic fibrosis transmembrane conductance regulator (CFTR) is a Cl- channel gated by ATP-driven nucleotide-binding domain (NBD) dimerization. Here we exploit species differences between human and murine CFTR to investigate CFTR channel gating. Using homologous recombination, we constructed human-murine CFTR (hmCFTR) chimeras with sequences from NBD1, NBD2, or the regulatory domain (RD) of human CFTR replaced by the equivalent regions of murine CFTR. The gating behavior of hmRD and human CFTR were indistinguishable, whereas hmNBD1 and hmNBD2 had subtle effects on channel gating, prolonging both burst duration and interburst interval. By contrast, hmNBD1+2, containing both NBDs of murine CFTR, reproduced the gating behavior of the subconductance state of murine CFTR, which has dramatically prolonged channel openings. The CFTR potentiator pyrophosphate (PPi) enhanced human, hmRD, and hmNBD1 CFTR Cl- currents, but not those of hmNBD2, hmNBD1+2, and murine CFTR. By analyzing the rate-equilibrium free-energy relationships of chimeric channels, we obtained snapshots of the conformation of the NBDs during ATIP-driven dimerization. Our data demonstrate that the conformation of NBD1 changes before that of NBD2 during channel opening. This finding suggests that NBD dimerization does not proceed by a symmetric tweezer-like motion, but instead in an asymmetric fashion led by NBD1. We conclude that the NBDs of murine CFTR determine the unique gating behavior of its subconductance state, whereas NBD2 controls channel potentiation by PPi.

Translated title of the contributionChimeric constructs endow the human CFTR Cl- channel with the gating behaviour of murine CFTR
Original languageEnglish
Pages (from-to)16365-16370
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume104
Issue number41
DOIs
Publication statusPublished - 9 Oct 2007

Bibliographical note

Publisher: National Academy of Sciences

Keywords

  • ATP-binding cassette transporter
  • chloride ion channel
  • cystic fibrosis
  • recombinational cloning
  • rate-equilibrium free-energy relationships
  • TRANSMEMBRANE-CONDUCTANCE-REGULATOR
  • NUCLEOTIDE-BINDING DOMAINS
  • ADENYLATE KINASE-ACTIVITY
  • CYSTIC-FIBROSIS
  • CL-CHANNELS
  • WILD-TYPE
  • MUTATIONS
  • MECHANISM
  • CLONING
  • CELLS

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