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Cystic Fibrosis-associated Mutations at Arginine 347 Alter the Pore Architecture of CFTR: EVIDENCE FOR DISRUPTION OF A SALT BRIDGE
Journal article   Open access   Peer reviewed

Cystic Fibrosis-associated Mutations at Arginine 347 Alter the Pore Architecture of CFTR: EVIDENCE FOR DISRUPTION OF A SALT BRIDGE

Joseph F Cotten and Michael J Welsh
The Journal of biological chemistry, Vol.274(9), pp.5429-5435
02/26/1999
DOI: 10.1074/jbc.274.9.5429
PMID: 10026154
url
https://doi.org/10.1074/jbc.274.9.5429View
Published (Version of record) Open Access

Abstract

Arginine 347 in the sixth transmembrane domain of cystic fibrosis transmembrane conductance regulator (CFTR) is a site of four cystic fibrosis-associated mutations. To better understand the function of Arg-347 and to learn how mutations at this site disrupt channel activity, we mutated Arg-347 to Asp, Cys, Glu, His, Leu, or Lys and examined single-channel function. Every Arg-347 mutation examined, except R347K, had a destabilizing effect on the pore, causing the channel to flutter between two conductance states. Chloride flow through the larger conductance state was similar to that of wild-type CFTR, suggesting that the residue at position 347 does not interact directly with permeating anions. We hypothesized that Arg-347 stabilizes the channel through an electrostatic interaction with an anionic residue in another transmembrane domain. To test this, we mutated anionic residues (Asp-924, Asp-993, and Glu-1104) to Arg in the context of either R347E or R347D mutations. Interestingly, the D924R mutation complemented R347D, yielding a channel that behaved like wild-type CFTR. These data suggest that Arg-347 plays an important structural role in CFTR, at least in part by forming a salt bridge with Asp-924; cystic fibrosis-associated mutations disrupt this interaction.

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