Arg352 is a major determinant of charge selectivity in the cystic fibrosis transmembrane conductance regulator chloride channel

Romain Guinamard, Myles Akabas

Research output: Contribution to journalArticle

33 Citations (Scopus)

Abstract

The cystic fibrosis transmembrane conductance regulator forms an anion- selective channel. We previously showed that charge selectivity, the ability to discriminate between anions and cations, occurs near the cytoplasmic end of the channel. The molecular determinants of charge selectivity, however, are unknown. We investigated the role of Arg352, a residue flanking the predicted cytoplasmic end of the M6 segment, in the mechanism of charge selectivity. We determined the Cl- to Na+ permeability ratio (P(Cl)/P(Na)) from the reversal potential measured in a 10-fold NaCl gradient. For the wild type, P(Cl)/P(Na) was 36 (range of 28-51). For the R352H mutant, P(Cl)/P(Na) was dependent on cytoplasmic pH. At pH 5.4, the P(Cl)/P(Na) was 33 (range of 27-41), similar to that of the wild type, but at pH 7.2, where the histidine should be largely uncharged, P(Cl)/P(Na) was 3 (range of 2.9-3.1). For the R352C and R352Q mutants, P(Cl)/P(Na) was 7 (range of 6-8) and 4 (range of 3.5-4.4), respectively. Furthermore, Na+ which does not carry a significant fraction of the current through the wild type is measurably conducted through R352Q. Thus, the charge of the side chain at position 352 is a strong determinant of charge selectivity. In the wild type, the positive charge on Arg352 contributes to an electrostatic potential in the channel that forms a barrier to cation permeation. Mutation of Arg352 did not alter the halide selectivity sequence. Selectivity among halides must involve other residues.

Original languageEnglish (US)
Pages (from-to)5528-5537
Number of pages10
JournalBiochemistry
Volume38
Issue number17
DOIs
StatePublished - Apr 27 1999
Externally publishedYes

Fingerprint

Cystic Fibrosis Transmembrane Conductance Regulator
Chloride Channels
Anions
Cations
Histidine
Permeation
Electrostatics
Static Electricity
Permeability
Mutation

ASJC Scopus subject areas

  • Biochemistry

Cite this

Arg352 is a major determinant of charge selectivity in the cystic fibrosis transmembrane conductance regulator chloride channel. / Guinamard, Romain; Akabas, Myles.

In: Biochemistry, Vol. 38, No. 17, 27.04.1999, p. 5528-5537.

Research output: Contribution to journalArticle

@article{8eff5f53fe90401892cc339fbe4bc987,
title = "Arg352 is a major determinant of charge selectivity in the cystic fibrosis transmembrane conductance regulator chloride channel",
abstract = "The cystic fibrosis transmembrane conductance regulator forms an anion- selective channel. We previously showed that charge selectivity, the ability to discriminate between anions and cations, occurs near the cytoplasmic end of the channel. The molecular determinants of charge selectivity, however, are unknown. We investigated the role of Arg352, a residue flanking the predicted cytoplasmic end of the M6 segment, in the mechanism of charge selectivity. We determined the Cl- to Na+ permeability ratio (P(Cl)/P(Na)) from the reversal potential measured in a 10-fold NaCl gradient. For the wild type, P(Cl)/P(Na) was 36 (range of 28-51). For the R352H mutant, P(Cl)/P(Na) was dependent on cytoplasmic pH. At pH 5.4, the P(Cl)/P(Na) was 33 (range of 27-41), similar to that of the wild type, but at pH 7.2, where the histidine should be largely uncharged, P(Cl)/P(Na) was 3 (range of 2.9-3.1). For the R352C and R352Q mutants, P(Cl)/P(Na) was 7 (range of 6-8) and 4 (range of 3.5-4.4), respectively. Furthermore, Na+ which does not carry a significant fraction of the current through the wild type is measurably conducted through R352Q. Thus, the charge of the side chain at position 352 is a strong determinant of charge selectivity. In the wild type, the positive charge on Arg352 contributes to an electrostatic potential in the channel that forms a barrier to cation permeation. Mutation of Arg352 did not alter the halide selectivity sequence. Selectivity among halides must involve other residues.",
author = "Romain Guinamard and Myles Akabas",
year = "1999",
month = "4",
day = "27",
doi = "10.1021/bi990155n",
language = "English (US)",
volume = "38",
pages = "5528--5537",
journal = "Biochemistry",
issn = "0006-2960",
publisher = "American Chemical Society",
number = "17",

}

TY - JOUR

T1 - Arg352 is a major determinant of charge selectivity in the cystic fibrosis transmembrane conductance regulator chloride channel

AU - Guinamard, Romain

AU - Akabas, Myles

PY - 1999/4/27

Y1 - 1999/4/27

N2 - The cystic fibrosis transmembrane conductance regulator forms an anion- selective channel. We previously showed that charge selectivity, the ability to discriminate between anions and cations, occurs near the cytoplasmic end of the channel. The molecular determinants of charge selectivity, however, are unknown. We investigated the role of Arg352, a residue flanking the predicted cytoplasmic end of the M6 segment, in the mechanism of charge selectivity. We determined the Cl- to Na+ permeability ratio (P(Cl)/P(Na)) from the reversal potential measured in a 10-fold NaCl gradient. For the wild type, P(Cl)/P(Na) was 36 (range of 28-51). For the R352H mutant, P(Cl)/P(Na) was dependent on cytoplasmic pH. At pH 5.4, the P(Cl)/P(Na) was 33 (range of 27-41), similar to that of the wild type, but at pH 7.2, where the histidine should be largely uncharged, P(Cl)/P(Na) was 3 (range of 2.9-3.1). For the R352C and R352Q mutants, P(Cl)/P(Na) was 7 (range of 6-8) and 4 (range of 3.5-4.4), respectively. Furthermore, Na+ which does not carry a significant fraction of the current through the wild type is measurably conducted through R352Q. Thus, the charge of the side chain at position 352 is a strong determinant of charge selectivity. In the wild type, the positive charge on Arg352 contributes to an electrostatic potential in the channel that forms a barrier to cation permeation. Mutation of Arg352 did not alter the halide selectivity sequence. Selectivity among halides must involve other residues.

AB - The cystic fibrosis transmembrane conductance regulator forms an anion- selective channel. We previously showed that charge selectivity, the ability to discriminate between anions and cations, occurs near the cytoplasmic end of the channel. The molecular determinants of charge selectivity, however, are unknown. We investigated the role of Arg352, a residue flanking the predicted cytoplasmic end of the M6 segment, in the mechanism of charge selectivity. We determined the Cl- to Na+ permeability ratio (P(Cl)/P(Na)) from the reversal potential measured in a 10-fold NaCl gradient. For the wild type, P(Cl)/P(Na) was 36 (range of 28-51). For the R352H mutant, P(Cl)/P(Na) was dependent on cytoplasmic pH. At pH 5.4, the P(Cl)/P(Na) was 33 (range of 27-41), similar to that of the wild type, but at pH 7.2, where the histidine should be largely uncharged, P(Cl)/P(Na) was 3 (range of 2.9-3.1). For the R352C and R352Q mutants, P(Cl)/P(Na) was 7 (range of 6-8) and 4 (range of 3.5-4.4), respectively. Furthermore, Na+ which does not carry a significant fraction of the current through the wild type is measurably conducted through R352Q. Thus, the charge of the side chain at position 352 is a strong determinant of charge selectivity. In the wild type, the positive charge on Arg352 contributes to an electrostatic potential in the channel that forms a barrier to cation permeation. Mutation of Arg352 did not alter the halide selectivity sequence. Selectivity among halides must involve other residues.

UR - http://www.scopus.com/inward/record.url?scp=0033608961&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0033608961&partnerID=8YFLogxK

U2 - 10.1021/bi990155n

DO - 10.1021/bi990155n

M3 - Article

VL - 38

SP - 5528

EP - 5537

JO - Biochemistry

JF - Biochemistry

SN - 0006-2960

IS - 17

ER -