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Article: Direct sensing of intracellular pH by the cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channel

TitleDirect sensing of intracellular pH by the cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channel
Authors
Issue Date2009
PublisherAmerican Society for Biochemistry and Molecular Biology, Inc. The Journal's web site is located at http://www.jbc.org/
Citation
Journal Of Biological Chemistry, 2009, v. 284 n. 51, p. 35495-35506 How to Cite?
AbstractIn cystic fibrosis (CF), dysfunction of the cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channel disrupts epithelial ion transport and perturbs the regulation of intracellular pH (pHi). CFTR modulates pHi through its role as an ion channel and by regulating transport proteins. However, it is unknown how CFTR senses pHi. Here, we investigate the direct effects of pHi on recombinant CFTR using excised membrane patches. By altering channel gating, acidic pHi increased the open probability (Po) of wild-type CFTR, whereas alkaline pHi decreased Po and inhibited Cl- flow through the channel. Acidic pHi potentiated the MgATP dependence of wild-type CFTR by increasing MgATP affinity and enhancing channel activity, whereas alkaline pHi inhibited the MgATP dependence of wild-type CFTR by decreasing channel activity. Because these data suggest that pHi modulates the interaction of MgATP with the nucleotide-binding domains (NBDs) of CFTR, we examined the pHi dependence of site-directed mutations in the two ATP-binding sites of CFTR that are located at the NBD1:NBD2 dimer interface (site 1: K464A-, D572N-, and G1349D-CFTR; site 2: G551D-, K1250M-, and D1370N-CFTR). Site 2 mutants, but not site 1 mutants, perturbed both potentiation by acidic pHi and inhibition by alkaline pHi, suggesting that site 2 is a critical determinant of the pHi sensitivity of CFTR. The effects of pHi also suggest that site 2 might employ substrate-assisted catalysis to ensure that ATP hydrolysis follows NBD dimerization. We conclude that the CFTR Cl- channel senses directly pHi. The direct regulation of CFTR by pHi has important implications for the regulation of epithelial ion transport. © 2009 by The American Society for Biochemistry and Molecular Biology, Inc.
Persistent Identifierhttp://hdl.handle.net/10722/137014
ISSN
2015 Impact Factor: 4.258
2015 SCImago Journal Rankings: 3.151
PubMed Central ID
ISI Accession Number ID
Funding AgencyGrant Number
Cystic Fibrosis Trust
University of Bristol
Overseas Research Student award
Funding Information:

This work was supported by the Cystic Fibrosis Trust.

References

 

DC FieldValueLanguage
dc.contributor.authorChen, JHen_HK
dc.contributor.authorCai, Zen_HK
dc.contributor.authorSheppard, DNen_HK
dc.date.accessioned2011-07-29T02:14:17Z-
dc.date.available2011-07-29T02:14:17Z-
dc.date.issued2009en_HK
dc.identifier.citationJournal Of Biological Chemistry, 2009, v. 284 n. 51, p. 35495-35506en_HK
dc.identifier.issn0021-9258en_HK
dc.identifier.urihttp://hdl.handle.net/10722/137014-
dc.description.abstractIn cystic fibrosis (CF), dysfunction of the cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channel disrupts epithelial ion transport and perturbs the regulation of intracellular pH (pHi). CFTR modulates pHi through its role as an ion channel and by regulating transport proteins. However, it is unknown how CFTR senses pHi. Here, we investigate the direct effects of pHi on recombinant CFTR using excised membrane patches. By altering channel gating, acidic pHi increased the open probability (Po) of wild-type CFTR, whereas alkaline pHi decreased Po and inhibited Cl- flow through the channel. Acidic pHi potentiated the MgATP dependence of wild-type CFTR by increasing MgATP affinity and enhancing channel activity, whereas alkaline pHi inhibited the MgATP dependence of wild-type CFTR by decreasing channel activity. Because these data suggest that pHi modulates the interaction of MgATP with the nucleotide-binding domains (NBDs) of CFTR, we examined the pHi dependence of site-directed mutations in the two ATP-binding sites of CFTR that are located at the NBD1:NBD2 dimer interface (site 1: K464A-, D572N-, and G1349D-CFTR; site 2: G551D-, K1250M-, and D1370N-CFTR). Site 2 mutants, but not site 1 mutants, perturbed both potentiation by acidic pHi and inhibition by alkaline pHi, suggesting that site 2 is a critical determinant of the pHi sensitivity of CFTR. The effects of pHi also suggest that site 2 might employ substrate-assisted catalysis to ensure that ATP hydrolysis follows NBD dimerization. We conclude that the CFTR Cl- channel senses directly pHi. The direct regulation of CFTR by pHi has important implications for the regulation of epithelial ion transport. © 2009 by The American Society for Biochemistry and Molecular Biology, Inc.en_HK
dc.languageengen_US
dc.publisherAmerican Society for Biochemistry and Molecular Biology, Inc. The Journal's web site is located at http://www.jbc.org/en_HK
dc.relation.ispartofJournal of Biological Chemistryen_HK
dc.titleDirect sensing of intracellular pH by the cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channelen_HK
dc.typeArticleen_HK
dc.identifier.emailChen, JH: jhlchen@hku.hken_HK
dc.identifier.authorityChen, JH=rp01518en_HK
dc.description.naturelink_to_subscribed_fulltexten_US
dc.identifier.doi10.1074/jbc.M109.072678en_HK
dc.identifier.pmid19837660-
dc.identifier.pmcidPMC2790979-
dc.identifier.scopuseid_2-s2.0-72149099330en_HK
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-72149099330&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume284en_HK
dc.identifier.issue51en_HK
dc.identifier.spage35495en_HK
dc.identifier.epage35506en_HK
dc.identifier.eissn1083-351X-
dc.identifier.isiWOS:000272645600026-
dc.publisher.placeUnited Statesen_HK
dc.identifier.scopusauthoridChen, JH=7501878156en_HK
dc.identifier.scopusauthoridCai, Z=7402905250en_HK
dc.identifier.scopusauthoridSheppard, DN=7201812458en_HK

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