Computational Studies Reveal Phosphorylation-dependent Changes in the Unstructured R Domain of CFTR

T. Hegedűs, Adrian W R Serohijos, Nikolay V. Dokholyan, Lihua He, John R. Riordan

Research output: Contribution to journalArticle

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Abstract

The cystic fibrosis transmembrane conductance regulator (CFTR) is a cAMP-dependent chloride channel that is mutated in cystic fibrosis, an inherited disease of high morbidity and mortality. The phosphorylation of its ∼ 200 amino acid R domain by protein kinase A is obligatory for channel gating under normal conditions. The R domain contains more than ten PKA phosphorylation sites. No individual site is essential but phosphorylation of increasing numbers of sites enables progressively greater channel activity. In spite of numerous studies of the role of the R domain in CFTR regulation, its mechanism of action remains largely unknown. This is because neither its structure nor its interactions with other parts of CFTR have been completely elucidated. Studies have shown that the R domain lacks well-defined secondary structural elements and is an intrinsically disordered region of the channel protein. Here, we have analyzed the disorder pattern and employed computational methods to explore low-energy conformations of the R domain. The specific disorder and secondary structure patterns detected suggest the presence of molecular recognition elements (MoREs) that may mediate phosphorylation-regulated intra- and inter-domain interactions. Simulations were performed to generate an ensemble of accessible R domain conformations. Although the calculated structures may represent more compact conformers than occur in vivo, their secondary structure propensities are consistent with predictions and published experimental data. Equilibrium simulations of a mimic of a phosphorylated R domain showed that it exhibited an increased radius of gyration. In one possible interpretation of these findings, by changing its size, the globally unstructured R domain may act as an entropic spring to perturb the packing of membrane-spanning sequences that constitute the ion permeability pathway and thereby activate channel gating.

Original languageEnglish
Pages (from-to)1052-1063
Number of pages12
JournalJournal of Molecular Biology
Volume378
Issue number5
DOIs
Publication statusPublished - May 16 2008

Fingerprint

Cystic Fibrosis Transmembrane Conductance Regulator
Phosphorylation
Chloride Channels
Cyclic AMP-Dependent Protein Kinases
Cystic Fibrosis
Permeability
Ions
Morbidity
Amino Acids
Membranes
Mortality
Proteins

Keywords

  • CFTR
  • disordered protein
  • molecular dynamics
  • phosphorylation
  • R domain

ASJC Scopus subject areas

  • Virology

Cite this

Computational Studies Reveal Phosphorylation-dependent Changes in the Unstructured R Domain of CFTR. / Hegedűs, T.; Serohijos, Adrian W R; Dokholyan, Nikolay V.; He, Lihua; Riordan, John R.

In: Journal of Molecular Biology, Vol. 378, No. 5, 16.05.2008, p. 1052-1063.

Research output: Contribution to journalArticle

Hegedűs, T. ; Serohijos, Adrian W R ; Dokholyan, Nikolay V. ; He, Lihua ; Riordan, John R. / Computational Studies Reveal Phosphorylation-dependent Changes in the Unstructured R Domain of CFTR. In: Journal of Molecular Biology. 2008 ; Vol. 378, No. 5. pp. 1052-1063.
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