Allosteric modulation balances thermodynamic stability and restores function of Δf508 CFTR

Andrei A. Aleksandrov, Pradeep Kota, Liying Cui, Tim Jensen, Alexey E. Alekseev, Santiago Reyes, Lihua He, Martina Gentzsch, Luba A. Aleksandrov, Nikolay V. Dokholyan, John R. Riordan

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60 Scopus citations

Abstract

Most cystic fibrosis is caused by a deletion of a single residue (F508) in CFTR (cystic fibrosis transmembrane conductance regulator) that disrupts the folding and biosynthetic maturation of the ion channel protein. Progress towards understanding the underlying mechanisms and overcoming the defect remains incomplete. Here, we show that the thermal instability of human ΔF508 CFTR channel activity evident in both cell-attached membrane patches and planar phospholipid bilayers is not observed in corresponding mutant CFTRs of several non-mammalian species. These more stable orthologs are distinguished from their mammalian counterparts by the substitution of proline residues at several key dynamic locations in first N-terminal nucleotide-binding domain (NBD1), including the structurally diverse region, the γ-phosphate switch loop, and the regulatory insertion. Molecular dynamics analyses revealed that addition of the prolines could reduce flexibility at these locations and increase the temperatures of unfolding transitions of ΔF508 NBD1 to that of the wild type. Introduction of these prolines experimentally into full-length human ΔF508 CFTR together with the already recognized I539T suppressor mutation, also in the structurally diverse region, restored channel function and thermodynamic stability as well as its trafficking to and lifetime at the cell surface. Thus, while cellular manipulations that circumvent its culling by quality control systems leave ΔF508 CFTR dysfunctional at physiological temperature, restoration of the delicate balance between the dynamic protein's inherent stability and channel activity returns a near-normal state.

Original languageEnglish (US)
Pages (from-to)41-60
Number of pages20
JournalJournal of Molecular Biology
Volume419
Issue number1-2
DOIs
StatePublished - May 25 2012

All Science Journal Classification (ASJC) codes

  • Structural Biology
  • Molecular Biology

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    Aleksandrov, A. A., Kota, P., Cui, L., Jensen, T., Alekseev, A. E., Reyes, S., He, L., Gentzsch, M., Aleksandrov, L. A., Dokholyan, N. V., & Riordan, J. R. (2012). Allosteric modulation balances thermodynamic stability and restores function of Δf508 CFTR. Journal of Molecular Biology, 419(1-2), 41-60. https://doi.org/10.1016/j.jmb.2012.03.001