scholarly journals Cystic Fibrosis Transmembrane Conductance Regulator: Temperature-Dependent Cysteine Reactivity Suggests Different Stable Conformers of the Conduction Pathway

Biochemistry ◽  
2011 ◽  
Vol 50 (47) ◽  
pp. 10311-10317 ◽  
Author(s):  
Xuehong Liu ◽  
David C. Dawson
Keyword(s):  
Cystic Fibrosis ◽  
Transmembrane Conductance Regulator ◽  
Transmembrane Conductance ◽  
Temperature Dependent ◽  
Conduction Pathway ◽  
Cystic Fibrosis Transmembrane

scholarly journals Cholesterol Interaction Directly Enhances Intrinsic Activity of the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR)

Cells ◽  
2019 ◽  
Vol 8 (8) ◽  
pp. 804 ◽  
Author(s):  
Chin ◽  
Ramjeesingh ◽  
Hung ◽  
Ereño-Oreba ◽  
Cui ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Catalytic Activity ◽  
Intrinsic Activity ◽  
Transmembrane Conductance Regulator ◽  
Channel Activity ◽  
Transmembrane Conductance ◽  
Activity Measurements ◽  
Conduction Pathway ◽  
Cftr Protein ◽  
Cystic Fibrosis Transmembrane

The recent cryo-electron microscopy structures of zebrafish and the human cystic fibrosis transmembrane conductance regulator (CFTR) provided unprecedented insights into putative mechanisms underlying gating of its anion channel activity. Interestingly, despite predictions based on channel activity measurements in biological membranes, the structure of the detergent purified, phosphorylated, and ATP-bound human CFTR protein did not reveal a stably open conduction pathway. This study tested the hypothesis that the functional properties of the detergent solubilized CFTR protein used for structural determinations are different from those exhibited by CFTR purified under conditions that retain associated lipids native to the membrane. It was found that CFTR purified together with phospholipids and cholesterol using amphipol: A8-35, exhibited higher rates of catalytic activity, phosphorylation dependent channel activation and potentiation by the therapeutic compound, ivacaftor, than did CFTR purified in detergent. The catalytic activity of phosphorylated CFTR detergent micelles was rescued by the addition of phospholipids plus cholesterol, but not by phospholipids alone, arguing for a specific role for cholesterol in modulating this function. In summary, these studies highlight the importance of lipid interactions in the intrinsic activities and pharmacological potentiation of CFTR.

scholarly journals Alteration of CFTR transmembrane span integration by disease-causing mutations

2011 ◽  
Vol 22 (23) ◽  
pp. 4461-4471 ◽  
Author(s):  
Anna E. Patrick ◽  
Andrey L. Karamyshev ◽  
Linda Millen ◽  
Philip J. Thomas
Keyword(s):  
Cystic Fibrosis ◽  
Endoplasmic Reticulum ◽  
Side Chain ◽  
Missense Mutations ◽  
Transmembrane Conductance Regulator ◽  
Transmembrane Conductance ◽  
Temperature Dependent ◽  
Regulator Protein ◽  
Cystic Fibrosis Transmembrane ◽  
Transmembrane Span

Many missense mutations in the cystic fibrosis transmembrane conductance regulator protein (CFTR) result in its misfolding, endoplasmic reticulum (ER) accumulation, and, thus, cystic fibrosis. A number of these mutations are located in the predicted CFTR transmembrane (TM) spans and have been projected to alter span integration. However, the boundaries of the spans have not been precisely defined experimentally. In this study, the ER luminal integration profiles of TM1 and TM2 were determined using the ER glycosylation machinery, and the effects of the CF-causing mutations G85E and G91R thereon were assessed. The mutations either destabilize the integrated conformation or alter the TM1 ER integration profile. G85E misfolding is based in TM1 destabilization by glutamic acid and loss of glycine and correlates with the temperature-insensitive ER accumulation of immature full-length CFTR harboring the mutation. By contrast, temperature-dependent misfolding owing to the G91R mutation depends on the introduction of the basic side chain rather than the loss of the glycine. This work demonstrates that CF-causing mutations predicted to have similar effects on CFTR structure actually result in disparate molecular perturbations that underlie ER accumulation and the pathology of CF.

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