On the interactions between nucleotide binding domains and membrane spanning domains in cystic fibrosis transmembrane regulator: A molecular dynamic study

Biochimie ◽  
2015 ◽  
Vol 111 ◽  
pp. 19-29 ◽  
Author(s):  
Luca Belmonte ◽  
Oscar Moran
Keyword(s):  
Cystic Fibrosis ◽  
Molecular Dynamic ◽  
Nucleotide Binding ◽  
Cystic Fibrosis Transmembrane Regulator ◽  
Dynamic Study ◽  
Binding Domains ◽  
Molecular Dynamic Study ◽  
Membrane Spanning ◽  
Cystic Fibrosis Transmembrane ◽  
Membrane Spanning Domains

scholarly journals Assembly and Misassembly of Cystic Fibrosis Transmembrane Conductance Regulator: Folding Defects Caused by Deletion of F508 Occur Before and After the Calnexin-dependent Association of Membrane Spanning Domain (MSD) 1 and MSD2

2008 ◽  
Vol 19 (11) ◽  
pp. 4570-4579 ◽  
Author(s):  
Meredith F. N. Rosser ◽  
Diane E. Grove ◽  
Liling Chen ◽  
Douglas M. Cyr
Keyword(s):  
Cystic Fibrosis ◽  
Transmembrane Conductance Regulator ◽  
Transmembrane Conductance ◽  
Binding Domains ◽  
Ubiquitin Ligase Complex ◽  
Before And After ◽  
Membrane Spanning ◽  
Polytopic Membrane Protein ◽  
Cystic Fibrosis Transmembrane ◽  
Membrane Spanning Domains

Cystic fibrosis transmembrane conductance regulator (CFTR) is a polytopic membrane protein that functions as a Cl− channel and consists of two membrane spanning domains (MSDs), two cytosolic nucleotide binding domains (NBDs), and a cytosolic regulatory domain. Cytosolic 70-kDa heat shock protein (Hsp70), and endoplasmic reticulum-localized calnexin are chaperones that facilitate CFTR biogenesis. Hsp70 functions in both the cotranslational folding and posttranslational degradation of CFTR. Yet, the mechanism for calnexin action in folding and quality control of CFTR is not clear. Investigation of this question revealed that calnexin is not essential for CFTR or CFTRΔF508 degradation. We identified a dependence on calnexin for proper assembly of CFTR's membrane spanning domains. Interestingly, efficient folding of NBD2 was also found to be dependent upon calnexin binding to CFTR. Furthermore, we identified folding defects caused by deletion of F508 that occurred before and after the calnexin-dependent association of MSD1 and MSD2. Early folding defects are evident upon translation of the NBD1 and R-domain and are sensed by the RMA-1 ubiquitin ligase complex.

scholarly journals Perturbation of the Pore of the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) Inhibits Its ATPase Activity

2000 ◽  
Vol 276 (15) ◽  
pp. 11575-11581 ◽  
Author(s):  
Ilana Kogan ◽  
Mohabir Ramjeesingh ◽  
Ling-Jun Huan ◽  
Yanchun Wang ◽  
Christine E. Bear
Keyword(s):  
Cystic Fibrosis ◽  
Atpase Activity ◽  
Cross Talk ◽  
Nucleotide Binding ◽  
Cystic Fibrosis Gene ◽  
Transmembrane Conductance Regulator ◽  
Transmembrane Conductance ◽  
Binding Domains ◽  
Cystic Fibrosis Transmembrane

Mutations in the cystic fibrosis gene coding for the cystic fibrosis transmembrane conductance regulator (CFTR) lead to altered chloride (Cl−) flux in affected epithelial tissues. CFTR is a Cl−channel that is regulated by phosphorylation, nucleotide binding, and hydrolysis. However, the molecular basis for the functional regulation of wild type and mutant CFTR remains poorly understood. CFTR possesses two nucleotide binding domains, a phosphorylation-dependent regulatory domain, and two transmembrane domains that comprise the pore through which Cl−permeates. Mutations of residues lining the channel pore (e.g.R347D) are typically thought to cause disease by altering the interaction of Cl−with the pore. However, in the present study we show that the R347D mutation and diphenylamine-2-carboxylate (an open pore inhibitor) also inhibit CFTR ATPase activity, revealing a novel mechanism for cross-talk from the pore to the catalytic domains. In both cases, the reduction in ATPase correlates with a decrease in nucleotide turnover rather than affinity. Finally, we demonstrate that glutathione (GSH) inhibits CFTR ATPase and that this inhibition is altered in the CFTR-R347D variant. These findings suggest that cross-talk between the pore and nucleotide binding domains of CFTR may be important in thein vivoregulation of CFTR in health and disease.

scholarly journals Curcumin Opens Cystic Fibrosis Transmembrane Conductance Regulator Channels by a Novel Mechanism That Requires neither ATP Binding nor Dimerization of the Nucleotide-binding Domains

2006 ◽  
Vol 282 (7) ◽  
pp. 4533-4544 ◽  
Author(s):  
Wei Wang ◽  
Karen Bernard ◽  
Ge Li ◽  
Kevin L. Kirk
Keyword(s):  
Cystic Fibrosis ◽  
Nucleotide Binding ◽  
Salt Transport ◽  
Atp Binding ◽  
Transmembrane Conductance Regulator ◽  
Transmembrane Conductance ◽  
Binding Domains ◽  
Channel Opening ◽  
Cystic Fibrosis Transmembrane ◽  
R Domain

Cystic fibrosis transmembrane conductance regulator (CFTR) chloride channels are essential mediators of salt transport across epithelia. Channel opening normally requires ATP binding to both nucleotide-binding domains (NBDs), probable dimerization of the two NBDs, and phosphorylation of the R domain. How phosphorylation controls channel gating is unknown. Loss-of-function mutations in the CFTR gene cause cystic fibrosis; thus, there is considerable interest in compounds that improve mutant CFTR function. Here we investigated the mechanism by which CFTR is activated by curcumin, a natural compound found in turmeric. Curcumin opened CFTR channels by a novel mechanism that required neither ATP nor the second nucleotide-binding domain (NBD2). Consequently, this compound potently activated CF mutant channels that are defective for the normal ATP-dependent mode of gating (e.g. G551D and W1282X), including channels that lack NBD2. The stimulation of NBD2 deletion mutants by curcumin was strongly inhibited by ATP binding to NBD1, which implicates NBD1 as a plausible activation site. Curcumin activation became irreversible during prolonged exposure to this compound following which persistently activated channels gated dynamically in the absence of any agonist. Although CFTR activation by curcumin required neither ATP binding nor heterodimerization of the two NBDs, it was strongly dependent on prior channel phosphorylation by protein kinase A. Curcumin is a useful functional probe of CFTR gating that opens mutant channels by circumventing the normal requirements for ATP binding and NBD heterodimerization. The phosphorylation dependence of curcumin activation indicates that the R domain can modulate channel opening without affecting ATP binding to the NBDs or their heterodimerization.

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