ABCMdb

ABCC7 p.Glu217Cys

ClinVar:	c.650A>G , p.Glu217Gly D , Pathogenic
CF databases:	c.650A>G , p.Glu217Gly (CFTR1) ? , The mutation was detected by heteroduplex analysis in a 2-year old male Polish patient with high sweat cloride (60-80 meq/l), pancreatic sufficiency, and moderate lung disease. His other CF mutation is unknown. It was also found by Yoshimura in 1999, in the CFTR alleles of a single patient with diffuse panbronchiolitis who has Q1352 H in the other allele.
Predicted by SNAP2:	A: N (66%), C: D (59%), D: N (93%), F: D (80%), G: N (66%), H: N (53%), I: D (59%), K: N (72%), L: D (59%), M: D (53%), N: N (82%), P: D (59%), Q: N (66%), R: D (66%), S: N (66%), T: N (66%), V: D (53%), W: D (85%), Y: D (75%),
Predicted by PROVEAN:	A: N, C: D, D: N, F: D, G: N, H: N, I: D, K: N, L: D, M: D, N: N, P: D, Q: N, R: N, S: N, T: N, V: D, W: D, Y: D,

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Publications
[hide] Modeling the conformational changes underlying cha... PLoS One. 2013 Sep 27;8(9):e74574. doi: 10.1371/journal.pone.0074574. eCollection 2013. Rahman KS, Cui G, Harvey SC, McCarty NA
Modeling the conformational changes underlying channel opening in CFTR.
PLoS One. 2013 Sep 27;8(9):e74574. doi: 10.1371/journal.pone.0074574. eCollection 2013., [PMID:24086355]

Abstract [show]
Mutations in the gene encoding the cystic fibrosis transmembrane conductance regulator protein (CFTR) cause cystic fibrosis (CF), the most common life-shortening genetic disease among Caucasians. Although general features of the structure of CFTR have been predicted from homology models, the conformational changes that result in channel opening and closing have yet to be resolved. We created new closed- and open-state homology models of CFTR, and performed targeted molecular dynamics simulations of the conformational transitions in a channel opening event. The simulations predict a conformational wave that starts at the nucleotide binding domains and ends with the formation of an open conduction pathway. Changes in side-chain interactions are observed in all major domains of the protein, and experimental confirmation was obtained for a novel intra-protein salt bridge that breaks near the end of the transition. The models and simulation add to our understanding of the mechanism of ATP-dependent gating in this disease-relevant ion channel.

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No. Sentence Comment
144 To provide experimental confirmation of the closed and open structures, and the transitions between the two, we asked whether cysteines engineered at these two positions in the double-mutant, R334C/E217C-CFTR, could be functionally crosslinked. Login to comment
146 The traces in Figure 7 show that R334C/E217C-CFTR can repeatedly be activated by stimulation of the co-expressed beta2-adrenergic receptor using isoproterenol, without substantial decrement in peak current prior to exposure to the crosslinker MTS-2-MTS. Login to comment
147 When the same cell was exposed to MTS-2-MTS in the absence of isoproterenol (Figure 7B), when most of the channels should be closed, subsequent exposure to isoproterenol failed to activate CFTR channels to the same degree as prior to MTS-2-MTS; these results are consistent with the notion that R334C and E217C are positioned very near each other in the channel closed state. Login to comment
152 In control experiments, exposure to MTS-2-MTS did not have similar effects on the single mutants R334C-CFTR and E217C-CFTR, with respect to the ability to re-open channels after MTS-2-MTS exposure (Figure S6). Login to comment
154 Inspection of the C0- and O-CFTR models indicates that the side chains of R334C and E217C are, indeed, close enough to be crosslinked by MTS-2-MTS only in the closed state (Figure S8). Login to comment
173 Crosslinking R334C to E217C locks CFTR channels into the closed state. Login to comment
176 B: Representative trace (left) and summary data (right) for macroscopic currents measured from R334C/E217C-CFTR with addition of the crosslinker MTS-2-MTS in the absence of isoproterenol (ISO), used to activate channels. Login to comment
178 C: Representative trace and summary data for currents measured from R334C/E217C-CFTR with the crosslinker MTS-2-MTS added in the continuing presence of isoproterenol. Login to comment
266 (TIF) Figure S6 Effects of 1 mM MTS2-2MTS on R334C-CFTR and E217C-CFTR channels. Representative traces (left) and summary data (right) for macroscopic currents measured from R334C- (A) and E217C-CFTR (B) by two-electrode voltage clamp. Login to comment
270 MTS-2-MTS also appeared to covalently decrease macroscopic current at R334C-CFTR, but not E217C-CFTR, perhaps due to alteration of charge or side-chain volume. Login to comment
275 (TIF) Figure S7 Effects of MTSET (ET+) and MTSES (ES-) on R334C/E217C-CFTR channels. Representative traces (left) and summary data (right) for macroscopic currents measured from R334C/E217C-CFTR by two-electrode voltage clamp with addition of the 1 mM monofunctional MTS reagents MTSET+ (ET+ ) or MTSES2 (ES2 ) in the presence of isoproterenol (ISO). Login to comment
277 Both ET+ and ES2 covalently bound to R334C/E217C-CFTR. Login to comment
284 (TIF) Figure S8 Distances between residues in R334C-E217C Double Mutant. Login to comment

[hide] Three charged amino acids in extracellular loop 1 ... J Gen Physiol. 2014 Aug;144(2):159-79. doi: 10.1085/jgp.201311122. Epub 2014 Jul 14. Cui G, Rahman KS, Infield DT, Kuang C, Prince CZ, McCarty NA
Three charged amino acids in extracellular loop 1 are involved in maintaining the outer pore architecture of CFTR.
J Gen Physiol. 2014 Aug;144(2):159-79. doi: 10.1085/jgp.201311122. Epub 2014 Jul 14., [PMID:25024266]

Abstract [show]
The cystic fibrosis (CF) transmembrane conductance regulator (CFTR) bears six extracellular loops (ECL1-6); ECL1 is the site of several mutations associated with CF. Mutation R117H has been reported to reduce current amplitude, whereas D110H, E116K, and R117C/L/P may impair channel stability. We hypothesized that these amino acids might not be directly involved in ion conduction and permeation but may contribute to stabilizing the outer vestibule architecture in CFTR. We used cRNA injected oocytes combined with electrophysiological techniques to test this hypothesis. Mutants bearing cysteine at these sites were not functionally modified by extracellular MTS reagents and were blocked by GlyH-101 similarly to WT-CFTR. These results suggest that these three residues do not contribute directly to permeation in CFTR. In contrast, mutants D110R-, E116R-, and R117A-CFTR exhibited instability of the open state and significantly shortened burst duration compared with WT-CFTR and failed to be locked into the open state by AMP-PNP (adenosine 5'-(beta,gamma-imido) triphosphate); charge-retaining mutants showed mainly the full open state with comparably longer open burst duration. These interactions suggest that these ECL1 residues might be involved in maintaining the outer pore architecture of CFTR. A CFTR homology model suggested that E116 interacts with R104 in both the closed and open states, D110 interacts with K892 in the fully closed state, and R117 interacts with E1126 in the open state. These interactions were confirmed experimentally. The results suggest that D110, E116, and R117 may contribute to stabilizing the architecture of the outer pore of CFTR by interactions with other charged residues.

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321 This is in contrast to the ability of MTS-2-MTS to lock R352C/D993C-CFTR into the open state or to lock R334C/E217C-CFTR into the closed state (Cui et al., 2013; Rahman et al., 2013). Login to comment