ABCC7 p.Cys590Val
| Predicted by SNAP2: | A: D (53%), D: D (91%), E: D (91%), F: D (91%), G: D (80%), H: D (85%), I: D (85%), K: D (75%), L: D (80%), M: D (85%), N: D (85%), P: D (91%), Q: D (85%), R: D (91%), S: D (71%), T: D (75%), V: D (75%), W: D (91%), Y: D (85%), |
| Predicted by PROVEAN: | A: D, D: D, E: D, F: D, G: D, H: D, I: N, K: D, L: D, M: D, N: D, P: D, Q: D, R: D, S: D, T: D, V: N, W: D, Y: D, |
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[hide] In vivo phosphorylation of CFTR promotes formation... EMBO J. 2006 Oct 18;25(20):4728-39. Epub 2006 Oct 12. Mense M, Vergani P, White DM, Altberg G, Nairn AC, Gadsby DC
In vivo phosphorylation of CFTR promotes formation of a nucleotide-binding domain heterodimer.
EMBO J. 2006 Oct 18;25(20):4728-39. Epub 2006 Oct 12., 2006-10-18 [PMID:17036051]
Abstract [show]
The human ATP-binding cassette (ABC) protein CFTR (cystic fibrosis transmembrane conductance regulator) is a chloride channel, whose dysfunction causes cystic fibrosis. To gain structural insight into the dynamic interaction between CFTR's nucleotide-binding domains (NBDs) proposed to underlie channel gating, we introduced target cysteines into the NBDs, expressed the channels in Xenopus oocytes, and used in vivo sulfhydryl-specific crosslinking to directly examine the cysteines' proximity. We tested five cysteine pairs, each comprising one introduced cysteine in the NH(2)-terminal NBD1 and another in the COOH-terminal NBD2. Identification of crosslinked product was facilitated by co-expression of NH(2)-terminal and COOH-terminal CFTR half channels each containing one NBD. The COOH-terminal half channel lacked all native cysteines. None of CFTR's 18 native cysteines was found essential for wild type-like, phosphorylation- and ATP-dependent, channel gating. The observed crosslinks demonstrate that NBD1 and NBD2 interact in a head-to-tail configuration analogous to that in homodimeric crystal structures of nucleotide-bound prokaryotic NBDs. CFTR phosphorylation by PKA strongly promoted both crosslinking and opening of the split channels, firmly linking head-to-tail NBD1-NBD2 association to channel opening.
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No. Sentence Comment
26 Nor could C590 and C592 be replaced by alanine, threonine or phenylalanine (Figure 2B), but function was similar to that of the 16CS background when they were replaced by leucines (16CS þ C590L/C592L; Figure 2A and B) or valines (16CS þ C590V/C592V; Figure 2B).
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ABCC7 p.Cys590Val 17036051:26:247
status: NEW29 B Resting Stimulated 16CS+C590V/C592V 16CS+C590L/C592L 16CS+C590F/C592F 16CS+C590T/C592T 16CS+C590S/C592S 16CS+C590/C592 16CS+C590A/C592A A 200 s 5 µA WT CFTR Cys-free CFTR 16CS+C590L/C592L 0 25 50 75 100 125 150 175 WT CFTR Whole-oocyte conductance (µS) 16CS+C590V/C592V 16CS+C590/C592 C (2.5 ng cRNA) (20 ng cRNA) 250 160 105 75 kD cRNA (ng) 0.25 20 2.5 20 WT CFTR 16CS+ C590V/C592V 1 2 3 4 Mature Core D Uninjected oocyte 40 µM forskolin 40 µM forskolin 40 µM forskolin Washout Washout Washout Figure 2 Expression and function of cysteine-deficient CFTR channels in Xenopus oocytes.
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ABCC7 p.Cys590Val 17036051:29:383
status: NEW33 (C) Conductances from oocytes injected with 2.5 ng cRNA, and measured 1 day later for WT (153717 mS, n ¼ 3), or 3 days later for HA-tagged 16CS mutants with C590/C592 (42710 mS, n ¼ 6) or C590V/C592 V (5173 mS, n ¼ 6).
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ABCC7 p.Cys590Val 17036051:33:198
status: NEW35 (D) WT CFTR and Cys-free CFTR (16CS þ C590V/C592V) were immunoprecipitated from membranes of oocytes injected with cRNA amounts indicated, and subjected to SDS-PAGE and Western blot analysis; arrows mark core-glycosylated and mature fully glycosylated CFTR.
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ABCC7 p.Cys590Val 17036051:35:43
status: NEW36 independently, Cys-free (16CS þ C590V/C592V) CFTR channels, like WT, required phosphorylation by PKA before they could be opened by ATP, closed upon ATP removal, and were activated half-maximally by B50 mM [ATP] (Supplementary Figure S1); their single-channel conductance was very slightly larger than that of WT CFTR channels.
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ABCC7 p.Cys590Val 17036051:36:37
status: NEW199 For recording macroscopic currents of split CFTR channels in excised patches (Figure 10), oocytes were Table I Forward primers for site-directed mutagenesis PCR C76S 50 -GCCCTTCGGCGATcgTTTTTCTGGAG-30 C276S 50 -CTGTTAAGGCCTACTcCTGGGAAGAAGC-30 C832S 50 -CGAAGAAGACCTTAAGGAGTcCTTTTTTGATGATATGGAGAGC-30 EagI site 50 -GGTAAAATTAAGCACAGcGGccGAATTTCATTCTGTTCTC-30 HA epitope 50 -CGGGCCGCCATGtAcccatAcGACGttccgGAttAcgcaAGGTCGCCTCTGG-30 CFTR 16CS C590A/C592A 50 -GGAGATCTTCGAGAGCgCTGTCgCTAAACTGATGGC-30 CFTR 16CS C590F/C592F 50 -GGAGATCTTCGAGAGCTtTGTCTtTAAACTGATGGC-30 CFTR 16CS C590L/C592L 50 -GGAGATCTTCGAGAGCctTGTCctTAAACTGATGGC-30 CFTR 16CS C590T/C592T 50 -GGAGATCTTCGAGAGCaCTGTCaCTAAACTGATGGC-30 CFTR 16CS C590V/C592V 50 -GGAGATCTTCGAGAGCgtcGTCgtTAAACTGATGGC-30 S434C 50 -CCTCTTCTTCAGTAATTTCTgtCTaCTTGGTACTCCTGTC-30 S459C 50 -GTTGGCGGTTGCTGGATgCACTGGAGCAGGCAAG-3 A462C 50 -GCTGGATCCACTGGGtgcGGCAAGACTTCACTTC-30 L549C 50 -GGTGGAATCACACtatGcGGAGGTCAACGAGCACG-30 S605C 50 -GGATTTTGGTCACaTgTAAAATGGAAC-30 S1248C 50 -CCTCTTGGGAAGAACCGGtTgtGGGAAGAGTAC-30 D1336C 50 -GTTTCCTGGGAAGCTTtgCTTTGTCCTTGTGG-30 L1346C 50 -GGATGGGGGCTCTGTCTgtAGTCATGGCCACAAGC-30 A1374C 50 -GATGAACCAAGCtgTCATTTAGATCC-30 V1379C 50 -GCTCATTTAGATCCgtgcACATACCAAATAATTCG-30 The underlined bases are the codons for the introduced serines, cysteines or other residues; lowercase letters mark base changes from the original sequence, including those for introducing diagnostic restriction endonuclease sites.
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ABCC7 p.Cys590Val 17036051:199:702
status: NEW[hide] Cysteine accessibility probes timing and extent of... J Gen Physiol. 2015 Apr;145(4):261-83. doi: 10.1085/jgp.201411347. Chaves LA, Gadsby DC
Cysteine accessibility probes timing and extent of NBD separation along the dimer interface in gating CFTR channels.
J Gen Physiol. 2015 Apr;145(4):261-83. doi: 10.1085/jgp.201411347., [PMID:25825169]
Abstract [show]
Cystic fibrosis transmembrane conductance regulator (CFTR) channel opening and closing are driven by cycles of adenosine triphosphate (ATP) binding-induced formation and hydrolysis-triggered disruption of a heterodimer of its cytoplasmic nucleotide-binding domains (NBDs). Although both composite sites enclosed within the heterodimer interface contain ATP in an open CFTR channel, ATP hydrolysis in the sole catalytically competent site causes channel closure. Opening of the NBD interface at that site then allows ADP-ATP exchange. But how frequently, and how far, the NBD surfaces separate at the other, inactive composite site remains unclear. We assessed separation at each composite site by monitoring access of nucleotide-sized hydrophilic, thiol-specific methanothiosulfonate (MTS) reagents to interfacial target cysteines introduced into either LSGGQ-like ATP-binding cassette signature sequence (replacing equivalent conserved serines: S549 and S1347). Covalent MTS-dependent modification of either cysteine while channels were kept closed by the absence of ATP impaired subsequent opening upon ATP readdition. Modification while channels were opening and closing in the presence of ATP caused macroscopic CFTR current to decline at the same speed as when the unmodified channels shut upon sudden ATP withdrawal. These results suggest that the target cysteines can be modified only in closed channels; that after modification the attached MTS adduct interferes with ATP-mediated opening; and that modification in the presence of ATP occurs rapidly once channels close, before they can reopen. This interpretation was corroborated by the finding that, for either cysteine target, the addition of the hydrolysis-impairing mutation K1250R (catalytic site Walker A Lys) similarly slowed, by an order of magnitude, channel closing on ATP removal and the speed of modification by MTS reagent in ATP. We conclude that, in every CFTR channel gating cycle, the NBD dimer interface separates simultaneously at both composite sites sufficiently to allow MTS reagents to access both signature-sequence serines. Relatively rapid modification of S1347C channels by larger reagents-MTS-glucose, MTS-biotin, and MTS-rhodamine-demonstrates that, at the noncatalytic composite site, this separation must exceed 8 A.
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No. Sentence Comment
287 As Po of Cys-free (16CS + C590V/C592V) CFTR was approximately twofold larger (Mense et al., 2006) than that of wild-type CFTR, which is &#e07a;0.1 under these conditions (Csan&#e1;dy et al., 2000; Vergani et al., 2003), if Po of these S549C- (C832S-C1458S) CFTR channels lies between these values, then our second-order rate constant estimate should be increased by up to 25%.
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ABCC7 p.Cys590Val 25825169:287:26
status: NEW[hide] Deletion of Phenylalanine 508 in the First Nucleot... J Biol Chem. 2015 Sep 18;290(38):22862-78. doi: 10.1074/jbc.M115.641134. Epub 2015 Jul 6. Chong PA, Farber PJ, Vernon RM, Hudson RP, Mittermaier AK, Forman-Kay JD
Deletion of Phenylalanine 508 in the First Nucleotide-binding Domain of the Cystic Fibrosis Transmembrane Conductance Regulator Increases Conformational Exchange and Inhibits Dimerization.
J Biol Chem. 2015 Sep 18;290(38):22862-78. doi: 10.1074/jbc.M115.641134. Epub 2015 Jul 6., [PMID:26149808]
Abstract [show]
Deletion of Phe-508 (F508del) in the first nucleotide-binding domain (NBD1) of the cystic fibrosis transmembrane conductance regulator (CFTR) results in destabilization of the domain, intramolecular interactions involving the domain, and the entire channel. The destabilization caused by F508del manifests itself in defective channel processing and channel gating defects. Here, we present NMR studies of the effect of F508del and the I539T stabilizing mutation on NBD1 dynamics, with a view to understanding these changes in stability. Qualitatively, F508del NMR spectra exhibit significantly more peak broadening than WT spectra due to the enhanced intermediate time scale (millisecond to microsecond) motions in the mutant. Unexpectedly, studies of fast (nanosecond to picosecond) motions revealed that F508del NBD1 tumbles more rapidly in solution than WT NBD1. Whereas F508del tumbles at a rate nearly consistent with the monomeric state, the WT protein tumbles significantly more slowly. Paramagnetic relaxation enhancement experiments confirm that NBD1 homodimerizes in solution in the expected head-to-tail orientation. NMR spectra of WT NBD1 reveal significant concentration-dependent chemical shift perturbations consistent with NBD1 dimerization. Chemical shift analysis suggests that the more rapid tumbling of F508del is the result of an impaired ability to dimerize. Based on previously published crystal structures and NMR spectra of various NBD1 mutants, we propose that deletion of Phe-508 affects Q-loop conformational sampling in a manner that inhibits dimerization. These results provide a potential mechanism for inhibition of channel opening by F508del and support the dimer interface as a target for cystic fibrosis therapeutics.
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No. Sentence Comment
56 A single cysteine mutant of NBD1, E402C NBD1 èc;RIèc;RE, was generated on a Cys-less NBD1 (C491V, C524T, C590V, and C592V) background by site-directed mutagenesis and confirmed by DNA sequencing.
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ABCC7 p.Cys590Val 26149808:56:113
status: NEW284 The single cysteine residue, E402C, was introduced on a Cys-less NBD1 èc;RIèc;RE (C491V, C524T, C590V, and C592V).
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ABCC7 p.Cys590Val 26149808:284:104
status: NEW288 Of note, we were not able to express or purify NBD1 using the previously published mutations C491S, C524S, C590V, and C592V (12), probably because these mutations destabilize NBD1.
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ABCC7 p.Cys590Val 26149808:288:107
status: NEW