ABCC7 p.Ser422Pro
| Predicted by SNAP2: | A: N (87%), C: N (87%), D: N (72%), E: N (82%), F: N (66%), G: N (82%), H: N (82%), I: N (72%), K: N (87%), L: N (78%), M: N (78%), N: N (87%), P: N (87%), Q: N (93%), R: N (82%), T: N (93%), V: N (78%), W: N (61%), Y: N (72%), |
| Predicted by PROVEAN: | A: N, C: N, D: N, E: N, F: N, G: N, H: N, I: N, K: N, L: N, M: N, N: N, P: N, Q: N, R: N, T: N, V: N, W: N, Y: N, |
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[hide] Allosteric modulation balances thermodynamic stabi... J Mol Biol. 2012 May 25;419(1-2):41-60. Epub 2012 Mar 8. Aleksandrov AA, Kota P, Cui L, Jensen T, Alekseev AE, Reyes S, He L, Gentzsch M, Aleksandrov LA, Dokholyan NV, Riordan JR
Allosteric modulation balances thermodynamic stability and restores function of DeltaF508 CFTR.
J Mol Biol. 2012 May 25;419(1-2):41-60. Epub 2012 Mar 8., [PMID:22406676]
Abstract [show]
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 DeltaF508 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 gamma-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 DeltaF508 NBD1 to that of the wild type. Introduction of these prolines experimentally into full-length human DeltaF508 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 DeltaF508 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.
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No. Sentence Comment
112 Combination of introduction of a proline into the Q-loop at position 492 together with I539T to generate ΔF/PT was sufficient to allow a high level of maturation even without further addition of the substitutions in the I539 loop (A534P) to generate ΔF/2PT or also in the RI (S422P and S434P) to generate ΔF/4PT.
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ABCC7 p.Ser422Pro 22406676:112:286
status: NEW128 (c) Western blot of WT and ΔF508 CFTR expressed in HEK-293 cells and ΔF508 modified with I539T (ΔF/T), S422P/S434P/S492P/A534P (ΔF/4P), I539T/S492P (ΔF/PT), I539T/S492P/A534P (ΔF/2PT), and I539T/S422P/S434P/S492P/A534P (ΔF/4PT).
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ABCC7 p.Ser422Pro 22406676:128:118
status: NEWX
ABCC7 p.Ser422Pro 22406676:128:121
status: NEWX
ABCC7 p.Ser422Pro 22406676:128:225
status: NEW178 HEK293 cells were transiently transfected with Cys-less CFTR or Cys-less ΔF508-CFTR in the presence or absence of the 4PT mutations (S422P/S434P/S492P/A534P/I539T), with the Cys pair V510C/G1069C introduced at the CL4/NBD1 interface.
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ABCC7 p.Ser422Pro 22406676:178:138
status: NEW[hide] Correctors of DeltaF508 CFTR restore global confor... FASEB J. 2013 Feb;27(2):536-45. doi: 10.1096/fj.12-216119. Epub 2012 Oct 26. He L, Kota P, Aleksandrov AA, Cui L, Jensen T, Dokholyan NV, Riordan JR
Correctors of DeltaF508 CFTR restore global conformational maturation without thermally stabilizing the mutant protein.
FASEB J. 2013 Feb;27(2):536-45. doi: 10.1096/fj.12-216119. Epub 2012 Oct 26., [PMID:23104983]
Abstract [show]
Most cystic fibrosis is caused by the deletion of a single amino acid (F508) from CFTR and the resulting misfolding and destabilization of the protein. Compounds identified by high-throughput screening to improve DeltaF508 CFTR maturation have already entered clinical trials, and it is important to understand their mechanisms of action to further improve their efficacy. Here, we showed that several of these compounds, including the investigational drug VX-809, caused a much greater increase (5- to 10-fold) in maturation at 27 than at 37 degrees C (<2-fold), and the mature product remained short-lived (T(1/2) approximately 4.5 h) and thermally unstable, even though its overall conformational state was similar to wild type, as judged by resistance to proteolysis and interdomain cross-linking. Consistent with its inability to restore thermodynamic stability, VX-809 stimulated maturation 2-5-fold beyond that caused by several different stabilizing modifications of NBD1 and the NBD1/CL4 interface. The compound also promoted maturation of several disease-associated processing mutants on the CL4 side of this interface. Although these effects may reflect an interaction of VX-809 with this interface, an interpretation supported by computational docking, it also rescued maturation of mutants in other cytoplasmic loops, either by allosteric effects or via additional sites of action. In addition to revealing the capabilities and some of the limitations of this important investigational drug, these findings clearly demonstrate that DeltaF508 CFTR can be completely assembled and evade cellular quality control systems, while remaining thermodynamically unstable. He, L., Kota, P., Aleksandrov, A. A., Cui, L., Jensen, T., Dokholyan, N. V., Riordan, J. R. Correctors of DeltaF508 CFTR restore global conformational maturation without thermally stabilizing the mutant protein.
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No. Sentence Comment
122 4PT, S422P/S434P/S492P/ A534P/I539T.
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ABCC7 p.Ser422Pro 23104983:122:5
status: NEW148 A) èc;F508 with NBD1-stabilizing mutations: 4S, I539T/G550E/R553M/R555K; èc;RI, deletion of amino acid residues 404-435; 4PT, S422P/S434P/S492P/A534P/I539T.
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ABCC7 p.Ser422Pro 23104983:148:134
status: NEW[hide] Restoration of NBD1 thermal stability is necessary... J Mol Biol. 2015 Jan 16;427(1):106-20. doi: 10.1016/j.jmb.2014.07.026. Epub 2014 Jul 30. He L, Aleksandrov AA, An J, Cui L, Yang Z, Brouillette CG, Riordan JR
Restoration of NBD1 thermal stability is necessary and sufficient to correct F508 CFTR folding and assembly.
J Mol Biol. 2015 Jan 16;427(1):106-20. doi: 10.1016/j.jmb.2014.07.026. Epub 2014 Jul 30., [PMID:25083918]
Abstract [show]
Cystic fibrosis transmembrane conductance regulator (CFTR) (ABCC7), unique among ABC exporters as an ion channel, regulates ion and fluid transport in epithelial tissues. Loss of function due to mutations in the cftr gene causes cystic fibrosis. The most common cystic-fibrosis-causing mutation, the deletion of F508 (DeltaF508) from the first nucleotide binding domain (NBD1) of CFTR, results in misfolding of the protein and clearance by cellular quality control systems. The DeltaF508 mutation has two major impacts on CFTR: reduced thermal stability of NBD1 and disruption of its interface with membrane-spanning domains (MSDs). It is unknown if these two defects are independent and need to be targeted separately. To address this question, we varied the extent of stabilization of NBD1 using different second-site mutations and NBD1 binding small molecules with or without NBD1/MSD interface mutation. Combinations of different NBD1 changes had additive corrective effects on F508 maturation that correlated with their ability to increase NBD1 thermostability. These effects were much larger than those caused by interface modification alone and accounted for most of the correction achieved by modifying both the domain and the interface. Thus, NBD1 stabilization plays a dominant role in overcoming the DeltaF508 defect. Furthermore, the dual target approach resulted in a locked-open ion channel that was constitutively active in the absence of the normally obligatory dependence on phosphorylation by protein kinase A. Thus, simultaneous targeting of both the domain and the interface, as well as being non-essential for correction of biogenesis, may disrupt normal regulation of channel function.
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No. Sentence Comment
45 2PT, S492P/A534P/I539T; 4PT, 2PT + S422P/S434P; 3SS, G550E/R553M/R555K; 4SS, 3SS + I539T; ƊRI, deletion of RI amino acids 404-435; combo, ƊRI + 2PT + 3SS.
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ABCC7 p.Ser422Pro 25083918:45:35
status: NEW[hide] Exploiting species differences to understand the C... Biochem Soc Trans. 2015 Oct 1;43(5):975-82. doi: 10.1042/BST20150129. Bose SJ, Scott-Ward TS, Cai Z, Sheppard DN
Exploiting species differences to understand the CFTR Cl- channel.
Biochem Soc Trans. 2015 Oct 1;43(5):975-82. doi: 10.1042/BST20150129., [PMID:26517912]
Abstract [show]
The anion channel cystic fibrosis transmembrane conductance regulator (CFTR) is a unique ATP-binding cassette (ABC) transporter. CFTR plays a pivotal role in transepithelial ion transport as its dysfunction in the genetic disease cystic fibrosis (CF) dramatically demonstrates. Phylogenetic analysis suggests that CFTR first appeared in aquatic vertebrates fulfilling important roles in osmosensing and organ development. Here, we review selectively, knowledge of CFTR structure, function and pharmacology, gleaned from cross-species comparative studies of recombinant CFTR proteins, including CFTR chimeras. The data argue that subtle changes in CFTR structure can affect strongly channel function and the action of CF mutations.
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No. Sentence Comment
120 Hypothesizing that structural differences between human and chicken CFTR account for the thermostability of F508del chicken CFTR, Aleksandrov et al. [41] demonstrated that the F508del revertant I539T and four proline residues at key positions within NBD1 (S422P, S434P, S492P and A534P) were responsible for rescuing the processing, plasma membrane stability and function of human CFTR.
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ABCC7 p.Ser422Pro 26517912:120:256
status: NEW