ABCC7 p.Trp496Phe
| ClinVar: |
c.1487G>A
,
p.Trp496*
?
, not provided
|
| CF databases: |
c.1487G>A
,
p.Trp496*
D
, CF-causing
c.1486T>C , p.Trp496Arg (CFTR1) ? , |
| Predicted by SNAP2: | A: D (91%), C: D (63%), D: D (95%), E: D (95%), F: D (80%), G: D (95%), H: D (91%), I: D (91%), K: D (95%), L: D (91%), M: D (91%), N: D (95%), P: D (95%), Q: D (91%), R: D (95%), S: D (95%), T: D (95%), V: D (80%), Y: D (80%), |
| Predicted by PROVEAN: | A: D, C: D, D: D, E: D, F: D, G: D, H: D, I: D, K: D, L: D, M: D, N: D, P: D, Q: D, R: D, S: D, T: D, V: D, Y: D, |
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[hide] Side chain and backbone contributions of Phe508 to... Nat Struct Mol Biol. 2005 Jan;12(1):10-6. Epub 2004 Dec 26. Thibodeau PH, Brautigam CA, Machius M, Thomas PJ
Side chain and backbone contributions of Phe508 to CFTR folding.
Nat Struct Mol Biol. 2005 Jan;12(1):10-6. Epub 2004 Dec 26., [PMID:15619636]
Abstract [show]
Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR), an integral membrane protein, cause cystic fibrosis (CF). The most common CF-causing mutant, deletion of Phe508, fails to properly fold. To elucidate the role Phe508 plays in the folding of CFTR, missense mutations at this position were generated. Only one missense mutation had a pronounced effect on the stability and folding of the isolated domain in vitro. In contrast, many substitutions, including those of charged and bulky residues, disrupted folding of full-length CFTR in cells. Structures of two mutant nucleotide-binding domains (NBDs) reveal only local alterations of the surface near position 508. These results suggest that the peptide backbone plays a role in the proper folding of the domain, whereas the side chain plays a role in defining a surface of NBD1 that potentially interacts with other domains during the maturation of intact CFTR.
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No. Sentence Comment
36 A tryptophan was also introduced at position 508 to assess the effects of substitution of a larger hydrophobic residue and to act as a spectral probe to track the folding of the NBD both in the wild-type domain and in a mutant background of W496F.
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ABCC7 p.Trp496Phe 15619636:36:241
status: NEW38 However, when the F508W mutation was introduced onto the background of W496F, folding of the NBD1 was partially restored and the protein was capable of refolding with higher efficiency (>90% soluble) at 4 °C (Fig.1b).
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ABCC7 p.Trp496Phe 15619636:38:71
status: NEW46 How does the isolated NBD accommodate such Temperature (ºC) 4 10 16 22 Fractionalyield 0.0 0.5 1.0 Temperature (ºC) 4 10 16 22 Temperature (ºC) 4 10 16 22 Wild type ∆F508 Wild type ∆F508 ̄ F508A ̄ F508M F508P F508W ͷ F508W W496F Wild type ∆F508 F508Q F508R F508D F508S a b c Figure 1 NBD1 folding efficiency as a function of folding temperature.
X
ABCC7 p.Trp496Phe 15619636:46:270
status: NEW52 (b) The F508W mutant, the only mutant that deviated markedly from the wild type, was rescued by the introduction of a second missense mutation, W496F.
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ABCC7 p.Trp496Phe 15619636:52:144
status: NEW104 The structures of NBD1 proteins also suggest a potential mechanism for the deleterious effects of the F508W substitution,as the phenylalanine side chain, although partially surface-exposed and accessible, interacts with surrounding residues.The nearest atom distances from both Trp496 and Met498 to Phe508 are ~4 Å.The additional physical size of the tryptophan side chain thus may not be accommodated by the local protein structure.However,when a second substitution,W496F,was introduced, the folding of the domain was rescued.Given the close proximity of both residues,theW496F substitution probably resolves a steric clash between the substituted tryptophan at position 508 and other local residues,consistent with the refolded protein reaching a native or near-native-state structure in vitro.
X
ABCC7 p.Trp496Phe 15619636:104:473
status: NEW[hide] Diminished self-chaperoning activity of the DeltaF... PLoS Comput Biol. 2008 Feb 29;4(2):e1000008. Serohijos AW, Hegedus T, Riordan JR, Dokholyan NV
Diminished self-chaperoning activity of the DeltaF508 mutant of CFTR results in protein misfolding.
PLoS Comput Biol. 2008 Feb 29;4(2):e1000008., [PMID:18463704]
Abstract [show]
The absence of a functional ATP Binding Cassette (ABC) protein called the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) from apical membranes of epithelial cells is responsible for cystic fibrosis (CF). Over 90% of CF patients carry at least one mutant allele with deletion of phenylalanine at position 508 located in the N-terminal nucleotide binding domain (NBD1). Biochemical and cell biological studies show that the DeltaF508 mutant exhibits inefficient biosynthetic maturation and susceptibility to degradation probably due to misfolding of NBD1 and the resultant misassembly of other domains. However, little is known about the direct effect of the Phe508 deletion on the NBD1 folding, which is essential for rational design strategies of cystic fibrosis treatment. Here we show that the deletion of Phe508 alters the folding dynamics and kinetics of NBD1, thus possibly affecting the assembly of the complete CFTR. Using molecular dynamics simulations, we find that meta-stable intermediate states appearing on wild type and mutant folding pathways are populated differently and that their kinetic accessibilities are distinct. The structural basis of the increased misfolding propensity of the DeltaF508 NBD1 mutant is the perturbation of interactions in residue pairs Q493/P574 and F575/F578 found in loop S7-H6. As a proof-of-principle that the S7-H6 loop conformation can modulate the folding kinetics of NBD1, we virtually design rescue mutations in the identified critical interactions to force the S7-H6 loop into the wild type conformation. Two redesigned NBD1-DeltaF508 variants exhibited significantly higher folding probabilities than the original NBD1-DeltaF508, thereby partially rescuing folding ability of the NBD1-DeltaF508 mutant. We propose that these observed defects in folding kinetics of mutant NBD1 may also be modulated by structures separate from the 508 site. The identified structural determinants of increased misfolding propensity of NBD1-DeltaF508 are essential information in correcting this pathogenic mutant.
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No. Sentence Comment
170 Interestingly, Thibodeau et al. found that NBD1F508W , the only F508X mutant with a lower folding efficiency than NBD1DF508 , can be rescued by introducing the compensating mutation W496F, which is exactly in the same loop that contains Q493 and F594 [9].
X
ABCC7 p.Trp496Phe 18463704:170:182
status: NEW