ABCC7 p.Val232Arg
| ClinVar: |
c.695T>A
,
p.Val232Asp
?
, not provided
|
| CF databases: |
c.695T>A
,
p.Val232Asp
(CFTR1)
D
, This mutation was was detected by DGGE and identified by direct sequencing in the CFTR gene. The defect is a T to A change at nucleotide 827 in exon 6a which would lead to a valine-to-aspartic acid replacement in the protein sequence at residue 232. This nucleotide change has been found in an infertile man with CBAVD having neither manifestation of gastrointestinal nor pulmonary disease but with a sweat teat at mmol/
|
| Predicted by SNAP2: | A: N (53%), C: N (61%), D: D (80%), E: D (71%), F: N (61%), G: D (75%), H: D (75%), I: N (97%), K: D (80%), L: N (93%), M: N (82%), N: D (71%), P: D (75%), Q: D (71%), R: D (80%), S: D (66%), T: D (63%), W: D (85%), Y: D (80%), |
| Predicted by PROVEAN: | A: N, C: D, D: D, E: D, F: N, G: D, H: D, I: N, K: D, L: N, M: N, N: D, P: D, Q: D, R: D, S: D, T: N, W: D, Y: N, |
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[hide] The cystic fibrosis V232D mutation inhibits CFTR m... Biochem Pharmacol. 2014 Mar 1;88(1):46-57. doi: 10.1016/j.bcp.2013.12.027. Epub 2014 Jan 9. Loo TW, Clarke DM
The cystic fibrosis V232D mutation inhibits CFTR maturation by disrupting a hydrophobic pocket rather than formation of aberrant interhelical hydrogen bonds.
Biochem Pharmacol. 2014 Mar 1;88(1):46-57. doi: 10.1016/j.bcp.2013.12.027. Epub 2014 Jan 9., [PMID:24412276]
Abstract [show]
Processing mutations that inhibit folding and trafficking of CFTR are the main cause of cystic fibrosis. Repair of CFTR mutants requires an understanding of the mechanisms of misfolding caused by processing mutations. Previous studies on helix-loop-helix fragments of the V232D processing mutation suggested that its mechanism was to lock transmembrane (TM) segments 3 and 4 together by a non-native hydrogen bond (Asp232(TM4)/Gln207(TM3)). Here, we performed mutational analysis to test for Asp232/Gln207 interactions in full-length CFTR. The rationale was that a V232N mutation should mimic V232D and a V232D/Q207A mutant should mature if the processing defect was caused by hydrogen bonds. We report that only Val232 mutations to charged amino acids severely blocked CFTR maturation. The V232N mutation did not mimic V232D as V232N showed 40% maturation compared to 2% for V232D. Mutation of Val232 to large nonpolar residues (Leu, Phe) had little effect. The Q207L mutation did not rescue V232D because Q207L showed about 50% maturation in the presence of corrector VX-809 while V232D/Q207A could no longer be rescued. These results suggest that V232D inhibits maturation by disrupting a hydrophobic pocket between TM segments rather than forming a non-native hydrogen bond. Disulfide cross-linking analysis of cysteines W356C(TM6) and W1145C(TM12) suggest that the V232D mutation inhibits maturation by trapping CFTR as a partially folded intermediate. Since correctors can efficiently rescue V232D CFTR, the results suggest that hydrophilic processing mutations facing a hydrophobic pocket are good candidates for rescue with pharmacological chaperones.
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No. Sentence Comment
134 To test if other charged amino acids inhibited maturation, we constructed mutants V232R and V232K.
X
ABCC7 p.Val232Arg 24412276:134:82
status: NEW160 We tested if mutations to Val232 that severely inhibited maturation (V232E, V232K, or V232R) could be rescued with other correctors predicted to act as pharmacological chaperones such as 4a [33], VX-809 [19], 2b [35], 5a [12], or VX-325 [36].
X
ABCC7 p.Val232Arg 24412276:160:86
status: NEW164 Mutant V232K was rescued with correctors 4a, VX-809 and VX-325 (25-60% mature product) (Fig. 4B and D) while mutant V232R could only be rescued with VX-809 (about 25% mature product) (Fig. 4C and D).
X
ABCC7 p.Val232Arg 24412276:164:116
status: NEW165 The V232R mutant may have been difficult to rescue because arginine is the largest and most highly charged amino acid replacement.
X
ABCC7 p.Val232Arg 24412276:165:4
status: NEW171 Accordingly, we introduced the V510D suppressor mutation into mutants V232E, V232K, or V232R.
X
ABCC7 p.Val232Arg 24412276:171:87
status: NEW175 The V510D suppressor caused a small increase in the amount of V232K mature protein (10%) but no detectable increase was observed in mutant V232R when expressed in the absence of VX-809 (Fig. 5A and B).
X
ABCC7 p.Val232Arg 24412276:175:139
status: NEW177 The relative maturation levels achieved using correctors or the V510D suppressor show that the V232E mutation could be more efficiently rescued than the V232K or V232R mutations.
X
ABCC7 p.Val232Arg 24412276:177:162
status: NEW188 Fig. 4. Rescue of V232E, V232K, and V232R mutants with correctors.
X
ABCC7 p.Val232Arg 24412276:188:36
status: NEW189 Whole cell extracts of cells expressing mutants V232E (A), V232K (B), or V232R (C) in the absence (none) or presence of various correctors were subjected to immunoblot analysis.
X
ABCC7 p.Val232Arg 24412276:189:73
status: NEW222 (A) Whole cell extracts of cells expressing CFTR mutants V232E/V510D, V232K/V510D or V232R/ V510D in the absence () or presence (+) of VX-809 or were subjected to immunoblot analysis.
X
ABCC7 p.Val232Arg 24412276:222:85
status: NEW285 Fig. 9. Replacement of hydrophobic residues predicted to be close to Val232 with arginine inhibits maturation.
X
ABCC7 p.Val232Arg 24412276:285:69
status: NEW