ABCC7 p.Gly228Asp
| Predicted by SNAP2: | A: N (82%), C: D (63%), D: D (80%), E: D (85%), F: D (71%), H: D (85%), I: D (75%), K: D (91%), L: D (53%), M: D (80%), N: D (71%), P: D (66%), Q: D (80%), R: D (91%), S: N (57%), T: D (71%), V: D (71%), W: D (85%), Y: D (71%), |
| Predicted by PROVEAN: | A: N, C: N, D: N, E: N, F: D, H: D, I: N, K: N, L: N, M: N, N: N, P: N, Q: N, R: N, S: N, T: N, V: N, W: D, Y: D, |
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[hide] Non-native interhelical hydrogen bonds in the cyst... Biochemistry. 2004 Jun 29;43(25):8077-83. Choi MY, Cardarelli L, Therien AG, Deber CM
Non-native interhelical hydrogen bonds in the cystic fibrosis transmembrane conductance regulator domain modulated by polar mutations.
Biochemistry. 2004 Jun 29;43(25):8077-83., [PMID:15209503]
Abstract [show]
Polar residues comprise about 15% of the transmembrane (TM) domains of proteins, where they can stabilize structure via native side chain-side chain interhelical hydrogen bonds between TM helices. However, non-native H-bonds may be implicated in disease states, through limiting protein dynamics during transport and/or misfolding the protein by inducing non-native rotational positions about TM helical axes. Here we have undertaken an investigation of the presence and strength of H-bond interactions within a series of helix-loop-helix ("hairpin") constructs derived from TM helices 3 and 4 (italic) of the cystic fibrosis transmembrane conductance regulator (CFTR) (prototypic sequence G(194)LALAHFVWIAPLQ(207)VALLMGLIWELLQASAFAGLGFLIV(232)LALFQ(237)AGLG(241)) in which wild-type Q207 in TM3 forms an interhelical H-bond with CF-phenotypic mutant V232D in TM4 [Therien, A. G., Grant, F. E., and Deber, C. M. (2001) Nat. Struct. Biol 8, 597-601]. In the present work, a library of 21 TM3/4 constructs was prepared, where Asp residues were placed individually at TM4 positions 221-241. Using gel shift assays-in which H-bond-linked hairpins (closed conformation) migrate faster than the elongated forms (open conformation)-we found that Q207 in TM3 is able to "capture" all 21 TM4 D mutations into measurable populations of interhelical H-bonds. A similar library of TM4 D mutants-but also containing Q207L-reverted to wild-type migration rates, confirming Q207 as the polar partner for TM4 D residues. In view of the broad capture range of Q207, these results emphasize the potential consequences to folding and dynamics of introducing polar mutations into the TM domains of membrane proteins in the vicinity of a native polar TM residue.
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No. Sentence Comment
89 Interestingly, mutants G228D through I231D, and L233D through F236D, have a more negative value of the percent of MW decrease relative to the wt than the CF-phenotypic mutant V232D (Figure 3b) (see the Discussion).
X
ABCC7 p.Gly228Asp 15209503:89:23
status: NEW180 Therefore, without Q237 (i.e., with Q237 mutated to Leu), the X f D mutants in TM4 become more open through regions encompassing A221D to G228D, and Q237D to G241D, and are ultimately unable to form an H-bond with Q207.
X
ABCC7 p.Gly228Asp 15209503:180:138
status: NEW188 Nevertheless, for any A f D or G f D mutants (in this case, A221D, A223D, G226D, G228D, A234D, A238D, G239D, and G241D), only a single-base change is required, and therefore, it is possible these mutants represent potential phenotypic CF mutants, which have yet to be discovered.
X
ABCC7 p.Gly228Asp 15209503:188:81
status: NEW