ABCMdb

ABCC7 p.Pro355Phe

CF databases:	c.1063C>T , p.Pro355Ser (CFTR1) ? , The mutation was detected by DGGE analysis and characterised by direct sequencing. We have seen it only once, in over 2500 control chromosomes from Italian population.
Predicted by SNAP2:	A: D (63%), C: D (63%), D: D (75%), E: D (75%), F: D (80%), G: D (71%), H: D (63%), I: D (75%), K: D (85%), L: D (80%), M: D (71%), N: D (71%), Q: D (59%), R: D (75%), S: D (63%), T: D (71%), V: D (75%), W: 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, Q: D, R: D, S: D, T: D, V: D, W: D, Y: D,

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Publications
[hide] Conserved allosteric hot spots in the transmembran... J Biol Chem. 2014 Jul 18;289(29):19942-57. doi: 10.1074/jbc.M114.562116. Epub 2014 May 29. Wei S, Roessler BC, Chauvet S, Guo J, Hartman JL 4th, Kirk KL
Conserved allosteric hot spots in the transmembrane domains of cystic fibrosis transmembrane conductance regulator (CFTR) channels and multidrug resistance protein (MRP) pumps.
J Biol Chem. 2014 Jul 18;289(29):19942-57. doi: 10.1074/jbc.M114.562116. Epub 2014 May 29., [PMID:24876383]

Abstract [show]
ATP-binding cassette (ABC) transporters are an ancient family of transmembrane proteins that utilize ATPase activity to move substrates across cell membranes. The ABCC subfamily of the ABC transporters includes active drug exporters (the multidrug resistance proteins (MRPs)) and a unique ATP-gated ion channel (cystic fibrosis transmembrane conductance regulator (CFTR)). The CFTR channel shares gating principles with conventional ligand-gated ion channels, but the allosteric network that couples ATP binding at its nucleotide binding domains (NBDs) with conformational changes in its transmembrane helices (TMs) is poorly defined. It is also unclear whether the mechanisms that govern CFTR gating are conserved with the thermodynamically distinct MRPs. Here we report a new class of gain of function (GOF) mutation of a conserved proline at the base of the pore-lining TM6. Multiple substitutions of this proline promoted ATP-free CFTR activity and activation by the weak agonist, 5'-adenylyl-beta,gamma-imidodiphosphate (AMP-PNP). TM6 proline mutations exhibited additive GOF effects when combined with a previously reported GOF mutation located in an outer collar of TMs that surrounds the pore-lining TMs. Each TM substitution allosterically rescued the ATP sensitivity of CFTR gating when introduced into an NBD mutant with defective ATP binding. Both classes of GOF mutations also rescued defective drug export by a yeast MRP (Yor1p) with ATP binding defects in its NBDs. We conclude that the conserved TM6 proline helps set the energy barrier to both CFTR channel opening and MRP-mediated drug efflux and that CFTR channels and MRP pumps utilize similar allosteric mechanisms for coupling conformational changes in their translocation pathways to ATP binding at their NBDs.

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158 Mean percentages of ATP-free currents afe; S.E. (error bars) were as follows: WT, 0.7 afe; 0.2% (n afd; 5); P355A, 5.0 afe; 1.4% (n afd; 10); P355S, 7.3 afe; 2.0% (n afd; 7); and P355F, 5.4 afe; 1.5% (n afd; 5). Login to comment
165 TABLE 1 Single channel data for multiple Pro-355 CFTR mutants in the absence of ATP and following AMP-PNP activation Conditions were identical to those described in the legend to Fig. 2. n afd; 6 (WT), 7 (P355A), 8 (P355F), and 5 (P355S) patches, respectively. Login to comment
166 WT P355A P355F P355S Mean Po With ATP 0.3074afe;.00514 0.4078 afe; 0.0601 0.4867 afe; 0.0429 0.5212 afe; 0.1048 Without ATP 0.0009 afe; 0.0004 0.0217 afe; 0.0065a 0.0413 afe; 0.0145a 0.0365 afe; 0.0131a With AMP-PNP 0.0127 afe; 0.0114 0.1942 afe; 0.0619a 0.1112 afe; 0.0342a 0.1549 afe; 0.0651a Mean open frequency (sd1a;1 ) With ATP 0.222 afe; 0.021 0.270 afe; 0.028 0.384 afe; 0.049 0.334 afe; 0.059 Without ATP 0.004 afe; 0.001 0.020 afe; 0.002a 0.046 afe; 0.010a 0.028 afe; 0.006a With AMP-PNP 0.013 afe; 0.006 0.131 afe; 0.053a 0.104 afe; 0.035a 0.118 afe; 0.045a a p b0d; 0.05 compared with WT. Login to comment
157 Mean percentages of ATP-free currents afe; S.E. (error bars) were as follows: WT, 0.7 afe; 0.2% (n afd; 5); P355A, 5.0 afe; 1.4% (n afd; 10); P355S, 7.3 afe; 2.0% (n afd; 7); and P355F, 5.4 afe; 1.5% (n afd; 5). Login to comment
164 TABLE 1 Single channel data for multiple Pro-355 CFTR mutants in the absence of ATP and following AMP-PNP activation Conditions were identical to those described in the legend to Fig. 2. n afd; 6 (WT), 7 (P355A), 8 (P355F), and 5 (P355S) patches, respectively. Login to comment