ABCMdb

PMID: 17700963

Bompadre SG, Hwang TC
Cystic fibrosis transmembrane conductance regulator: a chloride channel gated by ATP binding and hydrolysis.
Sheng Li Xue Bao. 2007 Aug 25;59(4):431-42., 2007-08-25 [PubMed]

Sentences

No. Mutations Sentence Comment

47 ABCC7 p.Gly551Asp ABCC7 p.Gly1349Asp In the S.S., there are two important disease-associated mutations, G551D in NBD1 and G1349D in NBD. Login to comment 90 ABCC7 p.Glu1371Ser This shortening of the open time by ADP was more evident in the hydrolysis-deficient mutants E1371S and D1370N[38] . Login to comment 133 ABCC7 p.Lys464Ala [51] showed that, in contrast to previous studies[25,27] , the K464A mutation does not affect the channel opening rate, but it shortens the mean open time. Login to comment 135 ABCC7 p.Lys1250Ala ABCC7 p.Lys1250Ala ABCC7 p.Lys464Ala In addition, introducing the K464A mutation into the K1250A mutant whose ATP hydrolysis at NBD2 is diminished[25,27] dramatically shortens the stable open state seen in the K1250A mutation (Fig.3). Login to comment 160 ABCC7 p.Lys1250Ala ABCC7 p.Lys464Ala ABCC7 p.Asp1370Asn This conclusion was reached after finding that the ATP dose-response relationships of the Walker A mutants K464A and K1250A and the Walker B mutant D1370N were shifted towards higher [ATP] com- paredto theATPdose-response curvefor wild-typechannels. Login to comment 164 ABCC7 p.Lys1250Ala ABCC7 p.Lys464Ala The K464A mutation shortens current relaxation of K1250A-CFTR. Login to comment 165 ABCC7 p.Lys1250Ala ABCC7 p.Lys1250Ala ABCC7 p.Lys464Ala A: Representative traces for the current relaxation of K1250A-CFTR and K464A/K1250A-CFTR upon withdrawal of ATP and PKA. Login to comment 168 ABCC7 p.Lys1250Ala ** P<0.01, *** P<0.005 vs K1250A. Login to comment 180 ABCC7 p.Tyr1219Gly ABCC7 p.Tyr1219Ile ABCC7 p.Tyr1219Phe The mutation Y1219G shows an ATP dose-response relationship shifted more than 50-fold towards higher [ATP], however more conservative mutations (Y1219I, Y1219F) show smaller shifts, indicating the importance of the nature of the side chain in the interaction with the ATP molecule. Login to comment 181 ABCC7 p.Lys1250Ala ABCC7 p.Asp1370Asn Single channel analysis indicates that theY1219G mutation reduces the opening rate of the channel while not affecting the open time (i.e. this mutation probably does not affect ATP hydrolysis in ABP2 like K1250A or D1370N). Login to comment 182 ABCC7 p.Trp401Gly Interestingly, the equivalent mutation in ABP1, W401G, does not change the opening rate of the channel but instead increases the closing rate (Fig.4). Login to comment 183 ABCC7 p.Lys464Ala This same effect was observed previously for K464A by Powe et al[51] . Login to comment 193 ABCC7 p.Trp401Gly A: τo for wild-type (WT) and W401G-CFTR in the presence of 2.75 mmol/L ATP. Login to comment 194 ABCC7 p.Glu1371Ser ABCC7 p.Glu1371Ser ABCC7 p.Glu1371Ser ABCC7 p.Glu1371Ser ABCC7 p.Trp401Gly ABCC7 p.Trp401Gly ABCC7 p.Phe430Gly ABCC7 p.Phe409Gly B: Representative current relaxation traces for E1371S, W401G/E1371S and W401G/ F409G/F430G/E1371S (or triple/E1371S). Login to comment 201 ABCC7 p.Glu1371Ser Interestingly, P-ATP also prolongs the open time of wild-type CFTR and a hydrolysis-deficient mutant, E1371S-CFTR, indicating that the effect of P-ATP on the open time is not due to a perturbation of ATP hydrolysis. Login to comment 208 ABCC7 p.Gly551Asp G551D, located in the signature sequence of NBD1, is the third most common CF-associated mutation (www.genet. Login to comment 210 ABCC7 p.Gly551Asp Patients carrying the G551D mutation present a severe phenotype[63,64] . Login to comment 211 ABCC7 p.Gly1349Asp In contrast, the corresponding mutation in the signature sequence of NBD2, G1349D, is associated with a milder clinical phenotype[65] . Login to comment 213 ABCC7 p.Gly551Asp [55] found that the G551D mutation (located at the ABP2) completely eliminates the ability of ATP to increase the opening rate of the channel (Fig.5). Login to comment 214 ABCC7 p.Gly551Asp ADP does not inhibit G551D-CFTR currents and AMP-PNP does not lock the channel open. Login to comment 215 ABCC7 p.Gly551Asp The observed low activity of G551D-CFTR channels likely represents the ATP-independent openings also seen with the wild-type channels[38,55] . Login to comment 217 ABCC7 p.Gly551Asp Interestingly, the high affinity ATP analog P-ATP increases G551D-CFTR currents mainly by increasing the open time of the channel[66] . Login to comment 218 ABCC7 p.Gly551Asp Introducing the mutationY1219G (located at ABP2) in the G551D background, which reduces the ATP-binding affinity by more than 50-fold in wild-type channels[56] , does not alter significantly the effect of P-ATP. Login to comment 219 ABCC7 p.Gly551Asp ABCC7 p.Gly551Asp ABCC7 p.Trp401Gly ABCC7 p.Trp401Gly However, the mutation W401G/G551D (W401G is located at ABP1) decreases remarkably the effect of P-ATP, suggesting that it is at this binding site (ABP1) where P-ATP binds to increase the G551D-CFTR activity[66] . Login to comment 221 ABCC7 p.Gly1349Asp In contrast, the G1349D mutation retains some ATP dependence (Fig.5), with a maximal Po approximately 10-fold lower than that of wild-type CFTR because of a reduced maximum opening rate. Login to comment 222 ABCC7 p.Gly1349Asp Although the exact mechanism for the functional defect of the G1349D mutation remains unclear, potential electrostaticrepulsionbetweennegativelychargedside chain of D1349 and bound ATP may hinder NBD dimerization (i.e., a post-binding event). Login to comment 224 ABCC7 p.Gly551Asp ABCC7 p.Gly1349Asp Gating of G551D-CFTR and G1349D-CFTR. Login to comment 225 ABCC7 p.Gly551Asp A: Recording of G551D-CFTR current in an excised inside-out membrane patch. Login to comment 228 ABCC7 p.Gly1349Asp B: Recording of G1349D-CFTR current in an excised inside-out membrane patch. Login to comment 263 ABCC7 p.Gly551Asp Lately, our observation that P-ATP enhances G551D by binding to ABP1 implicates that ABP1 can potentially be a target for drugs to bind and increase the channel activity. Login to comment