ABCMdb

ABCC1 p.Ser1334Ala

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Publications

PMID: 18088596 [PubMed] Yang R et al: "The hydroxyl group of S685 in Walker A motif and the carboxyl group of D792 in Walker B motif of NBD1 play a crucial role for multidrug resistance protein folding and function."

No. Sentence Comment

254 In order to rule out the possibility that the double mutant D1454L/E1455L might rescue the misfolding caused by D14 54L mutation, we have made single mutants including D1454L, D1454N, S1334A, S1334T, S1334C, S1334H, S1334D and S1334N. Login to comment

PMID: 18636743 [PubMed] Yang R et al: "Interaction between the bound Mg.ATP and the Walker A serine residue in NBD2 of multidrug resistance-associated protein MRP1 plays a crucial role for the ATP-dependent leukotriene C4 transport."

No. Sentence Comment

3 In contrast to the NBD1 mutations, none of the mutations in NBD2, including S1334A, S1334C, S1334D, S1334H, S1334N, and S1334T, caused misfolding of the protein. Login to comment
4 However, elimination of the hydroxyl group at S1334 in mutations including S1334A, S1334C, S1334D, S1334H, and S1334N drastically reduced the ATP binding and the ATP-enhanced ADP trapping at the mutated NBD2. Login to comment
15 In order to test this hypothesis, we have substituted the Walker A S1334 with an A (S1334A), a C (S1334C), a D (S1334D), an H (S1334H), an N (S1334N), or a T (S1334T). Login to comment
36 The forward and reverse primers used to introduce these mutations are as follows: S1334A/forward, 5'-CG GGA GCT GGG AAG GCG TCC CTG ACC CTG GGC-3'; S1334A/ reverse, 5'-GCC CAG GGT CAG GGA CGC CTT CCC AGC TCC CG-3'; S1334C/forward, 5'-CG GGA GCT GGG AAG TGC TCC CTG ACC CTG GGC-3'; S1334C/reverse, 5'-GCC CAG GGT CAG GGA GCA CTT CCC AGC TCC CG-3'; S1334D/forward, 5'-CG GGA GCT GGG AAG GAC TCC CTG ACC CTG GGC-3'; S1334D/reverse, 5'-GCC CAG GGT CAG GGA GTC CTT CCC AGC TCC CG-3'; S1334H/forward, 5'-CG GGA GCT GGG AAG CAC TCC CTG ACC CTG GGC-3'; S1334H/reverse, 5'-GCC CAG GGT CAG GGA GTG CTT CCC AGC TCC CG-3'; S1334N/forward, 5'-CG GGA GCT GGG AAG AAC TCC CTG ACC CTG GGC-3'; S1334N/reverse, 5'-GCC CAG GGT CAG GGA GTT CTT CCC AGC TCC CG-3'; S1334T/forward, 5'-CG GGA GCT GGG AAG ACG TCC CTG ACC CTG GGC-3'; S1334T/reverse, 5'-GCC CAG GGT CAG GGA CGT CTT CCC AGC TCC CG-3'. Login to comment
82 The results in Figure 1A showed that the 190 kDa wild-type MRP1 protein is resistant to endoglycosidase H digestion whereas the minor band is not, indicating that the majority of wild-type MRP1 protein is complex-glycosylated in vivo. All of the mutants, including S1334A, S1334C, S1334D, S1334H, S1334N, and S1334T, have a major band resistant to the endoglycosidase H digestion but sensitive to the PNGase F digestion (Figure 1B), indicating that all of these mutants mainly form complex-glycosylated mature proteins at 37 °C in vivo. Login to comment
88 As shown in Figure 2B, S1334A-, S1334C-, S1334D-, S1334H-, or S1334N-mutated MRP1 almost completely abolished the ATP-dependent LTC4 transport, whereas S1334T mutation, which retained the hydroxyl group at this position, exerted ~175% of wild-type MRP1 transport activity, suggesting that the hydroxyl group at this position plays a crucial role for the ATP binding/hydrolysis and ATP-dependent solute transport by MRP1. Login to comment
112 The intensities of the MRP1 bands were determined by a scanning densitometer. The mean ratios (n ) 2, including the results derived from 400 and 800 ng of protein), considering the amount of wild-type MRP1 as 1, of the mutant proteins are as follows: S1334A, 1.46 ( 0.06; S1334C, 0.84 ( 0.14; S1334D, 1.07 ( 0.69; S1334H, 1.17 ( 0.16; S1334N, 0.97 ( 0.08; S1334T, 1.30 ( 0.11. Login to comment
120 labeling intensity of MRP1 mutants, including S1334A, S1334C, S1334D, S1334H, and S1334N, with [R-32 P]-8-N3ATP is weaker than that of wild type or S1334T (Figure 4), indicating that these mutants without the hydroxyl group at this position affect ATP binding, hydrolysis, and vanadate-dependent [R-32 P]-8-N3ADP trapping. Login to comment
121 Comparison of labeling intensities with [R-32 P]-8-N3ATP and [γ-32 P]-8-N3ATP further supports this conclusion: (1) The labeling intensity of MRP1 mutants, including S1334A, S1334C, S1334D, S1334H, and S1334N, with [R-32 P]-8-N3ATP is either similar to or weaker than that of [γ-32 P]-8-N3ATP labeling (Figure 4), indicating that the bound ATP in these mutants is not efficiently hydrolyzed. Login to comment
122 (2) The intensity of [γ-32 P]-8-N3ATP labeling on the mutants, including S1334A, S1334C, S1334D, S1334H, and S1334N, is either stronger than wild type or similar to wild type (Figure 4), implying that most of those [γ-32 P]-8-N3ATP labeling might occur at the unmutated NBD1 (8). Login to comment
123 In order to prove this hypothesis, S1334A and S1334T mutations were introduced into pDual/N-half/C-half expression plasmid (12, 13) and expressed in Sf21 cells. Membrane vesicles prepared from Sf21 cells (Figure 5A) were used to do ATP-dependent LTC4 transport and the photoaffinity labeling with either [R-32 P]-8-N3ATP or [γ-32 P]-8-N3ATP. Login to comment
124 As shown in Figure 5B, the ATP-dependent LTC4 transport activity of wild type N-half plus S1334T-mutated C-half is more or less similar to that of wild-type, whereas the transport activity of the wild type N-half plus S1334A-mutated C-half is significantly reduced. Login to comment
126 In contrast, the [γ-32 P]-8-N3ATP or [R-32 P]-8-N3ATP labeling of the unmutated NBD1-containing N-half fragment is stronger than the corresponding labeling on the S1334A-mutated NBD2-containing C-half (Figure 5C), suggesting that most of the [γ-32 P]-8-N3ATP or [R-32 P]-8-N3ATP labeling occurred at FIGURE 4: Substitution of S1334 with an amino acid that eliminates the hydroxyl group at this position impaired ATP binding/hydrolysis at the mutated NBD2. Login to comment
134 The intensities of the MRP1 bands were determined by a scanning densitometer. The mean ratios (n ) 2, including the results derived from 200 and 300 ng of protein), considering the amount of wild type MRP1 as 1, of the mutant proteins are as follows: S1334A, 0.68 ( 0.06; S1334T, 0.90 ( 0.06. Login to comment
136 (C) S1334A-mutated MRP1 affects both ATP binding and hydrolysis at the mutated NBD2. Login to comment
137 Wild type MRP1 or S1334A- or S1334T-mutated MRP1 was introduced into the pDual/N-half/C-half and expressed in Sf21 insect cells (12, 25). Login to comment
141 In addition, the labeling intensity of the S1334A-mutated NBD2-containing C-half with [γ-32 P]- 8-N3ATP is stronger than that of corresponding labeling with [R-32 P]-8-N3ATP (Figure 5C), implying that the trace amount of ATP bound to the S1334A-mutated NBD2 is not efficiently hydrolyzed. Login to comment
145 However, based on the labeling intensities of the S1334A mutant in Figure 5C, the labeling of the mutated NBD2 fragments, after the partial trypsin digestion, might not be detected. Login to comment
155 As shown in Figure 6, 2.5 or 10 µM ATP significantly enhanced the vanadate-dependent [R-32 P]-8-N3ADP trapping in wild type MRP1 (Figure 6A) or in S1334T (Figure 6G), whereas there is no enhancement effect in S1334A (Figure 6B), S1334C (Figure 6C), S1334D (Figure 6D), S1334H (Figure 6E), or S1334N (Figure 6F), suggesting that these mutations significantly impaired the nucleotide binding at the mutated NBD2. Login to comment
161 In contrast, the labeling on S1334A, S1334C, S1334D, S1334H, or S1334N is only partially diminished, implying that ATP binding or vanadate-dependent ATP hydrolysis product ADP trapping at the mutated NBD2 is impaired. Login to comment
163 In contrast, mutation of the corresponding residue in NBD2 of MRP1, such as S1334A, S1334C, S1334D, S1334H, or S1334N, has no effect on the protein folding and processing (Figure 1), implying that the stereo structure surrounding the hydroxyl group of S1334 in NBD2 might be different from that of NBD1. Login to comment
172 Indeed, substitution of S1334 with an alanine residue (S1334A) reduced the ATP-dependent LTC4 transport activity to ~10% of wild type (Figure 2B). Login to comment
175 group (S1334C) exerted slightly higher transport activity than that of S1334A, S1334D, S1334H, or S1334N (Figure 2B), implying that the sulfhydryl group in S1334C might weakly bind to the magnesium cofactor and the -phosphate of the bound ATP. Login to comment
178 The labeling intensities of [R-32 P]-8-N3ATP in wild type or S1334T are stronger than that of [γ-32 P]-8-N3ATP (Figure 4), whereas the labeling intensities of [R-32 P]-8-N3ATP in S1334A, S1334C, S1334D, S1334H, or S1334N are slightly weaker than that of [γ-32 P]-8-N3ATP (Figure 4), suggesting that even though there might be a trace amount of ATP binding at the mutated NBD2, the bound nucleotide might not be efficiently hydrolyzed. Login to comment
179 Indeed, a certain amount of [R-32 P]-8-N3ATP hydrolysis product [R-32 P]-8-N3ADP was trapped in wild-type or S1334T-mutated NBD2, whereas there was no detectable amount of [R-32 P]-8-N3ADP trapped in S1334A-mutated NBD2 (Figure 5C). Login to comment
180 All of the S1334 mutants, including S1334A (Figure 6B), S1334C (Figure 6C), S1334D (Figure 6D), S1334H (Figure 6E), and S1334N (Figure 6F), lost the ATP-enhanced vanadate-dependent ADP trapping (16, 17) at the mutated NBD2, suggesting that these mutations significantly decreased the affinity for nucleotide at the mutated NBD2. Login to comment
182 The reduced nucleotide binding at the mutated NBD2, such as S1334A, S1334C, S1334D, S1334H, and S1334N, significantly decreased the ability to inhibit the LTC4 binding (Figure 7), similar to the mutations of K684E, G771A, or K1333E (19). Login to comment