ABCMdb

ABCC1 p.Asp1084Glu

Predicted by SNAP2:	A: D (95%), C: D (95%), E: D (95%), F: D (95%), G: D (95%), H: D (95%), I: D (95%), K: D (95%), L: D (95%), M: D (95%), N: D (95%), P: D (95%), Q: D (95%), R: D (95%), S: D (95%), T: D (95%), V: D (95%), W: D (95%), Y: D (95%),
Predicted by PROVEAN:	A: D, C: D, E: D, F: D, G: D, H: D, I: D, K: D, L: D, M: D, N: D, P: D, Q: D, R: D, S: D, T: D, V: D, W: D, Y: D,

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Publications
[hide] Functional importance of polar and charged amino a... J Biol Chem. 2003 Nov 14;278(46):46052-63. Epub 2003 Sep 3. Zhang DW, Gu HM, Situ D, Haimeur A, Cole SP, Deeley RG
Functional importance of polar and charged amino acid residues in transmembrane helix 14 of multidrug resistance protein 1 (MRP1/ABCC1): identification of an aspartate residue critical for conversion from a high to low affinity substrate binding state.
J Biol Chem. 2003 Nov 14;278(46):46052-63. Epub 2003 Sep 3., 2003-11-14 [PMID:12954620]

Abstract [show]
Human multidrug resistance protein 1 (MRP1) confers resistance to many chemotherapeutic agents and transports diverse conjugated organic anions. We previously demonstrated that Glu1089 in transmembrane (TM) 14 is critical for the protein to confer anthracycline resistance. We have now assessed the functional importance of all polar and charged amino acids in this TM helix. Asn1100, Ser1097, and Lys1092, which are all predicted to be on the same face of the helix as to Glu1089, are involved in determining the substrate specificity of the protein. Notably, elimination of the positively charged side chain of Lys1092, increased resistance to the cationic drugs vincristine and doxorubicin, but not the electroneutral drug etoposide (VP-16). In addition, mutations S1097A and N1100A selectively decreased transport of 17beta-estradiol 17-(beta-d-glucuronide) (E217betaG) but not cysteinyl leukotriene 4 (LTC4), demonstrating the importance of multiple residues in this helix in determining substrate specificity. In contrast, mutations of Asp1084 that eliminate the carboxylate side chain markedly decreased resistance to all drugs tested, as well as transport of both E217betaG and LTC4, despite the fact that LTC4 binding was unaffected. We show that these mutations prevent the ATP-dependent transition of the protein from a high to low affinity substrate binding state and drastically diminish ADP trapping at nucleotide binding domain 2. Based on results presented here and crystal structures of prokaryotic ATP binding cassette transporters, Asp1084 may be critical for interaction between the cytoplasmic loop connecting TM13 and TM14 and a region of nucleotide binding domain 2 between the conserved Walker A and ABC signature motifs.

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No. Sentence Comment
51 They are as follows: T1082A (5Ј-C TCC AAG GAG CTC GAC GCA GTG GAC TCC-3Ј), D1084N (5Ј-CTG GAC ACA GTG AAT TCC ATG ATC CCG-3Ј), D1084A (5Ј-CTG GAC ACA GTG AAA TCG ATG ATC CCG-3Ј), D1084E (5Ј-CTG GAC ACA GTG GAC TCG ATG ATC CCG-3Ј), D1084V (5Ј-CTG GAC ACA GTG GTA TCG ATG ATC CCG-3Ј), S1085A (5Ј-CTG GAC ACA GTC GAC GCC ATG ATC CCG G-3Ј), K1092M (5Ј-C CCG GAG GTC ATC ATG ATG TTC ATG GGC-3Ј), K1092A (5Ј-C CCG GAG GTC ATC GCG ATG TTC ATG GGC-3Ј), K1092E (5Ј-C CCG GAG GTC ATC GAG ATG TTC ATG GGC-3Ј), K1092R (5Ј-C CCG GAG GTC ATC AGG ATG TTC ATG GGC-3Ј), S1097A (5Ј-G ATG TTC ATG GGC GCC CTG TTC AAC-3Ј), N1100A (5Ј-TTC ATG GGC TCG CTC TTC GCC GTC ATT GGT G-3Ј), N1100S (5Ј-TTC ATG GGC TCG CTC TTC AGT GTC ATT GGT G-3Ј). Login to comment
218 Effects of Mutations D1084A, D1084E, D1084V, D1084R, K1092A, K1092E, K1092R, and N1100S on Transport of [3 H]LTC4 and [3 H]E217betaG by Wild Type MRP1-Because mutation D1084N dramatically affected all of the MRP1 functions tested, we also mutated Asp1084 to Ala, Glu, Arg, and Val. Login to comment
242 We also examined the ability of the mutants D1084E and D1084R to bind [3 H]LTC4 by photolabeling studies. Login to comment
243 As shown in Fig. 8E, the relative normalized densitometry values of photolabeling of D1084E and D1084R with [3 H]LTC4 were 120 and 100, respectively. Login to comment
244 Thus, similar to the results obtained with photolabeling of mutant D1084N with LTC4, substitution of Asp1084 by Arg or Glu had no significant effect on the photolabeling. Login to comment
273 In contrast, conservative substitution of Asp1084 with Glu resulted in a mutant protein which retained ϳ50% of the ability of the wild type protein to transport LTC4 and E217betaG, and to confer vincristine and doxorubicin resistance, while having no effect on VP-16 resistance. Login to comment
322 Photolabeling studies with [3 H]LTC4 also showed that the replacement of Asp1084 by Asn and Glu had no effect on binding of the substrate to the protein. Login to comment

[hide] Mutational analysis of ionizable residues proximal... J Biol Chem. 2004 Sep 10;279(37):38871-80. Epub 2004 Jun 18. Situ D, Haimeur A, Conseil G, Sparks KE, Zhang D, Deeley RG, Cole SP
Mutational analysis of ionizable residues proximal to the cytoplasmic interface of membrane spanning domain 3 of the multidrug resistance protein, MRP1 (ABCC1): glutamate 1204 is important for both the expression and catalytic activity of the transporter.
J Biol Chem. 2004 Sep 10;279(37):38871-80. Epub 2004 Jun 18., 2004-09-10 [PMID:15208328]

Abstract [show]
The multidrug resistance protein MRP1 is an ATP-dependent transporter of organic anions and chemotherapeutic agents. A significant number of ionizable amino acids are found in or proximal to the 17 transmembrane (TM) helices of MRP1, and we have investigated 6 of these at the cytoplasmic interface of TM13-17 for their role in MRP1 expression and transport activity. Opposite charge substitutions of TM13 Arg(1046) and TM15 Arg(1131) did not alter MRP1 expression nor did they substantially affect activity. In contrast, opposite charge substitutions of TM16 Arg(1202) and Glu(1204) reduced protein expression by >80%; however, MRP1 expression was not affected when Arg(1202) and Glu(1204) were replaced with neutral or same-charge residues. In addition, organic anion transport levels of the R1202L, R1202G, and R1202K mutants were comparable with wild-type MRP1. In contrast, organic anion transport by E1204L was substantially reduced, whereas transport by E1204D was comparable with wild-type MRP1, with the notable exception of GSH. Opposite charge substitutions of TM16 Arg(1197) and TM17 Arg(1249) did not affect MRP1 expression but substantially reduced transport. Mutants containing like-charge substitutions of Arg(1197) or Arg(1249) were also transport-inactive and no longer bound leukotriene C(4). In contrast, substrate binding by the transport-compromised E1204L mutant remained intact. Furthermore, vanadate-induced trapping of azido-ADP by E1204L was dramatically increased, indicating that this mutation may cause a partial uncoupling of the catalytic and transport activities of MRP1. Thus, Glu(1204) serves a dual role in membrane expression of MRP1 and a step in its catalytic cycle subsequent to initial substrate binding.

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No. Sentence Comment
93 A, MRP1 expression in membrane vesicles prepared from HEK293T cells transfected with empty vector [pcDNA3.1] and vector containing wild-type (WT-MRP1) and mutant (R1046D, D1084R, D1084E, and R1131E) cDNAs was determined by immunoblotting with mAb QCRL-1. Shown is a representative immunoblot of membrane vesicles (1 and 2 ␮g of protein) from a single transfection. Login to comment
95 B-F, levels of 3 H-labeled organic anion uptake by the membrane vesicles shown in A were determined and corrected to take into account any differences in MRP1 protein expression (empty pcDNA3.1 vector control (open bars), wild-type MRP1 (black bars), and mutants R1046D, D1084R, D1084E, and R1131E (gray bars)). Login to comment
100 Because the overall transport activity of the oppositely charged Asp1084 mutant was greatly diminished (Fig. 2, B-E), a like-charge substituted D1084E mutant was created to clarify whether it was the loss of the acidic character or a change in size of the amino acid side chain that was responsible for the diminished activity. Login to comment
101 Like the D1084R mutant, the D1084E mutant showed substantially reduced LTC4 uptake levels (Ͻ20% of wild-type MRP1) (27) (Fig. 2C). Login to comment
102 In contrast to D1084R, however, the D1084E mutant exhibited E217betaG (Fig. 2B), E1SO4 (Fig. 2D), and MTX (Fig. 2E) uptake levels that were similar or only moderately reduced compared with those of wild-type MRP1. Login to comment
103 Because of the apparent selectively greater loss of LTC4 transport activity by the D1084E mutant, GSH uptake by this mutant was also examined and compared with that of D1084R. Login to comment
104 As shown in Fig. 2F, apigenin-stimulated GSH uptake by the D1084R and D1084E mutants was reduced by Ͼ90 and 80%, respectively. Login to comment
118 Immunoblots of membrane vesicle proteins prepared from cells expressing the Glu1204 mutants E1204L and E1204D were carried out as described in A. TABLE I Summary of organic anion transport activity of MRP1 mutants with substitutions of ionizable amino acids in and proximal to TM13 to TM17 of MSD3 Mutation % Wild-type MRP1 transport activitya E217betaG LTC4 E1SO4 MTX GSH TM13 R1046D 115 70 80 120 NDb TM14 D1084R Ͻ10 Ͻ10 15 25 Ͻ10 D1084E 80 20 65 90 20 TM15 R1131E 70 50 80 60 ND TM16 R1197E Ͻ10 Ͻ10 Ͻ15 Ͻ10 ND R1197K 20 Ͻ25 Ͻ20 Ͻ10 ND R1202G 115 115 75 70 ND R1202L 115 120 50 110 ND E1204L Ͻ10 50 10 110 Ͻ25 E1204D 100 115 100 115 Ͻ25 TM17 R1249D Ͻ10 Ͻ15 Ͻ10 Ͻ10 ND R1249K Ͻ10 10 Ͻ15 Ͻ10 ND a The values shown are means of duplicate or triplicate determinations and are derived from Fig. 2, 4, and 5 (see figure legends for details). Login to comment
182 We reported previously (27) that nonconservative substitutions of Asp1084 proximal to TM14 caused a substantial reduction in E217betaG, LTC4, and GSH transport and drug resistance, and we have now shown that these mutations also reduce MTX and E1SO4 transport activity, demonstrating a global disruption of MRP1 activity. We have also found that the same-charge mutant, D1084E, has significant transport activity with respect to E217betaG, MTX, and E1SO4 whereas transport of GSH and the glutathione conjugate LTC4 remains quite low. Login to comment
184 However, neither physical property of Asp1084 appears necessary for substrate binding, because GSH is still able to stimulate E1SO4 transport indicating that GSH binding to D1084E is intact. Login to comment
185 Similarly, D1084E and D1084R can still be photolabeled with LTC4 as well as wild-type MRP1. Login to comment