ABCMdb

ABCC1 p.Trp1198Tyr

Predicted by SNAP2:	A: D (66%), C: D (59%), D: D (85%), E: D (80%), F: D (63%), G: D (80%), H: D (80%), I: D (59%), K: D (80%), L: D (63%), M: D (53%), N: D (80%), P: D (91%), Q: D (71%), R: D (75%), S: D (75%), T: D (80%), V: D (63%), Y: D (66%),
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, P: D, Q: D, R: D, S: D, T: D, V: D, Y: D,

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[hide] Multiple membrane-associated tryptophan residues c... J Biol Chem. 2002 Dec 20;277(51):49495-503. Epub 2002 Oct 17. Koike K, Oleschuk CJ, Haimeur A, Olsen SL, Deeley RG, Cole SP
Multiple membrane-associated tryptophan residues contribute to the transport activity and substrate specificity of the human multidrug resistance protein, MRP1.
J Biol Chem. 2002 Dec 20;277(51):49495-503. Epub 2002 Oct 17., 2002-12-20 [PMID:12388549]

Abstract [show]
The multidrug resistance protein, MRP1, is a clinically important ATP-binding cassette transporter in which the three membrane-spanning domains (MSDs), which contain up to 17 transmembrane (TM) helices, and two nucleotide binding domains (NBDs) are configured MSD1-MSD2-NBD1-MSD3-NBD2. In tumor cells, MRP1 confers resistance to a broad spectrum of drugs, but in normal cells, it functions as a primary active transporter of organic anions such as leukotriene C(4) and 17beta-estradiol 17beta-(D-glucuronide). We have previously shown that mutation of TM17-Trp(1246) eliminates 17beta-estradiol 17beta-(D-glucuronide) transport and drug resistance conferred by MRP1 while leaving leukotriene C(4) transport intact. By mutating the 11 remaining Trp residues that are in predicted TM segments of MRP1, we have now determined that five of them are also major determinants of MRP1 function. Ala substitution of three of these residues, Trp(445) (TM8), Trp(553) (TM10), and Trp(1198) (TM16), eliminated or substantially reduced transport levels of five organic anion substrates of MRP1. In contrast, Ala substitutions of Trp(361) (TM7) and Trp(459) (TM9) caused a more moderate and substrate-selective reduction in MRP1 function. More conservative substitutions (Tyr and Phe) of the Trp(445), Trp(553), and Trp(1198) mutants resulted in substrate selective retention of transport in some cases (Trp(445) and Trp(1198)) but not others (Trp(553)). Our findings suggest that the bulky polar aromatic indole side chain of each of these five Trp residues contributes significantly to the transport activity and substrate specificity of MRP1.

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No. Sentence Comment
48 Tryptophan substitutions were generated in the pGEM-3Z and pBluescriptSK(ϩ) plasmids above according to the manufacturer`s instructions with the following mutagenic primers (substituted nucleotides are underlined): MSD1 Trp mutants W40A (5Ј-G GTC CTC GTG GCC GTG CCT TG-3Ј, W47A (5Ј-GT TTT TAC CTC GCC GCC TGT TTC CCC-3Ј), W82A (5Ј-C TTG GGA TTT TTG CTG GCG ATC GTC TGC TGG GC-3Ј), W86A (5Ј-G CTG TGG ATC GTC TGC GCT GCA GAC CTC TTC TAC TC-3Ј), W94A (5Ј-C CTC TTC TAC TCT TTC GCG GAA AGA AGT CGG GGC-3Ј), W142A (5Ј-GGG ATC ATG CTC ACT TTC GCA CTG GTA GCC CTA ATG TG-3Ј), W142F (5Ј-G CTC ACT TTT TTC CTG GTA GCC C-3Ј); MSD2 Trp mutants W361A (5Ј-C ACG AAG GCC CCA GAT GCG CAG GGC TAC TTC TAC-3Ј), W445A (5Ј-G TAC ATT AAC ATG ATC GCG TCA GCC CCC CTG CAA G-3Ј), W445F (5Ј-CG TAC ATT AAC ATG ATC TTC TCA GCC CCC CTG CAA GTC-3Ј), W445Y (5Ј-CC ACG TAC ATT AAC ATG ATC TAC TCA GCG CCC CTG CAA GTC-3Ј), W459A (5Ј-GCT CTC TAC CTC CTG GCG CTG AAT CTG GGC CC-3Ј), W553A (5Ј-G GGC ACC TTC ACC GCG GTC TGC ACG CCC-3Ј), W553F (5Ј-G GGC ACC TTC ACC TTC GTC TGC ACG CCC-3Ј), W553Y (5Ј-GCC CTG GGC ACC TTC ACA TAT GTC TGC ACG CCC-3Ј; and MSD3 Trp mutants W1198A (5Ј-C GTG GCC AAC AGG GCG CTG GCC GTG CGG C-3Ј), W1198F (5Ј-GTG GCC AAC AGG TTC CTG GCC GTG CGG C-3Ј), W1198Y (5Ј-GTG GCC AAC AGG TAC CTG GCC GTG CGG C-3Ј). Login to comment
145 Thus, the LTC4, GSH, and E13SO4 transport activities of the W1198F mutant were similar to those of wild-type MRP1, whereas transport of these substrates by the W1198Y mutant exceeded that of wild-type MRP1 (Fig. 6, B, D, and E). Login to comment
146 Transport of E217betaG and MTX by the W1198F and W1198Y mutants was ϳ50-75% that of wild-type MRP1 when corrected for relative MRP1 expression levels (Fig. 6, C and F). Login to comment
147 For all substrates, transport activity was restored more effectively when Trp1198 was mutated to Tyr compared with Phe, suggesting that, as observed for the Trp445 mutants, both the aromatic and polar properties of the Trp residue at position 1198 contribute to MRP1 transport activity. Login to comment
189 Ala substitution of Trp1198 in MSD3 also resulted in a broad and profound decrease in MRP1 transport activity except for FIG. 6. ATP-dependent organic anion transport activity of wild-type and mutant MRP1 containing conservative Phe and Tyr substitutions of Trp1198 in TM16 of MSD3. A, immunoblot of membrane vesicles prepared from HEK293T cells transfected with empty vector (pcDNA3.1(-)), wild-type (WT-MRP1), and mutant (W445A, W445F, and W445Y; W553A, W553F and W553Y; W1198A, W1198F, and W1198Y) MRP1 cDNAs. MRP1 proteins were detected with monoclonal antibody QCRL-1, and relative levels of expression shown under the blot were estimated by densitometry. Login to comment
190 B-F, relative levels of 3 H-labeled organic anion uptake by the membrane vesicles shown in A enriched for wild-type MRP1 (solid bar), Trp 3 Phe-substituted MRP1 mutants (W445F, W553F, and W1198F; hatched bars), and Trp 3 Tyr-substituted MRP1 mutants (W445Y, W553Y, and W1198Y; open bars) were determined as described under "Experimental Procedures." Login to comment

[hide] Interaction with membrane mimics of transmembrane ... Biochim Biophys Acta. 2010 Mar;1798(3):401-14. Epub 2009 Dec 11. de Foresta B, Vincent M, Gallay J, Garrigos M
Interaction with membrane mimics of transmembrane fragments 16 and 17 from the human multidrug resistance ABC transporter 1 (hMRP1/ABCC1) and two of their tryptophan variants.
Biochim Biophys Acta. 2010 Mar;1798(3):401-14. Epub 2009 Dec 11., [PMID:20004175]

Abstract [show]
The human multidrug resistance-associated protein 1 (hMRP1/ABCC1) belongs to the ATP-binding cassette transporter superfamily. Together with P-glycoprotein (ABCB1) and the breast cancer resistance protein (BCRP/ABCG2), hMRP1 confers resistance to a large number of structurally diverse drugs. The current topological model of hMRP1 includes two cytosolic nucleotide-binding domains and 17 putative transmembrane (TM) helices forming three membrane-spanning domains. Mutagenesis and labeling studies have shown TM16 and TM17 to be important for function. We characterized the insertion of the TM16 fragment into dodecylphosphocholine (DPC) or n-dodecyl-beta-d-maltoside (DM) micelles as membrane mimics and extended our previous work on TM17 (Vincent et al., 2007, Biochim. Biophys. Acta 1768, 538). We synthesized TM16 and TM17, with the Trp residues, W1198 in TM16 and W1246 in TM17, acting as an intrinsic fluorescent probe, and TM16 and TM17 Trp variants, to probe different positions in the peptide sequence. We assessed the interaction of peptides with membrane mimics by evaluating the increase in fluorescence intensity resulting from such interactions. In all micelle-bound peptides, the tryptophan residue appeared to be located, on average, in the head group micelle region, as shown by its fluorescence spectrum. Each tryptophan residue was partially accessible to both acrylamide and the brominated acyl chains of two DM analogs, as shown by fluorescence quenching. Tryptophan fluorescence lifetimes were found to depend on the position of the tryptophan residue in the various peptides, probably reflecting differences in local structures. Far UV CD spectra showed that TM16 contained significant beta-strand structures. Together with the high Trp correlation times, the presence of these structures suggests that TM16 self-association may occur at the interface. In conclusion, this experimental study suggests an interfacial location for both TM16 and TM17 in membrane mimics. In terms of overall hMRP1 structure, the experimentally demonstrated amphipathic properties of these TM are consistent with a role in the lining of an at least partly hydrophilic transport pore, as suggested by the currently accepted structural model, the final structure being modified by interaction with other TM helices.

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No. Sentence Comment
348 For TM16, the variant results from the following two point mutations: W1198Y and F1113W. Login to comment