ABCB1 p.Ala129Cys
| Predicted by SNAP2: | C: N (57%), D: D (75%), E: D (75%), F: D (75%), G: N (93%), H: D (71%), I: D (66%), K: D (75%), L: D (75%), M: D (59%), N: D (59%), P: D (80%), Q: D (59%), R: D (66%), S: N (87%), T: N (82%), V: D (66%), W: D (80%), Y: D (80%), |
| Predicted by PROVEAN: | C: D, D: D, E: D, F: D, G: N, H: D, I: D, K: D, L: D, M: D, N: D, P: D, Q: D, R: D, S: N, T: D, V: D, W: D, Y: D, |
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[hide] Val133 and Cys137 in transmembrane segment 2 are c... J Biol Chem. 2004 Apr 30;279(18):18232-8. Epub 2004 Jan 28. Loo TW, Bartlett MC, Clarke DM
Val133 and Cys137 in transmembrane segment 2 are close to Arg935 and Gly939 in transmembrane segment 11 of human P-glycoprotein.
J Biol Chem. 2004 Apr 30;279(18):18232-8. Epub 2004 Jan 28., 2004-04-30 [PMID:14749322]
Abstract [show]
P-glycoprotein (P-gp; ABCB1) transports a wide variety of structurally diverse compounds out of the cell. The protein has two homologous halves joined by a linker region. Each half consists of a transmembrane (TM) domain with six TM segments and a nucleotide-binding domain. The drug substrate-binding pocket is at the interface between the TM segments in each half of the protein. Preliminary studies suggested that the arrangement of the two halves of P-gp shows rotational symmetry (i.e. "head-to-tail" arrangement). Here, we tested this model by determining whether the cytoplasmic ends of TM2 and TM3 in the N-terminal half are in close contact with TM11 in the C-terminal half. Mutants containing a pair of cysteines in TM2/TM11 or TM3/TM11 were subjected to oxidative cross-linking with copper phenanthroline. Two of the 110 TM2/TM11 mutants, V133C(TM2)/G939C(TM11) and C137C(TM2)/A935C (TM11), were cross-linked at 4 degrees C, when thermal motion is reduced. Cross-linking was specific since no cross-linked product was detected in the 100 double Cys TM3/TM11 mutants. Vanadate trapping of nucleotide or the presence of some drug substrates inhibited cross-linking of mutants V133C(TM2)/G939C(TM11) and C137C(TM2)/A935C(TM11). Cross-linking of TM2 and TM11 also blocked drug-stimulated ATPase activity. The close proximity of TM2/TM11 and TM5/TM8 (Loo, T. W., Bartlett, M. C., and Clarke, D. M. (2004) J. Biol. Chem. 279, 7692-7697) indicates that these regions between the two halves must enclose the drug-binding pocket at the cytoplasmic side of P-gp. They may form the "hinges" required for conformational changes during the transport cycle.
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No. Sentence Comment
124 TABLE I Cross-linking between residues in TM2 and TM11 -, no cross-linked product detected on SDS-polyacrylamide gels at 37 °C; ϩ, relatively weak cross-linking (Ͻ50% of P-gp cross-linked) at 37 °C; ϩϩ, relatively strong cross-linking (Ͼ50% of P-gp cross-linked) at 37 °C; *, cross-linked product also detected at 22 °C; **, cross-linked product also detected at 22 and 4 °C. TM2 TM11 A935C H936C I937C F938C G939C I940C T941C F942C S943C F944C A128C - - - - - - - - - - A129C - - - - - - - - - - Y130C - - - - ϩ ϩ - ϩ ϩ - I131C - - - - - - - - - - Q132C - - - - - - - - - - V133C - - - ϩ ϩϩ, ** - - ϩ ϩ - S134C ϩ ϩ - - ϩ ϩ - - - - F135C - - - - - - - - - - W136C - - - - - - - - - - C137C ϩϩ, ** - - - ϩ - - - - - L138C ϩϩ, * - - - - - - - - - TM11 are close to each other at their cytoplasmic ends.
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ABCB1 p.Ala129Cys 14749322:124:526
status: NEW[hide] Biochemical characterization of domains in the mem... Biochemistry. 2005 Feb 22;44(7):2661-70. Kaur P, Rao DK, Gandlur SM
Biochemical characterization of domains in the membrane subunit DrrB that interact with the ABC subunit DrrA: identification of a conserved motif.
Biochemistry. 2005 Feb 22;44(7):2661-70., 2005-02-22 [PMID:15709779]
Abstract [show]
DrrA and DrrB proteins confer resistance to the commonly used anticancer agents daunorubicin and doxorubicin in the producer organism Streptomyces peucetius. The drrAB locus has previously been cloned in Escherichia coli, and the proteins have been found to be functional in this host. DrrA, a soluble protein, belongs to the ABC family of proteins. It forms a complex with the integral membrane protein DrrB. Previous studies suggest that the function and stability of DrrA and DrrB are biochemically coupled. Thus, DrrA binds ATP only when it is in a complex with DrrB in the membrane. Further, DrrB is completely degraded if DrrA is absent. In the present study, we have characterized domains in DrrB that may be directly involved in interaction with DrrA. Several single-cysteine substitutions in DrrB were made. Interaction between DrrA and DrrB was studied by using a cysteine to amine chemical cross-linker that specifically cross-links a free sulfhydryl group in one protein (DrrB) to an amine in another (DrrA). We show here that DrrA cross-links with both the N- and the C-terminal ends of the DrrB protein, implying that they may be involved in interaction. Furthermore, this study identifies a motif within the N-terminal cytoplasmic tail of DrrB, which is similar to a motif recently shown by crystal structure analysis in BtuC and previously shown by sequence analysis to be also present in exporters, including MDR1. We propose that the motif present in DrrB and other exporters is actually a modified version of the EAA motif, which was originally believed to be present only in the importers of the ABC family. The present work is the first report where domains of interaction in the membrane component of an ABC drug exporter have been biochemically characterized.
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No. Sentence Comment
77 The mutants were named S4C, S15C, S23C, S35C, A44C, C260S up: 5'-GGCCTGGTCCTGTCCGTGTCGGCAGGG-3' C260S dn: 5'-CCCTGCCGACACGGACAGGACCAGGCC-3' S23C up: 5'- CGGACGGTGCTGTGCGCGGGTGAACGG-3' S23C dn: 5'- CCGTTCACCCGCGCACAGCACCGTCCG-3' V53C, T70C, S80C, V92C, S107C, V116C, A129C, T149C, A160C, V173C, S213C, S236C, T249C, A270C, and A282C, respectively.
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ABCB1 p.Ala129Cys 15709779:77:268
status: NEW168 substitutions, including V53C, T70C, V92C, A129C, S236C, and S249C, showed a decrease in resistance to doxorubicin (Table 1).
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ABCB1 p.Ala129Cys 15709779:168:43
status: NEW193 The location of the cross-linked species is marked as A+B. (A) S23C (positive control), A129C, T149C, A160C.
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ABCB1 p.Ala129Cys 15709779:193:88
status: NEW196 Table 1: Doxorubicin Resistance of E. coli N43 Cells Expressing Wild Type DrrA with DrrB Containing Different Cysteine Substitutionsa amt of dox, µg/mLdomain of DrrB location of cysteine 0 4 6 8 (wild type) C260 +++ +++ +++ ++ N-terminus S15C +++ +++ +++ ++ N-terminus S23C +++ +++ +++ ++ N-terminus S35C +++ +++ ++ ++ N-terminus A44C +++ +++ ++ + TM 1 V53C +++ ++ ++ - TM 1 T70C +++ + + + P 1 S80C +++ ++ + - TM 2 V92C +++ ( - - TM 2 S107C +++ +++ ++ ++ C 1 V116C +++ +++ +++ ++ TM 3 A129C +++ ++ + - TM 4 T149C +++ ++ ++ + C 2 A160C +++ +++ ++ + TM 5 V173C +++ +++ ++ + TM 6 S213C +++ +++ ++ + C 3 S236C +++ ++ + - TM 7 S249C +++ + + - TM 8 A270C +++ +++ ++ ++ C-terminus A282C +++ +++ ++ ++ cysteine-less DrrB C260S +++ +++ +++ +++ vector only pSU2718 ++++ ( - - a Legend: +++, very good growth; ++, good growth; +, some growth; -, no growth.
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ABCB1 p.Ala129Cys 15709779:196:490
status: NEW278 Six (V53C, T70C, V92C, A129C, S236C, S249C) out of 20 substitutions created in this study, however, showed varying levels of doxorubicin-sensitive phenotype (Table 1).
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ABCB1 p.Ala129Cys 15709779:278:23
status: NEW281 Secondary structure analysis by the Chou-Fasman method showed that five (V53C, T70C, V92C, A129C, S249C) of these six mutants, which resulted in doxorubicin sensitivity, showed no change at all in their predicted secondary structure, the exception being S236C, which showed a split in the helical stretch predicted between residues 226 and 248 in the C terminus of DrrB.
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ABCB1 p.Ala129Cys 15709779:281:91
status: NEW