Structure of a human multidrug transporter in an inward-facing conformation

Faculty of Life Sciences, Manchester Interdisciplinary Biocentre, The University of Manchester, 131 Princess Street, Manchester M1 7DN, UK.
Journal of Structural Biology (Impact Factor: 3.23). 06/2010; 170(3):540-7. DOI: 10.1016/j.jsb.2010.01.011
Source: PubMed


Multidrug resistance protein 1 (ABCC1) is a member of the 'C' class of ATP-binding cassette transporters, which can give rise to resistance to chemotherapy via drug export from cells. It also acts as a leukotriene C4 transporter, and hence has a role in adaptive immune response. Most C-class members have an additional NH(2)-terminal transmembrane domain versus other ATP-binding cassette transporters, but little is known about the structure and role of this domain. Using electron cryomicroscopy of 2D crystals, data at 1/6per A(-1) resolution was generated for the full-length ABCC1 protein in the absence of ATP. Analysis using homologous structures from bacteria and mammals allowed the core transmembrane domains to be localised in the map. These display an inward-facing conformation and there is a noteworthy separation of the cytoplasmic nucleotide-binding domains. Examination of non-core features in the map suggests that the additional NH(2)-terminal domain has extensive contacts on one side of both core domains, and mirrors their inward-facing configuration in the absence of nucleotide.

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Available from: Robert C Ford, Oct 02, 2015
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    • "It plays, however , an important role in processing and trafficking of the transporter. The most recent structure of MRP1 obtained by cryoelectron microscopy of 2D crystals (Rosenberg et al., 2010) has revealed an inward-facing structure with separated NBD domains similar to the structure obtained previously for P-gp (Aller et al., 2009). Unfortunately, the resolution of the MRP1 structure (1/6 per Å –1 ) was too low to allow for identification of protein fragments engaged in the formation of the drug binding pocket. "
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    ABSTRACT: Multidrug resistance (MDR) of cancer cells poses a serious obstacle to successful chemotherapy. The overexpression of multispecific ATP-binding cassette transporters appears to be the main mechanism of MDR. A search for MDR-reversing agents able to sensitize resistant cells to chemotherapy is ongoing in the hope of their possible clinical use. Studies of MDR modulators, although they have not produced clinically beneficial effects yet, may greatly enrich our knowledge about MDR transporters, their specificity and mechanism of action, especially substrate and/or inhibitor recognition. In the present review, interactions of three groups of modulators: phenothiazines, flavonoids and stilbenes with both P-glycoprotein and MRP1 are discussed. Each group of compounds is likely to interact with the MDR transporters by a different mechanism. Phenothiazines probably interact with drug binding sites, but they also could indirectly affect the transporter's activity by perturbing lipid bilayers. Flavonoids mainly interact with ABC proteins within their nucleotide-binding domains, though the more hydrophobic flavonoids may bind to regions within transmembrane domains. The possible mechanism of MDR reversal by stilbenes may result from their direct interaction with the transporter (possibly within substrate recognition sites) but some indirect effects such as stilbene-induced changes in gene expression pattern and in apoptotic pathways should also be considered. Literature data as well as some of our recent results are discussed. Special emphasis is put on cases when the interactions of a given compound with both P-glycoprotein and MRP1 have been studied simultaneously.
    Acta biochimica Polonica 12/2011; 58(4):433-48. · 1.15 Impact Factor
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    • "However, it is possible that regulatory domains of ABC proteins may act in a similar fashion, by influencing the dimerisation of the NBDs [7] [10] [11]. Medium resolution data from 2D crystals of another member of the 'C' subclass of ABC proteins have also been recently published [12]. Low-resolution structural data from 2D crystals and single-particle analysis of the whole CFTR protein have been reported. "
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    ABSTRACT: The domain organisation of the cystic fibrosis transmembrane conductance regulator (CFTR) protein was studied using electron microscopy of detergent-solubilised dimeric complexes. Ni-NTA nanogold labelling data suggest that in the nonphosphorylated, nucleotide-free state, the C-terminus is intimately associated with the cytoplasmic ATP-binding regions, whilst part of the regulatory domain occupies a position close to the cytoplasmic surface of the lipid membrane. Removal of the entire second nucleotide binding domain (NBD2) results in a deficit in the CFTR structure that is consistent with the size and shape of a single NBD. The data suggest that NBD2 lies closer to the C2 symmetry axis than the first nucleotide binding domain (NBD1) and that NBD2 from one CFTR monomer also contacts NBD1 from the opposing one. These data suggest that current homology models for CFTR based on other ATP-binding cassette proteins appear to be reasonable, at least to low resolution. We also find that Ni-NTA nanogold labelling of an internal hexa-Histidine sequence is a valuable approach to locate individual protein domains.
    Biochimica et Biophysica Acta 01/2011; 1808(1):399-404. DOI:10.1016/j.bbamem.2010.08.012 · 4.66 Impact Factor
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    ABC Proteins, 01/2003: pages 65-80; , ISBN: 9780123525512
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