Structure and mechanism of ATP-binding cassette transporters

ATP-binding cassette (ABC) transporters constitute a large superfamily of integral membrane proteins that includes both importers and exporters. In recent years, several structures of complete ABC transporters have been determined by X-ray crystallography. These structures suggest a mechanism by which binding and hydrolysis of ATP by the cytoplasmic, nucleotide-binding domains control the conformation of the transmembrane domains and therefore which side of the membrane the translocation pathway is exposed to. A basic, conserved two-state mechanism can explain active transport of both ABC importers and ABC exporters, but various questions remain unresolved. In this article, I will review some of the crystal structures and the mechanistic insight gained from them. Future challenges for a better understanding of the mechanism of ABC transporters will be outlined.

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Insect ATP-Binding Cassette (ABC) Transporters: Roles in Xenobiotic Detoxification and Bt Insecticidal Activity

International Journal of Molecular Sciences ◽

10.3390/ijms20112829 ◽

2019 ◽

Vol 20 (11) ◽

pp. 2829 ◽

Cited By ~ 9

Author(s):

Chao Wu ◽

Swapan Chakrabarty ◽

Minghui Jin ◽

Kaiyu Liu ◽

Yutao Xiao

Keyword(s):

Abc Transporter ◽

Conformational Changes ◽

Abc Transporters ◽

Insecticidal Activity ◽

Atp Hydrolysis ◽

Atp Binding ◽

Bt Toxin ◽

Xenobiotic Detoxification ◽

Binding Domains ◽

Atp Binding Cassette

ATP-binding cassette (ABC) transporters, a large class of transmembrane proteins, are widely found in organisms and play an important role in the transport of xenobiotics. Insect ABC transporters are involved in insecticide detoxification and Bacillus thuringiensis (Bt) toxin perforation. The complete ABC transporter is composed of two hydrophobic transmembrane domains (TMDs) and two nucleotide binding domains (NBDs). Conformational changes that are needed for their action are mediated by ATP hydrolysis. According to the similarity among their sequences and organization of conserved ATP-binding cassette domains, insect ABC transporters have been divided into eight subfamilies (ABCA–ABCH). This review describes the functions and mechanisms of ABC transporters in insecticide detoxification, plant toxic secondary metabolites transport and insecticidal activity of Bt toxin. With improved understanding of the role and mechanisms of ABC transporter in resistance to insecticides and Bt toxins, we can identify valuable target sites for developing new strategies to control pests and manage resistance and achieve green pest control.

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A new twist in ABC transporter mediated multidrug resistance − Pdr5 is a drug/proton co-transporter

10.1101/2021.05.26.445758 ◽

2021 ◽

Author(s):

Manuel Wagner ◽

Daniel Blum ◽

Stefanie Raschka ◽

Christoph Gertzen ◽

Sander Smits ◽

...

Keyword(s):

Multidrug Resistance ◽

Abc Transporters ◽

Drug Transport ◽

Molecular Mechanisms ◽

Efflux Pump ◽

Coupled Processes ◽

Atp Binding ◽

Cytotoxic Compounds ◽

Hydrolysis Of ◽

Atp Binding Cassette

The two major efflux pump systems that are involved in multidrug resistance (MDR) are (i) ATP binding cassette (ABC) transporters and (ii) secondary transporters. While the former use binding and hydrolysis of ATP to facilitate export of cytotoxic compounds, the latter utilize electrochemical gradients to expel their substrates. Pdr5 from Saccharomyces cerevisiae is a prominent member of eukaryotic ATP binding cassette (ABC) transporters that are involved in multidrug resistance (MDR) and used as a frequently studied model system. Although investigated for decades, the underlying molecular mechanisms of drug transport and substrate specificity remain elusive. Here, we provide electrophysiological data on the reconstituted Pdr5 demonstrating that this MDR efflux pump does not only actively translocate its substrates across the lipid bilayer, but at the same time generates a proton motif force in the presence of Mg2+-ATP and substrates by acting as a proton/drug co-transporter. Similar observations have not yet been reported for any other MDR efflux pump. We conclude from these results that the mechanism of MDR conferred by Pdr5 and likely other transporters is more complex than the sole extrusion of cytotoxic compounds and involves secondary coupled processes suitable to increase the effectiveness.

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Characterization of Oligomeric Human Half-ABC Transporter ATP-binding Cassette G2

Journal of Biological Chemistry ◽

10.1074/jbc.m310785200 ◽

2004 ◽

Vol 279 (19) ◽

pp. 19781-19789 ◽

Cited By ~ 178

Author(s):

Junkang Xu ◽

Yang Liu ◽

Youyun Yang ◽

Susan Bates ◽

Jian-Ting Zhang

Keyword(s):

Abc Transporters ◽

Transmembrane Domain ◽

Gel Filtration ◽

Nucleotide Binding ◽

Sucrose Density Gradient ◽

Atp Binding ◽

Cancer Resistance ◽

Binding Domains ◽

Resistance Protein ◽

Atp Binding Cassette

Human ATP-binding cassette G2 (ABCG2, also known as mitoxantrone resistance protein, breast cancer-resistance protein, ABC placenta) is a member of the superfamily of ATP-binding cassette (ABC) transporters that have a wide variety of substrates. Overexpression of human ABCG2 in model cancer cell lines causes multidrug resistance by actively effluxing anticancer drugs. Unlike most of the other ABC transporters which usually have two nucleotide-binding domains and two transmembrane domains, ABCG2 consists of only one nucleotide-binding domain followed by one transmembrane domain. Thus, ABCG2 has been thought to be a half-transporter that may function as a homodimer. In this study, we characterized the oligomeric feature of human ABCG2 using non-denaturing detergent perfluoro-octanoic acid and Triton X-100 in combination with gel filtration, sucrose density gradient sedimentation, and gel electrophoresis. Unexpectedly, we found that human ABCG2 exists mainly as a tetramer, with a possibility of a higher form of oligomerization. Monomeric and dimeric ABCG2 did not appear to be the major form of the protein. Further immunoprecipitation analysis showed that the oligomeric ABCG2 did not contain any other proteins. Taken together, we conclude that human ABCG2 likely exists and functions as a homotetramer.

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The Human ATP-Binding Cassette (ABC) Transporter Superfamily

10.22541/au.164001179.92800452/v1 ◽

2021 ◽

Author(s):

Michael Dean ◽

Karobi Moitra ◽

Rando Allikmets

Keyword(s):

Abc Transporter ◽

Abc Transporters ◽

Rare Variants ◽

Mendelian Inheritance ◽

Atp Binding ◽

Evolutionary Diversification ◽

Binding Domains ◽

Cholesterol Levels ◽

Human Disorders ◽

Atp Binding Cassette

The ATP-binding cassette (ABC) transporter superfamily comprises membrane proteins that efflux various substrates across extra- and intra-cellular membranes. Mutations in ABC genes cause 21 human disorders or phenotypes with Mendelian inheritance, including cystic fibrosis, adrenoleukodystrophy, retinal degeneration, cholesterol, and bile transport defects. Common polymorphisms and rare variants in ABC genes are associated with several complex phenotypes such as gout, gallstones, and cholesterol levels. Overexpression or amplification of specific drug efflux genes contributes to chemotherapy multidrug resistance. Conservation of the ATP-binding domains of ABC transporters defines the superfamily members, and phylogenetic analysis groups the 48 human ABC transporters into seven distinct subfamilies. While the conservation of ABC genes across most vertebrate species is high, there is also considerable gene duplication, deletion, and evolutionary diversification.

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How do ABC transporters drive transport?

Biological Chemistry ◽

10.1515/bc.2004.121 ◽

2004 ◽

Vol 385 (10) ◽

pp. 927-933 ◽

Cited By ~ 59

Author(s):

Chris Van Der Does ◽

Robert Tampé

Keyword(s):

High Resolution ◽

Membrane Proteins ◽

Crystal Structures ◽

Abc Transporters ◽

Nucleotide Binding ◽

Integral Membrane Proteins ◽

Biochemical Data ◽

Atp Binding ◽

Binding Domains ◽

Biochemical Level

Abstract Members of the ATP-binding cassette (ABC) superfamily are integral membrane proteins that hydrolyze ATP to drive transport. In the last two decades these proteins have been extensively characterized on a genetic and biochemical level, and in recent years high-resolution crystal structures of several nucleotide-binding domains and full-length transporters have extended our knowledge. Here we discuss the possible mechanisms of transport that have been derived from these crystal structures and the extensive available biochemical data.

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Functional Significance of the E Loop, a Novel Motif Conserved in the Lantibiotic Immunity ATP-Binding Cassette Transport Systems

Journal of Bacteriology ◽

10.1128/jb.00003-10 ◽

2010 ◽

Vol 192 (11) ◽

pp. 2801-2808 ◽

Cited By ~ 18

Author(s):

Ken-ichi Okuda ◽

Sae Yanagihara ◽

Tomomichi Sugayama ◽

Takeshi Zendo ◽

Jiro Nakayama ◽

...

Keyword(s):

Amino Acids ◽

Abc Transporters ◽

Amino Acid Replacement ◽

Transport Systems ◽

Atp Binding ◽

Transport Activity ◽

Multiple Sequence ◽

Binding Domains ◽

Alignment Analysis ◽

Atp Binding Cassette

ABSTRACT Lantibiotics are peptide-derived antibacterial substances produced by some Gram-positive bacteria and characterized by the presence of unusual amino acids, like lanthionines and dehydrated amino acids. Because lantibiotic producers may be attacked by self-produced lantibiotics, they express immunity proteins on the cytoplasmic membrane. An ATP-binding cassette (ABC) transport system mediated by the LanFEG protein complex is a major system in lantibiotic immunity. Multiple-sequence alignment analysis revealed that LanF proteins contain the E loop, a variant of the Q loop, which is a well-conserved motif in the nucleotide-binding domains (NBDs) of general ABC transporters. To elucidate E loop function, we introduced a mutation in the NukF protein, which is involved in the nukacin-ISK-1 immunity system. Amino acid replacement of glutamic acid in the E loop with glutamine (E85Q) resulted in slight decreases in the immunity level and transport activity. Additionally, the E85A mutation severely impaired the immunity level and transport activity. On the other hand, ATPase activities of purified E85Q and E85A mutants were almost similar to that of the wild type. These results suggested that the E loop found in ABC transporters involved in lantibiotic immunity plays a significant role in the function of these transporters, especially in the structural change of transmembrane domains.

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Preparation and structural analysis of (±)-threo-ritalinic acid

Acta Crystallographica Section C Crystal Structure Communications ◽

10.1107/s010827011302595x ◽

2013 ◽

Vol 69 (11) ◽

pp. 1225-1228 ◽

Cited By ~ 2

Author(s):

Sara Wyss ◽

Irmgard A. Werner ◽

W. Bernd Schweizer ◽

Simon M. Ametamey ◽

Selena Milicevic Sephton

Keyword(s):

Methyl Ester ◽

Free Acid ◽

Nmr Analysis ◽

Intermolecular Hydrogen Bonds ◽

X Ray ◽

X Ray Crystallography ◽

Ph Values ◽

Ritalinic Acid ◽

Methyl Phenidate ◽

Hydrolysis Of

Hydrolysis of the methyl ester (±)-threo-methyl phenidate afforded the free acid in 40% yield,viz.(±)-threo-ritalinic acid, C13H17NO2. Hydrolysis and subsequent crystallization were accomplished at pH values between 5 and 7 to yield colourless prisms which were analysed by X-ray crystallography. Crystals of (±)-threo-ritalinic acid belong to theP21/nspace group and form intermolecular hydrogen bonds. An antiperiplanar disposition of the H atoms of the (HOOC—)CH—CHpygroup (py is pyridine) was found in both the solid (diffraction analysis) and solution state (NMR analysis). It was also determined that (±)-threo-ritalinic acid conforms to the minimization of negativegauche+–gauche−interactions.

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Growth Promotion and Increased ATP-Binding Cassette Transporters Expression by Liraglutide in Triple Negative Breast Cancer Cell Line MDA-MB-231

Drug Research ◽

10.1055/a-1345-7890 ◽

2021 ◽

Author(s):

Amir Shadboorestan ◽

Parastoo Tarighi ◽

Mahsa Koosha ◽

Homa Faghihi ◽

Mohammad Hossein Ghahremani ◽

...

Keyword(s):

Breast Cancer ◽

Cell Line ◽

Triple Negative Breast Cancer ◽

Abc Transporters ◽

Triple Negative ◽

Epithelial Mesenchymal Transition ◽

Growth Promotion ◽

Atp Binding ◽

Mesenchymal Transition ◽

Atp Binding Cassette

Background Glucagon-like petide-1 (GLP-1) agonists such as liraglutide are widely employed in type 2 diabetes due to their glucose reducing properties and small risk of hypoglycemia. Recently, it has been shown that GLP-1agonists can inhibit breast cancer cells growth. Nonetheless, concerns are remained about liraglutide tumor promoting effects as stated by population studies. Material and Methods We evaluated the effects liraglutide on proliferation of MDA-MB-231 cells by MTT assay and then ATP-binding cassette (ABC) transporters expressions assessed by Real time PCR. Statistical comparisons were made using one-way analysis of variance followed by a post hoc Dunnett test. Results Here, we report that liraglutide can stimulate the growth of highly invasive triple negative cell line MDA-MB-231; which can be attributed to AMPK-dependent epithelial-mesenchymal transition (EMT) happening in MDA-MB-231 context. Toxicity effects were only observed with concentrations far above the serum liraglutide concentration. ATP-binding cassette (ABC) transporters expressions were upregulated, indicating the possible drug resistance and increased EMT. Conclusion In conclusion, these results suggest that liraglutide should be used with caution in patients who are suffering or have the personal history of triple negative breast cancer. However, more detailed studies are required to deepen understanding of liraglutide consequences in triple negative breast cancer. ▶Graphical Abstract.

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