scholarly journals Overexpression and functional characterization of an ABC (ATP-binding cassette) transporter encoded by the genes drrA and drrB of Mycobacterium tuberculosis

2002 ◽  
Vol 367 (1) ◽  
pp. 279-285 ◽  
Author(s):  
Baisakhee Saha CHOUDHURI ◽  
Sanjib BHAKTA ◽  
Rajib BARIK ◽  
Joyoti BASU ◽  
Manikuntala KUNDU ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Abc Transporters ◽  
Efflux Pump ◽  
Functional Characterization ◽  
Atp Binding ◽  
E Coli ◽  
Neutral Compound ◽  
Genes Encoding ◽  
Simultaneous Expression ◽  
Atp Binding Cassette

The genes encoding ATP-binding cassette (ABC) transporters occupy 2.5% of the genome of Mycobacterium tuberculosis. However, none of these putative ABC transporters has been characterized so far. We describe the development of expression systems for simultaneous expression of the ATP-binding protein DrrA and the membrane integral protein DrrB which together behave as a functional doxorubicin efflux pump. Doxorubicin uptake in Escherichia coli or Mycobacterium smegmatis expressing DrrAB was inhibited by reserpine, an inhibitor of ABC transporters. The localization of DrrA to the membrane depended on the simultaneous expression of DrrB. ATP binding was positively regulated by doxorubicin and daunorubicin. At the same time, DrrB appeared to be sensitive to proteolysis when expressed alone in the absence of DrrA. Simultaneous expression of the two polypeptides was essential to obtain a functional doxorubicin efflux pump. Expression of DrrAB in E. coli conferred 8-fold increased resistance to ethidium bromide, a cationic compound. 2′,7′-bis-(2-Carboxyethyl)-5(6)-carboxyfluorescein (BCECF), a neutral compound, also behaved as a substrate of the reconstituted efflux pump. When expressed in M. smegmatis, DrrAB conferred resistance to a number of clinically relevant, structurally unrelated antibiotics. The resistant phenotype could be reversed by verapamil and reserpine, two potent inhibitors of ABC transporters.

scholarly journals Genetic Analysis of the Mode of Interplay between an ATPase Subunit and Membrane Subunits of the Lipoprotein-Releasing ATP-Binding Cassette Transporter LolCDE

2006 ◽  
Vol 188 (8) ◽  
pp. 2856-2864 ◽  
Author(s):  
Yasuko Ito ◽  
Hitomi Matsuzawa ◽  
Shin-ichi Matsuyama ◽  
Shin-ichiro Narita ◽  
Hajime Tokuda
Keyword(s):  
Abc Transporters ◽  
Atp Hydrolysis ◽  
Dominant Negative ◽  
Growth Defect ◽  
Atp Binding ◽  
Inner Membrane ◽  
Atpase Subunit ◽  
E Coli ◽  
Atp Binding Cassette Transporter ◽  
Atp Binding Cassette

ABSTRACT The LolCDE complex, an ATP-binding cassette (ABC) transporter, releases lipoproteins from the inner membrane, thereby initiating lipoprotein sorting to the outer membrane of Escherichia coli. The LolCDE complex is composed of two copies of an ATPase subunit, LolD, and one copy each of integral membrane subunits LolC and LolE. LolD hydrolyzes ATP on the cytoplasmic side of the inner membrane, while LolC and/or LolE recognize and release lipoproteins anchored to the periplasmic leaflet of the inner membrane. Thus, functional interaction between LolD and LolC/E is critically important for coupling of ATP hydrolysis to the lipoprotein release reaction. LolD contains a characteristic sequence called the LolD motif, which is highly conserved among LolD homologs but not other ABC transporters of E. coli. The LolD motif is suggested to be a region in contact with LolC/E, judging from the crystal structures of other ABC transporters. To determine the functions of the LolD motif, we mutagenized each of the 32 residues of the LolD motif and isolated 26 dominant-negative mutants, whose overexpression arrested growth despite the chromosomal lolD + background. We then selected suppressor mutations of the lolC and lolE genes that correct the growth defect caused by the LolD mutations. Mutations of the lolC suppressors were mainly located in the periplasmic loop, whereas ones of lolE suppressors were mainly located in the cytoplasmic loop, suggesting that the mode of interaction with LolD differs between LolC and LolE. Moreover, the LolD motif was found to be critical for functional interplay with LolC/E, since some LolD mutations lowered the ATPase activity of LolCDE without affecting that of LolD.

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

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.

scholarly journals The ATP-Binding Cassette (ABC) Transport Systems in Mycobacterium tuberculosis: Structure, Function, and Possible Targets for Therapeutics

Biology ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 443
Author(s):  
Marcelo Cassio Barreto de Oliveira ◽  
Andrea Balan
Keyword(s):  
Drug Resistance ◽  
Mycobacterium Tuberculosis ◽  
Abc Transporters ◽  
Nutrient Recycling ◽  
Structural Features ◽  
Transport Systems ◽  
Multiple Drug ◽  
Atp Binding ◽  
Substrate Uptake ◽  
Atp Binding Cassette

Mycobacterium tuberculosis is the etiological agent of tuberculosis (TB), a disease that affects millions of people in the world and that is associated with several human diseases. The bacillus is highly adapted to infect and survive inside the host, mainly because of its cellular envelope plasticity, which can be modulated to adapt to an unfriendly host environment; to manipulate the host immune response; and to resist therapeutic treatment, increasing in this way the drug resistance of TB. The superfamily of ATP-Binding Cassette (ABC) transporters are integral membrane proteins that include both importers and exporters. Both types share a similar structural organization, yet only importers have a periplasmic substrate-binding domain, which is essential for substrate uptake and transport. ABC transporter-type importers play an important role in the bacillus physiology through the transport of several substrates that will interfere with nutrition, pathogenesis, and virulence. Equally relevant, exporters have been involved in cell detoxification, nutrient recycling, and antibiotics and drug efflux, largely affecting the survival and development of multiple drug-resistant strains. Here, we review known ABC transporters from M. tuberculosis, with particular focus on the diversity of their structural features and relevance in infection and drug resistance.

scholarly journals LAMC2 promotes cancer progression and gemcitabine resistance through modulation of EMT and ATP-binding cassette transporters in pancreatic ductal adenocarcinoma

2021 ◽  
Author(s):  
Yasuyuki Okada ◽  
Naoki Takahashi ◽  
Tetsuji Takayama ◽  
Ajay Goel
Keyword(s):  
Pancreatic Ductal Adenocarcinoma ◽  
Abc Transporters ◽  
Functional Characterization ◽  
Predictive Biomarkers ◽  
Ductal Adenocarcinoma ◽  
Migration And Invasion ◽  
Atp Binding ◽  
Mesenchymal Transition ◽  
Atp Binding Cassette

Abstract Pancreatic ductal adenocarcinoma (PDAC) is an aggressive disease with poor prognosis. Gemcitabine remains an effective option for the majority of PDAC patients. Unfortunately, currently no reliable prognostic and predictive biomarkers of therapeutic response are available for the patients with PDAC. Laminin γ2 (LAMC2) is overexpressed in several cancers, and its high expression facilitates cancer development and chemoresistance. However, its functional role in PDAC remains unclear, and a better understanding of this will likely help improve the prognosis of PDAC patients. This study aimed to elucidate the clinical and biological role of LAMC2 in PDAC. We first analyzed the expression levels of LAMC2 by real-time reverse transcription PCR in a cohort of 114 PDAC patients. Interestingly, higher expression of LAMC2 significantly correlated with poor survival in PDAC cohort. In addition, elevated LAMC2 expression served as a potential prognostic marker for survival. Subsequently, functional characterization for the role of LAMC2 in PDAC was performed by small interfering RNA (siRNA) knockdown in pancreatic cancer (PC) cell lines. Interestingly, inhibition of LAMC2 in PC cells enhanced the gemcitabine sensitivity and induction of apoptosis. Moreover, it inhibited colony formation ability, migration, and invasion potential. Furthermore, LAMC2 regulated the expression of epithelial-mesenchymal transition (EMT) phenotype. In addition, LAMC2 significantly correlated with genes associated with the expression of ATP-binding cassette (ABC) transporters in PC cells and PDAC patients. In conclusion, these results suggest that LAMC2 regulates gemcitabine sensitivity through EMT and ABC transporters in PDAC and may be a novel therapeutic target in PDAC patients.

scholarly journals Mutagenic Analysis of the Putative ABCC6 Substrate-Binding Cavity Using a New Homology Model

2021 ◽  
Vol 22 (13) ◽  
pp. 6910
Author(s):  
Flora Szeri ◽  
Valentina Corradi ◽  
Fatemeh Niaziorimi ◽  
Sylvia Donnelly ◽  
Gwenaëlle Conseil ◽  
...  
Keyword(s):  
Binding Site ◽  
Efflux Pump ◽  
Substrate Binding ◽  
Functional Characterization ◽  
Atp Release ◽  
Homology Model ◽  
Atp Binding ◽  
Atp Binding Site ◽  
Binding Cavity ◽  
Atp Efflux

Inactivating mutations in ABCC6 underlie the rare hereditary mineralization disorder pseudoxanthoma elasticum. ABCC6 is an ATP-binding cassette (ABC) integral membrane protein that mediates the release of ATP from hepatocytes into the bloodstream. The released ATP is extracellularly converted into pyrophosphate, a key mineralization inhibitor. Although ABCC6 is firmly linked to cellular ATP release, the molecular details of ABCC6-mediated ATP release remain elusive. Most of the currently available data support the hypothesis that ABCC6 is an ATP-dependent ATP efflux pump, an un-precedented function for an ABC transporter. This hypothesis implies the presence of an ATP-binding site in the substrate-binding cavity of ABCC6. We performed an extensive mutagenesis study using a new homology model based on recently published structures of its close homolog, bovine Abcc1, to characterize the substrate-binding cavity of ABCC6. Leukotriene C4 (LTC4), is a high-affinity substrate of ABCC1. We mutagenized fourteen amino acid residues in the rat ortholog of ABCC6, rAbcc6, that corresponded to the residues in ABCC1 found in the LTC4 binding cavity. Our functional characterization revealed that most of the amino acids in rAbcc6 corresponding to those found in the LTC4 binding pocket in bovine Abcc1 are not critical for ATP efflux. We conclude that the putative ATP binding site in the substrate-binding cavity of ABCC6/rAbcc6 is distinct from the bovine Abcc1 LTC4-binding site.

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

Drug Research ◽  
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.

scholarly journals Correction to: ATP binding cassette (ABC) transporters: expression and clinical value in glioblastoma

2018 ◽  
Vol 138 (3) ◽  
pp. 487-487
Author(s):  
Antonin Dréan ◽  
Shai Rosenberg ◽  
François-Xavier Lejeune ◽  
Larissa Goli ◽  
Aravindan Arun Nadaradjane ◽  
...  
Keyword(s):  
Abc Transporters ◽  
Atp Binding ◽  
Clinical Value ◽  
Atp Binding Cassette

scholarly journals Expression of some ATP-binding cassette transporters in acute myeloid leukemia

2017 ◽  
Vol 9 (4) ◽  
Author(s):  
Antonella Maria Salvia ◽  
Flavia Cuviello ◽  
Sabrina Coluzzi ◽  
Roberta Nuccorini ◽  
Immacolata Attolico ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Acute Myeloid Leukemia ◽  
Abc Transporters ◽  
Healthy Subjects ◽  
Myeloid Leukemia ◽  
Resistance Mechanisms ◽  
Atp Binding ◽  
Atp Binding Cassette Transporters ◽  
Acute Myeloid ◽  
Atp Binding Cassette

Hematopoietic cells express ATP binding cassette (ABC) transporters in relation to different degrees of differentiation. One of the known multidrug resistance mechanisms in acute myeloid leukemia (AML) is the overexpression of efflux pumps belonging to the superfamily of ABC transporters such as ABCB1, ABCG2 and ABCC1. Although several studies were carried out to correlate ABC transporters expression with drug resistance, little is known about their role as markers of diagnosis and progression of the disease. For this purpose we investigated the expression, by real-time PCR, of some ABC genes in bone marrow samples of AML patients at diagnosis and after induction therapy. At diagnosis, ABCG2 was always down-regulated, while an up regulated trend for ABCC1 was observed. After therapy the examined genes showed a different expression trend and approached the values of healthy subjects suggesting that this event could be considered as a marker of AML regression. The expression levels of some ABC transporters such as ABCC6, seems to be related to gender, age and to the presence of FLT3/ITD gene mutation.

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