scholarly journals Role of VltAB, an ABC Transporter Complex, in Viologen Tolerance inStreptococcus mutans

2011 ◽  
Vol 55 (4) ◽  
pp. 1460-1469 ◽  
Author(s):  
Saswati Biswas ◽  
Indranil Biswas
Keyword(s):  
Abc Transporter ◽  
Efflux Pump ◽  
Ammonium Compound ◽  
Multidrug Efflux ◽  
Multidrug Efflux Pump ◽  
Antibiotic Resistance Marker ◽  
Gram Positive ◽  
Wide Range ◽  
Insertion Mutants

ABSTRACTStreptococcus mutans, a Gram-positive organism, is the primary causative agent in the formation of dental caries in humans. To persist in the oral cavity,S. mutansmust be able to tolerate rapid environmental fluctuations and exposure to various toxic chemicals. However, the mechanisms underlying the ability of this cariogenic pathogen to survive and proliferate under harsh environmental conditions remain largely unknown. Here, we wanted to understand the mechanisms by whichS. mutanswithstands exposure to methyl viologen (MV), a quaternary ammonium compound (QAC) that generates superoxide radicals in the cell. To elucidate the essential genes for MV tolerance, screening of ∼3,500 mutants generated by ISS1mutagenesis, revealed 15 MV-sensitive mutants. Among them, five and four independent insertions had occurred in SMU.905 and SMU.906 genes, respectively. These two genes are appeared to be organized in an operon and encode a putative ABC transporter complex; we designated the genes asvltAandvltB, forviologentransporter. To verify our results,vltAwas deleted by using an antibiotic resistance marker; the mutant was just as sensitive to MV as the ISS1insertion mutants. Furthermore,vltAandvltBmutants were also sensitive to other viologen compounds such as benzyl and ethyl viologens. Complementation assays were also carried out to confirm the role of VltA and VltB in viologen tolerance. Sensitivity to various drugs, including a wide range of QACs, was evaluated. It appears that a functional VltA is also required for full resistance toward acriflavin, ethidium bromide, and safranin; all are well-known QACs. These results indicate that VltA/B constitute a heterodimeric multidrug efflux pump of the ABC family. BLAST-P analysis suggests that homologs of VltA/B are widely present in streptococci, enterococci, and other important Gram-positive pathogens.

scholarly journals AcrAB Multidrug Efflux Pump Is Associated with Reduced Levels of Susceptibility to Tigecycline (GAR-936) in Proteus mirabilis

2003 ◽  
Vol 47 (2) ◽  
pp. 665-669 ◽  
Author(s):  
Melissa A. Visalli ◽  
Ellen Murphy ◽  
Steven J. Projan ◽  
Patricia A. Bradford
Keyword(s):  
Proteus Mirabilis ◽  
Efflux Pump ◽  
Wild Type ◽  
Multidrug Efflux ◽  
Multidrug Efflux Pump ◽  
Transposon Insertion ◽  
Spectrum Activity ◽  
Insertion Mutants ◽  
Broad Spectrum Activity ◽  
Increased Susceptibility

ABSTRACT Tigecycline has good broad-spectrum activity against many gram-positive and gram-negative pathogens with the notable exception of the Proteeae. A study was performed to identify the mechanism responsible for the reduced susceptibility to tigecycline in Proteus mirabilis. Two independent transposon insertion mutants of P. mirabilis that had 16-fold-increased susceptibility to tigecycline were mapped to the acrB gene homolog of the Escherichia coli AcrRAB efflux system. Wild-type levels of decreased susceptibility to tigecycline were restored to the insertion mutants by complementation with a clone containing a PCR-derived fragment from the parental wild-type acrRAB efflux gene cluster. The AcrAB transport system appears to be associated with the intrinsic reduced susceptibility to tigecycline in P. mirabilis.

scholarly journals NorM of Vibrio parahaemolyticus Is an Na+-Driven Multidrug Efflux Pump

2000 ◽  
Vol 182 (23) ◽  
pp. 6694-6697 ◽  
Author(s):  
Yuji Morita ◽  
Atsuko Kataoka ◽  
Sumiko Shiota ◽  
Tohru Mizushima ◽  
Tomofusa Tsuchiya
Keyword(s):  
Vibrio Parahaemolyticus ◽  
Efflux Pump ◽  
Sequence Similarity ◽  
Multidrug Efflux ◽  
Multidrug Efflux Pump ◽  
Significant Sequence Similarity ◽  
Wide Range ◽  
New Type ◽  
Biological World ◽  
Energy Dependent

ABSTRACT NorM of Vibrio parahaemolyticusapparently is a new type of multidrug efflux protein, with no significant sequence similarity to any known transport proteins. Based on the following experimental results, we conclude that NorM is an Na+-driven Na+/drug antiporter. (i) Energy-dependent ethidium efflux from cells possessing NorM was observed in the presence of Na+ but not of K+. (ii) An artificially imposed, inwardly directed Na+gradient elicited ethidium efflux from cells. (iii) The addition of ethidium to cells loaded with Na+ elicited Na+efflux. Thus, NorM is an Na+/drug antiporting multidrug efflux pump, the first to be found in the biological world. Judging from the similarity of the NorM sequence to those of putative proteins in sequence databases, it seems that Na+/drug antiporters are present not only in V. parahaemolyticus but also in a wide range of other organisms.

scholarly journals Characterization of a Unique Outer Membrane Protein Required for Oxidative Stress Resistance and Virulence of Francisella tularensis

2018 ◽  
Vol 200 (8) ◽  
Author(s):  
Maha Alqahtani ◽  
Zhuo Ma ◽  
Harshada Ketkar ◽  
Ragavan Varadharajan Suresh ◽  
Meenakshi Malik ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Membrane Protein ◽  
Outer Membrane ◽  
Francisella Tularensis ◽  
Efflux Pump ◽  
Multidrug Efflux ◽  
Multidrug Efflux Pump ◽  
Content Type

ABSTRACT Francisella tularensis , the causative agent of tularemia, lacks typical bacterial virulence factors and toxins but still exhibits extreme virulence. The bacterial multidrug efflux systems consist of an inner membrane, a transmembrane membrane fusion protein, and an outer membrane (OM) component that form a contiguous channel for the secretion of a multitude of bacterial products. Francisella contains three orthologs of the OM proteins; two of these, termed TolC and FtlC, are important for tularemia pathogenesis. The third OM protein, SilC, is homologous to the silver cation efflux protein of other bacterial pathogens. The silC gene ( FTL_0686 ) is located on an operon encoding an Emr-type multidrug efflux pump of F. tularensis . The role of SilC in tularemia pathogenesis is not known. In this study, we investigated the role of SilC in secretion and virulence of F. tularensis by generating a silC gene deletion (Δ silC ) mutant and its transcomplemented strain. Our results demonstrate that the Δ silC mutant exhibits increased sensitivity to antibiotics, oxidants, silver, diminished intramacrophage growth, and attenuated virulence in mice compared to wild-type F. tularensis . However, the secretion of antioxidant enzymes of F. tularensis is not impaired in the Δ silC mutant. The virulence of the Δ silC mutant is restored in NADPH oxidase-deficient mice, indicating that SilC resists oxidative stress in vivo . Collectively, this study demonstrates that the OM component SilC serves a specialized role in virulence of F. tularensis by conferring resistance against oxidative stress and silver. IMPORTANCE Francisella tularensis , the causative agent of a fatal human disease known as tularemia, is a category A select agent and a potential bioterror agent. The virulence mechanisms of Francisella are not completely understood. This study investigated the role of a unique outer membrane protein, SilC, of a multidrug efflux pump in the virulence of F. tularensis . This is the first report demonstrating that the OM component SilC plays an important role in efflux of silver and contributes to the virulence of F. tularensis primarily by providing resistance against oxidative stress. Characterization of these unique virulence mechanisms will provide an understanding of the pathogenesis of tularemia and identification of potential targets for the development of effective therapeutics and prophylactics for protection from this lethal disease.

scholarly journals Induction of Pseudomonas syringae pv. tomato DC3000 MexAB-OprM Multidrug Efflux Pump by Flavonoids Is Mediated by the Repressor PmeR

2011 ◽  
Vol 24 (10) ◽  
pp. 1207-1219 ◽  
Author(s):  
Paola Vargas ◽  
Antonia Felipe ◽  
Carmen Michán ◽  
María-Trinidad Gallegos
Keyword(s):  
Pseudomonas Syringae ◽  
Efflux Pump ◽  
Regulatory Gene ◽  
Multidrug Efflux ◽  
Tomato Dc3000 ◽  
Multidrug Efflux Pump ◽  
Tomato Plants ◽  
In Vivo Experiments

In this study, we have analyzed the expression of the Pseudomonas syringae pv. tomato DC3000 mexAB-oprM efflux pump operon and of the regulatory gene pmeR, and we have investigated the role of the PmeR protein on transcription from both promoters. We demonstrate that mexAB-oprM and pmeR are expressed in vivo at a relatively high and moderate basal level, respectively, which, in both cases, increases in the presence of different flavonoids and other compounds, such as butyl and methylparaben. We show that PmeR is the local repressor of the mexAB-oprM promoter and is able to regulate its own expression. The mechanism for this regulation includes binding to a pseudopalindromic operator site which overlaps both mexAB-oprM and pmeR promoters. We have also proven that flavonoids are able to interact with PmeR and induce a conformational change that interferes with the DNA binding ability of PmeR, thereby modulating mexAB-oprM and pmeR expression. Finally, we demonstrate by in vivo experiments that the PmeR/MexAB-OprM system contributes to the colonization of tomato plants. These results provide new insight into a transcriptional regulator and a transport system that play essential roles in the ability of P. syringae pv. tomato DC3000 to resist the action of flavonoids produced by the host.

scholarly journals Novel Ciprofloxacin-Resistant, Nalidixic Acid-Susceptible Mutant of Staphylococcus aureus

2002 ◽  
Vol 46 (7) ◽  
pp. 2276-2278 ◽  
Author(s):  
Laura J. V. Piddock ◽  
Yu Fang Jin ◽  
Mark A. Webber ◽  
Martin J. Everett
Keyword(s):  
Staphylococcus Aureus ◽  
Nalidixic Acid ◽  
Promoter Region ◽  
Efflux Pump ◽  
Multidrug Efflux ◽  
Multidrug Efflux Pump

ABSTRACT A ciprofloxacin-resistant, nalidixic acid-susceptible mutant of Staphylococcus aureus (F145) contained no mutations within gyrA, gyrB, grlA, and grlB or within norA or its promoter region. MICs and accumulation studies suggest the role of a novel multidrug efflux pump.

scholarly journals Phylogenetic and functional characterisation of the Haemophilus influenzae multidrug efflux pump AcrB

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Martijn Zwama ◽  
Akihito Yamaguchi ◽  
Kunihiko Nishino
Keyword(s):  
Haemophilus Influenzae ◽  
Efflux Pump ◽  
Multidrug Efflux ◽  
Multidrug Efflux Pump ◽  
Efflux Pump Inhibitor ◽  
Over Expression ◽  
Multidrug Efflux Pumps ◽  
Functional Characterisation ◽  
Outer Membrane Porin ◽  
Wide Range

Abstract Multidrug resistance in Gram-negative bacteria can arise by the over-expression of multidrug efflux pumps, which can extrude a wide range of antibiotics. Here we describe the ancestral Haemophilus influenzae efflux pump AcrB (AcrB-Hi). We performed a phylogenetic analysis of hundreds of RND-type transporters. We found that AcrB-Hi is a relatively ancient efflux pump, which nonetheless can export the same range of antibiotics as its evolved colleague from Escherichia coli. AcrB-Hi was not inhibited by the efflux pump inhibitor ABI-PP, and could export bile salts weakly. This points to an environmental adaptation of RND transporters. We also explain the sensitivity of H. influenzae cells to β-lactams and novobiocin by the outer membrane porin OmpP2. This porin counterbalances the AcrB-Hi efflux by leaking the drugs back into the cells. We hypothesise that multidrug recognition by RND-type pumps is not an evolutionarily acquired ability, and has been present since ancient promiscuous transporters.

Role of AcrAB-TolC multidrug efflux pump in drug-resistance acquisition by plasmid transfer

Science ◽  
2019 ◽  
Vol 364 (6442) ◽  
pp. 778-782 ◽  
Author(s):  
Sophie Nolivos ◽  
Julien Cayron ◽  
Annick Dedieu ◽  
Adeline Page ◽  
Frederic Delolme ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Efflux Pump ◽  
Recipient Cell ◽  
Plasmid Transfer ◽  
Cell Protein ◽  
Antibiotics Resistance ◽  
Multidrug Efflux ◽  
Multidrug Efflux Pump ◽  
Live Cell Microscopy

Drug-resistance dissemination by horizontal gene transfer remains poorly understood at the cellular scale. Using live-cell microscopy, we reveal the dynamics of resistance acquisition by transfer of the Escherichia coli fertility factor–conjugation plasmid encoding the tetracycline-efflux pump TetA. The entry of the single-stranded DNA plasmid into the recipient cell is rapidly followed by complementary-strand synthesis, plasmid-gene expression, and production of TetA. In the presence of translation-inhibiting antibiotics, resistance acquisition depends on the AcrAB-TolC multidrug efflux pump, because it reduces tetracycline concentrations in the cell. Protein synthesis can thus persist and TetA expression can be initiated immediately after plasmid acquisition. AcrAB-TolC efflux activity can also preserve resistance acquisition by plasmid transfer in the presence of antibiotics with other modes of action.

scholarly journals Characterization of Posttranslationally Modified Multidrug Efflux Pumps Reveals an Unexpected Link between Glycosylation and Antimicrobial Resistance

mBio ◽  
2020 ◽  
Vol 11 (6) ◽  
Author(s):  
Sherif Abouelhadid ◽  
John Raynes ◽  
Tam Bui ◽  
Jon Cuccui ◽  
Brendan W. Wren
Keyword(s):  
Antimicrobial Resistance ◽  
Efflux Pump ◽  
Multidrug Resistant ◽  
Multidrug Efflux ◽  
Multidrug Efflux Pump ◽  
Gram Negative ◽  
Content Type ◽  
Multidrug Efflux Pumps ◽  
Pump Activity

ABSTRACT The substantial rise in multidrug-resistant bacterial infections is a current global imperative. Cumulative efforts to characterize antimicrobial resistance in bacteria has demonstrated the spread of six families of multidrug efflux pumps, of which resistance-nodulation-cell division (RND) is the major mechanism of multidrug resistance in Gram-negative bacteria. RND is composed of a tripartite protein assembly and confers resistance to a range of unrelated compounds. In the major enteric pathogen Campylobacter jejuni, the three protein components of RND are posttranslationally modified with N-linked glycans. The direct role of N-linked glycans in C. jejuni and other bacteria has long been elusive. Here, we present the first detailed account of the role of N-linked glycans and the link between N-glycosylation and antimicrobial resistance in C. jejuni. We demonstrate the multifunctional role of N-linked glycans in enhancing protein thermostability, stabilizing protein complexes and the promotion of protein-protein interaction, thus mediating antimicrobial resistance via enhancing multidrug efflux pump activity. This affirms that glycosylation is critical for multidrug efflux pump assembly. We present a generalized strategy that could be used to investigate general glycosylation system in Campylobacter genus and a potential target to develop antimicrobials against multidrug-resistant pathogens. IMPORTANCE Nearly all bacterial species have at least a single glycosylation system, but the direct effects of these posttranslational protein modifications are unresolved. Glycoproteome-wide analysis of several bacterial pathogens has revealed general glycan modifications of virulence factors and protein assemblies. Using Campylobacter jejuni as a model organism, we have studied the role of general N-linked glycans in the multidrug efflux pump commonly found in Gram-negative bacteria. We show, for the first time, the direct link between N-linked glycans and multidrug efflux pump activity. At the protein level, we demonstrate that N-linked glycans play a role in enhancing protein thermostability and mediating the assembly of the multidrug efflux pump to promote antimicrobial resistance, highlighting the importance of this posttranslational modification in bacterial physiology. Similar roles for glycans are expected to be found in other Gram-negative pathogens that possess general protein glycosylation systems.

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