scholarly journals Mdt(A), a New Efflux Protein Conferring Multiple Antibiotic Resistance in Lactococcus lactis andEscherichia coli

2001 ◽  
Vol 45 (4) ◽  
pp. 1109-1114 ◽  
Author(s):  
Vincent Perreten ◽  
Franziska V. Schwarz ◽  
Michael Teuber ◽  
Stuart B. Levy
Keyword(s):  
Escherichia Coli ◽  
Lactococcus Lactis ◽  
Major Facilitator Superfamily ◽  
Multiple Drug ◽  
Drug Transporter ◽  
Multiple Antibiotic Resistance ◽  
Atp Binding Site ◽  
E Coli ◽  
Transmembrane Segments ◽  
Major Facilitator

ABSTRACT The mdt(A) gene, previously designatedmef214, from Lactococcus lactis subsp.lactis plasmid pK214 encodes a protein [Mdt(A) (multiple drug transporter)] with 12 putative transmembrane segments (TMS) that contain typical motifs conserved among the efflux proteins of the major facilitator superfamily. However, it also has two C-motifs (conserved in the fifth TMS of the antiporters) and a putative ATP-binding site. Expression of the cloned mdt(A) gene decreased susceptibility to macrolides, lincosamides, streptogramins, and tetracyclines in L. lactis and Escherichia coli, but not in Enterococcus faecalis or inStaphylococcus aureus. Glucose-dependent efflux of erythromycin and tetracycline was demonstrated in L. lactisand in E. coli.

scholarly journals A selC-Associated Genomic Island of the Extraintestinal Avian Pathogenic Escherichia coli Strain BEN2908 Is Involved in Carbohydrate Uptake and Virulence

2006 ◽  
Vol 188 (3) ◽  
pp. 977-987 ◽  
Author(s):  
Iman Chouikha ◽  
Pierre Germon ◽  
Annie Brée ◽  
Philippe Gilot ◽  
Maryvonne Moulin-Schouleur ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Genomic Island ◽  
Bacterial Species ◽  
Coli Strain ◽  
Major Facilitator Superfamily ◽  
Integrase Gene ◽  
E Coli ◽  
Pathogenic Escherichia Coli ◽  
Major Facilitator Superfamily Transporter ◽  
Major Facilitator

ABSTRACT The complete nucleotide sequence and genetic organization of a new genomic island (AGI-3) isolated from the extraintestinal avian pathogenic Escherichia coli strain BEN2908 is reported. This 49,600-bp island is inserted at the selC locus and contains putative mobile genetic elements such as a phage-related integrase gene, transposase genes, and direct repeats. AGI-3 shows a mosaic structure of five modules. Some of these modules are present in other E. coli strains and in other pathogenic bacterial species. The gene cluster aec-35 to aec-37 of module 1 encodes proteins associated with carbohydrates assimilation such as a major facilitator superfamily transporter (Aec-36), a glycosidase (Aec-37), and a putative transcriptional regulator of the LacI family (Aec-35). The aec-35 to aec-37 cluster was found in 11.6% of the tested pathogenic and nonpathogenic E. coli strains. When present, the aec-35 to aec-37 cluster is strongly associated with the selC locus (97%). Deletion of the aec-35-aec-37 region affects the assimilation of seven carbohydrates, decreases the growth rate of the strain in minimal medium containing galacturonate or trehalose, and attenuates the virulence of E. coli BEN2908 for chickens.

scholarly journals Influence of theyjiL-mdtMGene Cluster on the Antibacterial Activity of Proline-Rich Antimicrobial Peptides Overcoming Escherichia coli Resistance Induced by the Missing SbmA Transporter System

2015 ◽  
Vol 59 (10) ◽  
pp. 5992-5998 ◽  
Author(s):  
Andor Krizsan ◽  
Daniel Knappe ◽  
Ralf Hoffmann
Keyword(s):  
Escherichia Coli ◽  
Antimicrobial Peptides ◽  
Random Mutagenesis ◽  
Major Facilitator Superfamily ◽  
Multiresistant Pathogens ◽  
Content Type ◽  
E Coli ◽  
Cytotoxic Compounds ◽  
Major Facilitator ◽  
Mfs Transporters

ABSTRACTIn view of increasing health threats from multiresistant pathogens, antimicrobial peptides (AMPs) and, specifically, proline-rich AMPs (PrAMPs) have been investigated in animal models. PrAMPs enter bacteria via the ABC transporter SbmA and inhibit intracellular targets. We used phage transduction (Tn10insertion) to screen by random mutagenesis for alternative uptake mechanisms for analogs of apidaecin 1b, a honeybee-derived PrAMP. All 24 apidaecin-resistant mutants had the Tn10insertion in thesbmAgene. ThesesbmA::Tn10insertion mutants and theEscherichia coliBW25113 ΔsbmA(JW0368) strain were still susceptible to the bactenecin PrAMP Bac7(1-35) and oncocin PrAMPs Onc18 and Onc112, as well as to Chex1-Arg20, despite significantly reduced internalizations. In a second round of random mutagenesis, the remaining susceptibility was linked to theyjiL-mdtMgene cluster.E. coliBW25113 and its ΔyjiLnull mutant (JW5785) were equally susceptible to all PrAMPs tested, whereas the BW25113 ΔmdtMmutant was less susceptible to oncocins. The JW0368yjiL::Tn10transposon mutant (BS2) was resistant to all short PrAMPs and susceptible only to full-length Bac7 and A3-APO. Interestingly, PrAMPs appear to enter bacteria via MdtM, a multidrug resistance transporter (drug/H+antiporter) of the major facilitator superfamily (MFS) that can efflux antibiotics, biocides, and bile salts. In conclusion, PrAMPs enter bacteria via ABC and MFS transporters that efflux antibiotics and cytotoxic compounds from the cytoplasm to the periplasm.

scholarly journals New Plasmid-Mediated Fluoroquinolone Efflux Pump, QepA, Found in an Escherichia coli Clinical Isolate

2007 ◽  
Vol 51 (9) ◽  
pp. 3354-3360 ◽  
Author(s):  
Kunikazu Yamane ◽  
Jun-ichi Wachino ◽  
Satowa Suzuki ◽  
Kouji Kimura ◽  
Naohiro Shibata ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Molecular Mechanisms ◽  
Efflux Pump ◽  
Resistance Mechanisms ◽  
Major Facilitator Superfamily ◽  
Gene Encoding ◽  
Resistance Level ◽  
E Coli ◽  
Susceptibility Tests ◽  
Major Facilitator

ABSTRACT Plasmid-mediated Qnr and AAC(6′)-Ib-cr have been recognized as new molecular mechanisms affecting fluoroquinolone (FQ) resistance. C316, an Escherichia coli strain demonstrating resistance to various FQs, was isolated in Japan. Resistance to FQs was augmented in an E. coli CSH2 transconjugant, but PCR failed to detect qnr genes, suggesting the presence of novel plasmid-mediated FQ resistance mechanisms. Susceptibility tests, DNA manipulation, and analyses of the gene and its product were performed to characterize the genetic determinant. A novel FQ-resistant gene, qepA, was identified in a plasmid, pHPA, of E. coli C316, and both qepA and rmtB genes were mediated by a probable transposable element flanked by two copies of IS26. Levels of resistance to norfloxacin, ciprofloxacin, and enrofloxacin were significantly elevated in E. coli transformants harboring qepA under AcrB-TolC-deficient conditions. QepA showed considerable similarities to transporters belonging to the 14-transmembrane-segment family of environmental actinomycetes. The effect of carbonyl cyanide m-chlorophenylhydrazone (CCCP) on accumulation of norfloxacin was assayed in a qepA-harboring E. coli transformant. The intracellular accumulation of norfloxacin was decreased in a qepA-expressing E. coli transformant, but this phenomenon was canceled by CCCP. The augmented FQ resistance level acquired by the probable intergeneric transfer of a gene encoding a major facilitator superfamily-type efflux pump from some environmental microbes to E. coli was first identified. Surveillance of the qepA-harboring clinical isolates should be encouraged to minimize further dissemination of the kind of plasmid-dependent FQ resistance determinants among pathogenic microbes.

scholarly journals GntP Is the Escherichia coli Fructuronic Acid Transporter and Belongs to the UxuR Regulon

2004 ◽  
Vol 186 (22) ◽  
pp. 7690-7696 ◽  
Author(s):  
Cristina Bates Utz ◽  
Ann B. Nguyen ◽  
Darren J. Smalley ◽  
April B. Anderson ◽  
Tyrrell Conway
Keyword(s):  
Escherichia Coli ◽  
Protein A ◽  
Physiological Role ◽  
Major Facilitator Superfamily ◽  
Receptor Protein ◽  
E Coli ◽  
The Subject ◽  
Camp Receptor ◽  
Major Facilitator

ABSTRACT Escherichia coli has four gluconate transporters, GntP, GntU, GntT, and IdnT, which are members of the major facilitator superfamily. The physiological function of GntP was previously unknown and is the subject of this study. GntP is not induced by gluconate, and despite being located adjacent to genes involved in glucuronate catabolism, gntP does not encode a glucuronate transporter. Here we identify gntP as the gene which encodes the fructuronate transporter. We show that gntP is induced by fructuronate and is a new member of the UxuR regulon: gntP is derepressed in an uxuR strain, UxuR binds in vitro specifically to an operator site that overlaps the gntP promoter, and UxuR binding is eliminated by fructuronate. Transcription of gntP requires activation by cyclic AMP (cAMP)-cAMP receptor protein. A gntP mutant cannot grow on fructuronate but grows normally on glucuronate and gluconate. Thus, the UxuR regulon is a module of sugar acid catabolism whose physiological role is for growth on fructuronate. Glucuronate, because it proceeds through a fructuronate intermediate, must induce the UxuR regulon and must also induce the ExuR regulon, which encodes the glucuronate transporter, ExuT, and the first step in its catabolism, UxaC. Thus, hexuronate catabolism in E. coli requires both the ExuR and UxuR regulons, while fructuronate catabolism requires only the UxuR regulon.

Characterization of novel ybjG and dacC variants in Escherichia coli

2013 ◽  
Vol 62 (11) ◽  
pp. 1728-1734 ◽  
Author(s):  
Dongguo Wang ◽  
Enping Hu ◽  
Jiayu Chen ◽  
Xiulin Tao ◽  
Katelyn Gutierrez ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Multiple Drug Resistance ◽  
Multiple Drug ◽  
The Novel ◽  
Conventional Pcr ◽  
E Coli ◽  
Novel Variants ◽  
Restriction Sites ◽  
Genetic Structures

A total of 69 strains of Escherichia coli from patients in the Taizhou Municipal Hospital, China, were isolated, and 11 strains were identified that were resistant to bacitracin, chloramphenicol, tetracycline and erythromycin. These strains were PCR positive for at least two out of three genes, ybjG, dacC and mdfA, by gene mapping with conventional PCR detection. Conjugation experiments demonstrated that these genes existed in plasmids that conferred resistance. Novel ybjG and dacC variants were isolated from E. coli strains EC2163 and EC2347, which were obtained from the sputum of intensive care unit patients. Genetic mapping showed that the genes were located on 8200 kb plasmid regions flanked by EcoRI restriction sites. Three distinct genetic structures were identified among the 11 PCR-positive strains of E. coli, and two contained the novel ybjG and dacC variants. The putative amino acid differences in the ybjG and dacC gene variants were characterized. These results provide evidence for novel variants of ybjG and dacC, and suggest that multiple drug resistance in hospital strains of E. coli depends on the synergistic function of ybjG, dacC and mdfA within three distinct genetic structures in conjugative plasmids.

scholarly journals A novel report of colistin-resistant Escherichia coli carrying mcr-1 gene from animal and human feacal samples in Nigeria

2018 ◽  
Vol 1 (1) ◽  
pp. 7-10 ◽  
Author(s):  
Olugbenga A. Olowe ◽  
Rita A. Olowe ◽  
Adeolu S. Oluremi ◽  
Olusolabomi J. Adefioye
Keyword(s):  
Escherichia Coli ◽  
Animal Husbandry ◽  
Multiple Drug ◽  
Colistin Resistance ◽  
Pcr Assay ◽  
Southwestern Nigeria ◽  
E Coli ◽  
Multiple Drug Resistant ◽  
Microbiological Methods ◽  
Faecal Samples

Background: The mobilized colistin resistance (m cr)-1 gene confers transferable colistin resistance. Reports of mcr-1-positive Escherichia coli (MCRPE) have attracted substantial attention. However, in Nigeria, there is no report of mcr-1 gene resistance. Since colistin is a last resort for multiple drug-resistant isolates, this study therefore report the prevalence of mcr-1 gene among E. coli isolated from human and animal sources. Methods: Out of a total of 280 samples collected from animal and hum an faecal samples from selected farms in Oyo and Osun States, Southwestern Nigeria between July 2015 and June 2016, 60 E. coli were identified using standard microbiological methods. The mcr-1 gene was detected in the isolates by conventional PCR assay. Results: The m cr-1 gene was low and not statistically significant (p≥0.05). It was detected in 5 (8.3%) of 60 E. coli isolates (4= animals; 1= human) Conclusion: This study is the first report of mcr -1 gene from E. coli from human and animal sources in Nigeria. This calls for urgent caution in the use of colistin in animal husbandry.

scholarly journals Competition between protons and substrate for binding to the major facilitator superfamily multidrug/H+ antiporter MdtM

2021 ◽  
Vol 2 ◽  
Author(s):  
Christopher J. Law
Keyword(s):  
Escherichia Coli ◽  
General Feature ◽  
Pathogenic Bacteria ◽  
Major Facilitator Superfamily ◽  
Electrochemical Gradient ◽  
Multidrug Efflux ◽  
Protein Fluorescence ◽  
Ph Values ◽  
Major Facilitator ◽  
Intrinsic Protein Fluorescence

Abstract Proton electrochemical gradient-driven multidrug efflux activity of representatives of the major facilitator superfamily (MFS) of secondary active transporters contributes to antimicrobial resistance of pathogenic bacteria. Integral to the mechanism of these transporters is a proposed competition between substrate and protons for the binding site of the protein. The current work investigated the competition between protons and antimicrobial substrate for binding to the Escherichia coli MFS multidrug/H+ antiporter MdtM by measuring the quench of intrinsic protein fluorescence upon titration of substrate tetraphenylphosphonium into a solution of purified MdtM over a range of pH values between pH 8.8 and 5.9. The results, which revealed that protons inhibit binding of substrate to MdtM in a competitive manner, are consistent with those reported in a study on the related MFS multidrug/H+ antiporter MdfA and provide further evidence that competition for binding between substrate and protons is a general feature of secondary multidrug efflux.

scholarly journals Structural and Functional Study of the Phenicol-Specific Efflux Pump FloR Belonging to the Major Facilitator Superfamily

2005 ◽  
Vol 49 (7) ◽  
pp. 2965-2971 ◽  
Author(s):  
Martine Braibant ◽  
Jacqueline Chevalier ◽  
Elisabeth Chaslus-Dancla ◽  
Jean-Marie Pagès ◽  
Axel Cloeckaert
Keyword(s):  
Efflux Pump ◽  
Major Facilitator Superfamily ◽  
Site Directed Mutagenesis ◽  
Functional Study ◽  
Efflux Transporters ◽  
Chloramphenicol Resistance ◽  
Active Efflux ◽  
Transmembrane Segments ◽  
Efflux Mechanism ◽  
Major Facilitator

ABSTRACT The florfenicol-chloramphenicol resistance gene floR from Salmonella enterica was previously identified and postulated to belong to the major facilitator (MF) superfamily of drug exporters. Here, we confirmed a computer-predicted transmembrane topological model of FloR, using the phoA gene fusion method, and classified this protein in the DHA12 family (containing 12 transmembrane domains) of MF efflux transporters. We also showed that FloR is a transporter specific for structurally associated phenicol drugs (chloramphenicol, florfenicol, thiamphenicol) which utilizes the proton motive force to energize an active efflux mechanism. By site-directed mutagenesis of specific charged residues belonging to putative transmembrane segments (TMS), two residues essential for active efflux function, D23 in TMS1 and R109 in TMS4, were identified. Of these, the acidic residue D23 seems to participate directly in the affinity pocket involved in phenicol derivative recognition. A third residue, E283 in TMS9, seems to be necessary for correct membrane folding of the transporter.

scholarly journals Inhibition of the multiple antibiotic resistance (mar) operon in Escherichia coli by antisense DNA analogs.

1997 ◽  
Vol 41 (12) ◽  
pp. 2699-2704 ◽  
Author(s):  
D G White ◽  
K Maneewannakul ◽  
E von Hofe ◽  
M Zillman ◽  
W Eisenberg ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Antibiotic Resistance ◽  
Antisense Oligonucleotides ◽  
Multiple Antibiotic Resistance ◽  
Wild Type ◽  
Lacz Expression ◽  
E Coli ◽  
Plasmid Construct ◽  
Dna Analogs ◽  
Susceptibility And Resistance

The multiple antibiotic resistance operon (marORAB) in Escherichia coli controls intrinsic susceptibility and resistance to multiple, structurally different antibiotics and other noxious agents. A plasmid construct with marA cloned in the antisense direction reduced LacZ expression from a constitutively expressed marA::lacZ translational fusion and inhibited the induced expression of LacZ in cells bearing the wild-type repressed fusion. The marA antisense construction also decreased the multiple antibiotic resistance of a Mar mutant. Two antisense phosphorothioate oligonucleotides, one targeted to marO and the other targeted to marA of the mar operon, introduced by heat shock or electroporation reduced LacZ expression in the strain having the marA::lacZ fusion. One antisense oligonucleotide, tested against a Mar mutant of E. coli ML308-225, increased the bactericidal activity of norfloxacin. These studies demonstrate the efficacy of exogenously delivered antisense oligonucleotides targeted to the marRAB operon in inhibiting expression of this chromosomal regulatory locus.

Tigecycline efflux in Acinetobacter baumannii is mediated by TetA in synergy with RND-type efflux transporters

2020 ◽  
Vol 75 (5) ◽  
pp. 1135-1139 ◽  
Author(s):  
Wuen Ee Foong ◽  
Jochen Wilhelm ◽  
Heng-Keat Tam ◽  
Klaas M Pos
Keyword(s):  
Acinetobacter Baumannii ◽  
Efflux Pump ◽  
Gene Knockout ◽  
Drug Susceptibility ◽  
Major Facilitator Superfamily ◽  
Rt Pcr ◽  
E Coli ◽  
Rnd Efflux Pump ◽  
Major Facilitator

Abstract Objectives To investigate the role of Major Facilitator Superfamily (MFS)-type transporters from Acinetobacter baumannii AYE in tigecycline efflux. Methods Two putative tetracycline transporter genes of A. baumannii AYE (tetA and tetG) were heterologously expressed in Escherichia coli and drug susceptibility assays were conducted with tigecycline and three other tetracycline derivatives. The importance of TetA in tigecycline transport in A. baumannii was determined by complementation of tetA in WT and Resistance Nodulation cell Division (RND) gene knockout strains of A. baumannii ATCC 19606. Gene expression of the MFS-type tetA gene and RND efflux pump genes adeB, adeG and adeJ in A. baumannii AYE in the presence of tigecycline was analysed by quantitative real-time RT–PCR. Results Overproduction of TetA or TetG conferred resistance to doxycycline, minocycline and tetracycline in E. coli. Cells expressing tetA, but not those expressing tetG, conferred resistance to tigecycline, implying that TetA is a determinant for tigecycline transport. A. baumannii WT and RND-knockout strains complemented with plasmid-encoded tetA are significantly less susceptible to tigecycline compared with non-complemented strains. Efflux pump genes tetA and adeG are up-regulated in A. baumannii AYE in the presence of subinhibitory tigecycline concentrations. Conclusions TetA plays an important role in tigecycline efflux of A. baumannii by removing the drug from cytoplasm to periplasm and, subsequently, the RND-type transporters AdeABC and AdeIJK extrude tigecycline across the outer membrane. When challenged with tigecycline, tetA is up-regulated in A. baumannii AYE. Synergy between TetA and the RND-type transporters AdeABC and/or AdeIJK appears necessary for A. baumannii to confer higher tigecycline resistance via drug efflux.

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