scholarly journals Selection of multiple-antibiotic-resistant (mar) mutants of Escherichia coli by using the disinfectant pine oil: roles of the mar and acrAB loci.

1997 ◽  
Vol 41 (12) ◽  
pp. 2770-2772 ◽  
Author(s):  
M C Moken ◽  
L M McMurry ◽  
S B Levy
Keyword(s):  
Escherichia Coli ◽  
Efflux Pump ◽  
Wild Type ◽  
Multidrug Efflux ◽  
Multidrug Efflux Pump ◽  
Antibiotic Resistant ◽  
Pine Oil ◽  
Mutant Strains ◽  
Selection Of ◽  
Multiple Antibiotics

Mutants of Escherichia coli selected for resistance to the disinfectant pine oil or to a household product containing pine oil also showed resistance to multiple antibiotics (tetracycline, ampicillin, chloramphenicol, and nalidixic acid) and overexpressed the marA gene. Likewise, antibiotic-selected Mar mutants, which also overexpress marA, were resistant to pine oil. Deletion of the mar or acrAB locus, the latter encoding a multidrug efflux pump positively regulated in part by MarA, increased the susceptibility of wild-type and mutant strains to pine oil.

scholarly journals The Biocide Triclosan Selects Stenotrophomonas maltophilia Mutants That Overproduce the SmeDEF Multidrug Efflux Pump

2005 ◽  
Vol 49 (2) ◽  
pp. 781-782 ◽  
Author(s):  
Patricia Sanchez ◽  
Eduardo Moreno ◽  
Jose L. Martinez
Keyword(s):  
Type Strain ◽  
Stenotrophomonas Maltophilia ◽  
Wild Type Strain ◽  
Efflux Pump ◽  
Resistant Bacteria ◽  
Wild Type ◽  
Multidrug Efflux ◽  
Multidrug Efflux Pump ◽  
Antibiotic Resistant ◽  
Selection Of

ABSTRACT The possibility that triclosan selects Stenotrophomonas maltophilia mutants overexpressing the multidrug resistance pump SmeDEF is analyzed. Five out of 12 triclosan-selected mutants were less susceptible to antibiotics than the wild-type strain and overproduced SmeDEF. Results are discussed in relation to current debates on the potential selection of antibiotic-resistant bacteria by household biocides.

scholarly journals The channel-tunnel HI1462 of Haemophilus influenzae reveals differences to Escherichia coli TolC

Microbiology ◽  
2006 ◽  
Vol 152 (6) ◽  
pp. 1639-1647 ◽  
Author(s):  
Georg Polleichtner ◽  
Christian Andersen
Keyword(s):  
Escherichia Coli ◽  
Single Channel ◽  
Efflux Pump ◽  
Wild Type ◽  
Multidrug Efflux ◽  
Channel Conductance ◽  
Single Channel Conductance ◽  
Multidrug Efflux Pump ◽  
E Coli ◽  
Tunnel Entrance

Efflux pumps play a major role in multidrug resistance of pathogenic bacteria. The TolC homologue HI1462 was identified as the single channel-tunnel in Haemophilus influenzae required to form a functional multidrug efflux pump. The outer-membrane protein was expressed in Escherichia coli, purified and reconstituted in black lipid membranes. It exhibited a comparatively small single-channel conductance of 43 pS in 1 M KCl and is the first known TolC homologue which is anion-selective. The HI1462 structure was modelled and an arginine residue lining the tunnel entrance was identified. The channel-tunnel of a mutant with the arginine substituted by an alanine residue was cation-selective and had a sevenfold higher single-channel conductance compared to wild-type. These results confirm that the arginine is responsible for anion selectivity and forms a salt bridge with a glutamate residue of the adjacent monomer, establishing a circular network, which keeps the tunnel entrance in a tightly closed conformation. In in vivo experiments, both the wild-type HI1462 and the mutant were able to substitute for E. coli TolC in the haemolysin secretion system, but not in the AcrAB/TolC multidrug efflux pump. The structure–function relationship of HI1462 is discussed in the context of the well-studied TolC channel-tunnel of E. coli.

The assembly and disassembly of the AcrAB-TolC three-component multidrug efflux pump

2015 ◽  
Vol 396 (9-10) ◽  
pp. 1083-1089 ◽  
Author(s):  
Reinke Tobias Müller ◽  
Klaas Martinus Pos
Keyword(s):  
Escherichia Coli ◽  
Efflux Pump ◽  
Gram Negative Bacteria ◽  
Electrochemical Gradient ◽  
Multidrug Efflux ◽  
Multidrug Efflux Pump ◽  
Gram Negative ◽  
E Coli ◽  
Pump Assembly ◽  
Multiple Antibiotics

Abstract In Gram-negative bacteria, tripartite efflux pumps, like AcrAB-TolC from Escherichia coli, play a prominent role in the resistance against multiple antibiotics. Transport of the drugs across the outer membrane and its coupling to the electrochemical gradient is dependent on the presence of all three components. As the activity of the E. coli AcrAB-TolC efflux pump is dependent on both the concentration of substrates and the extent of the electrochemical gradient across the inner membrane, the dynamics of tripartite pump assembly and disassembly might be crucial for effective net transport of drugs towards the outside of the cell.

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 A Broad-Specificity Multidrug Efflux Pump Requiring a Pair of Homologous SMR-Type Proteins

2000 ◽  
Vol 182 (8) ◽  
pp. 2311-2313 ◽  
Author(s):  
Donald L. Jack ◽  
Michael L. Storms ◽  
Jason H. Tchieu ◽  
Ian T. Paulsen ◽  
Milton H. Saier
Keyword(s):  
Escherichia Coli ◽  
Efflux Pump ◽  
Multidrug Resistant ◽  
Drug Efflux ◽  
Multidrug Efflux ◽  
Multidrug Efflux Pump ◽  
Resistant Phenotype ◽  
Small Multidrug Resistance ◽  
Drug Efflux Pumps ◽  
Broad Specificity

ABSTRACT The Bacillus subtilis genome encodes seven homologues of the small multidrug resistance (SMR) family of drug efflux pumps. Six of these homologues are paired in three distinct operons, and coexpression in Escherichia coli of one such operon,ykkCD, but not expression of either ykkC orykkD alone, gives rise to a broad specificity, multidrug-resistant phenotype including resistance to cationic, anionic, and neutral drugs.

scholarly journals oqxAB Encoding a Multidrug Efflux Pump in Human Clinical Isolates of Enterobacteriaceae

2009 ◽  
Vol 53 (8) ◽  
pp. 3582-3584 ◽  
Author(s):  
Hong Bin Kim ◽  
Minghua Wang ◽  
Chi Hye Park ◽  
Eui-Chong Kim ◽  
George A. Jacoby ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Klebsiella Pneumoniae ◽  
Efflux Pump ◽  
Clinical Isolates ◽  
Multidrug Efflux ◽  
Multidrug Efflux Pump

ABSTRACT The genes for multidrug efflux pump OqxAB, which is active on fluoroquinolones, were found in human clinical isolates on a plasmid in Escherichia coli and on the chromosome of Klebsiella pneumoniae. IS26-like sequences flanked the plasmid-mediated oqxAB genes, suggesting that they had been mobilized as part of a composite transposon.

scholarly journals Cloning and Characterization of SmeT, a Repressor of the Stenotrophomonas maltophilia Multidrug Efflux Pump SmeDEF

2002 ◽  
Vol 46 (11) ◽  
pp. 3386-3393 ◽  
Author(s):  
Patricia Sánchez ◽  
Ana Alonso ◽  
Jose L. Martinez
Keyword(s):  
Stenotrophomonas Maltophilia ◽  
Efflux Pump ◽  
Wild Type ◽  
Multidrug Efflux ◽  
Multidrug Efflux Pump ◽  
S1 Nuclease ◽  
Cellular Factor ◽  
S1 Nuclease Mapping ◽  
Nuclease Mapping

ABSTRACT We report on the cloning of the gene smeT, which encodes the transcriptional regulator of the Stenotrophomonas maltophilia efflux pump SmeDEF. SmeT belongs to the TetR and AcrR family of transcriptional regulators. The smeT gene is located upstream from the structural operon of the pump genes smeDEF and is divergently transcribed from those genes. Experiments with S. maltophilia and the heterologous host Escherichia coli have demonstrated that SmeT is a transcriptional repressor. S1 nuclease mapping has demonstrated that expression of smeT is driven by a single promoter lying close to the 5′ end of the gene and that expression of smeDEF is driven by an unique promoter that overlaps with promoter PsmeT. The level of expression of smeT is higher in smeDEF-overproducing S. maltophilia strain D457R, which suggests that SmeT represses its own expression. Band-shifting assays have shown that wild-type strain S. maltophilia D457 contains a cellular factor(s) capable of binding to the intergenic smeT-smeD region. That cellular factor(s) was absent from smeDEF-overproducing S. maltophilia strain D457R. The sequence of smeT from D457R showed a point mutation that led to a Leu166Gln change within the SmeT protein. This change allowed overexpression of both smeDEF and smeT in D457R. It was noteworthy that expression of wild-type SmeT did not fully complement the smeT mutation in D457R. This suggests that the wild-type protein is not dominant over the mutant SmeT.

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