scholarly journals SatR Is a Repressor of Fluoroquinolone Efflux Pump SatAB

2013 ◽  
Vol 57 (7) ◽  
pp. 3430-3433 ◽  
Author(s):  
Jose Antonio Escudero ◽  
Alvaro San Millan ◽  
Natalia Montero ◽  
Belen Gutierrez ◽  
Cristina Martinez Ovejero ◽  
...  
Keyword(s):  
Abc Transporter ◽  
High Mortality ◽  
Human Population ◽  
Efflux Pump ◽  
Streptococcus Suis ◽  
Open Reading Frame ◽  
Fluoroquinolone Resistance ◽  
Content Type ◽  
Reading Frame

ABSTRACTStreptococcus suisis an emerging zoonotic agent responsible for high-mortality outbreaks among the human population in China. In this species, the ABC transporter SatAB mediates fluoroquinolone resistance when overexpressed. Here, we describe and characterizesatR, an open reading frame (ORF) encoding a MarR superfamily regulator that acts as a repressor ofsatAB. satRis cotranscribed withsatAB, and its interruption entails the overexpression of the pump, leading to a clinically relevant increase in resistance to fluoroquinolones.

scholarly journals Novel Mechanisms of Efflux-Mediated Levofloxacin Resistance and Reduced Amikacin Susceptibility in Stenotrophomonas maltophilia

2020 ◽  
Vol 65 (1) ◽  
pp. e01284-20
Author(s):  
Punyawee Dulyayangkul ◽  
Karina Calvopiña ◽  
Kate J. Heesom ◽  
Matthew B. Avison
Keyword(s):  
Abc Transporter ◽  
Abc Transporters ◽  
Stenotrophomonas Maltophilia ◽  
Efflux Pump ◽  
Regulatory System ◽  
Fluoroquinolone Resistance ◽  
Content Type ◽  
Antimicrobial Drug Resistance ◽  
Regulatory Systems ◽  
Selection Of

ABSTRACTFluoroquinolone resistance in Stenotrophomonas maltophilia is multifactorial, but the most significant factor is overproduction of efflux pumps, particularly SmeDEF, following mutation. Here, we report that mutations in the glycosyl transferase gene smlt0622 in S. maltophilia K279a mutant K M6 cause constitutive activation of SmeDEF production, leading to elevated levofloxacin MIC. Selection of a levofloxacin-resistant K M6 derivative, K M6 LEVr, allowed identification of a novel two-component regulatory system, Smlt2645/6 (renamed SmaRS). The sensor kinase Smlt2646 (SmaS) is activated by mutation in K M6 LEVr causing overproduction of two novel ABC transporters and the known aminoglycoside efflux pump SmeYZ. Overproduction of one ABC transporter, Smlt1651-4 (renamed SmaCDEF), causes levofloxacin resistance in K M6 LEVr. Overproduction of the other ABC transporter, Smlt2642/3 (renamed SmaAB), and SmeYZ both contribute to the elevated amikacin MIC against K M6 LEVr. Accordingly, we have identified two novel ABC transporters associated with antimicrobial drug resistance in S. maltophilia and two novel regulatory systems whose mutation causes resistance to levofloxacin, clinically important as a promising drug for monotherapy against this highly resistant pathogen.

scholarly journals Heterologous Expression of Thuricin CD Immunity Genes in Listeria monocytogenes

2014 ◽  
Vol 58 (6) ◽  
pp. 3421-3428 ◽  
Author(s):  
Harsh Mathur ◽  
Paula M. O'Connor ◽  
Paul D. Cotter ◽  
Colin Hill ◽  
R. Paul Ross
Keyword(s):  
Heterologous Expression ◽  
Abc Transporter ◽  
Transmembrane Protein ◽  
Open Reading Frame ◽  
Gene Products ◽  
Relative Importance ◽  
Content Type ◽  
Reading Frame ◽  
Immunity Genes ◽  
The Individual

ABSTRACTBacteriocins are ribosomally synthesized peptides that can have a narrow or broad spectrum of antimicrobial activity. Bacteriocin producers typically possess dedicated immunity systems that often consist of an ATP-binding cassette (ABC) transporter system and/or a dedicated immunity protein. Here we investigated the genes responsible for immunity to thuricin CD, a narrow-spectrum two-peptide sactibiotic produced byBacillus thuringiensisDPC6431. Heterologous expression of putative thuricin CD immunity determinants allowed us to identify and investigate the relative importance of the individual genes and gene products that contribute to thuricin CD immunity. We established that TrnF and TrnG are the individual components of an ABC transporter system that provides immunity to thuricin CD. We also identified a hitherto overlooked open reading frame located upstream oftrnFpredicted to encode a 79-amino-acid transmembrane protein. We designated this newly discovered genetrnIand established that TrnI alone can provide protection against thuricin CD.

scholarly journals Identification of an Efflux Pump Gene,pmrA, Associated with Fluoroquinolone Resistance inStreptococcus pneumoniae

1999 ◽  
Vol 43 (1) ◽  
pp. 187-189 ◽  
Author(s):  
Martin J. Gill ◽  
Nigel P. Brenwald ◽  
Richard Wise
Keyword(s):  
Drug Sensitivity ◽  
Amino Acid Sequence Identity ◽  
Efflux Pump ◽  
Open Reading Frame ◽  
Fluoroquinolone Resistance ◽  
Transmembrane Segment ◽  
Reading Frame ◽  
Sequence Identity ◽  
Major Facilitator ◽  
Resistant Pneumococcus

ABSTRACT An open reading frame (ORF) homologous to norA was insertionally inactivated with cat in a fluoroquinolone-resistant pneumococcus with an efflux phenotype; this inactivation caused reversion to drug sensitivity. The ORF product has 24% amino acid sequence identity each to NorA and Bmr, which suggests that it is a major facilitator system pump of the 12-transmembrane-segment class.

scholarly journals A Novel Gene Amplification Causes Upregulation of the PatAB ABC Transporter and Fluoroquinolone Resistance in Streptococcus pneumoniae

2015 ◽  
Vol 59 (6) ◽  
pp. 3098-3108 ◽  
Author(s):  
Alison J. Baylay ◽  
Alasdair Ivens ◽  
Laura J. V. Piddock
Keyword(s):  
Antibiotic Resistance ◽  
Streptococcus Pneumoniae ◽  
Abc Transporter ◽  
Stress Responses ◽  
Fluorescent Protein ◽  
Gene Dosage ◽  
Fluoroquinolone Resistance ◽  
Reporter System ◽  
Content Type ◽  
Genomic Duplication

ABSTRACTOverexpression of the ABC transporter genespatAandpatBconfers efflux-mediated fluoroquinolone resistance inStreptococcus pneumoniaeand is also linked to pneumococcal stress responses. Although upregulation ofpatABhas been observed in many laboratory mutants and clinical isolates, the regulatory mechanisms controlling expression of these genes are unknown. In this study, we aimed to identify the cause of high-level constitutive overexpression ofpatABin M184, a multidrug-resistant mutant of S.pneumoniaeR6. Using a whole-genome transformation and sequencing approach, we identified a novel duplication of a 9.2-kb region of the M184 genome which included thepatABgenes. This duplication did not affect growth and was semistable with a low segregation rate. The expression levels ofpatABin M184 were much higher than those that could be fully explained by doubling of the gene dosage alone, and inactivation of the first copy ofpatAhad no effect on multidrug resistance. Using a green fluorescent protein reporter system, increasedpatABexpression was ascribed to transcriptional read-through from a tRNA gene upstream of the second copy ofpatAB. This is the first report of a large genomic duplication causing antibiotic resistance inS. pneumoniaeand also of a genomic duplication causing antibiotic resistance by a promoter switching mechanism.

scholarly journals Characterization of BcaA, a Putative Classical Autotransporter Protein in Burkholderia pseudomallei

2013 ◽  
Vol 81 (4) ◽  
pp. 1121-1128 ◽  
Author(s):  
Cristine G. Campos ◽  
Luke Borst ◽  
Peggy A. Cotter
Keyword(s):  
Burkholderia Pseudomallei ◽  
Efflux Pump ◽  
Outer Membrane Proteins ◽  
Lung Epithelial Cells ◽  
Wild Type ◽  
Passenger Domain ◽  
Content Type ◽  
Reading Frame ◽  
Type V

ABSTRACTBurkholderia pseudomalleiis a tier 1 select agent, and the causative agent of melioidosis, a disease with effects ranging from chronic abscesses to fulminant pneumonia and septic shock, which can be rapidly fatal. Autotransporters (ATs) are outer membrane proteins belonging to the type V secretion system family, and many have been shown to play crucial roles in pathogenesis. The open reading frame Bp1026b_II1054 (bcaA) inB. pseudomalleistrain 1026b is predicted to encode a classical autotransporter protein with an approximately 80-kDa passenger domain that contains a subtilisin-related domain. Immediately 3′ tobcaAis Bp11026_II1055 (bcaB), which encodes a putative prolyl 4-hydroxylase. To investigate the role of these genes in pathogenesis, large in-frame deletion mutations ofbcaAandbcaBwere constructed in strain Bp340, an efflux pump mutant derivative of the melioidosis clinical isolate 1026b. Comparison of Bp340ΔbcaAand Bp340ΔbcaBmutants to wild-typeB. pseudomalleiin vitrodemonstrated similar levels of adherence to A549 lung epithelial cells, but the mutant strains were defective in their ability to invade these cells and to form plaques. In a BALB/c mouse model of intranasal infection, similar bacterial burdens were observed after 48 h in the lungs and liver of mice infected with Bp340ΔbcaA, Bp340ΔbcaB, and wild-type bacteria. However, significantly fewer bacteria were recovered from the spleen of Bp340ΔbcaA-infected mice, supporting the idea of a role for this AT in dissemination or in survival in the passage from the site of infection to the spleen.

scholarly journals Mechanisms of Resistance to Chloramphenicol in Pseudomonas putida KT2440

2011 ◽  
Vol 56 (2) ◽  
pp. 1001-1009 ◽  
Author(s):  
Matilde Fernández ◽  
Susana Conde ◽  
Jesús de la Torre ◽  
Carlos Molina-Santiago ◽  
Juan-Luis Ramos ◽  
...  
Keyword(s):  
Pseudomonas Putida ◽  
Efflux Pump ◽  
Protein Biosynthesis ◽  
Cellular Stress Response ◽  
Knockout Mutant ◽  
Pseudomonas Putida Kt2440 ◽  
Altered Expression ◽  
Content Type ◽  
Reading Frame ◽  
A Genome

ABSTRACTPseudomonas putidaKT2440 is a chloramphenicol-resistant bacterium that is able to grow in the presence of this antibiotic at a concentration of up to 25 μg/ml. Transcriptomic analyses revealed that the expression profile of 102 genes changed in response to this concentration of chloramphenicol in the culture medium. The genes that showed altered expression include those involved in general metabolism, cellular stress response, gene regulation, efflux pump transporters, and protein biosynthesis. Analysis of a genome-wide collection of mutants showed that survival of a knockout mutant in the TtgABC resistance-nodulation-division (RND) efflux pump and mutants in the biosynthesis of pyrroloquinoline (PQQ) were compromised in the presence of chloramphenicol. The analysis also revealed that an ABC extrusion system (PP2669/PP2668/PP2667) and the AgmR regulator (PP2665) were needed for full resistance toward chloramphenicol. Transcriptional arrays revealed that AgmR controls the expression of thepqqgenes and the operon encoding the ABC extrusion pump from the promoter upstream of open reading frame (ORF) PP2669.

scholarly journals Molecular Organization of Small Plasmids BearingblaTEM-1and Conferring Resistance to β-Lactams in Haemophilus influenzae

2012 ◽  
Vol 56 (9) ◽  
pp. 4958-4960 ◽  
Author(s):  
Annette Søndergaard ◽  
Alvaro San Millan ◽  
Alfonso Santos-Lopez ◽  
Signe M. Nielsen ◽  
Bruno Gonzalez-Zorn ◽  
...  
Keyword(s):  
Haemophilus Influenzae ◽  
Open Reading Frame ◽  
Molecular Organization ◽  
Gram Positive ◽  
Content Type ◽  
Reading Frame ◽  
Enzyme Gene ◽  
Gram Positive Bacteria ◽  
Resistant Phenotype ◽  
Plasmid Recombination

ABSTRACTTEM-1 is the dominant β-lactamase ofHaemophilus influenzaeand can be located on small plasmids. Three distinct plasmids with sizes from 4,304 to 5,646 nucleotides (nt) were characterized: pA1606, pA1209, and pPN223. In addition to TEM-1 and a replication enzyme of the Rep 3 superfamily, pA1606 carries a Tn3resolvase gene and pA1606 and pA1209 carry an open reading frame (ORF) similar to a plasmid recombination enzyme gene described in Gram-positive bacteria. The plasmids transformed strain Rd to the ampicillin-resistant phenotype.

scholarly journals Mechanisms of Fluoroquinolone Resistance in Escherichia coli Isolates from Food-Producing Animals

2011 ◽  
Vol 77 (20) ◽  
pp. 7113-7120 ◽  
Author(s):  
Maria Karczmarczyk ◽  
Marta Martins ◽  
Teresa Quinn ◽  
Nola Leonard ◽  
Séamus Fanning
Keyword(s):  
Escherichia Coli ◽  
Nalidixic Acid ◽  
Target Genes ◽  
Efflux Pump ◽  
Multidrug Resistant ◽  
Fluoroquinolone Resistance ◽  
Efflux Pump Inhibitor ◽  
Content Type ◽  
Field Isolates ◽  
K 12

ABSTRACTEleven multidrug-resistantEscherichia coliisolates (comprising 6 porcine and 5 bovine field isolates) displaying fluoroquinolone (FQ) resistance were selected from a collection obtained from the University Veterinary Hospital (Dublin, Ireland). MICs of nalidixic acid and ciprofloxacin were determined by Etest. All showed MICs of nalidixic acid of >256 μg/ml and MICs of ciprofloxacin ranging from 4 to >32 μg/ml. DNA sequencing was used to identify mutations within the quinolone resistance-determining regions of target genes, and quantitative real-time PCR (qRT-PCR) was used to evaluate the expression of the major porin, OmpF, and component genes of the AcrAB-TolC efflux pump and its associated regulatory loci. Decreased MIC values to nalidixic acid and/or ciprofloxacin were observed in the presence of the efflux pump inhibitor phenylalanine-arginine-β-naphthylamide (PAβN) in some but not all isolates. Several mutations were identified in genes coding for quinolone target enzymes (3 to 5 mutations per strain). All isolates harbored GyrA amino acid substitutions at positions 83 and 87. Novel GyrA (Asp87 → Ala), ParC (Ser80 → Trp), and ParE (Glu460 → Val) substitutions were observed. The efflux activity of these isolates was evaluated using a semiautomated ethidium bromide (EB) uptake assay. Compared to wild-typeE. coliK-12 AG100, isolates accumulated less EB, and in the presence of PAβN the accumulation of EB increased. Upregulation of theacrBgene, encoding the pump component of the AcrAB-TolC efflux pump, was observed in 5 of 11 isolates, while 10 isolates showed decreased expression of OmpF. This study identified multiple mechanisms that likely contribute to resistance to quinolone-based drugs in the field isolates studied.

scholarly journals Transcription of TP0126, Treponema pallidum Putative OmpW Homolog, Is Regulated by the Length of a Homopolymeric Guanosine Repeat

2015 ◽  
Vol 83 (6) ◽  
pp. 2275-2289 ◽  
Author(s):  
Lorenzo Giacani ◽  
Stephanie L. Brandt ◽  
Wujian Ke ◽  
Tara B. Reid ◽  
Barbara J. Molini ◽  
...  
Keyword(s):  
Phenotypic Diversity ◽  
Signal Sequence ◽  
Transcriptional Start Site ◽  
Treponema Pallidum ◽  
Phase Variation ◽  
Open Reading Frame ◽  
Gene Promoters ◽  
Structural Homology ◽  
Content Type ◽  
Reading Frame

An effective mechanism for introduction of phenotypic diversity within a bacterial population exploits changes in the length of repetitive DNA elements located within gene promoters. This phenomenon, known as phase variation, causes rapid activation or silencing of gene expression and fosters bacterial adaptation to new or changing environments. Phase variation often occurs in surface-exposed proteins, and inTreponema pallidumsubsp.pallidum, the syphilis agent, it was reported to affect transcription of three putative outer membrane protein (OMP)-encoding genes. When theT. pallidumsubsp.pallidumNichols strain genome was initially annotated, the TP0126 open reading frame was predicted to include a poly(G) tract and did not appear to have a predicted signal sequence that might suggest the possibility of its being an OMP. Here we show that the initial annotation was incorrect, that this poly(G) is instead located within the TP0126 promoter, and that it varies in lengthin vivoduring experimental syphilis. Additionally, we show that TP0126 transcription is affected by changes in the poly(G) length consistent with regulation by phase variation.In silicoanalysis of the TP0126 open reading frame based on the experimentally identified transcriptional start site shortens this hypothetical protein by 69 amino acids, reveals a predicted cleavable signal peptide, and suggests structural homology with the OmpW family of porins. Circular dichroism of recombinant TP0126 supports structural homology to OmpW. Together with the evidence that TP0126 is fully conserved amongT. pallidumsubspecies and strains, these data suggest an important role for TP0126 inT. pallidumbiology and syphilis pathogenesis.

scholarly journals YojI of Escherichia coli Functions as a Microcin J25 Efflux Pump

2005 ◽  
Vol 187 (10) ◽  
pp. 3465-3470 ◽  
Author(s):  
Mónica A. Delgado ◽  
Paula A. Vincent ◽  
Ricardo N. Farías ◽  
Raúl A. Salomón
Keyword(s):  
Escherichia Coli ◽  
Efflux Pump ◽  
Open Reading Frame ◽  
Peptide Antibiotic ◽  
Toxic Level ◽  
Reading Frame ◽  
Increased Sensitivity ◽  
Multicopy Vector ◽  
Microcin J25 ◽  
Sequence Similarities

ABSTRACT In the present study, we showed that yojI, an Escherichia coli open reading frame with an unknown function, mediates resistance to the peptide antibiotic microcin J25 when it is expressed from a multicopy vector. Disruption of the single chromosomal copy of yojI increased sensitivity of cells to microcin J25. The YojI protein was previously assumed to be an ATP-binding-cassette-type exporter on the basis of sequence similarities. We demonstrate that YojI is capable of pumping out microcin molecules. Thus, one obvious explanation for the protective effect against microcin J25 is that YojI action keeps the intracellular concentration of the peptide below a toxic level. The outer membrane protein TolC in addition to YojI is required for export of microcin J25 out of the cell. Microcin J25 is thus the first known substrate for YojI.

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