scholarly journals Dynamic Boolean modelling reveals the influence of energy supply on bacterial efflux pump expression

2021 ◽  
Author(s):  
Ryan Kerr ◽  
Sara Jabbari ◽  
Jessica M A Blair ◽  
Iain Johnston
Keyword(s):  
Gene Expression ◽  
Antimicrobial Resistance ◽  
Energy Supply ◽  
Regulatory Networks ◽  
Efflux Pump ◽  
Bacterial Species ◽  
Efflux Pumps ◽  
Resistant Bacteria ◽  
Energy Availability ◽  
Bacterial Populations

Antimicrobial resistance (AMR) is a global health issue. One key factor contributing to AMR is the ability of bacteria to export drugs through efflux pumps, which relies on the ATP-dependent expression and interaction of several controlling genes. Recent studies have shown significant cell-to-cell ATP variability exists within clonal bacterial populations, but the contribution of intrinsic cell-to-cell ATP heterogeneity is generally overlooked in understanding efflux pumps. Here, we consider how ATP variability influences gene regulatory networks controlling expression of efflux pump genes in two bacterial species. We develop and apply a generalisable Boolean modelling framework, developed to incorporate the dependence of gene expression dynamics on available cellular energy supply. Theoretical results show differences in energy availability can cause pronounced downstream heterogeneity in efflux gene expression. Cells with higher energy availability have a superior response to stressors. Further, in the absence of stress, model bacteria develop heterogeneous pulses of efflux pump gene expression which contribute to a sustained sub-population of cells with increased efflux expression activity, potentially conferring a continuous pool of intrinsically resistant bacteria. This modelling approach thus reveals an important source of heterogeneity in cell responses to antimicrobials and sheds light on potentially targetable aspects of efflux pump-related antimicrobial resistance.

scholarly journals Low nutrient levels reduce the fitness cost of MexCD-OprJ efflux pump overexpression in ciprofloxacin-resistant Pseudomonas aeruginosa

2018 ◽  
Author(s):  
Wenfang Lin ◽  
Kun Wan ◽  
Jie Zeng ◽  
Jingjing Li ◽  
Xi Li ◽  
...  
Keyword(s):  
Gene Expression ◽  
Antibiotic Resistance ◽  
Efflux Pump ◽  
Efflux Pumps ◽  
Fitness Cost ◽  
Resistant Bacteria ◽  
Nutrient Levels ◽  
High Nutrient ◽  
Key Factor ◽  
Nutrient Conditions

AbstractThe long-term persistence of antibiotic resistance in the environment is a public health concern. Expression of an efflux pump, an important mechanism of resistance to antibiotics, is usually associated with a fitness cost in bacteria. In this study, we aimed to determine why antibiotic resistance conferred by overexpression of an efflux pump persists in environments such as drinking and source water in which antibiotic selective pressure may be very low or even absent. Competition experiments between wild-type Pseudomonas aeruginosa and ciprofloxacin-resistant mutants revealed that the fitness cost of ciprofloxacin resistance (strains cip_1, cip_2, and cip_3) significantly decreased (P < 0.05) under low-nutrient (0.5 mg/l total organic carbon (TOC)) relative to high-nutrient (500 mg/l TOC) conditions. Mechanisms underlying this fitness cost were analyzed. MexD gene expression in resistant bacteria (cip_3 strain) was significantly lower (P < 0.05) in low-nutrient conditions, with 10 mg/l TOC (8.01 ± 0.82-fold), than in high-nutrient conditions, with 500 mg/l TOC (48.89 ± 4.16-fold). Moreover, rpoS gene expression in resistant bacteria (1.36 ± 0.13-fold) was significantly lower (P < 0.05) than that in the wild-type strain (2.78 ± 0.29-fold) under low-nutrient conditions (10 mg/l TOC), suggesting a growth advantage. Furthermore, the difference in metabolic activity between the two competing strains was significantly smaller (P < 0.05) in low-nutrient conditions (5 and 0.5 mg/l TOC). These results suggest that nutrient levels are a key factor in determining the persistence and spread of antibiotic resistance conferred by efflux pumps in the natural environment with trace amounts or no antibiotics.ImportanceThe widespread of antibiotic resistance has led to an increasing concern about the environmental and public health risks. Mechanisms associated with antibiotic resistance including efflux pumps often increase bacterial fitness cost. Our study showed that the fitness cost of ciprofloxacin resistance conferred by overexpression of MexCD-OprJ efflux pump significantly decreased under low-nutrient relative to high-nutrient conditions. The significance of our research is to reveal that nutrient levels are key factor in determining the persistence of antibiotic resistance conferred by efflux pumps under conditions with trace amounts or no antibiotics, which can be mediated by some mechanisms including MexD gene expression, SOURs differences, and rpoS gene regulation.

scholarly journals Burkholderia collagen-like protein 8, Bucl8, is a unique outer membrane component of a tetrapartite efflux pump in Burkholderia pseudomallei and Burkholderia mallei

2020 ◽  
Author(s):  
Megan E Grund ◽  
Soo J Choi ◽  
Dudley H McNitt ◽  
Mariette Barbier ◽  
Gangqing Hu ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Burkholderia Pseudomallei ◽  
Triple Helix ◽  
Efflux Pump ◽  
Fusaric Acid ◽  
Efflux Pumps ◽  
Resistant Bacteria ◽  
Burkholderia Mallei ◽  
Membrane Component ◽  
Collagen Triple Helix

AbstractBacterial efflux pumps are an important pathogenicity trait because they extrude a variety of xenobiotics. Our laboratory previously identified in silico Burkholderia collagen-like protein 8 (Bucl8) in the Tier one select agents Burkholderia pseudomallei and Burkholderia mallei. We hypothesize that Bucl8, which contains two predicted tandem outer membrane efflux pump domains, is a component of a putative efflux pump. Unique to Bucl8, as compared to other outer membrane proteins, is the presence of an extended extracellular region containing a collagen-like (CL) domain and a non-collagenous C-terminus (Ct). Molecular modeling and circular dichroism spectroscopy with a recombinant protein, corresponding to this extracellular CL-Ct portion of Bucl8, demonstrated that it adopts a collagen triple helix, whereas functional assays screening for Bucl8 ligands identified binding to fibrinogen. Bioinformatic analysis of the bucl8 gene locus revealed it resembles a classical efflux-pump operon. The bucl8 gene is co-localized with downstream fusCDE genes encoding fusaric acid (FA) resistance, and with an upstream gene, designated as fusR, encoding a LysR-type transcriptional regulator. Using RT-qPCR, we defined the boundaries and transcriptional organization of the fusR-bucl8-fusCDE operon. We found exogenous FA induced bucl8 transcription over 80-fold in B. pseudomallei, while deletion of the entire bucl8 locus decreased the MIC of FA 4-fold in its isogenic mutant. We furthermore showed that the Bucl8 pump expressed in the heterologous Escherichia coli host confers FA resistance. On the contrary, the Bucl8 pump did not confer resistance to a panel of clinically-relevant antimicrobials in Burkholderia and E. coli. We finally demonstrated that deletion of the bucl8-locus drastically affects the growth of the mutant in L-broth. We determined that Bucl8 is a component of a novel tetrapartite efflux pump, which confers FA resistance, fibrinogen binding, and optimal growth.Author SummaryBurkholderia pseudomallei and Burkholderia mallei are highly infectious and multidrug resistant bacteria that are classified by the National Institute of Allergy and Infectious Diseases as Tier one select agents partly due to the intrinsic multidrug resistance associated with expression of the efflux pumps. To date, only few efflux pumps predicted in Burkholderia spp. have been studied in detail. In the current study we introduce Bucl8, an outer membrane component of an unreported putative efflux pump with a unique extended extracellular portion that forms a collagen triple helix and binds fibrinogen. We demonstrate Bucl8’s role in fusaric acid resistance by defining its operon via bioinformatic and transcriptional analyses, as well as by employing loss-of-function and gain-of-function genetic approaches. Our studies also implicate the Bucl8-associated pump in metabolic and physiologic homeostasis. Understanding how Bucl8 efflux pump contributes to Burkholderia pathology will foster development of pump inhibitors targeting transport mechanism or identifying potential surface-exposed vaccine targets.

scholarly journals An alkylaminoquinazoline restores antibiotic activity in Gram-negative resistant isolates

Microbiology ◽  
2011 ◽  
Vol 157 (2) ◽  
pp. 566-571 ◽  
Author(s):  
Abdallah Mahamoud ◽  
Jacqueline Chevalier ◽  
Milad Baitiche ◽  
Elissavet Adam ◽  
Jean-Marie Pagès
Keyword(s):  
Efflux Pump ◽  
Bacterial Species ◽  
Efflux Pumps ◽  
Multidrug Resistant ◽  
Side Chain ◽  
Structural Class ◽  
Gram Negative ◽  
Activity Spectrum ◽  
Efflux Pump Inhibitors ◽  
Drug Efflux Pump

To date, various bacterial drug efflux pump inhibitors (EPIs) have been described. They exhibit variability in their activity spectrum with respect to antibiotic structural class and bacterial species. Among the various 4-alkylaminoquinazoline derivatives synthesized and studied in this work, one molecule, 1167, increased the susceptibility of important human-pathogenic, resistant, Gram-negative bacteria towards different antibiotic classes. This 4-(3-morpholinopropylamino)-quinazoline induced an increase in the activity of chloramphenicol, nalidixic acid, norfloxacin and sparfloxacin, which are substrates of the AcrAB-TolC and MexAB-OprM efflux pumps that act in these multidrug-resistant isolates. In addition, 1167 increased the intracellular concentration of chloramphenicol in efflux pump-overproducing strains. The rate of restoration depended on the structure of the antibiotic, suggesting that different sites in the efflux pumps may be involved. A molecule exhibiting a morpholine functional group and a propyl extension of the side chain was more active.

scholarly journals The Varied Role of Efflux Pumps of the MFS Family in the Interplay of Bacteria with Animal and Plant Cells

2019 ◽  
Vol 7 (9) ◽  
pp. 285 ◽  
Author(s):  
Pasqua ◽  
Grossi ◽  
Zennaro ◽  
Fanelli ◽  
Micheli ◽  
...  
Keyword(s):  
Regulatory Networks ◽  
Efflux Pump ◽  
Efflux Pumps ◽  
Major Facilitator Superfamily ◽  
Host Cells ◽  
Multidrug Efflux ◽  
Animal Cells ◽  
Multidrug Efflux Pumps ◽  
Wide Range ◽  
Major Facilitator

Efflux pumps represent an important and large group of transporter proteins found in all organisms. The importance of efflux pumps resides in their ability to extrude a wide range of antibiotics, resulting in the emergence of multidrug resistance in many bacteria. Besides antibiotics, multidrug efflux pumps can also extrude a large variety of compounds: Bacterial metabolites, plant-produced compounds, quorum-sensing molecules, and virulence factors. This versatility makes efflux pumps relevant players in interactions not only with other bacteria, but also with plant or animal cells. The multidrug efflux pumps belonging to the major facilitator superfamily (MFS) are widely distributed in microbial genomes and exhibit a large spectrum of substrate specificities. Multidrug MFS efflux pumps are present either as single-component transporters or as tripartite complexes. In this review, we will summarize how the multidrug MFS efflux pumps contribute to the interplay between bacteria and targeted host cells, with emphasis on their role in bacterial virulence, in the colonization of plant and animal host cells and in biofilm formation. We will also address the complexity of these interactions in the light of the underlying regulatory networks required for the effective activation of efflux pump genes.

scholarly journals Clinically Relevant Chromosomally Encoded Multidrug Resistance Efflux Pumps in Bacteria

2006 ◽  
Vol 19 (2) ◽  
pp. 382-402 ◽  
Author(s):  
Laura J. V. Piddock
Keyword(s):  
Antibiotic Resistance ◽  
Drug Transport ◽  
Efflux Pump ◽  
Regulatory Gene ◽  
Structural Data ◽  
Efflux Pumps ◽  
Resistant Bacteria ◽  
Multiple Drug ◽  
Transporter Gene ◽  
Resistance Nodulation Division

SUMMARY Efflux pump genes and proteins are present in both antibiotic-susceptible and antibiotic-resistant bacteria. Pumps may be specific for one substrate or may transport a range of structurally dissimilar compounds (including antibiotics of multiple classes); such pumps can be associated with multiple drug (antibiotic) resistance (MDR). However, the clinical relevance of efflux-mediated resistance is species, drug, and infection dependent. This review focuses on chromosomally encoded pumps in bacteria that cause infections in humans. Recent structural data provide valuable insights into the mechanisms of drug transport. MDR efflux pumps contribute to antibiotic resistance in bacteria in several ways: (i) inherent resistance to an entire class of agents, (ii) inherent resistance to specific agents, and (iii) resistance conferred by overexpression of an efflux pump. Enhanced efflux can be mediated by mutations in (i) the local repressor gene, (ii) a global regulatory gene, (iii) the promoter region of the transporter gene, or (iv) insertion elements upstream of the transporter gene. Some data suggest that resistance nodulation division systems are important in pathogenicity and/or survival in a particular ecological niche. Inhibitors of various efflux pump systems have been described; typically these are plant alkaloids, but as yet no product has been marketed.

scholarly journals Involvement of the AcrAB-TolC Efflux Pump in the Resistance, Fitness, and Virulence of Enterobacter cloacae

2012 ◽  
Vol 56 (4) ◽  
pp. 2084-2090 ◽  
Author(s):  
Astrid Pérez ◽  
Margarita Poza ◽  
Ana Fernández ◽  
Maria del Carmen Fernández ◽  
Susana Mallo ◽  
...  
Keyword(s):  
Antimicrobial Resistance ◽  
Pathogenic Bacteria ◽  
Efflux Pump ◽  
Enterobacter Cloacae ◽  
Efflux Pumps ◽  
Clinical Isolates ◽  
Wild Type ◽  
Content Type

ABSTRACTMultidrug efflux pumps have emerged as important mechanisms of antimicrobial resistance in bacterial pathogens. In order to cause infection, pathogenic bacteria require mechanisms to avoid the effects of host-produced compounds, and express efflux pumps may accomplish this task. In this study, we evaluated the effect of the inactivation of AcrAB-TolC on antimicrobial resistance, fitness, and virulence inEnterobacter cloacae, an opportunistic pathogen usually involved in nosocomial infections. Two different clinical isolates ofE. cloacaewere used, EcDC64 (multidrug resistance overexpressing the AcrAB-TolC efflux pump) and Jc194 (basal AcrAB-TolC expression). TheacrAandtolCgenes were deleted in strains EcDC64 and Jc194 to produce, respectively, EcΔacrAand EcΔtolCand JcΔacrAand JcΔtolCknockout (KO) derivatives. Antibiotic susceptibility testing was performed with all isolates, and we discovered that these mechanisms are involved in the resistance ofE. cloacaeto several antibiotics. Competition experiments were also performed with wild-type and isogenic KO strains. The competition index (CI), defined as the mutant/wild-type ratio, revealed that theacrAandtolCgenes both affect the fitness ofE. cloacae, as fitness was clearly reduced in theacrAandtolCKO strains. The median CI values obtainedin vitroandin vivowere, respectively, 0.42 and 0.3 for EcDC64/EcΔacrA, 0.24 and 0.38 for EcDC64/EcΔtolC, 0.15 and 0.11 for Jc194/JcΔacrA, and 0.38 and 0.39 for Jc194/JcΔtolC. Use of an intraperitoneal mouse model of systemic infection revealed reduced virulence in bothE. cloacaeclinical strains when either theacrAortolCgene was inactivated. In conclusion, the structural components of the AcrAB-TolC efflux pump appear to play a role in antibiotic resistance as well as environmental adaptation and host virulence in clinical isolates ofE. cloacae.

scholarly journals Two resistance nodulation division-family efflux pumps inChromobacteriumspecies and their role in antibiotic resistance and tolerance

2019 ◽  
Author(s):  
Saida Benomar ◽  
Kara C Evans ◽  
Robert L Unckless ◽  
Josephine R Chandler
Keyword(s):  
Antibiotic Resistance ◽  
Efflux Pump ◽  
Bacterial Species ◽  
Efflux Pumps ◽  
Resistance Mechanisms ◽  
Antibiotic Resistant ◽  
Burkholderia Thailandensis ◽  
New Information ◽  
Resistance Nodulation Division ◽  
Culture Growth

ABSTRACTVery little is known of the antibiotic resistance mechanisms of members of theChromobacteriumgenus. In previous studies ofChromobacterium subtsugae(formerlyC. violaceum) strain CV017, we identified a resistance nodulation division (RND)-family efflux pump (CdeAB-OprM). Here, we show thecdeAB-oprMgenes are widely distributed in members of theChromobacteriumgenus. We use antimicrobial susceptibility testing with a CV017cdeAB-oprMmutant to show the products of these genes confers resistance to a variety of antibiotics including ciprofloxacin, a clinically important antibiotic. We also identified a related RND-family pump,cseAB-oprN, in the genome of CV017 and otherC. subtsugaespecies, that is not present in other members of theChromobacteriumgenus. We demonstrate that CdeAB-OprM and CseAB-OprN are both transcriptionally induced in CV017 cells treated with sub-lethal antibiotic concentrations and they are important for induction of tolerance to different antibiotics. While CdeAB-OprM has a broad antibiotic specificity, the CseAB-OprN system is highly specific for a ribosome-targeting antibiotic produced by the saprophytic bacteriumBurkholderia thailandensis,bactobolin. Finally, we use a previously developedB. thailandensis-C. subtsugaeCV017 co-culture model to demonstrate that adding sub-lethal bactobolin at the beginning of co-culture growth increases the ability of CV017 to compete withB. thailandensisin a manner that is dependent on the CseAB-OprN system. Our results provide new information on the antibiotic resistance mechanisms ofChromobacteriumspecies and highlight the importance of efflux pumps during competition with other bacterial species.IMPORTANCEThis study describes two closely related efflux pumps in members of theChromobacteriumgenus, which includes opportunistic but often-fatal pathogens and species with highly versatile metabolic capabilities. Efflux pumps remove antibiotics from the cell and are important for antibiotic resistance. One of these pumps is broadly distributed in theChromobacteriumgenus and increases resistance to clinically relevant antibiotics. The other efflux pump is present only inChromobacterium subtsugaeand is highly specific for bactobolin, an antibiotic produced by the soil saprophyteBurkholderia thailandensis. We demonstrate these pumps can be activated to increase resistance by their antibiotic substrates, and that this activation is important forC. subtsugaeto survive in a laboratory competition experiment withB. thailandensis.These results have implications for managing antibiotic-resistantChromobacteriuminfections, bioengineering ofChromobacteriumspecies, and for understanding the evolution of efflux pumps.

scholarly journals Multidrug Resistance Efflux Pumps in Acinetobacter spp.: An Update

2021 ◽  
Author(s):  
Vanessa Kornelsen ◽  
Ayush Kumar
Keyword(s):  
Multidrug Resistance ◽  
Antimicrobial Resistance ◽  
Bacterial Species ◽  
Clinical Importance ◽  
Efflux Pumps ◽  
Major Facilitator Superfamily ◽  
Small Multidrug Resistance ◽  
Resistance Nodulation Division ◽  
Rnd Efflux Pumps ◽  
Major Facilitator

Acinetobacter spp. have become of increased clinical importance as studies have shown the antimicrobial resistant potential of these species. Efflux pumps can lead to reduced susceptibility to a variety of antibiotics and are present in large number across Acinetobacter spp. There are six families of efflux pumps that have been shown to be of clinical relevance: the Major Facilitator Superfamily (MFS), Small Multidrug Resistance (SMR) family, ATP-binding cassette (ABC) family, Multidrug and Toxic Compound Extrusion (MATE) family, Proteobacterial Antimicrobial Compound Efflux (PACE) family and Resistance-Nodulation-Division (RND) family. A lot of work has been done on understanding and characterizing the roles that these efflux pumps play in relation to antimicrobial resistance and the physiology of these bacteria. RND efflux pumps, with their expansive substrate profiles, are a major component of Acinetobacter spp. antimicrobial resistance. New discoveries over the last decade have shed a lot of light on to the complex regulation of these efflux pumps leading to greater understanding and potential of slowing the reduced susceptibility seen by these bacterial species.

scholarly journals Efflux Pump Mediated Antimicrobial Resistance by Staphylococci in Health-Related Environments: Challenges and the Quest for Inhibition

Antibiotics ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 1502
Author(s):  
Abolfazl Dashtbani-Roozbehani ◽  
Melissa H. Brown
Keyword(s):  
Antimicrobial Resistance ◽  
Antimicrobial Agents ◽  
Efflux Pump ◽  
Current Knowledge ◽  
Efflux Pumps ◽  
Multidrug Resistant ◽  
Resistance Mechanisms ◽  
Multidrug Efflux Pump ◽  
New Antibiotics ◽  
Efflux Pump Inhibitors

The increasing emergence of antimicrobial resistance in staphylococcal bacteria is a major health threat worldwide due to significant morbidity and mortality resulting from their associated hospital- or community-acquired infections. Dramatic decrease in the discovery of new antibiotics from the pharmaceutical industry coupled with increased use of sanitisers and disinfectants due to the ongoing COVID-19 pandemic can further aggravate the problem of antimicrobial resistance. Staphylococci utilise multiple mechanisms to circumvent the effects of antimicrobials. One of these resistance mechanisms is the export of antimicrobial agents through the activity of membrane-embedded multidrug efflux pump proteins. The use of efflux pump inhibitors in combination with currently approved antimicrobials is a promising strategy to potentiate their clinical efficacy against resistant strains of staphylococci, and simultaneously reduce the selection of resistant mutants. This review presents an overview of the current knowledge of staphylococcal efflux pumps, discusses their clinical impact, and summarises compounds found in the last decade from plant and synthetic origin that have the potential to be used as adjuvants to antibiotic therapy against multidrug resistant staphylococci. Critically, future high-resolution structures of staphylococcal efflux pumps could aid in design and development of safer, more target-specific and highly potent efflux pump inhibitors to progress into clinical use.

scholarly journals Antagonism and population dynamics of Acinetobacter baumannii from US military treatment centers

2017 ◽  
Author(s):  
Rae A Heitkamp ◽  
Amy M Zale ◽  
Benjamin C Kirkup
Keyword(s):  
Population Dynamics ◽  
Acinetobacter Baumannii ◽  
Bacterial Species ◽  
Hospital Setting ◽  
Antagonistic Activity ◽  
Resistant Bacteria ◽  
Natural Environments ◽  
Bacterial Populations ◽  
Starting Point ◽  
Before And After

Antibiotic-resistant bacteria complicate many infections and can be difficult to eradicate from hospitals. The population dynamics and ecology of these organisms in the hospital setting, however, is not well understood. Here, we report extensive strain-based antagonistic interactions occurring in military clinical isolates of Acinetobacter baumannii, a bacterial species that causes many drug-resistant hospital-associated infections. Sequence-based phylogenetic analysis of isolates allowed for differentiation to two major clades, with one of the clades representing two closely related genetic groups. Antagonistic activity was detected using a spot-plate assay to test pairwise interactions of all isolates. Isolates exhibited extensive and diverse patterns of antagonism against other isolates. One major clade of isolates had a distinct change in antagonism phenotype between isolates that differed by one base pair out of ~1500bp sequenced, with consistent antagonism of one group of isolates by the other. Both the antagonistic and the sensitive group exhibited extensive drug resistance. The first isolate of the antagonistic group was cultured in May 2010. The proportion of isolates from the antagonistic group collected before and after July 2010 increased from 2% to 76%. The results of this early study of the ecology of hospital-associated bacterial populations are discussed in the context of the species ecology of bacteria in natural environments. This work is a potential starting point for investigations into ecological interventions for infection control in hospitals.

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