scholarly journals Effects of Stress, Reactive Oxygen Species, and the SOS Response onDe NovoAcquisition of Antibiotic Resistance in Escherichia coli

2015 ◽  
Vol 60 (3) ◽  
pp. 1319-1327 ◽  
Author(s):  
Nadine Händel ◽  
Marloes Hoeksema ◽  
Marina Freijo Mata ◽  
Stanley Brul ◽  
Benno H. ter Kuile
Keyword(s):  
Escherichia Coli ◽  
Antibiotic Resistance ◽  
Cellular Response ◽  
De Novo ◽  
Sos Response ◽  
Optimal Growth ◽  
Growth Conditions ◽  
Regulation Of Transcription ◽  
Ph Homeostasis ◽  
Content Type

Strategies to prevent the development of antibiotic resistance in bacteria are needed to reduce the threat of infectious diseases to human health. Thede novoacquisition of resistance due to mutations and/or phenotypic adaptation occurs rapidly as a result of interactions of gene expression and mutations (N. Handel, J. M. Schuurmans, Y. Feng, S. Brul, and B. H. Ter Kuile, Antimicrob Agents Chemother 58:4371–4379, 2014,http://dx.doi.org/10.1128/AAC.02892-14). In this study, the contribution of several individual genes to thede novoacquisition of antibiotic resistance inEscherichia coliwas investigated using mutants with deletions of genes known to be involved in antibiotic resistance. The results indicate thatrecA, vital for the SOS response, plays a crucial role in the development of antibiotic resistance. Likewise, deletion of global transcriptional regulators, such asgadEorsoxS, involved in pH homeostasis and superoxide removal, respectively, can slow the acquisition of resistance to a degree depending on the antibiotic. Deletion of the transcriptional regulatorsoxS, involved in superoxide removal, slowed the acquisition of resistance to enrofloxacin. Acquisition of resistance occurred at a lower rate in the presence of a second stress factor, such as a lowered pH or increased salt concentration, than in the presence of optimal growth conditions. The overall outcome suggests that a central cellular mechanism is crucial for the development of resistance and that genes involved in the regulation of transcription play an essential role. The actual cellular response, however, depends on the class of antibiotic in combination with environmental conditions.

scholarly journals Increase in Furfural Tolerance in Ethanologenic Escherichia coli LY180 by Plasmid-Based Expression ofthyA

2012 ◽  
Vol 78 (12) ◽  
pp. 4346-4352 ◽  
Author(s):  
Huabao Zheng ◽  
Xuan Wang ◽  
Lorraine P. Yomano ◽  
Keelnatham T. Shanmugam ◽  
Lonnie O. Ingram
Keyword(s):  
Escherichia Coli ◽  
Cellular Response ◽  
De Novo ◽  
Content Type ◽  
Genomic Libraries ◽  
Methyl Donor ◽  
E Coli ◽  
Furfural Tolerance ◽  
Small Benefit ◽  
Ethanologenic Escherichia Coli

ABSTRACTFurfural is an inhibitory side product formed during the depolymerization of hemicellulose by mineral acids. Genomic libraries from three different bacteria (Bacillus subtilisYB886,Escherichia coliNC3, andZymomonas mobilisCP4) were screened for genes that conferred furfural resistance on plates. Beneficial plasmids containing thethyAgene (coding for thymidylate synthase) were recovered from all three organisms. Expression of this key gene in thede novopathway for dTMP biosynthesis improved furfural resistance on plates and during fermentation. A similar benefit was observed by supplementation with thymine, thymidine, or the combination of tetrahydrofolate and serine (precursors for 5,10-methylenetetrahydrofolate, the methyl donor for ThyA). Supplementation with deoxyuridine provided a small benefit, and deoxyribose was of no benefit for furfural tolerance. A combination of thymidine and plasmid expression ofthyAwas no more effective than either alone. Together, these results demonstrate that furfural tolerance is increased by approaches that increase the supply of pyrimidine deoxyribonucleotides. However, ThyA activity was not directly affected by the addition of furfural. Furfural has been previously shown to damage DNA inE. coliand to activate a cellular response to oxidative damage in yeast. The added burden of repairing furfural-damaged DNA inE. coliwould be expected to increase the cellular requirement for dTMP. Increased expression ofthyA(E. coli,B. subtilis, orZ. mobilis), supplementation of cultures with thymidine, and supplementation with precursors for 5,10-methylenetetrahydrofolate (methyl donor) are each proposed to increase furfural tolerance by increasing the availability of dTMP for DNA repair.

scholarly journals Genomewide Screen for Modulators of Evolvability under Toxic Antibiotic Exposure

2013 ◽  
Vol 57 (7) ◽  
pp. 3453-3456 ◽  
Author(s):  
Orsolya Méhi ◽  
Balázs Bogos ◽  
Bálint Csörgő ◽  
Csaba Pál
Keyword(s):  
Escherichia Coli ◽  
Antibiotic Resistance ◽  
Iron Homeostasis ◽  
De Novo ◽  
Antibiotic Exposure ◽  
Wild Type ◽  
Content Type ◽  
Translation Fidelity ◽  
Evolution Of Resistance ◽  
Resistant Mutants

ABSTRACTAntibiotic resistance is generally selected within a window of concentrations high enough to inhibit wild-type growth but low enough for new resistant mutants to emerge. We studiedde novoevolution of resistance to ciprofloxacin in anEscherichia coliknockout library. Five null mutations had little or no effect on intrinsic antibiotic susceptibility but increased the upper antibiotic dosage to which initially sensitive populations could adapt. These mutations affect mismatch repair, translation fidelity, and iron homeostasis.

scholarly journals A Rhodobacter sphaeroides Protein Mechanistically Similar to Escherichia coli DksA Regulates Photosynthetic Growth

mBio ◽  
2014 ◽  
Vol 5 (3) ◽  
Author(s):  
Christopher W. Lennon ◽  
Kimberly C. Lemmer ◽  
Jessica L. Irons ◽  
Max I. Sellman ◽  
Timothy J. Donohue ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Structure Function ◽  
Rhodobacter Sphaeroides ◽  
Fatty Acid Content ◽  
Regulatory Protein ◽  
Growth Conditions ◽  
Globular Domain ◽  
Content Type ◽  
E Coli

ABSTRACTDksA is a global regulatory protein that, together with the alarmone ppGpp, is required for the “stringent response” to nutrient starvation in the gammaproteobacteriumEscherichia coliand for more moderate shifts between growth conditions. DksA modulates the expression of hundreds of genes, directly or indirectly. Mutants lacking a DksA homolog exhibit pleiotropic phenotypes in other gammaproteobacteria as well. Here we analyzed the DksA homolog RSP2654 in the more distantly relatedRhodobacter sphaeroides, an alphaproteobacterium. RSP2654 is 42% identical and similar in length toE. coliDksA but lacks the Zn finger motif of theE. coliDksA globular domain. Deletion of the RSP2654 gene results in defects in photosynthetic growth, impaired utilization of amino acids, and an increase in fatty acid content. RSP2654 complements the growth and regulatory defects of anE. colistrain lacking thedksAgene and modulates transcriptionin vitrowithE. coliRNA polymerase (RNAP) similarly toE. coliDksA. RSP2654 reduces RNAP-promoter complex stabilityin vitrowith RNAPs fromE. coliorR. sphaeroides, alone and synergistically with ppGpp, suggesting that even though it has limited sequence identity toE. coliDksA (DksAEc), it functions in a mechanistically similar manner. We therefore designate the RSP2654 protein DksARsp. Our work suggests that DksARsphas distinct and important physiological roles in alphaproteobacteria and will be useful for understanding structure-function relationships in DksA and the mechanism of synergy between DksA and ppGpp.IMPORTANCEThe role of DksA has been analyzed primarily in the gammaproteobacteria, in which it is best understood for its role in control of the synthesis of the translation apparatus and amino acid biosynthesis. Our work suggests that DksA plays distinct and important physiological roles in alphaproteobacteria, including the control of photosynthesis inRhodobacter sphaeroides. The study of DksARsp, should be useful for understanding structure-function relationships in the protein, including those that play a role in the little-understood synergy between DksA and ppGpp.

scholarly journals Vibrio cholerae Triggers SOS and Mutagenesis in Response to a Wide Range of Antibiotics: a Route towards Multiresistance

2011 ◽  
Vol 55 (5) ◽  
pp. 2438-2441 ◽  
Author(s):  
Zeynep Baharoglu ◽  
Didier Mazel
Keyword(s):  
Escherichia Coli ◽  
Antibiotic Resistance ◽  
Vibrio Cholerae ◽  
Fluorescent Protein ◽  
Resistance Development ◽  
Content Type ◽  
E Coli ◽  
Wide Range ◽  
Green Fluorescent ◽  
Regulated Promoters

ABSTRACTAntibiotic resistance development has been linked to the bacterial SOS stress response. InEscherichia coli, fluoroquinolones are known to induce SOS, whereas other antibiotics, such as aminoglycosides, tetracycline, and chloramphenicol, do not. Here we address whether various antibiotics induce SOS inVibrio cholerae. Reporter green fluorescent protein (GFP) fusions were used to measure the response of SOS-regulated promoters to subinhibitory concentrations of antibiotics. We show that unlike the situation withE. coli, all these antibiotics induce SOS inV. cholerae.

scholarly journals Correlation of Intracellular Trehalose Concentration with Desiccation Resistance of Soil Escherichia coli Populations

2012 ◽  
Vol 78 (20) ◽  
pp. 7407-7413 ◽  
Author(s):  
Qian Zhang ◽  
Tao Yan
Keyword(s):  
Escherichia Coli ◽  
De Novo ◽  
Potassium Acetate ◽  
Desiccation Stress ◽  
Desiccation Resistance ◽  
Content Type ◽  
Soil Desiccation ◽  
E Coli ◽  
Organic Solute ◽  
Trehalose Synthesis

ABSTRACTNaturalized soilEscherichia colipopulations need to resist common soil desiccation stress in order to inhabit soil environments. In this study, four representative soilE. colistrains and one lab strain, MG1655, were tested for desiccation resistance via die-off experiments in sterile quartz sand under a potassium acetate-induced desiccation condition. The desiccation stress caused significantly lower die-off rates of the four soil strains (0.17 to 0.40 day−1) than that of MG1655 (0.85 day−1). Cellular responses, including extracellular polymeric substance (EPS) production, exogenous glycine betaine (GB) uptake, and intracellular compatible organic solute synthesis, were quantified and compared under the desiccation and hydrated control conditions. GB uptake appeared not to be a specific desiccation response, while EPS production showed considerable variability among theE. colistrains. AllE. colistrains produced more intracellular trehalose, proline, and glutamine under the desiccation condition than the hydrated control, and only the trehalose concentration exhibited a significant correlation with the desiccation-contributed die-off coefficients (Spearman's ρ = −1.0;P= 0.02).De novotrehalose synthesis was further determined for 15E. colistrains from both soil and nonsoil sources to determine its prevalence as a specific desiccation response. MostE. colistrains (14/15) synthesized significantly more trehalose under the desiccation condition, and the soilE. colistrains produced more trehalose (106.5 ± 44.9 μmol/mg of protein [mean ± standard deviation]) than the nonsoil reference strains (32.5 ± 10.5 μmol/mg of protein).

Mutagenesis and More: umuDC and the Escherichia coli SOS Response

Genetics ◽  
1998 ◽  
Vol 148 (4) ◽  
pp. 1599-1610 ◽  
Author(s):  
Bradley T Smith ◽  
Graham C Walker
Keyword(s):  
Escherichia Coli ◽  
Dna Damage ◽  
Cellular Response ◽  
Sos Response ◽  
Posttranslational Regulation ◽  
E Coli ◽  
Sos Mutagenesis ◽  
Induced Mutagenesis ◽  
Mechanistic Basis ◽  
Increase Cell Survival

Abstract The cellular response to DNA damage that has been most extensively studied is the SOS response of Escherichia coli. Analyses of the SOS response have led to new insights into the transcriptional and posttranslational regulation of processes that increase cell survival after DNA damage as well as insights into DNA-damage-induced mutagenesis, i.e., SOS mutagenesis. SOS mutagenesis requires the recA and umuDC gene products and has as its mechanistic basis the alteration of DNA polymerase III such that it becomes capable of replicating DNA containing miscoding and noncoding lesions. Ongoing investigations of the mechanisms underlying SOS mutagenesis, as well as recent observations suggesting that the umuDC operon may have a role in the regulation of the E. coli cell cycle after DNA damage has occurred, are discussed.

scholarly journals Identification and Regulation of a Novel Citrobacter rodentium Gut Colonization Fimbria (Gcf)

2015 ◽  
Vol 197 (8) ◽  
pp. 1478-1491 ◽  
Author(s):  
Gustavo G. Caballero-Flores ◽  
Matthew A. Croxen ◽  
Verónica I. Martínez-Santos ◽  
B. Brett Finlay ◽  
José L. Puente
Keyword(s):  
Escherichia Coli ◽  
Intestinal Epithelium ◽  
Pathogenic Bacteria ◽  
Critical Role ◽  
Growth Conditions ◽  
Citrobacter Rodentium ◽  
Content Type ◽  
Gut Colonization ◽  
Successful Infection

ABSTRACTThe Gram-negative enteric bacteriumCitrobacter rodentiumis a natural mouse pathogen that has been extensively used as a surrogate model for studying the human pathogens enteropathogenic and enterohemorrhagicEscherichia coli. All three pathogens produce similar attaching and effacing (A/E) lesions in the intestinal epithelium. During infection, these bacteria employ surface structures called fimbriae to adhere and colonize the host intestinal epithelium. ForC. rodentium, the roles of only a small number of its genome-carried fimbrial operons have been evaluated. Here, we report the identification of a novelC. rodentiumcolonization factor, calledgutcolonizationfimbria (Gcf), which is encoded by a chaperone-usher fimbrial operon. AgcfAmutant shows a severe colonization defect within the first 10 days of infection. Thegcfpromoter is not active inC. rodentiumunder severalin vitrogrowth conditions; however, it is readily expressed in aC. rodentiumΔhns1mutant lacking the closest ortholog of theEscherichia colihistone-like nucleoid structuring protein (H-NS) but not in mutants with deletion of the other four genes encoding H-NS homologs. H-NS binds to the regulatory region ofgcf, further supporting its direct role as a repressor of thegcfpromoter that starts transcription 158 bp upstream of the start codon of its first open reading frame. Thegcfoperon possesses interesting novel traits that open future opportunities to expand our knowledge of the structure, regulation, and function during infection of these important bacterial structures.IMPORTANCEFimbriae are surface bacterial structures implicated in a variety of biological processes. Some have been shown to play a critical role during host colonization and thus in disease. Pathogenic bacteria possess the genetic information for an assortment of fimbriae, but their function and regulation and the interplay between them have not been studied in detail. This work provides new insights into the function and regulation of a novel fimbria called Gcf that is important for early establishment of a successful infection byC. rodentiumin mice, despite being poorly expressed underin vitrogrowth conditions. This discovery offers an opportunity to better understand the individual role and the regulatory mechanisms controlling the expression of specific fimbrial operons that are critical during infection.

scholarly journals Increased Survival of Antibiotic-Resistant Escherichia coli inside Macrophages

2012 ◽  
Vol 57 (1) ◽  
pp. 189-195 ◽  
Author(s):  
Migla Miskinyte ◽  
Isabel Gordo
Keyword(s):  
Escherichia Coli ◽  
Antibiotic Resistance ◽  
Bacterial Infections ◽  
Resistance Mutation ◽  
Fitness Cost ◽  
Resistance Mutations ◽  
Content Type ◽  
E Coli ◽  
Fitness Effects ◽  
K 12

ABSTRACTMutations causing antibiotic resistance usually incur a fitness cost in the absence of antibiotics. The magnitude of such costs is known to vary with the environment. Little is known about the fitness effects of antibiotic resistance mutations when bacteria confront the host's immune system. Here, we study the fitness effects of mutations in therpoB,rpsL, andgyrAgenes, which confer resistance to rifampin, streptomycin, and nalidixic acid, respectively. These antibiotics are frequently used in the treatment of bacterial infections. We measured two important fitness traits—growth rate and survival ability—of 12Escherichia coliK-12 strains, each carrying a single resistance mutation, in the presence of macrophages. Strikingly, we found that 67% of the mutants survived better than the susceptible bacteria in the intracellular niche of the phagocytic cells. In particular, allE. colistreptomycin-resistant mutants exhibited an intracellular advantage. On the other hand, 42% of the mutants incurred a high fitness cost when the bacteria were allowed to divide outside of macrophages. This study shows that single nonsynonymous changes affecting fundamental processes in the cell can contribute to prolonged survival ofE. coliin the context of an infection.

scholarly journals Basal-Level Effects of (p)ppGpp in the Absence of Branched-Chain Amino Acids in Actinobacillus pleuropneumoniae

2020 ◽  
Vol 202 (8) ◽  
Author(s):  
Gang Li ◽  
Qian Zhao ◽  
Tian Luan ◽  
Yangbo Hu ◽  
Yueling Zhang ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Amino Acids ◽  
De Novo ◽  
Model Organism ◽  
Stringent Response ◽  
Actinobacillus Pleuropneumoniae ◽  
Branched Chain Amino Acids ◽  
Content Type ◽  
Phenotypic Differences ◽  
Branched Chain

ABSTRACT The (p)ppGpp-mediated stringent response (SR) is a highly conserved regulatory mechanism in bacterial pathogens, enabling adaptation to adverse environments, and is linked to pathogenesis. Actinobacillus pleuropneumoniae can cause damage to the lungs of pigs, its only known natural host. Pig lungs are known to have a low concentration of free branched-chain amino acids (BCAAs) compared to the level in plasma. We had investigated the role for (p)ppGpp in viability and biofilm formation of A. pleuropneumoniae. Now, we sought to determine whether (p)ppGpp was a trigger signal for the SR in A. pleuropneumoniae in the absence of BCAAs. Combining transcriptome and phenotypic analyses of the wild type (WT) and an relA spoT double mutant [which does not produce (p)ppGpp], we found that (p)ppGpp could repress de novo purine biosynthesis and activate antioxidant pathways. There was a positive correlation between GTP and endogenous hydrogen peroxide content. Furthermore, the growth, viability, morphology, and virulence were altered by the inability to produce (p)ppGpp. Genes involved in the biosynthesis of BCAAs were constitutively upregulated, regardless of the existence of BCAAs, without accumulation of (p)ppGpp beyond a basal level. Collectively, our study shows that the absence of BCAAs was not a sufficient signal to trigger the SR in A. pleuropneumoniae. (p)ppGpp-mediated regulation in A. pleuropneumoniae is different from that described for the model organism Escherichia coli. Further work will establish whether the (p)ppGpp-dependent SR mechanism in A. pleuropneumoniae is conserved among other veterinary pathogens, especially those in the Pasteurellaceae family. IMPORTANCE (p)ppGpp is a key player in reprogramming transcriptomes to respond to nutritional challenges. Here, we present transcriptional and phenotypic differences of A. pleuropneumoniae grown in different chemically defined media in the absence of (p)ppGpp. We show that the deprivation of branched-chain amino acids (BCAAs) does not elicit a change in the basal-level (p)ppGpp, but this level is sufficient to regulate the expression of BCAA biosynthesis. The mechanism found in A. pleuropneumoniae is different from that of the model organism Escherichia coli but similar to that found in some Gram-positive bacteria. This study not only broadens the research scope of (p)ppGpp but also further validates the complexity and multiplicity of (p)ppGpp regulation in microorganisms that occupy different biological niches.

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