758 - Helicobacter Hepaticus Infection Increases Colonization of PKS+ Escherichia Coli and Promotes Mutagenesis in the Lower Bowel Mucosa of RAG2−/−IL10−/−GPT Mice in a Sex- and IL-10-Dependent Manner

ABSTRACT The CpxA/R two-component signal transduction system ofEscherichia coli can combat a variety of extracytoplasmic protein-mediated toxicities. The Cpx system performs this function, in part, by increasing the synthesis of the periplasmic protease, DegP. However, other factors are also employed by the Cpx system for this stress-combative function. In an effort to identify these remaining factors, we screened a collection of random lacZ operon fusions for those fusions whose transcription is regulated by CpxA/R. Through this approach, we have identified a new locus,cpxP, whose transcription is stimulated by activation of the Cpx pathway. cpxP specifies a periplasmic protein that can combat the lethal phenotype associated with the synthesis of a toxic envelope protein. In addition, we show that cpxPtranscription is strongly induced by alkaline pH in a CpxA-dependent manner and that cpxP and cpx mutant strains display hypersensitivity to growth in alkaline conditions.

Download Full-text

Tyrosine phosphorylation-dependent localization of TmaR that controls activity of a major bacterial sugar regulator by polar sequestration

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2016017118 ◽

2020 ◽

Vol 118 (2) ◽

pp. e2016017118

Author(s):

Tamar Szoke ◽

Nitsan Albocher ◽

Sutharsan Govindarajan ◽

Anat Nussbaum-Shochat ◽

Orna Amster-Choder

Keyword(s):

Escherichia Coli ◽

Sugar Uptake ◽

Dependent Manner ◽

Tyrosine Residue ◽

Sugar Consumption ◽

E Coli ◽

Acidic Conditions ◽

Enzyme I ◽

Uptake And Metabolism ◽

Protein Enzyme

The poles of Escherichia coli cells are emerging as hubs for major sensory systems, but the polar determinants that allocate their components to the pole are largely unknown. Here, we describe the discovery of a previously unannotated protein, TmaR, which localizes to the E. coli cell pole when phosphorylated on a tyrosine residue. TmaR is shown here to control the subcellular localization and activity of the general PTS protein Enzyme I (EI) by binding and polar sequestration of EI, thus regulating sugar uptake and metabolism. Depletion or overexpression of TmaR results in EI release from the pole or enhanced recruitment to the pole, which leads to increasing or decreasing the rate of sugar consumption, respectively. Notably, phosphorylation of TmaR is required to release EI and enable its activity. Like TmaR, the ability of EI to be recruited to the pole depends on phosphorylation of one of its tyrosines. In addition to hyperactivity in sugar consumption, the absence of TmaR also leads to detrimental effects on the ability of cells to survive in mild acidic conditions. Our results suggest that this survival defect, which is sugar- and EI-dependent, reflects the difficulty of cells lacking TmaR to enter stationary phase. Our study identifies TmaR as the first, to our knowledge, E. coli protein reported to localize in a tyrosine-dependent manner and to control the activity of other proteins by their polar sequestration and release.

Download Full-text

The yliA, -B, -C, and -D Genes of Escherichia coli K-12 Encode a Novel Glutathione Importer with an ATP-Binding Cassette

Journal of Bacteriology ◽

10.1128/jb.187.17.5861-5867.2005 ◽

2005 ◽

Vol 187 (17) ◽

pp. 5861-5867 ◽

Cited By ~ 61

Author(s):

Hideyuki Suzuki ◽

Takashi Koyanagi ◽

Shunsuke Izuka ◽

Akiko Onishi ◽

Hidehiko Kumagai

Keyword(s):

Escherichia Coli ◽

Atp Binding ◽

Sulfur Source ◽

Dependent Manner ◽

Oxygen Species ◽

E Coli ◽

Living Organisms ◽

K 12 ◽

Atp Binding Cassette

ABSTRACT Glutathione protects cells and organisms from oxygen species and peroxides and is indispensable for aerobically living organisms. Moreover, it acts against xenobiotics and drugs by the formation and excretion of glutathione S conjugates. In this study, we show that the yliA, -B, -C, and -D genes of Escherichia coli K-12 encode a glutathione transporter with the ATP-binding cassette. The transporter imports extracellular glutathione into the cytoplasm in an ATP-dependent manner. This transporter, along with γ-glutamyltranspeptidase, has an important role in E. coli growth with glutathione as a sole sulfur source.

Download Full-text

Mutational Analysis of the Locus of Enterocyte Effacement-Encoded Regulator (Ler) of Enteropathogenic Escherichia coli

Journal of Bacteriology ◽

10.1128/jb.00663-08 ◽

2008 ◽

Vol 190 (23) ◽

pp. 7808-7818 ◽

Cited By ~ 23

Author(s):

Gal Yerushalmi ◽

Chen Nadler ◽

Tatiana Berdichevski ◽

Ilan Rosenshine

Keyword(s):

Escherichia Coli ◽

Type Iii Secretion ◽

Mutational Analysis ◽

Bacterial Colonization ◽

Point Mutations ◽

Dominant Negative ◽

Compensatory Mechanism ◽

Dependent Manner ◽

Enterocyte Effacement ◽

Related Proteins

ABSTRACT The locus of enterocyte effacement (LEE) pathogenicity island of enterohemorrhagic and enteropathogenic Escherichia coli (EHEC and EPEC, respectively) comprises a cluster of operons encoding a type III secretion system and related proteins, all of which are essential for bacterial colonization of the host intestines. The LEE1 operon encodes Ler, which positively regulates many EPEC and EHEC virulence genes located in the LEE region and elsewhere in the chromosome. In addition, Ler is a specific autorepressor of LEE1 transcription. To better understand the function of Ler, we screened for Ler mutants defective in autorepression. We isolated 18 different point mutations in Ler, rendering it defective in autorepression and in DNA binding. Among these mutants were those defective in positive regulation as well as in autorepression, dominant-negative mutants, and a mutant deficient in oligomerization. Importantly, a group of Ler autorepression mutants complemented an EPEC ler deletion mutant for transcription activation in a dosage-dependent manner, suggesting that Ler and possibly other autorepressors have an intrinsic compensatory mechanism that enables them to sustain mutations. In addition, the phenotypes of the different mutants identified by the screen define a novel domain in Ler that is required for oligomerization.

Download Full-text

SdiA Aids Enterohemorrhagic Escherichia coli Carriage by Cattle Fed a Forage or Grain Diet

Infection and Immunity ◽

10.1128/iai.00702-13 ◽

2013 ◽

Vol 81 (9) ◽

pp. 3472-3478 ◽

Cited By ~ 12

Author(s):

Haiqing Sheng ◽

Y. N. Nguyen ◽

Carolyn J. Hovde ◽

Vanessa Sperandio

Keyword(s):

Escherichia Coli ◽

Type Strain ◽

Deletion Mutant ◽

Wild Type Strain ◽

Rumen Fluid ◽

Acid Resistance ◽

Enterohemorrhagic Escherichia Coli ◽

Dependent Manner ◽

Bacterial Survival ◽

Wild Type

ABSTRACTEnterohemorrhagicEscherichia coli(EHEC) causes hemorrhagic colitis and life-threatening complications. The main reservoirs for EHEC are healthy ruminants. We reported that SdiA senses acyl homoserine lactones (AHLs) in the bovine rumen to activate expression of the glutamate acid resistance (gad) genes priming EHEC's acid resistance before they pass into the acidic abomasum. Conversely, SdiA represses expression of the locus of enterocyte effacement (LEE) genes, whose expression is not required for bacterial survival in the rumen but is necessary for efficient colonization at the rectoanal junction (RAJ) mucosa. Our previous studies show that SdiA-dependent regulation was necessary for efficient EHEC colonization of cattle fed a grain diet. Here, we compared the SdiA role in EHEC colonization of cattle fed a forage hay diet. We detected AHLs in the rumen of cattle fed a hay diet, and these AHLs activatedgadgene expression in an SdiA-dependent manner. The rumen fluid and fecal samples from hay-fed cattle were near neutrality, while the same digesta samples from grain-fed animals were acidic. Cattle fed either grain or hay and challenged with EHEC orally carried the bacteria similarly. EHEC was cleared from the rumen within days and from the RAJ mucosa after approximately one month. In competition trials, where animals were challenged with both wild-type and SdiA deletion mutant bacteria, diet did not affect the outcome that the wild-type strain was better able to persist and colonize. However, the wild-type strain had a greater advantage over the SdiA deletion mutant at the RAJ mucosa among cattle fed the grain diet.

Download Full-text

Identification of domains of the v-crk oncogene product sufficient for association with phosphotyrosine-containing proteins

Molecular and Cellular Biology ◽

10.1128/mcb.11.3.1607-1613.1991 ◽

1991 ◽

Vol 11 (3) ◽

pp. 1607-1613

Author(s):

M Matsuda ◽

B J Mayer ◽

H Hanafusa

Keyword(s):

Escherichia Coli ◽

Kinase Activity ◽

Binding Activity ◽

Transformed Cells ◽

Dependent Manner ◽

Tyrosine Kinase Activity ◽

Sh3 Domains ◽

Sh2 Domains ◽

Sarcoma Virus ◽

Avian Sarcoma

The oncogene product of the avian sarcoma virus CT10, P47gag-crk, contains the SH2, SH2', and SH3 domains and binds proteins in a phosphotyrosine (ptyr)-dependent manner. In this study, we have determined the region of P47gag-crk essential for binding to ptyr-containing proteins. Mutant P47gag-crk proteins expressed in Escherichia coli that have the intact SH2 and SH2' regions retained the capacity to bind ptyr-containing proteins obtained from cells transformed by crk and src. The deletion of SH2 resulted in the loss of binding activity. Other mutants that have altered SH2 or SH2' bound few, if any, of the ptyr-containing proteins. Those mutants that bound ptyr-containing proteins associated with tyrosine kinase activity. We also found that polypeptides containing SH2, SH2', and SH3 of p60v-src and p60c-src associated with ptyr-containing proteins from crk-transformed cells. Thus, the SH2 and SH2' domains of P47gag-crk are responsible for their binding to ptyr-containing proteins.

Download Full-text

Essential Oils of Aromatic Plants with Antibacterial, Anti-Biofilm and Anti-Quorum Sensing Activities against Pathogenic Bacteria

Antibiotics ◽

10.3390/antibiotics9040147 ◽

2020 ◽

Vol 9 (4) ◽

pp. 147 ◽

Cited By ~ 5

Author(s):

Marlon Cáceres ◽

William Hidalgo ◽

Elena Stashenko ◽

Rodrigo Torres ◽

Claudia Ortiz

Keyword(s):

Escherichia Coli ◽

Antimicrobial Activity ◽

Quorum Sensing ◽

Essential Oils ◽

Pathogenic Bacteria ◽

Bacterial Resistance ◽

Thymus Vulgaris ◽

Dependent Manner ◽

Concentration Dependent Manner ◽

Biofilm Inhibition

Both the ability of bacteria to form biofilms and communicate through quorum sensing allows them to develop different survival or virulence traits that lead to increased bacterial resistance against conventional antibiotic therapy. Here, seventeen essential oils (EOs) were investigated for the antimicrobial, antibiofilm, and anti-quorum sensing activities on Escherichia. coli O157:H7, Escherichia coli O33, and Staphylococcus epidermidis ATCC 12228. All essential oils were isolated from plant material by using hydrodistillation and analyzed by GC-MS. The antimicrobial activity was performed by using the microdilution technique. Subinhibitory concentrations of each EO were assayed for biofilm inhibition in both bacterial strains. Quantification of violacein in Chromobacterium violaceum CV026 was performed for the anti-quorum sensing activity. The cytotoxicity activity of the EOs was evaluated on Vero cell line by using MTT method. Thymol-carvacrol-chemotype (I and II) oils from Lippia origanoides and Thymus vulgaris oil exhibited the higher antimicrobial activity with MIC values of 0.37–0.75 mg/mL. In addition, these EOs strongly inhibited the biofilm formation and violacein (QS) production in a concentration-dependent manner, highlighting thymol-carvacrol-chemotype (II) oil as the best candidate for further studies in antibiotic design and development against bacterial resistance.

Download Full-text

Intracellular Free Iron and Its Potential Role in Ultrahigh-Pressure-Induced Inactivation of Escherichia coli

Applied and Environmental Microbiology ◽

10.1128/aem.02202-12 ◽

2012 ◽

Vol 79 (2) ◽

pp. 722-724 ◽

Cited By ~ 4

Author(s):

Yuan Yan ◽

Joy G. Waite-Cusic ◽

Periannan Kuppusamy ◽

Ahmed E. Yousef

Keyword(s):

Escherichia Coli ◽

Iron Chelator ◽

Ultrahigh Pressure ◽

Dependent Manner ◽

Paramagnetic Resonance ◽

Free Iron ◽

Content Type ◽

E Coli ◽

Electron Paramagnetic ◽

Dose Dependent

ABSTRACTIntracellular free iron ofEscherichia coliwas determined by whole-cell electron paramagnetic resonance spectrometry. Ultrahigh pressure (UHP) increased both intracellular free iron and cell lethality in a pressure-dose-dependent manner. The iron chelator 2,2′-dipyridyl protected cells against UHP treatments. A mutation that produced iron overload conditions sensitizedE. colito UHP treatment.

Download Full-text

617. Efficacy of Dimercaptosuccinic Acid (DMSA), a Zinc Chelator, in Combination with Imipenem Against Metallo-β-Lactamase Producing Escherichia coli in a Murine Peritonitis Model

Open Forum Infectious Diseases ◽

10.1093/ofid/ofz360.685 ◽

2019 ◽

Vol 6 (Supplement_2) ◽

pp. S287-S287

Author(s):

Geoffrey Cheminet ◽

Patrice Nordmann ◽

Francoise Chau ◽

Nicolas Kieffer ◽

Katell Peoc’h ◽

...

Keyword(s):

Escherichia Coli ◽

Maximum Effect ◽

Dependent Manner ◽

Bacterial Strains ◽

Concentration Dependent Manner ◽

Bacterial Counts ◽

E Coli ◽

Zinc Chelator ◽

Peritonitis Model

Abstract Background A strategy used by bacterial strains to resist β-lactam antibiotics is the expression of metallo-β-lactamases (MBL) requiring zinc for activity. The use of a zinc chelator may restore carbapenem activity against MBL-producing Enterobacteriaceae. DMSA is a heavy metal chelator approved in humans with a satisfactory safety record. Our objective was to evaluate the activity of DMSA in combination with carbapenems, in vitro and in a fatal murine peritonitis model, against MBL-producing Escherichia coli. Methods Isogenic derivatives of wild-type E. coli CFT073 producing the MBL NDM-1, VIM-2, IMP-1, and the serine carbapenemases OXA-48 and KPC-3 were constructed. Minimum inhibitory concentrations (MICs) of imipenem, meropenem, and ertapenem were determined against each strain alone or in combination with DMSA. Mice were infected with E. coli CFT073 or NDM-1 and treated intraperitoneally for 24 hours with imipenem 100 mg/kg every 4 hours, DMSA 200 mg/kg every 4 hours, or both. Mice survival rates and bacterial counts in peritoneal fluid (PF) and spleen were assessed at 24 hours. Results In vitro, DMSA in combination with each carbapenem permitted a significant decrease of the MICs against all MBL-producing strains, in a concentration-dependent manner. The maximum effect was found for the NDM-1 strain with a 6- to 8-fold MIC reduction, depending on the carbapenem used. NDM-1 strain became susceptible to carbapenems with concentrations of DMSA ≥6 mM. Increasing zinc concentrations above 1 mg/L (average human plasma concentration) did not alter this effect. No benefit of DMSA was observed against non-MBL strains. In vivo, when used alone, the DMSA regimen was not toxic in uninfected mice and ineffective against NDM-1-infected mice (100% mortality). Combination of imipenem and DMSA significantly reduced bacterial counts in PF and spleen as compared with imipenem alone (P < 0.001), and reduced mortality, although not significantly (11% vs. 37%, respectively, P = 0.12). No benefit of the combination was observed against CFT073. Conclusion DMSA is highly effective in vitro in reducing carbapenems MICs against MBL-producing E. coli and appears as a promising strategy in combination with carbapenems for the treatment of NDM-1-related infections. Disclosures All authors: No reported disclosures.

Download Full-text