GLORIA

GEOMAR Library Ocean Research Information Access

X

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • American Society for Microbiology  (5)
  • 1
    Online Resource
    Online Resource
    Examination of Enterococcus faecalis Toxin-Antitoxin System Toxin Fst Function Utilizing a Pheromone-Inducible Expression Vector with Tight Repression and Broad Dynamic Range
    American Society for Microbiology ; 2017
    In:  Journal of Bacteriology Vol. 199, No. 12 ( 2017-06-15)
    Details
    In: Journal of Bacteriology, American Society for Microbiology, Vol. 199, No. 12 ( 2017-06-15)
    Abstract: Tools for regulated gene expression in Enterococcus faecalis are extremely limited. In this report, we describe the construction of an expression vector for E. faecalis , designated pCIE, utilizing the P Q pheromone-responsive promoter of plasmid pCF10. We demonstrate that this promoter is tightly repressed, responds to nanogram quantities of the peptide pheromone, and has a large dynamic range. To demonstrate its utility, the promoter was used to control expression of the toxic peptides of two par family toxin-antitoxin (TA) loci present in E. faecalis , par pAD1 of the pAD1 plasmid and par EF0409 located on the E. faecalis chromosome. The results demonstrated differences in the modes of regulation of toxin expression and in the effects of toxins of these two related systems. We anticipate that this vector will be useful for further investigation of par TA system function as well as the regulated expression of other genes in E. faecalis . IMPORTANCE E. faecalis is an important nosocomial pathogen and a model organism for examination of the genetics and physiology of Gram-positive cocci. While numerous genetic tools have been generated for the manipulation of this organism, vectors for the regulated expression of cloned genes remain limited by high background expression and the use of inducers with undesirable effects on the cell. Here we demonstrate that the P Q pheromone-responsive promoter is repressed tightly enough to allow cloning of TA system toxins and evaluate their effects at very low induction levels. This tool will allow us to more fully examine TA system function in E. faecalis and to further elucidate its potential roles in cell physiology.
    Type of Medium: Online Resource
    ISSN: 0021-9193 , 1098-5530
    URL: Article
    DOI: 10.1128/JB.00065-17
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2017
    detail.hit.zdb_id: 1481988-0
    SSG: 12
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 2
    Online Resource
    Online Resource
    Direct Evidence for Control of the Pheromone-Inducible prgQ Operon of Enterococcus faecalis Plasmid pCF10 by a Countertranscript-Driven Attenuation Mechanism
    American Society for Microbiology ; 2010
    In:  Journal of Bacteriology Vol. 192, No. 6 ( 2010-03-15), p. 1634-1642
    Details
    In: Journal of Bacteriology, American Society for Microbiology, Vol. 192, No. 6 ( 2010-03-15), p. 1634-1642
    Abstract: The mating response of Enterococcus faecalis cells carrying the conjugative plasmid pCF10 is controlled by multiple regulatory circuits. Initiation of transcription of the prgQ conjugation operon is controlled by the peptide receptor protein PrgX; binding of the pheromone peptide cCF10 to PrgX abolishes PrgX repression, while binding of the inhibitor peptide iCF10 enhances repression. The results of molecular analysis of prgQ transcripts and genetic studies suggested that the elongation of prgQ transcripts past a putative terminator (IRS1) may be controlled by the interaction of nascent prgQ mRNAs with a small antisense RNA (Anti-Q) encoded within prgQ . Direct evidence for interaction of these RNAs, as well as the resulting effects on readthrough of prgQ transcription, has been limited. Here we report the results of experiments that (i) determine the inherent termination properties of prgQ transcripts in the absence of Anti-Q; (ii) determine the direct effects of the interaction of Anti-Q with nascent prgQ transcripts in the absence of complicating effects of the PrgX protein; and (iii) begin to dissect the structural components involved in these interactions. The results confirm the existence of alternative terminating and antiterminating forms of nascent prgQ transcripts in vivo and demonstrate that the interaction of Anti-Q with these transcripts leads to termination via inhibition of antiterminator formation. In vitro transcription assays support the major results of the in vivo studies. The data support a model for Anti-Q function suggested from recent studies of these RNAs and their interactions in vitro (S. Shokeen, C. M. Johnson, T. J. Greenfield, D. A. Manias, G. M. Dunny, and K. E. Weaver, submitted for publication).
    Type of Medium: Online Resource
    ISSN: 0021-9193 , 1098-5530
    URL: Article
    DOI: 10.1128/JB.01525-09
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2010
    detail.hit.zdb_id: 1481988-0
    SSG: 12
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 3
    Online Resource
    Online Resource
    Control of Recombination Directionality by the Listeria Phage A118 Protein Gp44 and the Coiled-Coil Motif of Its Serine Integrase
    American Society for Microbiology ; 2017
    In:  Journal of Bacteriology Vol. 199, No. 11 ( 2017-06)
    Details
    In: Journal of Bacteriology, American Society for Microbiology, Vol. 199, No. 11 ( 2017-06)
    Abstract: The serine integrase of phage A118 catalyzes integrative recombination between attP on the phage and a specific attB locus on the chromosome of Listeria monocytogenes , but it is unable to promote excisive recombination between the hybrid attL and attR sites found on the integrated prophage without assistance by a recombination directionality factor (RDF). We have identified and characterized the phage-encoded RDF Gp44, which activates the A118 integrase for excision and inhibits integration. Gp44 binds to the C-terminal DNA binding domain of integrase, and we have localized the primary binding site to be within the mobile coiled-coil (CC) motif but distinct from the distal tip of the CC that is required for recombination. This interaction is sufficient to inhibit integration, but a second interaction involving the N-terminal end of Gp44 is also required to activate excision. We provide evidence that these two contacts modulate the trajectory of the CC motifs as they extend out from the integrase core in a manner dependent upon the identities of the four att sites. Our results support a model whereby Gp44 shapes the Int-bound complexes to control which att sites can synapse and recombine. IMPORTANCE Serine integrases mediate directional recombination between bacteriophage and bacterial chromosomes. These highly regulated site-specific recombination reactions are integral to the life cycle of temperate phage and, in the case of Listeria monocytogenes lysogenized by A118 family phage, are an essential virulence determinant. Serine integrases are also utilized as tools for genetic engineering and synthetic biology because of their exquisite unidirectional control of the DNA exchange reaction. Here, we identify and characterize the recombination directionality factor (RDF) that activates excision and inhibits integration reactions by the phage A118 integrase. We provide evidence that the A118 RDF binds to and modulates the trajectory of the long coiled-coil motif that extends from the large carboxyl-terminal DNA binding domain and is postulated to control the early steps of recombination site synapsis.
    Type of Medium: Online Resource
    ISSN: 0021-9193 , 1098-5530
    URL: Article
    DOI: 10.1128/JB.00019-17
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2017
    detail.hit.zdb_id: 1481988-0
    SSG: 12
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 4
    Online Resource
    Online Resource
    Race/Ethnicity and Protease Inhibitor Use Influence Plasma Tenofovir Exposure in Adults Living with HIV-1 in AIDS Clinical Trials Group Study A5202
    American Society for Microbiology ; 2019
    In:  Antimicrobial Agents and Chemotherapy Vol. 63, No. 4 ( 2019-04)
    Details
    In: Antimicrobial Agents and Chemotherapy, American Society for Microbiology, Vol. 63, No. 4 ( 2019-04)
    Abstract: AIDS Clinical Trial Group study A5202 (ClinicalTrials.gov identifier NCT00118898) was a phase 3b, randomized, partially blinded equivalence study of open-label atazanavir/ritonavir or efavirenz, plus either placebo-controlled tenofovir disoproxil fumarate/emtricitabine or abacavir/lamivudine, in treatment-naive adults living with HIV-1, evaluating efficacy, safety, and tolerability. We report an analysis of the contribution of participant characteristics to the disposition of tenofovir plasma concentrations. Tenofovir concentration data from a total of 817 individuals (88% of the total number of eligible patients randomly assigned to receive treatment in the TDF-containing arms of A5202) were available for analysis. Pharmacokinetic analysis was performed using nonlinear mixed-effects modeling. One- and two-compartment models with first-order absorption and first-order elimination were evaluated. An exponential error model was used for examination of interindividual variability (IIV), and a proportional and mixed-error model was assessed for residual variability. The final structural model contained two compartments with first-order absorption and elimination. IIV was estimated for apparent clearance (CL/F) and the first-order absorption rate constant ( k a ), and a proportional residual variability model was selected. The final mean parameter estimates were as follows: k a = 2.87 h −1 , CL/F = 37.2 liters/h, apparent volumes of the central and peripheral compartments = 127 and 646 liters, respectively, and apparent intercompartmental clearance = 107 liters/h. In addition to race/ethnicity, creatinine clearance and assignment to atazanavir/ritonavir or efavirenz were significantly associated with CL/F ( P 〈 0.001). In conclusion, race/ethnicity is associated with tenofovir oral CL in HIV-1 positive, treatment-naive adults. This covariate relationship raises questions about the possibility of differences in efficacy and risk of adverse events in different patient populations and suggests that examining preexposure prophylaxis regimens and tenofovir exposure in different race/ethnicity groups be considered.
    Type of Medium: Online Resource
    ISSN: 0066-4804 , 1098-6596
    URL: Article
    DOI: 10.1128/AAC.01638-18
    RVK:
    XA 24552
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2019
    detail.hit.zdb_id: 1496156-8
    SSG: 12
    SSG: 15,3
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 5
    Online Resource
    Online Resource
    Evaluation of Immunogenicity and Efficacy of Anthrax Vaccine Adsorbed for Postexposure Prophylaxis
    American Society for Microbiology ; 2013
    In:  Clinical and Vaccine Immunology Vol. 20, No. 7 ( 2013-07), p. 1016-1026
    Details
    In: Clinical and Vaccine Immunology, American Society for Microbiology, Vol. 20, No. 7 ( 2013-07), p. 1016-1026
    Abstract: Antimicrobials administered postexposure can reduce the incidence or progression of anthrax disease, but they do not protect against the disease resulting from the germination of spores that may remain in the body after cessation of the antimicrobial regimen. Such additional protection may be achieved by postexposure vaccination; however, no anthrax vaccine is licensed for postexposure prophylaxis (PEP). In a rabbit PEP study, animals were subjected to lethal challenge with aerosolized Bacillus anthracis spores and then were treated with levofloxacin with or without concomitant intramuscular (i.m.) vaccination with anthrax vaccine adsorbed (AVA) (BioThrax; Emergent BioDefense Operations Lansing LLC, Lansing, MI), administered twice, 1 week apart. A significant increase in survival rates was observed among vaccinated animals compared to those treated with antibiotic alone. In preexposure prophylaxis studies in rabbits and nonhuman primates (NHPs), animals received two i.m. vaccinations 1 month apart and were challenged with aerosolized anthrax spores at day 70. Prechallenge toxin-neutralizing antibody (TNA) titers correlated with animal survival postchallenge and provided the means for deriving an antibody titer associated with a specific probability of survival in animals. In a clinical immunogenicity study, 82% of the subjects met or exceeded the prechallenge TNA value that was associated with a 70% probability of survival in rabbits and 88% probability of survival in NHPs, which was estimated based on the results of animal preexposure prophylaxis studies. The animal data provide initial information on protective antibody levels for anthrax, as well as support previous findings regarding the ability of AVA to provide added protection to B. anthracis -infected animals compared to antimicrobial treatment alone.
    Type of Medium: Online Resource
    ISSN: 1556-6811 , 1556-679X
    URL: Article
    DOI: 10.1128/CVI.00099-13
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2013
    detail.hit.zdb_id: 1496863-0
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...