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  • American Society for Microbiology  (47)
  • 1
    Online Resource
    Online Resource
    Cellular and Structural Basis of Synthesis of the Unique Intermediate Dehydro-F 420 -0 in Mycobacteria
    American Society for Microbiology ; 2020
    In:  mSystems Vol. 5, No. 3 ( 2020-06-30)
    Details
    In: mSystems, American Society for Microbiology, Vol. 5, No. 3 ( 2020-06-30)
    Abstract: F 420 is a low-potential redox cofactor used by diverse bacteria and archaea. In mycobacteria, this cofactor has multiple roles, including adaptation to redox stress, cell wall biosynthesis, and activation of the clinical antitubercular prodrugs pretomanid and delamanid. A recent biochemical study proposed a revised biosynthesis pathway for F 420 in mycobacteria; it was suggested that phosphoenolpyruvate served as a metabolic precursor for this pathway, rather than 2-phospholactate as long proposed, but these findings were subsequently challenged. In this work, we combined metabolomic, genetic, and structural analyses to resolve these discrepancies and determine the basis of F 420 biosynthesis in mycobacterial cells. We show that, in whole cells of Mycobacterium smegmatis , phosphoenolpyruvate rather than 2-phospholactate stimulates F 420 biosynthesis. Analysis of F 420 biosynthesis intermediates present in M. smegmatis cells harboring genetic deletions at each step of the biosynthetic pathway confirmed that phosphoenolpyruvate is then used to produce the novel precursor compound dehydro-F 420 -0. To determine the structural basis of dehydro-F 420 -0 production, we solved high-resolution crystal structures of the enzyme responsible (FbiA) in apo-, substrate-, and product-bound forms. These data show the essential role of a single divalent cation in coordinating the catalytic precomplex of this enzyme and demonstrate that dehydro-F 420 -0 synthesis occurs through a direct substrate transfer mechanism. Together, these findings resolve the biosynthetic pathway of F 420 in mycobacteria and have significant implications for understanding the emergence of antitubercular prodrug resistance. IMPORTANCE Mycobacteria are major environmental microorganisms and cause many significant diseases, including tuberculosis. Mycobacteria make an unusual vitamin-like compound, F 420 , and use it to both persist during stress and resist antibiotic treatment. Understanding how mycobacteria make F 420 is important, as this process can be targeted to create new drugs to combat infections like tuberculosis. In this study, we show that mycobacteria make F 420 in a way that is different from other bacteria. We studied the molecular machinery that mycobacteria use to make F 420 , determining the chemical mechanism for this process and identifying a novel chemical intermediate. These findings also have clinical relevance, given that two new prodrugs for tuberculosis treatment are activated by F 420 .
    Type of Medium: Online Resource
    ISSN: 2379-5077
    URL: Article
    DOI: 10.1128/mSystems.00389-20
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2020
    detail.hit.zdb_id: 2844333-0
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  • 2
    Online Resource
    Online Resource
    Cellular Immune Responses against Simian T-Lymphotropic Virus Type 1 Target Tax in Infected Baboons
    American Society for Microbiology ; 2016
    In:  Journal of Virology Vol. 90, No. 11 ( 2016-06), p. 5280-5291
    Details
    In: Journal of Virology, American Society for Microbiology, Vol. 90, No. 11 ( 2016-06), p. 5280-5291
    Abstract: There are currently 5 million to 10 million human T-lymphotropic virus type 1 (HTLV-1)-infected people, and many of them will develop severe complications resulting from this infection. A vaccine is urgently needed in areas where HTLV-1 is endemic. Many vaccines are best tested in nonhuman primate animal models. As a first step in designing an effective HTLV-1 vaccine, we defined the CD8 + and CD4 + T cell response against simian T-lymphotropic virus type 1 (STLV-1), a virus closely related to HTLV-1, in olive baboons ( Papio anubis ). Consistent with persistent antigenic exposure, we observed that STLV-1-specific CD8 + T cells displayed an effector memory phenotype and usually expressed CD107a, gamma interferon (IFN-γ), and tumor necrosis factor alpha (TNF-α). To assess the viral targets of the cellular immune response in STLV-1-infected animals, we used intracellular cytokine staining to detect responses against overlapping peptides covering the entire STLV-1 proteome. Our results show that, similarly to humans, the baboon CD8 + T cell response narrowly targeted the Tax protein. Our findings suggest that the STLV-1-infected baboon model may recapitulate some of the important aspects of the human response against HTLV-1 and could be an important tool for the development of immune-based therapy and prophylaxis. IMPORTANCE HTLV-1 infection can lead to many different and often fatal conditions. A vaccine deployed in areas of high prevalence might reduce the incidence of HTLV-1-induced disease. Unfortunately, there are very few animal models of HTLV-1 infection useful for testing vaccine approaches. Here we describe cellular immune responses in baboons against a closely related virus, STLV-1. We show for the first time that the immune response against STLV-1 in naturally infected baboons is largely directed against the Tax protein. Similar findings in humans and the sequence similarity between the human and baboon viruses suggest that the STLV-1-infected baboon model might be useful for developing a vaccine against HTLV-1.
    Type of Medium: Online Resource
    ISSN: 0022-538X , 1098-5514
    URL: Article
    DOI: 10.1128/JVI.00281-16
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2016
    detail.hit.zdb_id: 1495529-5
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  • 3
    Online Resource
    Online Resource
    Molecular cloning of a highly repeated DNA element from Mycobacterium tuberculosis and its use as an epidemiological tool
    American Society for Microbiology ; 1992
    In:  Journal of Clinical Microbiology Vol. 30, No. 4 ( 1992-04), p. 942-946
    Details
    In: Journal of Clinical Microbiology, American Society for Microbiology, Vol. 30, No. 4 ( 1992-04), p. 942-946
    Abstract: In order to develop a technique for distinguishing between isolates of Mycobacterium tuberculosis, we cloned two hypervariable DNA fragments from NdeII-digested genomic DNA. The cloned DNA fragments of 3.8 and 4.7 kb were found to contain the same repetitive element, which was different from previously characterized repetitive elements. It is present in at least 30 copies per genome and is distributed among mycobacterial species other than those of the tuberculosis complex, including M. kansaii, M. gastri, and M. szulgai. When used as a probe on restriction enzyme-digested DNA, it can distinguish between strains from unrelated cases of tuberculosis while demonstrating identical banding patterns for isolates from epidemiologically related cases.
    Type of Medium: Online Resource
    ISSN: 0095-1137 , 1098-660X
    URL: Article
    DOI: 10.1128/jcm.30.4.942-946.1992
    RVK:
    XA 10000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 1992
    detail.hit.zdb_id: 1498353-9
    SSG: 12
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  • 4
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    Online Resource
    DNA binding and bending are necessary but not sufficient for Fis-dependent activation of rrnB P1
    American Society for Microbiology ; 1993
    In:  Journal of Bacteriology Vol. 175, No. 6 ( 1993-03), p. 1580-1589
    Details
    In: Journal of Bacteriology, American Society for Microbiology, Vol. 175, No. 6 ( 1993-03), p. 1580-1589
    Abstract: The Escherichia coli Fis protein binds to three sites in the upstream activation region of the rrnB P1 promoter and enhances transcription 5- to 10-fold in vivo. In this report, we investigate the mechanism of Fis-dependent activation of transcription. We show that stimulation of rrnB P1 transcription by Fis can occur on linear DNA templates and does not require DNA upstream of the promoter-proximal Fis site I. Mutants of Fis defective for Hin-mediated recombination have been isolated previously and have defined an N-terminal domain required for DNA inversion by Hin in addition to the C-terminal domain which is required for DNA binding. Several of these mutants were found to be defective in stimulation of rrnB P1 transcription in vivo and in vitro. Activation-defective mutants fall into three classes: those that fail to bind to the upstream activation region, those that bind but fail to bend the DNA normally, and those that bind and bend but still fail to activate transcription. We conclude that it is unlikely that Fis functions by simply bringing upstream sequences or bound factors into the proximity of RNA polymerase to activate transcription. Rather, the data are most easily interpreted in terms of transcription activation by direct interactions between Fis and RNA polymerase, requiring precise positioning of the two proteins facilitated by bending of the DNA binding site.
    Type of Medium: Online Resource
    ISSN: 0021-9193 , 1098-5530
    URL: Article
    DOI: 10.1128/jb.175.6.1580-1589.1993
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 1993
    detail.hit.zdb_id: 1481988-0
    SSG: 12
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  • 5
    Online Resource
    Online Resource
    Determination of Disk Diffusion and MIC Quality Control Guidelines for GSK2140944, a Novel Bacterial Type II Topoisomerase Inhibitor Antimicrobial Agent
    American Society for Microbiology ; 2014
    In:  Journal of Clinical Microbiology Vol. 52, No. 7 ( 2014-07), p. 2629-2632
    Details
    In: Journal of Clinical Microbiology, American Society for Microbiology, Vol. 52, No. 7 ( 2014-07), p. 2629-2632
    Abstract: GSK2140944 is a novel bacterial type II topoisomerase inhibitor in development for the treatment of conventional and biothreat pathogens, including Gram-positive pathogens and methicillin-resistant Staphylococcus aureus . This quality control study was performed to establish ranges for selected control strains: S. aureus ATCC 29213 and ATCC 25923, Escherichia coli ATCC 25922, Haemophilus influenzae ATCC 49247, and Streptococcus pneumoniae ATCC 49619. The control ranges will be crucial for the accurate evaluation of GSK2140944 potency as it progresses through clinical trial development.
    Type of Medium: Online Resource
    ISSN: 0095-1137 , 1098-660X
    URL: Article
    DOI: 10.1128/JCM.00656-14
    RVK:
    XA 10000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2014
    detail.hit.zdb_id: 1498353-9
    SSG: 12
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  • 6
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    Significant Shift in Median Guinea Pig Infectious Dose Shown by an Outbreak-Associated Listeria monocytogenes Epidemic Clone Strain and a Strain Carrying a Premature Stop Codon Mutation in inlA
    American Society for Microbiology ; 2011
    In:  Applied and Environmental Microbiology Vol. 77, No. 7 ( 2011-04), p. 2479-2487
    Details
    In: Applied and Environmental Microbiology, American Society for Microbiology, Vol. 77, No. 7 ( 2011-04), p. 2479-2487
    Abstract: Listeria monocytogenes contains (i) epidemic clone (EC) strains, which have been linked to the majority of listeriosis outbreaks worldwide and are overrepresented among sporadic cases in the United States, and (ii) strains commonly isolated from ready-to-eat foods that carry a mutation leading to a premature stop codon (PMSC) in inlA , which encodes the key virulence factor internalin A (InlA). Internalin A binds certain isoforms of the cellular receptor E-cadherin to facilitate crossing the intestinal barrier during the initial stages of an L. monocytogenes infection. Juvenile guinea pigs, which express the human isoform of E-cadherin that binds InlA, were intragastrically challenged with a range of doses of (i) an EC strain associated with a listeriosis outbreak or (ii) a strain carrying a PMSC mutation in inlA . Recovery of L. monocytogenes from tissues (i.e., liver, spleen, mesenteric lymph nodes, and ileum) was used to develop strain-specific dose-response curves on the basis of individual and combined organ data. Modeling of individual and combined organ data revealed an approximate 1.2 to 1.3 log 10 increase in the median infectious dose for the strain carrying a PMSC in inlA relative to that for the EC strain. Inclusion of the strain parameter significantly improved the goodness of fit for individual and combined organ models, indicating a significant shift in median infectious dose for guinea pigs challenged with an inlA PMSC strain compared to that for guinea pigs challenged with an EC strain. Results from this work provide evidence that the L. monocytogenes dose-response relationship is strain specific and will provide critical data for enhancement of current risk assessments and development of future risk assessments.
    Type of Medium: Online Resource
    ISSN: 0099-2240 , 1098-5336
    URL: Article
    DOI: 10.1128/AEM.02626-10
    RVK:
    WA 15000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2011
    detail.hit.zdb_id: 223011-2
    detail.hit.zdb_id: 1478346-0
    SSG: 12
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  • 7
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    Characterization of Mycobacterium tuberculosis strains from Vietnamese patients by Southern blot hybridization
    American Society for Microbiology ; 1993
    In:  Journal of Clinical Microbiology Vol. 31, No. 6 ( 1993-06), p. 1615-1618
    Details
    In: Journal of Clinical Microbiology, American Society for Microbiology, Vol. 31, No. 6 ( 1993-06), p. 1615-1618
    Abstract: A total of 41 Mycobacterium tuberculosis strains from patients of Vietnamese origin were analyzed by Southern blot hybridization with two different probes, IS6110 (Otal, I., et al., J. Clin. Microbiol. 29:1252-1254, 1991; Ross, B. C., et al., J. Clin. Microbiol. 30:942-946, 1992; Thierry, D., et al., J. Clin. Microbiol. 28:2668-2673, 1990; van Soolingen, D., et al., J. Clin. Microbiol. 29:2578-2586, 1991) and pTBN12 (Ross, B. C., et al., J. Clin. Microbiol. 30:942-946, 1992). The restriction fragment patterns of nine of these strains were virtually identical when the pTBN12 probe was used; five strains had a single copy of IS6110, and four strains failed to hybridize with the IS6110 probe. This relatively high frequency of strains with no or one copy of IS6110 suggests that the usefulness of IS6110 for epidemiological study may be limited in certain populations.
    Type of Medium: Online Resource
    ISSN: 0095-1137 , 1098-660X
    URL: Article
    DOI: 10.1128/jcm.31.6.1615-1618.1993
    RVK:
    XA 10000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 1993
    detail.hit.zdb_id: 1498353-9
    SSG: 12
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  • 8
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    Online Resource
    Calprotectin Expression In Vitro by Oral Epithelial Cells Confers Resistance to Infection by Porphyromonas gingivalis
    American Society for Microbiology ; 2001
    In:  Infection and Immunity Vol. 69, No. 7 ( 2001-07), p. 4242-4247
    Details
    In: Infection and Immunity, American Society for Microbiology, Vol. 69, No. 7 ( 2001-07), p. 4242-4247
    Abstract: Calprotectin, an S100 calcium-binding protein with broad-spectrum antimicrobial activity in vitro, is expressed in neutrophils, monocytes, and gingival keratinocytes. In periodontitis, calprotectin appears upregulated and is detected at higher levels in gingival crevicular fluid and tissue specimens. How calprotectin contributes to the pathogenesis of periodontal diseases is unknown. To isolate the effects of calprotectin, a calprotectin-negative oral epithelial cell line was transfected with calprotectin genes to enable expression. Porphyromonas gingivalis was permitted to bind and invade transfected cells expressing calprotectin and sham transfectants. Rates of invasion into both cell lines were compared using the antibiotic protection assay. Transfected cells expressing calprotectin showed 40 to 50% fewer internalized P. gingivalis than sham transfectants. Similarly, binding to calprotectin expressing cells was reduced approximately twofold at all time points (15, 30, 45, and 60 min) as estimated by immunofluorescence analysis. Independent of invasion, however, prolonged exposure to P. gingivalis induced epithelial cell rounding and detachment from the substratum. These morphological changes were delayed, however, in cells expressing calprotectin. Using P. gingivalis protease-deficient mutants, we found that Arg-gingipain and Lys-gingipain contributed to epithelial cell rounding and detachment. In conclusion, expression of calprotectin appears to protect epithelial cells in culture against binding and invasion by P. gingivalis . In addition, cells expressing calprotectin are more resistant to detachment mediated by Arg-gingipain and Lys-gingipain. In periodontal disease, calprotectin may augment both the barrier protection and innate immune functions of the gingival epithelium to promote resistance to P. gingivalis infection.
    Type of Medium: Online Resource
    ISSN: 0019-9567 , 1098-5522
    URL: Article
    DOI: 10.1128/IAI.69.7.4242-4247.2001
    RVK:
    XA 10000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2001
    detail.hit.zdb_id: 1483247-1
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  • 9
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    Biological Effects of Short-Term or Prolonged Administration of 9-[2-(Phosphonomethoxy)Propyl]Adenine (Tenofovir) to Newborn and Infant Rhesus Macaques
    American Society for Microbiology ; 2004
    In:  Antimicrobial Agents and Chemotherapy Vol. 48, No. 6 ( 2004-06), p. 2346-2346
    Details
    In: Antimicrobial Agents and Chemotherapy, American Society for Microbiology, Vol. 48, No. 6 ( 2004-06), p. 2346-2346
    Type of Medium: Online Resource
    ISSN: 0066-4804 , 1098-6596
    URL: Article
    DOI: 10.1128/AAC.48.6.2346.2004
    RVK:
    XA 24552
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2004
    detail.hit.zdb_id: 1496156-8
    SSG: 12
    SSG: 15,3
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  • 10
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    Biological Effects of Short-Term or Prolonged Administration of 9-[2-(Phosphonomethoxy)Propyl]Adenine (Tenofovir) to Newborn and Infant Rhesus Macaques
    American Society for Microbiology ; 2004
    In:  Antimicrobial Agents and Chemotherapy Vol. 48, No. 5 ( 2004-05), p. 1469-1487
    Details
    In: Antimicrobial Agents and Chemotherapy, American Society for Microbiology, Vol. 48, No. 5 ( 2004-05), p. 1469-1487
    Abstract: The reverse transcriptase inhibitor 9-[2-(phosphonomethoxy)propyl]adenine (PMPA; tenofovir) was previously found to offer strong prophylactic and therapeutic benefits in an infant macaque model of pediatric human immunodeficiency virus (HIV) infection. We now summarize the toxicity and safety of PMPA in these studies. When a range of PMPA doses (4 to 30 mg/kg of body weight administered subcutaneously once daily) was administered to 39 infant macaques for a short period of time (range, 1 day to 12 weeks), no adverse effects on their health or growth were observed; this included a subset of 12 animals which were monitored for more than 2 years. In contrast, daily administration of a high dose of PMPA (30 mg/kg subcutaneously) for prolonged periods of time ( 〉 8 to 21 months) to 13 animals resulted in a Fanconi-like syndrome (proximal renal tubular disorder) with glucosuria, aminoaciduria, hypophosphatemia, growth restriction, bone pathology (osteomalacia), and reduced clearance of PMPA. The adverse effects were reversible or were alleviated following either complete withdrawal of PMPA treatment or reduction of the daily regimen from 30 mg/kg to 2.5 to 10 mg/kg subcutaneously. Finally, to evaluate the safety of a prolonged low-dose treatment regimen, two newborn macaques were started on a 10-mg/kg/day subcutaneous regimen; these animals are healthy and have normal bone density and growth after 5 years of daily treatment. In conclusion, our findings suggest that chronic daily administration of a high dose of PMPA results in adverse effects on kidney and bone, while short-term administration of relatively high doses and prolonged low-dose administration are safe.
    Type of Medium: Online Resource
    ISSN: 0066-4804 , 1098-6596
    URL: Article
    DOI: 10.1128/AAC.48.5.1469-1487.2004
    RVK:
    XA 24552
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2004
    detail.hit.zdb_id: 1496156-8
    SSG: 12
    SSG: 15,3
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