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  • 1
    Online Resource
    Online Resource
    On the Enigma of Glutathione-Dependent Styrene Degradation in Gordonia rubripertincta CWB2
    American Society for Microbiology ; 2018
    In:  Applied and Environmental Microbiology Vol. 84, No. 9 ( 2018-05)
    Details
    In: Applied and Environmental Microbiology, American Society for Microbiology, Vol. 84, No. 9 ( 2018-05)
    Abstract: Among bacteria, only a single styrene-specific degradation pathway has been reported so far. It comprises the activity of styrene monooxygenase, styrene oxide isomerase, and phenylacetaldehyde dehydrogenase, yielding phenylacetic acid as the central metabolite. The alternative route comprises ring-hydroxylating enzymes and yields vinyl catechol as central metabolite, which undergoes meta -cleavage. This was reported to be unspecific and also allows the degradation of benzene derivatives. However, some bacteria had been described to degrade styrene but do not employ one of those routes or only parts of them. Here, we describe a novel “hybrid” degradation pathway for styrene located on a plasmid of foreign origin. As putatively also unspecific, it allows metabolizing chemically analogous compounds (e.g., halogenated and/or alkylated styrene derivatives). Gordonia rubripertincta CWB2 was isolated with styrene as the sole source of carbon and energy. It employs an assembled route of the styrene side-chain degradation and isoprene degradation pathways that also funnels into phenylacetic acid as the central metabolite. Metabolites, enzyme activity, genome, transcriptome, and proteome data reinforce this observation and allow us to understand this biotechnologically relevant pathway, which can be used for the production of ibuprofen. IMPORTANCE The degradation of xenobiotics by bacteria is not only important for bioremediation but also because the involved enzymes are potential catalysts in biotechnological applications. This study reveals a novel degradation pathway for the hazardous organic compound styrene in Gordonia rubripertincta CWB2. This study provides an impressive illustration of horizontal gene transfer, which enables novel metabolic capabilities. This study presents glutathione-dependent styrene metabolization in an (actino-)bacterium. Further, the genomic background of the ability of strain CWB2 to produce ibuprofen is demonstrated.
    Type of Medium: Online Resource
    ISSN: 0099-2240 , 1098-5336
    URL: Article
    DOI: 10.1128/AEM.00154-18
    RVK:
    WA 15000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2018
    detail.hit.zdb_id: 223011-2
    detail.hit.zdb_id: 1478346-0
    SSG: 12
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  • 2
    Online Resource
    Online Resource
    Bacteria Associated with Spores of the Arbuscular Mycorrhizal Fungi Glomus geosporum and Glomus constrictum
    American Society for Microbiology ; 2005
    In:  Applied and Environmental Microbiology Vol. 71, No. 11 ( 2005-11), p. 6673-6679
    Details
    In: Applied and Environmental Microbiology, American Society for Microbiology, Vol. 71, No. 11 ( 2005-11), p. 6673-6679
    Abstract: Spores of the arbuscular mycorrhizal fungi (AMF) Glomus geosporum and Glomus constrictum were harvested from single-spore-derived pot cultures with either Plantago lanceolata or Hieracium pilosella as host plants. PCR-denaturing gradient gel electrophoresis analysis revealed that the bacterial communities associated with the spores depended more on AMF than host plant identity. The composition of the bacterial populations linked to the spores could be predominantly influenced by a specific spore wall composition or AMF exudate rather than by specific root exudates. The majority of the bacterial sequences that were common to both G. geosporum and G. constrictum spores were affiliated with taxonomic groups known to degrade biopolymers ( Cellvibrio , Chondromyces , Flexibacter , Lysobacter , and Pseudomonas ). Scanning electron microscopy of G. geosporum spores revealed that these bacteria are possibly feeding on the outer hyaline spore layer. The process of maturation and eventual germination of AMF spores might then benefit from the activity of the surface microorganisms degrading the outer hyaline wall layer.
    Type of Medium: Online Resource
    ISSN: 0099-2240 , 1098-5336
    URL: Article
    DOI: 10.1128/AEM.71.11.6673-6679.2005
    RVK:
    WA 15000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2005
    detail.hit.zdb_id: 223011-2
    detail.hit.zdb_id: 1478346-0
    SSG: 12
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  • 3
    Online Resource
    Online Resource
    Dissecting Colistin Resistance Mechanisms in Extensively Drug-Resistant Acinetobacter baumannii Clinical Isolates
    American Society for Microbiology ; 2019
    In:  mBio Vol. 10, No. 4 ( 2019-08-27)
    Details
    In: mBio, American Society for Microbiology, Vol. 10, No. 4 ( 2019-08-27)
    Abstract: Nosocomial infections with Acinetobacter baumannii are a global problem in intensive care units with high mortality rates. Increasing resistance to first- and second-line antibiotics has forced the use of colistin as last-resort treatment, and increasing development of colistin resistance in A. baumannii has been reported. We evaluated the transcriptional regulator PmrA as potential drug target to restore colistin efficacy in A. baumannii . Deletion of pmrA restored colistin susceptibility in 10 of the 12 extensively drug-resistant A. baumannii clinical isolates studied, indicating the importance of PmrA in the drug resistance phenotype. However, two strains remained highly resistant, indicating that PmrA-mediated overexpression of the phosphoethanolamine (PetN) transferase PmrC is not the exclusive colistin resistance mechanism in A. baumannii . A detailed genetic characterization revealed a new colistin resistance mechanism mediated by genetic integration of the insertion element IS AbaI upstream of the PmrC homolog EptA (93% identity), leading to its overexpression. We found that eptA was ubiquitously present in clinical strains belonging to the international clone 2, and IS AbaI integration upstream of eptA was required to mediate the colistin-resistant phenotype. In addition, we found a duplicated IS AbaI - eptA cassette in one isolate, indicating that this colistin resistance determinant may be embedded in a mobile genetic element. Our data disprove PmrA as a drug target for adjuvant therapy but highlight the importance of PetN transferase-mediated colistin resistance in clinical strains. We suggest that direct targeting of the homologous PetN transferases PmrC/EptA may have the potential to overcome colistin resistance in A. baumannii . IMPORTANCE The discovery of antibiotics revolutionized modern medicine and enabled us to cure previously deadly bacterial infections. However, a progressive increase in antibiotic resistance rates is a major and global threat for our health care system. Colistin represents one of our last-resort antibiotics that is still active against most Gram-negative bacterial pathogens, but increasing resistance is reported worldwide, in particular due to the plasmid-encoded protein MCR-1 present in pathogens such as Escherichia coli and Klebsiella pneumoniae . Here, we showed that colistin resistance in A. baumannii , a top-priority pathogen causing deadly nosocomial infections, is mediated through different avenues that result in increased activity of homologous phosphoethanolamine (PetN) transferases. Considering that MCR-1 is also a PetN transferase, our findings indicate that PetN transferases might be the Achilles heel of superbugs and that direct targeting of them may have the potential to preserve the activity of polymyxin antibiotics.
    Type of Medium: Online Resource
    ISSN: 2161-2129 , 2150-7511
    URL: Article
    DOI: 10.1128/mBio.01083-19
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2019
    detail.hit.zdb_id: 2557172-2
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  • 4
    Online Resource
    Online Resource
    Two-Component Nanoparticle Vaccine Displaying Glycosylated Spike S1 Domain Induces Neutralizing Antibody Response against SARS-CoV-2 Variants
    American Society for Microbiology ; 2021
    In:  mBio Vol. 12, No. 5 ( 2021-10-26)
    Details
    In: mBio, American Society for Microbiology, Vol. 12, No. 5 ( 2021-10-26)
    Abstract: Vaccines pave the way out of the SARS-CoV-2 pandemic. Besides mRNA and adenoviral vector vaccines, effective protein-based vaccines are needed for immunization against current and emerging variants. We have developed a virus-like particle (VLP)-based vaccine using the baculovirus-insect cell expression system, a robust production platform known for its scalability, low cost, and safety. Baculoviruses were constructed encoding SARS-CoV-2 spike proteins: full-length S, stabilized secreted S, or the S1 domain. Since subunit S only partially protected mice from SARS-CoV-2 challenge, we produced S1 for conjugation to bacteriophage AP205 VLP nanoparticles using tag/catcher technology. The S1 yield in an insect-cell bioreactor was ∼11 mg/liter, and authentic protein folding, efficient glycosylation, partial trimerization, and ACE2 receptor binding was confirmed. Prime-boost immunization of mice with 0.5 μg S1-VLPs showed potent neutralizing antibody responses against Wuhan and UK/B.1.1.7 SARS-CoV-2 variants. This two-component nanoparticle vaccine can now be further developed to help alleviate the burden of COVID-19. IMPORTANCE Vaccination is essential to reduce disease severity and limit the transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Protein-based vaccines are useful to vaccinate the world population and to boost immunity against emerging variants. Their safety profiles, production costs, and vaccine storage temperatures are advantageous compared to mRNA and adenovirus vector vaccines. Here, we use the versatile and scalable baculovirus expression vector system to generate a two-component nanoparticle vaccine to induce potent neutralizing antibody responses against SARS-CoV-2 variants. These nanoparticle vaccines can be quickly adapted as boosters by simply updating the antigen component.
    Type of Medium: Online Resource
    ISSN: 2150-7511
    URL: Article
    DOI: 10.1128/mBio.01813-21
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2021
    detail.hit.zdb_id: 2557172-2
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  • 5
    Online Resource
    Online Resource
    Styrene Oxide Isomerase of Rhodococcus opacus 1CP, a Highly Stable and Considerably Active Enzyme
    American Society for Microbiology ; 2012
    In:  Applied and Environmental Microbiology Vol. 78, No. 12 ( 2012-06-15), p. 4330-4337
    Details
    In: Applied and Environmental Microbiology, American Society for Microbiology, Vol. 78, No. 12 ( 2012-06-15), p. 4330-4337
    Abstract: Styrene oxide isomerase (SOI) is involved in peripheral styrene catabolism of bacteria and converts styrene oxide to phenylacetaldehyde. Here, we report on the identification, enrichment, and biochemical characterization of a novel representative from the actinobacterium Rhodococcus opacus 1CP. The enzyme, which is strongly induced during growth on styrene, was shown to be membrane integrated, and a convenient procedure was developed to highly enrich the protein in active form from the wild-type host. A specific activity of about 370 U mg −1 represents the highest activity reported for this enzyme class so far. This, in combination with a wide pH and temperature tolerance, the independence from cofactors, and the ability to convert a spectrum of substituted styrene oxides, makes a biocatalytic application imaginable. First, semipreparative conversions were performed from which up to 760 μmol of the pure phenylacetaldehyde could be obtained from 130 U of enriched SOI. Product concentrations of up to 76 mM were achieved. However, due to the high chemical reactivity of the aldehyde function, SOI was shown to be the subject of an irreversible product inhibition. A half-life of 15 min was determined at a phenylacetaldehyde concentration of about 55 mM, indicating substantial limitations of applicability and the need to modify the process.
    Type of Medium: Online Resource
    ISSN: 0099-2240 , 1098-5336
    URL: Article
    DOI: 10.1128/AEM.07641-11
    RVK:
    WA 15000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2012
    detail.hit.zdb_id: 223011-2
    detail.hit.zdb_id: 1478346-0
    SSG: 12
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  • 6
    Online Resource
    Online Resource
    Identification of Varicella-Zoster Virus-Specific CD8 T Cells in Patients after T-Cell-Depleted Allogeneic Stem Cell Transplantation
    American Society for Microbiology ; 2009
    In:  Journal of Virology Vol. 83, No. 14 ( 2009-07-15), p. 7361-7364
    Details
    In: Journal of Virology, American Society for Microbiology, Vol. 83, No. 14 ( 2009-07-15), p. 7361-7364
    Abstract: To study the role of CD8 T cells in the control of varicella-zoster virus (VZV) reactivation, we developed multimeric major histocompatibility complexes to identify VZV-specific CD8 T cells. Potential HLA-A2 binding peptides from the putative immediate-early 62 protein (IE62) of VZV were tested for binding, and peptides with sufficient binding capacity were used to generate pentamers. Patients with VZV reactivation following stem cell transplantation were screened with these pentamers, leading to the identification of the first validated class I-restricted epitope of VZV. In 42% of HLA-A2 patients following VZV reactivation, these IE62-ALW-A2 T cells could be detected ex vivo.
    Type of Medium: Online Resource
    ISSN: 0022-538X , 1098-5514
    URL: Article
    DOI: 10.1128/JVI.02662-08
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2009
    detail.hit.zdb_id: 1495529-5
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  • 7
    Online Resource
    Online Resource
    Isoniazid Bactericidal Activity Involves Electron Transport Chain Perturbation
    American Society for Microbiology ; 2019
    In:  Antimicrobial Agents and Chemotherapy Vol. 63, No. 3 ( 2019-03)
    Details
    In: Antimicrobial Agents and Chemotherapy, American Society for Microbiology, Vol. 63, No. 3 ( 2019-03)
    Abstract: Accumulating evidence suggests that the bactericidal activity of some antibiotics may not be directly initiated by target inhibition. The activity of isoniazid (INH), a key first-line bactericidal antituberculosis drug currently known to inhibit mycolic acid synthesis, becomes extremely poor under stress conditions, such as hypoxia and starvation. This suggests that the target inhibition may not fully explain the bactericidal activity of the drug. Here, we report that INH rapidly increased Mycobacterium bovis BCG cellular ATP levels and enhanced oxygen consumption. The INH-triggered ATP increase and bactericidal activity were strongly compromised by Q203 and bedaquiline, which inhibit mycobacterial cytochrome bc 1 and F o F 1 ATP synthase, respectively. Moreover, the antioxidant N -acetylcysteine (NAC) but not 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPOL) abrogated the INH-triggered ATP increase and killing. These results reveal a link between the energetic (ATP) perturbation and INH’s killing. Furthermore, the INH-induced energetic perturbation and killing were also abrogated by chemical inhibition of NADH dehydrogenases (NDHs) and succinate dehydrogenases (SDHs), linking INH’s bactericidal activity further to the electron transport chain (ETC) perturbation. This notion was also supported by the observation that INH dissipated mycobacterial membrane potential. Importantly, inhibition of cytochrome bd oxidase significantly reduced cell recovery during INH challenge in a culture settling model, suggesting that the respiratory reprogramming to the cytochrome bd oxidase contributes to the escape of INH killing. This study implicates mycobacterial ETC perturbation through NDHs, SDHs, cytochrome bc 1 , and F o F 1 ATP synthase in INH’s bactericidal activity and pinpoints the participation of the cytochrome bd oxidase in protection against this drug under stress conditions.
    Type of Medium: Online Resource
    ISSN: 0066-4804 , 1098-6596
    URL: Article
    DOI: 10.1128/AAC.01841-18
    RVK:
    XA 24552
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2019
    detail.hit.zdb_id: 1496156-8
    SSG: 12
    SSG: 15,3
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  • 8
    Online Resource
    Online Resource
    A Novel Genome-Editing Platform for Drug-Resistant Acinetobacter baumannii Reveals an AdeR-Unrelated Tigecycline Resistance Mechanism
    American Society for Microbiology ; 2016
    In:  Antimicrobial Agents and Chemotherapy Vol. 60, No. 12 ( 2016-12), p. 7263-7271
    Details
    In: Antimicrobial Agents and Chemotherapy, American Society for Microbiology, Vol. 60, No. 12 ( 2016-12), p. 7263-7271
    Abstract: Infections with the Gram-negative coccobacillus Acinetobacter baumannii are a major threat in hospital settings. The progressing emergence of multidrug-resistant clinical strains significantly reduces the treatment options for clinicians to fight A. baumannii infections. The current lack of robust methods to genetically manipulate drug-resistant A. baumannii isolates impedes research on resistance and virulence mechanisms in clinically relevant strains. In this study, we developed a highly efficient and versatile genome-editing platform enabling the markerless modification of the genome of A. baumannii clinical and laboratory strains, regardless of their resistance profiles. We applied this method for the deletion of AdeR, a transcription factor that regulates the expression of the AdeABC efflux pump in tigecycline-resistant A. baumannii , to evaluate its function as a putative drug target. Loss of adeR reduced the MIC 90 of tigecycline from 25 μg/ml in the parental strains to 3.1 μg/ml in the Δ adeR mutants, indicating its importance in the drug resistance phenotype. However, 60% of the clinical isolates remained nonsusceptible to tigecycline after adeR deletion. Evolution of artificial tigecycline resistance in two strains followed by whole-genome sequencing revealed loss-of-function mutations in trm , suggesting its role in an alternative AdeABC-independent tigecycline resistance mechanism. This finding was strengthened by the confirmation of trm disruption in the majority of the tigecycline-resistant clinical isolates. This study highlights the development and application of a powerful genome-editing platform for A. baumannii enabling future research on drug resistance and virulence pathways in clinically relevant strains.
    Type of Medium: Online Resource
    ISSN: 0066-4804 , 1098-6596
    URL: Article
    DOI: 10.1128/AAC.01275-16
    RVK:
    XA 24552
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2016
    detail.hit.zdb_id: 1496156-8
    SSG: 12
    SSG: 15,3
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