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  • 1
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    Transient Presence of Live Leptospira interrogans in Murine Testes
    American Society for Microbiology ; 2022
    In:  Microbiology Spectrum Vol. 10, No. 3 ( 2022-06-29)
    Details
    In: Microbiology Spectrum, American Society for Microbiology, Vol. 10, No. 3 ( 2022-06-29)
    Abstract: Analysis of Leptospira dissemination and colonization of sex organs in rodents is of significant value as it queries the possibility of mammal-to-mammal venereal transmission. The aim of our study was to evaluate the presence and viability of Leptospira interrogans in testes of mice using models of infection that we previously developed. Using sublethal and lethal doses of bioluminescent strains of L. interrogans serovars Manilae and Copenhageni, we visualized the presence of leptospires in testes of C57BL/6 mice as early as 30 min and up to days 3–4 postinfection. This was confirmed by qPCR for the Copenhageni serovar after lethal infection of C3H/HeJ mice. In this model, no histopathological changes were noticed in testis. We further studied persistence of serovar Copenhageni in C3H/HeJ testes after lethal and sublethal infection, with different doses of leptospires. No viable leptospires were recovered from testes of lethally infected mice. However, we found live culturable Leptospira in testes of 19/19 (100%) sublethally infected mice at the acute phase but not at 15 days postinfection, which corresponds to the chronic phase of renal colonization. The data suggest that colonization of testes with live and potentially infectious leptospires is transient and limited to the spirochetemic phase of infection. Further studies are necessary to evaluate if presence of Leptospira in testes of mice leads to excretion in semen and to venereal transmission to female mice. IMPORTANCE Analysis of venereal transmission of Leptospira is important to determine if direct animal to animal transmission occurs, which could impact measures to prevent and treat leptospirosis. The goal of this study was to determine if live Leptospira colonize mouse testes. We found that colonization of mouse testes with live Leptospira was transient and limited to the acute spirochetemic phase of infection and that transient colonization of the testes was insufficient to cause histopathological changes.
    Type of Medium: Online Resource
    ISSN: 2165-0497
    URL: Article
    DOI: 10.1128/spectrum.02775-21
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2022
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  • 2
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    Bacterial Surface Detachment during Nebulization with Contaminated Reusable Home Nebulizers
    American Society for Microbiology ; 2022
    In:  Microbiology Spectrum Vol. 10, No. 1 ( 2022-02-23)
    Details
    In: Microbiology Spectrum, American Society for Microbiology, Vol. 10, No. 1 ( 2022-02-23)
    Abstract: Patients with chronic respiratory diseases use home nebulizers that are often contaminated with pathogenic microbes to deliver aerosolized medications. The conditions under which these microbes leave the surface as bioaerosols during nebulization are not well characterized. The objectives of this study were to (i) determine whether different pathogens detach and disperse from the nebulizer surface during aerosolization and (ii) measure the effects of relative humidity and drying times on bacterial surface detachment and aerosolization. Bacteria were cultured from bioaerosols after Pari LC Plus albuterol nebulization using two different sources, as follows: (i) previously used nebulizers donated by anonymous patients with cystic fibrosis (CF) and (ii) nebulizers inoculated with bacteria isolated from the lungs of CF patients. Fractionated bioaerosols were collected with a Next-Generation Impactor. For a subset of bacteria, surface adherence during rewetting was measured with fluorescence microscopy. Bacteria dispersed from the surface of used CF patient nebulizers during albuterol nebulization. Eighty percent (16/20) of clinical isolates inoculated on the nebulizer in the laboratory formed bioaerosols. Detachment from the plastic surface into the chamber solution predicted bioaerosol production. Increased relative humidity and decreased drying times after inoculation favored bacterial dispersion on aerosols during nebulized therapy. Pathogenic bacteria contaminating nebulizer surfaces detached from the surface as bioaerosols during nebulized therapies, especially under environmental conditions when contaminated nebulizers were dried or stored at high relative humidity. This finding emphasizes the need for appropriate nebulizer cleaning, disinfection, and complete drying during storage and informs environmental conditions that favor bacterial surface detachment during nebulization. IMPORTANCE Studies from around the world have demonstrated that many patients use contaminated nebulizers to deliver medication into their lungs. While it is known that using contaminated medications in a nebulizer can lead to a lung infection, whether bacteria on the surface of a contaminated nebulizer detach as bioaerosols capable of reaching the lung has not been studied. This work demonstrates that a subset of clinical bacteria enter solution from the surface during nebulization and are aerosolized. Environmental conditions of high relative humidity during storage favor dispersion from the surface. We also provide results of an in vitro assay conducted to monitor bacterial surface detachment during multiple cycles of rewetting that correlate with the results of nebulizer/bacterial surface interactions. These studies demonstrate for the first time that pathogenic bacteria on the nebulizer surface pose a risk of bacterial inhalation to patients who use contaminated nebulizers.
    Type of Medium: Online Resource
    ISSN: 2165-0497
    URL: Article
    DOI: 10.1128/spectrum.02535-21
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2022
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  • 3
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    Online Resource
    The Performance of Nine Commercial Serological Screening Assays for the Diagnosis of Lyme Borreliosis: a Multicenter Modified Two-Gate Design Study
    American Society for Microbiology ; 2022
    In:  Microbiology Spectrum Vol. 10, No. 2 ( 2022-04-27)
    Details
    In: Microbiology Spectrum, American Society for Microbiology, Vol. 10, No. 2 ( 2022-04-27)
    Abstract: In this retrospective study, the performance of nine serological screening assays for Lyme borreliosis (LB) diagnostics was evaluated using a study population of LB cases and controls. Sera derived from 74 well-defined LB cases and 122 controls were included. The LB cases were diagnosed with erythema migrans (EM; n  = 11), Lyme neuroborreliosis (LNB; n  = 35), Lyme arthritis (LA; n  = 20), or acrodermatitis chronica atrophicans (ACA; n  = 8). Controls comprised 74 age- and gender-matched healthy individuals and 48 patients with other diseases with anticipated high rates of cross-reactivity. The assays under evaluation were selected based on a literature review and expected continued availability with CE marking under the new in vitro diagnostic regulation (European Union) 2017/746. The overall sensitivity (IgG and IgM results combined) among LB cases ranged between 54.5% (6 of 11) and 90.9% (10 of 11) for EM patients and between 97.1% (34 of 35) and 100% for patients with LNB, LA, and ACA. The positivity rate ranged between 8.1% (6 of 74) and 29.7% (22 of 74) among the healthy controls and between 22.9% (11 of 48) and 64.6% (31 of 48) among the cross-reactivity controls. The IgM results were more heterogeneous than the IgG and IgM/IgG results and did not contribute to the overall sensitivity but substantially increased the positivity rates among the controls. In conclusion, all evaluated Borrelia serological screening assays performed comparably with respect to early- and late-disseminated LB. The addition of an IgM assay to the screening of Borrelia -specific IgG antibodies had no added value for the diagnosis of Lyme borreliosis. IMPORTANCE Serology plays an important role in the diagnosis of Lyme borreliosis. Guidelines prescribe a two-tier testing algorithm in which a highly sensitive screening assay is used for screening and reactive sera are retested with an immunoblot to reduce false positivity rates. Recently, two commonly used screening assays were discontinued, including the very well-performing C6 Lyme enzyme-linked immunosorbent assay (ELISA) (Immunetics). This study provides an evaluation of the performance of nine different Borrelia serology screening assays, eight with expected future availably and the C6 Lyme ELISA, using a well-defined study panel of Lyme borreliosis patients, healthy population controls, and cross-reactivity controls. Evaluation data on multiple assays aid diagnostic laboratories in their choice for a reliable Borrelia serology screening assay to improve their diagnostic algorithm for Lyme borreliosis.
    Type of Medium: Online Resource
    ISSN: 2165-0497
    URL: Article
    DOI: 10.1128/spectrum.00510-22
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2022
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  • 4
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    Primary Murine Macrophages as a Tool for Virulence Factor Discovery in Coxiella burnetii
    American Society for Microbiology ; 2022
    In:  Microbiology Spectrum Vol. 10, No. 4 ( 2022-08-31)
    Details
    In: Microbiology Spectrum, American Society for Microbiology, Vol. 10, No. 4 ( 2022-08-31)
    Abstract: Coxiella burnetii requires a type IVB secretion system (T4SS) to promote intracellular replication and virulence. We hypothesized that Coxiella employs its T4SS to secrete effectors that enable stealthy colonization of immune cells. To address this, we used RNA sequencing to compare the transcriptional response of murine bone marrow-derived macrophages (BMDM) infected with those of wild-type Coxiella and a T4SS-null mutant at 8 and 24 h postinfection. We found a T4SS-independent upregulation of proinflammatory transcripts which was consistent with a proinflammatory polarization phenotype. Despite this, infected BMDM failed to completely polarize, as evidenced by modest surface expression of CD38 and CD11c, nitrate production, and reduced proinflammatory cytokine and chemokine secretion compared to positive controls. As these BMDM permitted replication of C. burnetii , we employed them to identify T4SS effectors that are essential in the specific cellular context of a primary macrophage. We found five Himar1 transposon mutants in T4SS effectors that had a replication defect in BMDM but not J774A.1 cells. The mutants were also attenuated in a SCID mouse model of infection. Among these candidate virulence factors, we found that CBU1639 contributed to the inhibition of macrophage proinflammatory responses to Coxiella infection. These data demonstrate that while T4SS is dispensable for the stealthy invasion of primary macrophages, Coxiella has evolved multiple T4SS effectors that specifically target macrophage function to proliferate within that specific cellular context. IMPORTANCE Coxiella burnetii , the causative agent of Q fever, preferentially infects macrophages of the respiratory tract when causing human disease. This work describes how primary macrophages respond to C. burnetii at the earliest stages of infection, before bacterial replication. We found that while infected macrophages increase expression of proinflammatory genes after bacterial entry, they fail to activate the accompanying antibacterial functions that might ultimately control the infection. This disconnect between initial response and downstream function was not mediated by the bacterium’s type IVB secretion system, suggesting that Coxiella has other virulence factors that dampen host responses early in the infection process. Nevertheless, we were able to identify several type IVB secreted effectors that were specifically required for survival in macrophages and mice. This work is the first to identify type IVB secretion effectors that are specifically required for infection and replication within primary macrophages.
    Type of Medium: Online Resource
    ISSN: 2165-0497
    URL: Article
    DOI: 10.1128/spectrum.02484-21
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2022
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  • 5
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    Evolution of the vls Antigenic Variability Locus of the Lyme Disease Pathogen and Development of Recombinant Monoclonal Antibodies Targeting Conserved VlsE Epitopes
    American Society for Microbiology ; 2022
    In:  Microbiology Spectrum Vol. 10, No. 5 ( 2022-10-26)
    Details
    In: Microbiology Spectrum, American Society for Microbiology, Vol. 10, No. 5 ( 2022-10-26)
    Abstract: VlsE (variable major protein-like sequence, expressed) is an outer surface protein of the Lyme disease pathogen ( Borreliella species) responsible for its within-host antigenic variation and a key diagnostic biomarker of Lyme disease. However, the high sequence variability of VlsE poses a challenge to the development of consistent VlsE-based diagnostics and therapeutics. In addition, the standard diagnostic protocols detect immunoglobins elicited by the Lyme pathogen, not the presence of the pathogen or its derived antigens. Here, we described the development of recombinant monoclonal antibodies (rMAbs) that bound specifically to conserved epitopes on VlsE. We first quantified amino-acid sequence variability encoded by the vls genes from 13 B. burgdorferi genomes by evolutionary analyses. We showed broad inconsistencies of the sequence phylogeny with the genome phylogeny, indicating rapid gene duplications, losses, and recombination at the vls locus. To identify conserved epitopes, we synthesized peptides representing five long conserved invariant regions (IRs) on VlsE. We tested the antigenicity of these five IR peptides using sera from three mammalian host species including human patients, the natural reservoir white-footed mouse ( Peromyscus leucopus ), and VlsE-immunized New Zealand rabbits ( Oryctolagus cuniculus ). The IR4 and IR6 peptides emerged as the most antigenic and reacted strongly with both the human and rabbit sera, while all IR peptides reacted poorly with sera from natural hosts. Four rMAbs binding specifically to the IR4 and IR6 peptides were identified, cloned, and purified. Given their specific recognition of the conserved epitopes on VlsE, these IR-specific rMAbs are potential novel diagnostic and research agents for direct detection of Lyme disease pathogens regardless of strain heterogeneity. IMPORTANCE Current diagnostic protocols of Lyme disease indirectly detect the presence of antibodies produced by the patient upon infection by the bacterial pathogen, not the pathogen itself. These diagnostic tests tend to underestimate early-stage bacterial infections before the patients develop robust immune responses. Further, the indirect tests do not distinguish between active or past infections by the Lyme disease bacteria in a patient sample. Here, we described novel monoclonal antibodies that have the potential to become the basis of direct and definitive diagnostic detection of the Lyme disease pathogen, regardless of its genetic heterogeneity.
    Type of Medium: Online Resource
    ISSN: 2165-0497
    URL: Article
    DOI: 10.1128/spectrum.01743-22
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2022
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  • 6
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    Online Resource
    Staphylococcal Corneocyte Adhesion: Assay Optimization and Roles of Aap and SasG Adhesins in the Establishment of Healthy Skin Colonization
    American Society for Microbiology ; 2022
    In:  Microbiology Spectrum Vol. 10, No. 6 ( 2022-12-21)
    Details
    In: Microbiology Spectrum, American Society for Microbiology, Vol. 10, No. 6 ( 2022-12-21)
    Abstract: Staphylococcus aureus is an opportunistic pathogen that causes the majority of wound and soft tissue infections. The accumulation-associated protein (Aap) from S. epidermidis and surface protein G (SasG) from S. aureus are cell wall-anchored (CWA) proteins known to be important in adhesion to healthy corneocytes from human skin. We investigated the mechanisms by which S. aureus colonizes healthy human skin by developing an optimized corneocyte adhesion assay. Trypan blue was used for enhanced red autofluorescent visualization of corneocytes with an overlay of green-fluorescent bacteria. The percent area of bacterial adhesion for images acquired by a fluorescence microscope was quantified using Fiji ImageJ. Using this optimized imaging procedure, differences in adhesion between various species and strains of staphylococci were measured. The ability of purified SasG to reduce Staphylococcus epidermidis adhesion was investigated in order to determine if these CWA proteins can compete for binding sites. To further test CWA-mediated adhesion, we engineered a nonadhering S. carnosus strain to express full-length SasG from two methicillin-resistant S. aureus (MRSA) strains. Finally, we demonstrated that the SasG A domain was a critical region of this surface protein for adherence to healthy human corneocytes. The developed imaging and expression methods are useful for studying staphylococcal adhesion to healthy human skin and have the potential to be used with a wide variety of fluorescently labeled organisms on both healthy and disease-state (such as atopic dermatitis) corneocytes. IMPORTANCE The skin is the largest organ of the human body and acts as a shield against hazards such as harmful bacteria like Staphylococcus aureus . A diverse skin microbiota and immune cross talk control S. aureus numbers. S. aureus can bind to healthy skin and subsequently proliferate when the skin barrier is compromised, such as in a wound or in patients with atopic dermatitis (AD). It is important to understand these mechanisms in an effort to prevent pathogenic bacteria from causing infection. We describe an augmented corneocyte adhesion assay using fluorescence microscopy to study binding of various staphylococcal species to healthy human skin cells. In addition, we tested the ability of homologous proteins from different staphylococcal species to reduce binding, and developed a new S. carnosus expression system to test individual protein binding properties. Our newly developed methods and findings will enhance the understanding of how staphylococci bind to healthy human skin.
    Type of Medium: Online Resource
    ISSN: 2165-0497
    URL: Article
    DOI: 10.1128/spectrum.02469-22
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2022
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  • 7
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    Implication of the IL-10-Expression Signature in the Pathogenicity of Leptospira -Infected Macrophages
    American Society for Microbiology ; 2022
    In:  Microbiology Spectrum Vol. 10, No. 3 ( 2022-06-29)
    Details
    In: Microbiology Spectrum, American Society for Microbiology, Vol. 10, No. 3 ( 2022-06-29)
    Abstract: Leptospirosis, an emerging infectious disease caused by pathogenic Leptospira spp., occurs in ecoregions with heavy rainfall and has public health implications. Macrophages are the major anti- Leptospira phagocytes that infiltrate the kidneys during renal leptospirosis, which is caused by leptospires residing in the renal tubules. The pathogenicity of Leptospira spp. in immune effector cells such as macrophages is not well understood. To evaluate this pathogenesis, we characterized and compared the transcriptome-wide alterations in macrophages infected with pathogenic and nonpathogenic Leptospira spp. Using transcriptome data and quantitative reverse transcription PCR analysis, at 2 h postinfection, the hypoxia-inducible factor-1α-dependent glycolysis pathway was implicated in pathogenic Leptospira -infected macrophages but not in nonpathogenic leptospiral infections. Immune-related biological processes were mostly activated in pathogenic Leptospira -infected macrophages, and flow cytometry investigations revealed that classically activated macrophages represent the predominant polarization status. At 24 h after infection, biological pathways associated with interleukin-10, IL-10, signaling the induction of macrophage tolerance, as well as higher levels of IL-10 mRNA and protein expression, were observed in nonpathogenic Leptospira -infected macrophages compared to in pathogenic leptospiral infection. Following leptospiral infection of macrophages, strong IL-10-expressing transcriptome signatures were observed following nonpathogenic leptospiral infection. The transcriptional programs generated in Leptospira -infected macrophages revealed an inflammatory milieu following the production of a critical anti-inflammatory cytokine, IL-10, which is implicated in controlling the pathogenicity of activated macrophages. These findings imply that IL-10-mediated anti-inflammatory responses and tolerance in activated macrophages induced by nonpathogenic Leptospira spp. infection reduce inflammation and tissue damage, thus providing a potential therapeutic target for leptospirosis. IMPORTANCE Activation of macrophages by Leptospira spp. infection is thought to be involved in the pathogenesis of leptospirosis. To evaluate the innate macrophage responses to Leptospira spp., specifically pathogenic versus nonpathogenic Leptospira spp., we characterized the entire transcriptome-wide alterations in infected macrophages. We showed that hypoxia-inducible factor-1α and immune-related pathways are activated in pathogenic leptospiral-infected macrophages. We confirmed the significantly high levels of IL-10-expressing signatures and tolerance in activated macrophages caused by nonpathogenic Leptospira infection. Furthermore, nonpathogenic leptospiral infections attenuated macrophage activation responses. These findings suggest a potential therapeutic strategy for the immune microenvironment caused by macrophage activation driven by IL-10 overexpression, which may contribute to regulating inflammation in leptospirosis.
    Type of Medium: Online Resource
    ISSN: 2165-0497
    URL: Article
    DOI: 10.1128/spectrum.02595-21
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2022
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  • 8
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    Multi-Omics Analysis Reveals the Resistance Mechanism and the Pathogens Causing Root Rot of Coptis chinensis
    American Society for Microbiology ; 2023
    In:  Microbiology Spectrum Vol. 11, No. 2 ( 2023-04-13)
    Details
    In: Microbiology Spectrum, American Society for Microbiology, Vol. 11, No. 2 ( 2023-04-13)
    Abstract: Coptis chinensis is a traditional Chinese medicinal herb used for more than 2,000 years. Root rot in C. chinensis can cause brown discoloration (necrosis) in the fibrous roots and rhizomes, leading to plants wilting and dying. However, little information exists about the resistance mechanism and the potential pathogens of the root rot of C. chinensis plants. As a result, in order to investigate the relationship between the underlying molecular processes and the pathogenesis of root rot, transcriptome and microbiome analyses were performed on healthy and diseased C. chinensis rhizomes. This study found that root rot can lead to the significant reduction of medicinal components of Coptis, including thaliotrine, columbamine, epiberberin, coptisine, palmatine chloride, and berberine, affecting its efficacy quality. In the present study, Diaporthe eres , Fusarium avenaceum , and Fusarium solani were identified as the main pathogens causing root rot in C. chinensis . At the same time, the genes in phenylpropanoid biosynthesis, plant hormone signal transduction, plant-pathogen interaction, and alkaloid synthesis pathways were involved in the regulation of root rot resistance and medicinal component synthesis. In addition, harmful pathogens ( D. eres , F. avenaceum and F. solani ) also induce the expression of related genes in C. chinensis root tissues to reduce active medicinal ingredients. These results provide insights into the root rot tolerance study and pave the way for process disease resistance breeding and quality production of C. chinensis . IMPORTANCE Root rot disease significantly reduces the medicinal quality of Coptis chinensis . In the present study, results found that the C. chinensis fibrous and taproot have different tactics in response to rot pathogen infection. Diaporthe eres , Fusarium avenaceum , and Fusarium solani were isolated and identified to cause different degrees of C. chinensis root rot. These results are helpful for researchers to further explore the mechanism of resistance to rhizoma Coptis root rot.
    Type of Medium: Online Resource
    ISSN: 2165-0497
    URL: Article
    DOI: 10.1128/spectrum.04803-22
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2023
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  • 9
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    Helicobacter pylori Modulates Heptose Metabolite Biosynthesis and Heptose-Dependent Innate Immune Host Cell Activation by Multiple Mechanisms
    American Society for Microbiology ; 2023
    In:  Microbiology Spectrum Vol. 11, No. 3 ( 2023-06-15)
    Details
    In: Microbiology Spectrum, American Society for Microbiology, Vol. 11, No. 3 ( 2023-06-15)
    Abstract: Heptose metabolites including ADP- d -glycero-β- d -manno-heptose (ADP-heptose) are involved in bacterial lipopolysaccharide and cell envelope biosynthesis. Recently, heptoses were also identified to have potent proinflammatory activity on human cells as novel microbe-associated molecular patterns. The gastric pathogenic bacterium Helicobacter pylori produces heptose metabolites, which it transports into human cells through its Cag type 4 secretion system. Using H. pylori as a model, we have addressed the question of how proinflammatory ADP-heptose biosynthesis can be regulated by bacteria. We have characterized the interstrain variability and regulation of heptose biosynthesis genes and the modulation of heptose metabolite production by H. pylori , which impact cell-autonomous proinflammatory human cell activation. HldE, a central enzyme of heptose metabolite biosynthesis, showed strong sequence variability between strains and was also variably expressed between strains. Amounts of gene transcripts in the hldE gene cluster displayed intrastrain and interstrain differences, were modulated by host cell contact and the presence of the cag pathogenicity island, and were affected by carbon starvation regulator A (CsrA). We reconstituted four steps of the H. pylori lipopolysaccharide (LPS) heptose biosynthetic pathway in vitro using recombinant purified GmhA, HldE, and GmhB proteins. On the basis of one- and two-dimensional nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry, the structures of major reaction products were identified as β- d- ADP-heptose and β-heptose-1-monophosphate. A proinflammatory heptose-monophosphate variant was also identified for the first time as a novel cell-active product in H. pylori bacteria. Separate purified HldE subdomains and variant HldE allowed us to uncover additional strain variation in generating heptose metabolites. IMPORTANCE Bacterial heptose metabolites, intermediates of lipopolysaccharide (LPS) biosynthesis, are novel microbe-associated molecular patterns (MAMPs) that activate proinflammatory signaling. In the gastric pathogen Helicobacter pylori , heptoses are transferred into host cells by the Cag type IV secretion system, which is also involved in carcinogenesis. Little is known about how H. pylori , which is highly strain variable, regulates heptose biosynthesis and downstream host cell activation. We report here that the regulation of proinflammatory heptose production by H. pylori is strain specific. Heptose gene cluster activity is modulated by the presence of an active cag pathogenicity island ( cag PAI), contact with human cells, and the carbon starvation regulator A. Reconstitution with purified biosynthesis enzymes and purified bacterial lysates allowed us to biochemically characterize heptose pathway products, identifying a heptose-monophosphate variant as a novel proinflammatory metabolite. These findings emphasize that the bacteria use heptose biosynthesis to fine-tune inflammation and also highlight opportunities to mine the heptose biosynthesis pathway as a potential therapeutic target against infection, inflammation, and cancer.
    Type of Medium: Online Resource
    ISSN: 2165-0497
    URL: Article
    DOI: 10.1128/spectrum.03132-22
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2023
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  • 10
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    Two Permeases Associated with the Multifunctional CtaP Cysteine Transport System in Listeria monocytogenes Play Distinct Roles in Pathogenesis
    American Society for Microbiology ; 2023
    In:  Microbiology Spectrum Vol. 11, No. 3 ( 2023-06-15)
    Details
    In: Microbiology Spectrum, American Society for Microbiology, Vol. 11, No. 3 ( 2023-06-15)
    Abstract: The soil-dwelling bacterium Listeria monocytogenes survives a multitude of conditions when residing in the outside environment and as a pathogen within host cells. Key to survival within the infected mammalian host is the expression of bacterial gene products necessary for nutrient acquisition. Similar to many bacteria, L. monocytogenes uses peptide import to acquire amino acids. Peptide transport systems play an important role in nutrient uptake as well as in additional functions that include bacterial quorum sensing and signal transduction, recycling of peptidoglycan fragments, adherence to eukaryotic cells, and alterations in antibiotic susceptibility. It has been previously described that CtaP, encoded by lmo0135 , is a multifunctional protein associated with activities that include cysteine transport, resistance to acid, membrane integrity, and bacterial adherence to host cells. ctaP is located next to two genes predicted to encode membrane-bound permeases lmo0136 and lmo0137 , termed CtpP1 and CtpP2, respectively. Here, we show that CtpP1 and CtpP2 are required for bacterial growth in the presence of low concentrations of cysteine and for virulence in mouse infection models. Taken together, the data identify distinct nonoverlapping roles for two related permeases that are important for the growth and survival of L. monocytogenes within host cells. IMPORTANCE Bacterial peptide transport systems are important for nutrient uptake and may additionally function in a variety of other roles, including bacterial communication, signal transduction, and bacterial adherence to eukaryotic cells. Peptide transport systems often consist of a substrate-binding protein associated with a membrane-spanning permease. The environmental bacterial pathogen Listeria monocytogenes uses the substrate-binding protein CtaP not only for cysteine transport but also for resistance to acid, maintenance of membrane integrity, and bacterial adherence to host cells. In this study, we demonstrate complementary yet distinct functional roles for two membrane permeases, CtpP1 and CtpP2, that are encoded by genes linked to ctaP and that contribute to bacterial growth, invasion, and pathogenicity.
    Type of Medium: Online Resource
    ISSN: 2165-0497
    URL: Article
    DOI: 10.1128/spectrum.03317-22
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2023
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