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  • American Society for Microbiology  (11)
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  • American Society for Microbiology  (11)
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  • 1
    Online Resource
    Online Resource
    Identification and Characterization of Key Charged Residues in the Cofilin Protein Involved in Azole Susceptibility, Apoptosis, and Virulence of Aspergillus fumigatus
    American Society for Microbiology ; 2018
    In:  Antimicrobial Agents and Chemotherapy Vol. 62, No. 5 ( 2018-05)
    Details
    In: Antimicrobial Agents and Chemotherapy, American Society for Microbiology, Vol. 62, No. 5 ( 2018-05)
    Abstract: Through some specific amino acid residues, cofilin, a ubiquitous actin depolymerization factor, can significantly affect mitochondrial function related to drug resistance and apoptosis in Saccharomyces cerevisiae ; however, this modulation in a major fungal pathogen, Aspergillus fumigatus , was still unclear. Hereby, it was found, first, that mutations on several charged residues in cofilin to alanine, D19A-R21A, E48A, and K36A, increased the formation of reactive oxygen species and induced apoptosis along with typical hallmarks, including mitochondrial membrane potential depolarization, cytochrome c release, upregulation of metacaspases, and DNA cleavage, in A. fumigatus . Two of these mutations (D19A-R21A and K36A) increased acetyl coenzyme A and ATP concentrations by triggering fatty acid β-oxidation. The upregulated acetyl coenzyme A affected the ergosterol biosynthetic pathway, leading to overexpression of cyp51A and - B , while excess ATP fueled ATP-binding cassette transporters. Besides, both of these mutations reduced the susceptibility of A. fumigatus to azole drugs and enhanced the virulence of A. fumigatus in a Galleria mellonella infection model. Taken together, novel and key charged residues in cofilin were identified to be essential modules regulating the mitochondrial function involved in azole susceptibility, apoptosis, and virulence of A. fumigatus .
    Type of Medium: Online Resource
    ISSN: 0066-4804 , 1098-6596
    URL: Article
    DOI: 10.1128/AAC.01659-17
    RVK:
    XA 24552
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2018
    detail.hit.zdb_id: 1496156-8
    SSG: 12
    SSG: 15,3
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  • 2
    Online Resource
    Online Resource
    Elevated MIC Values of Imidazole Drugs against Aspergillus fumigatus Isolates with TR 34 /L98H/S297T/F495I Mutation
    American Society for Microbiology ; 2018
    In:  Antimicrobial Agents and Chemotherapy Vol. 62, No. 5 ( 2018-05)
    Details
    In: Antimicrobial Agents and Chemotherapy, American Society for Microbiology, Vol. 62, No. 5 ( 2018-05)
    Abstract: The use of azole fungicides in agriculture is believed to be one of the main reasons for the emergence of azole resistance in Aspergillus fumigatus . Though widely used in agriculture, imidazole fungicides have not been linked to resistance in A. fumigatus . This study showed that elevated MIC values of imidazole drugs were observed against A. fumigatus isolates with TR 34 /L98H/S297T/F495I mutation, but not among isolates with TR 34 /L98H mutation. Short-tandem-repeat (STR) typing analysis of 580 A. fumigatus isolates from 20 countries suggested that the majority of TR 34 /L98H/S297T/F495I strains from China were genetically different from the predominant major clade comprising most of the azole-resistant strains and the strains with the same mutation from the Netherlands and Denmark. Alignments of sterol 14α-demethylase sequences suggested that F495I in A. fumigatus was orthologous to F506I in Penicillium digitatum and F489L in Pyrenophora teres , which have been reported to be associated with imidazole resistance. In vitro antifungal susceptibility testing of different recombinants with cyp51A mutations further confirmed the association of the F495I mutation with imidazole resistance. In conclusion, this study suggested that environmental use of imidazole fungicides might confer selection pressure for the emergence of azole resistance in A. fumigatus .
    Type of Medium: Online Resource
    ISSN: 0066-4804 , 1098-6596
    URL: Article
    DOI: 10.1128/AAC.01549-17
    RVK:
    XA 24552
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2018
    detail.hit.zdb_id: 1496156-8
    SSG: 12
    SSG: 15,3
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    Online Resource
  • 3
    Online Resource
    Online Resource
    Epidemiology and Molecular Characterizations of Azole Resistance in Clinical and Environmental Aspergillus fumigatus Isolates from China
    American Society for Microbiology ; 2016
    In:  Antimicrobial Agents and Chemotherapy Vol. 60, No. 10 ( 2016-10), p. 5878-5884
    Details
    In: Antimicrobial Agents and Chemotherapy, American Society for Microbiology, Vol. 60, No. 10 ( 2016-10), p. 5878-5884
    Abstract: Azole resistance in Aspergillus fumigatus has emerged as a worldwide public health problem. We sought here to demonstrate the occurrence and characteristics of azole resistance in A. fumigatus from different parts of China. A total of 317 clinical and 144 environmental A. fumigatus isolates from 12 provinces were collected and subjected to screening for azole resistance. Antifungal susceptibility, cyp51A gene sequencing, and genotyping were carried out for all suspected azole-resistant isolates and a subset of azole-susceptible isolates. As a result, 8 (2.5%) clinical and 2 (1.4%) environmental A. fumigatus isolates were identified as azole resistant. Five azole-resistant strains exhibit the TR 34 /L98H mutation, whereas four carry the TR 34 /L98H/S297T/F495I mutation in the cyp51A gene. Genetic typing and phylogenetic analysis showed that there was a worldwide clonal expansion of the TR 34 /L98H isolates, while the TR 34 /L98H/S297T/F495I isolates from China harbored a distinct genetic background with resistant isolates from other countries. High polymorphisms existed in the cyp51A gene that produced amino acid changes among azole-susceptible A. fumigatus isolates, with N248K being the most common mutation. These data suggest that the wide distribution of azole-resistant A. fumigatus might be attributed to the environmental resistance mechanisms in China.
    Type of Medium: Online Resource
    ISSN: 0066-4804 , 1098-6596
    URL: Article
    DOI: 10.1128/AAC.01005-16
    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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  • 4
    Online Resource
    Online Resource
    Long Terminal Repeat Retrotransposon Afut4 Promotes Azole Resistance of Aspergillus fumigatus by Enhancing the Expression of sac1 Gene
    American Society for Microbiology ; 2021
    In:  Antimicrobial Agents and Chemotherapy Vol. 65, No. 12 ( 2021-11-17)
    Details
    In: Antimicrobial Agents and Chemotherapy, American Society for Microbiology, Vol. 65, No. 12 ( 2021-11-17)
    Abstract: Aspergillus fumigatus causes a series of invasive diseases, including the high-mortality invasive aspergillosis, and has been a serious global health threat because of its increased resistance to the first-line clinical triazoles. We analyzed the whole-genome sequence of 15 A. fumigatus strains from China and found that long terminal repeat retrotransposons (LTR-RTs), including Afut1 , Afut2, Afut3, and Afut4 , are most common and have the largest total nucleotide length among all transposable elements in A. fumigatus . Deleting one of the most enriched Afut4 977-sac1 in azole-resistant strains decreased azole resistance and downregulated its nearby gene, sac1 , but it did not significantly affect the expression of genes of the ergosterol synthesis pathway. We then discovered that 5'LTR of Afut4 977-sac1 had promoter activity and enhanced the adjacent sac1 gene expression. We found that sac1 is important to A. fumigatus , and the upregulated sac1 caused elevated resistance of A. fumigatus to azoles. Finally, we showed that Afut4 977-sac1 has an evolution pattern similar to that of the whole genome of azole-resistant strains due to azoles; phylogenetic analysis of both the whole genome and Afut4 977-sac1 suggests that the insertion of Afut4 977-sac1 might have preceded the emergence of azole-resistant strains. Taking these data together, we found that the Afut4 977-sac1 LTR-RT might be involved in the regulation of azole resistance of A. fumigatus by upregulating its nearby sac1 gene.
    Type of Medium: Online Resource
    ISSN: 0066-4804 , 1098-6596
    URL: Article
    DOI: 10.1128/AAC.00291-21
    RVK:
    XA 24552
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2021
    detail.hit.zdb_id: 1496156-8
    SSG: 12
    SSG: 15,3
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    Online Resource
  • 5
    Online Resource
    Online Resource
    Emergence of TR46/Y121F/T289A in an Aspergillus fumigatus Isolate from a Chinese Patient
    American Society for Microbiology ; 2015
    In:  Antimicrobial Agents and Chemotherapy Vol. 59, No. 11 ( 2015-11), p. 7148-7150
    Details
    In: Antimicrobial Agents and Chemotherapy, American Society for Microbiology, Vol. 59, No. 11 ( 2015-11), p. 7148-7150
    Type of Medium: Online Resource
    ISSN: 0066-4804 , 1098-6596
    URL: Article
    DOI: 10.1128/AAC.00887-15
    RVK:
    XA 24552
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2015
    detail.hit.zdb_id: 1496156-8
    SSG: 12
    SSG: 15,3
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  • 6
    Online Resource
    Online Resource
    Mutations in troABCD against Copper Overload in a copA Mutant of Streptococcus suis
    American Society for Microbiology ; 2023
    In:  Applied and Environmental Microbiology Vol. 89, No. 1 ( 2023-01-31)
    Details
    In: Applied and Environmental Microbiology, American Society for Microbiology, Vol. 89, No. 1 ( 2023-01-31)
    Abstract: Streptococcus suis is a major swine pathogen that is increasingly recognized as a porcine zoonotic pathogen that threatens the health of both pigs and humans. Metal homeostasis plays a critical role during the process of bacterial infection. In this study, RNA sequencing was used to identify potential candidate genes involved in the maintenance of intracellular copper homeostasis. CopA was identified as the primary copper exporter in S. suis . The copA deletion mutant strain was found to be more sensitive to copper and accumulated more intracellular copper than the wild-type (WT) parent strain. In addition, adding manganese increased the ability of S. suis to resist copper, and the manganese transporter, TroABCD, was involved in tolerance to copper. The copA deletion mutant strain accumulated less copper when supplemented with manganese. Furthermore, when cultured with copper, the double deletion mutant (Δ copA Δ troA ) exhibited improved growth compared to the copA deletion mutant strain. In addition, the double deletion mutant (Δ copA Δ troA ) accumulated less copper than the copA deletion mutant strain. These data were consistent with a model wherein defective TroABCD resulted in decreased cellular copper accumulation and protected the strain against copper poisoning. IMPORTANCE Metal homeostasis plays a critical role during the process of bacterial infection. We identified three important potential candidate genes involved in maintenance of intracellular copper homeostasis. CopA was demonstrated to be the main copper exporter in Streptococcus suis , and manganese increased the tolerance of S. suis to copper. The double deletion mutant (Δ copA Δ troA ) improved growth ability over the copA deletion mutant strain in the presence of high concentrations of copper and accumulated less copper. These findings are consistent with a model wherein defective TroABCD resulted in decreased cellular accumulation of copper and protected the strain against copper poisoning.
    Type of Medium: Online Resource
    ISSN: 0099-2240 , 1098-5336
    URL: Article
    DOI: 10.1128/aem.01841-22
    RVK:
    WA 15000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2023
    detail.hit.zdb_id: 223011-2
    detail.hit.zdb_id: 1478346-0
    SSG: 12
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  • 7
    Online Resource
    Online Resource
    PerR-Regulated Manganese Import Contributes to Oxidative Stress Defense in Streptococcus suis
    American Society for Microbiology ; 2022
    In:  Applied and Environmental Microbiology Vol. 88, No. 9 ( 2022-05-10)
    Details
    In: Applied and Environmental Microbiology, American Society for Microbiology, Vol. 88, No. 9 ( 2022-05-10)
    Abstract: Streptococcus suis has been increasingly recognized as a porcine zoonotic pathogen that threatens the health of both pigs and humans. Metal homeostasis plays a critical role in the antioxidative capability of bacteria, thus facilitating the escape of pathogenic species from the innate immunity systems of hosts. Here, we revealed that manganese increased the ability of S. suis to resist oxidative stress. RNA sequencing was used to identify potential candidate genes involved in the maintenance of intracellular manganese homeostasis. Four genes, termed troABCD , were identified by NCBI BLASTp analysis. The troA , troB , troC , and troD deletion mutant strains exhibited decreased intracellular manganese content and tolerance to H 2 O 2 compared to the wild-type strain. Thus, troABCD were determined to be involved in manganese uptake and played an important role in H 2 O 2 tolerance in S. suis . Furthermore, the inactivation of perR increased the survival of H 2 O 2 -pulsed S. suis 2.18-fold and elevated the intracellular manganese content. H 2 O 2 -pulsed S. suis and perR deletion mutants upregulated troABCD . This finding suggested that H 2 O 2 released the suppression of troABCD by perR . In addition, an electrophoretic mobility shift assay (EMSA) showed that PerR at 500 ng binds to the troABCD promoter, indicating that troABCD were directly regulated by PerR. In conclusion, this study revealed that manganese increases tolerance to H 2 O 2 by upregulating the expression of troABCD . Moreover, PerR-regulated Mn import in S. suis and increased the tolerance of S. suis to oxidative stress by regulating troABCD . IMPORTANCE During infection, it is extremely important for bacteria to defend against oxidative stress. While manganese plays an important role in this process, its role is unclear in S. suis . Here, we demonstrated that manganese increased S. suis tolerance to oxidative stress. Four manganese ABC transporter genes, troABCD , were identified. Oxidative stress increased the content of manganese in the cell. Furthermore, PerR increased the tolerance to oxidative stress of S. suis by regulating troABCD . Manganese played an important role in bacterial defense against oxidative stress. These findings provide novel insight into the mechanism by which S. suis resists oxidative stress and approaches to inhibit bacterial infection by limiting manganese intake.
    Type of Medium: Online Resource
    ISSN: 0099-2240 , 1098-5336
    URL: Article
    DOI: 10.1128/aem.00086-22
    RVK:
    WA 15000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2022
    detail.hit.zdb_id: 223011-2
    detail.hit.zdb_id: 1478346-0
    SSG: 12
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  • 8
    Online Resource
    Online Resource
    The Live Attenuated Actinobacillus pleuropneumoniae Triple-Deletion Mutant Δ apxIC Δ apxIIC Δ apxIV - ORF1 Strain, SLW05, Immunizes Pigs against Lethal Challenge with Haemophilus parasuis
    American Society for Microbiology ; 2013
    In:  Clinical and Vaccine Immunology Vol. 20, No. 2 ( 2013-02), p. 134-139
    Details
    In: Clinical and Vaccine Immunology, American Society for Microbiology, Vol. 20, No. 2 ( 2013-02), p. 134-139
    Abstract: Haemophilus parasuis and Actinobacillus pleuropneumoniae both belong to the family Pasteurellaceae and are major respiratory pathogens that cause large economic losses in the pig industry worldwide. We previously constructed an attenuated A. pleuropneumoniae serovar 1 live vaccine prototype, SLW05 (Δ apxIC Δ apxIIC Δ apxIV - ORF1 ), which is able to produce nontoxic but immunogenic ApxIA, ApxIIA, and ApxIVA. This triple-deletion mutant strain was shown to elicit protective immunity against virulent A. pleuropneumoniae . In the present study, we investigated whether immunization with SLW05 could also protect against lethal challenge with virulent H. parasuis SH0165 (serovar 5) or MD0322 (serovar 4). The SLW05 strain was found to elicit a strong humoral antibody response in pigs and to confer significant protection against challenge with a lethal dose of H. parasuis SH0165 or MD0322. IgG subtype analysis revealed that SLW05 induces a bias toward a Th1-type immune response and stimulates interleukin 2 (IL-2) and gamma interferon (IFN-γ) production. Moreover, antisera from SLW05-vaccinated pigs efficiently inhibited both A. pleuropneumoniae and H. parasuis growth in a whole-blood assay. This is the first report that a live attenuated A. pleuropneumoniae vaccine with SLW05 can protect against lethal H. parasuis infection, which provides a novel approach for developing an attenuated H. parasuis vaccine.
    Type of Medium: Online Resource
    ISSN: 1556-6811 , 1556-679X
    URL: Article
    DOI: 10.1128/CVI.00458-12
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2013
    detail.hit.zdb_id: 1496863-0
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  • 9
    Online Resource
    Online Resource
    Role of the Two-Component System CiaRH in the Regulation of Efflux Pump SatAB and Its Correlation with Fluoroquinolone Susceptibility
    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: Streptococcus suis is an important pathogen in both pigs and humans. Although the diseases associated with S. suis can typically be treated with antibiotics, such use has resulted in a sustained increase in drug resistance. Bacteria can sense and respond to antibiotics via two-component systems (TCSs). In this study, the TCS CiaRH was identified as playing an important role in the susceptibility of S. suis to fluoroquinolones (FQs). We found that a Δ ciaRH mutant possessed lower susceptibility to FQs than the wild-type strain, with no observed growth defects at the tested concentrations and lower levels of intracellular drugs and dye. Proteomic data revealed that the levels of SatA and SatB expression were upregulated in the Δ ciaRH mutant compared with their levels in the wild-type strain. The satA and satB genes encode a narrow-spectrum FQ efflux pump. The phenomena associated with combined ciaRH -and- satAB deletion mutations almost returned the Δ ciaRH Δ satAB mutant to the phenotype of the wild-type strain compared to the phenotype of the Δ ciaRH mutant, suggesting that the resistance of the Δ ciaRH strain to FQs could be attributed to satAB overexpression. Moreover, SatAB expression was regulated by CiaR (a response regulator of CiaRH) and SatR (a regulator of the MarR family). The ciaRH genes were consistently downregulated in response to antibiotic stress. The results of electrophoretic mobility shift assays (EMSAs) and affinity assays revealed that both regulator proteins directly controlled the ABC transporter proteins SatAB. Together, the results show that cascade-mediated regulation of antibiotic export by CiaRH is crucial for the ability of S. suis to adapt to conditions of antibiotic pressure. Our study may provide a new target for future antibiotic research and development. IMPORTANCE Streptococcus suis is a zoonotic pathogen with high incidence and mortality rates in both swine and humans. Following antibiotic treatment, the organism has evolved many resistance mechanisms, among which efflux pump overexpression can promote drug extrusion from the cell. This study clarified the role of CiaRH in fluoroquinolone resistance. A mutant with the ciaRH genes deleted showed decreased susceptibility to the antibiotics tested, an invariant growth rate, and reduced intracellular efflux pump substrates. This research also demonstrated that overexpression of the efflux pump SatAB was the main cause of Δ ciaRH resistance. In addition, CiaR could combine with the promoter region of satAB to further directly suppress target gene transcription. Simultaneously, satAB was also directly regulated by SatR. Our findings may provide novel insights for the development of drug targets and help to exploit corresponding inhibitors to combat bacterial multidrug resistance.
    Type of Medium: Online Resource
    ISSN: 2165-0497
    URL: Article
    DOI: 10.1128/spectrum.00417-22
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2022
    detail.hit.zdb_id: 2807133-5
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  • 10
    Online Resource
    Online Resource
    CpxAR of Actinobacillus pleuropneumoniae Contributes to Heat Stress Response by Repressing Expression of Type IV Pilus Gene apfA
    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: Acute pleuropneumonia in swine, caused by Actinobacillus pleuropneumoniae , is characterized by a high and sustained fever. Fever creates an adverse environment for many bacteria, leading to reduced bacterial proliferation; however, most pathogenic bacteria can tolerate higher temperatures. CpxAR is a two-component regulation system, ubiquitous among Gram-negative bacteria, which senses and responds to envelope alterations that are mostly associated with protein misfolding in the periplasm. Our previous study showed that CpxAR is necessary for the optimal growth of Actinobacillus pleuropneumoniae under heat stress. Here, we showed that mutation of the type IV pilin gene apfA rescued the growth defect of the cpxAR deletion strain under heat stress. RNA sequencing (RNA-seq) analyses revealed that 265 genes were differentially expressed in the Δ cpxAR strains grown at 42°C, including genes involved in type IV pilus biosynthesis. We also demonstrated direct binding of the CpxR protein to the promoter of the apf operon by an electrophoretic mobility shift assay and identified the binding site by a DNase I footprinting assay. In conclusion, our results revealed the important role of CpxAR in A. pleuropneumoniae resistance to heat stress by directly suppressing the expression of ApfA. IMPORTANCE Heat acts as a danger signal for pathogens, especially those infecting mammalian hosts in whom fever indicates infection. However, some bacteria have evolved exquisite mechanisms to survive under heat stress. Studying the mechanism of resistance to heat stress is crucial to understanding the pathogenesis of A. pleuropneumoniae during the acute stage of infection. Our study revealed that CpxAR plays an important role in A. pleuropneumoniae resistance to heat stress by directly suppressing expression of the type IV pilin protein ApfA.
    Type of Medium: Online Resource
    ISSN: 2165-0497
    URL: Article
    DOI: 10.1128/spectrum.02523-22
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2022
    detail.hit.zdb_id: 2807133-5
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