Histone-Like Nucleoid Structuring Protein Modulates the Fitness of tet(X4)-Bearing IncX1 Plasmids in Gram-Negative Bacteria

The emergence of plasmid-mediated tigecycline resistance gene tet(X4) poses a challenging threat to public health. Based on the analysis of tet(X4)-positive plasmids in the NCBI database, we found that the IncX1-type plasmid is one of the most common vectors for spreading tet(X4) gene, but the mechanisms by which these plasmids adapt to host bacteria and maintain the persistence of antibiotic resistance genes (ARGs) remain unclear. Herein, we investigated the underlying mechanisms of how host bacteria modulate the fitness cost of IncX1 plasmids carrying tet(X4) gene. Interestingly, we found that the tet(X4)-bearing IncX1 plasmids encoding H-NS protein imposed low or no fitness cost in Escherichia coli and Klebsiella pneumoniae; instead, they partially promoted the virulence and biofilm formation in host bacteria. Regression analysis revealed that the expression of hns gene in plasmids was positively linked to the relative fitness of host bacteria. Furthermore, when pCE2::hns was introduced, the fitness of tet(X4)-positive IncX1 plasmid pRF55-1 without hns gene was significantly improved, indicating that hns mediates the improvement of fitness. Finally, we showed that the expression of hns gene is negatively correlated with the expression of tet(X4) gene, suggesting that the regulatory effect of H-NS on adaptability may be attributed to its inhibitory effect on the expression of ARGs. Together, our findings suggest the important role of plasmid-encoded H-NS protein in modulating the fitness of tet(X4)-bearing IncX1 plasmids, which shed new insight into the dissemination of tet(X4) gene in a biological environment.

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Exopolysaccharide protectsVibrio choleraefrom exogenous attacks by the type 6 secretion system

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1808469115 ◽

2018 ◽

Vol 115 (31) ◽

pp. 7997-8002 ◽

Cited By ~ 35

Author(s):

Jonida Toska ◽

Brian T. Ho ◽

John J. Mekalanos

Keyword(s):

Biofilm Formation ◽

Potential Role ◽

Secretion System ◽

Effector Proteins ◽

Solid Surfaces ◽

Gram Negative Bacteria ◽

Bacterial Cells ◽

Macromolecular Protein ◽

Insight Into

The type 6 secretion system (T6SS) is a nanomachine used by many Gram-negative bacteria, includingVibrio cholerae, to deliver toxic effector proteins into adjacent eukaryotic and bacterial cells. Because the activity of the T6SS is dependent on direct contact between cells, its activity is limited to bacteria growing on solid surfaces or in biofilms.V. choleraecan produce an exopolysaccharide (EPS) matrix that plays a role in adhesion and biofilm formation. In this work, we investigated the effect of EPS production on T6SS activity between cells. We found that EPS produced byV. choleraecells functions as a unidirectional protective armor that blocks exogenous T6SS attacks without interfering with its own T6SS functionality. This EPS armor is effective against both same-species and heterologous attackers. Mutations modulating the level of EPS biosynthesis gene expression result in corresponding modulation inV. choleraeresistance to exogenous T6SS attack. These results provide insight into the potential role of extracellular biopolymers, including polysaccharides, capsules, and S-layers in protecting bacterial cells from attacks involving cell-associated macromolecular protein machines that cannot readily diffuse through these mechanical defenses.

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RND Efflux Systems Contribute to Resistance and Virulence of Aliarcobacter butzleri

Antibiotics ◽

10.3390/antibiotics10070823 ◽

2021 ◽

Vol 10 (7) ◽

pp. 823

Author(s):

Cristiana Mateus ◽

Ana Rita Nunes ◽

Mónica Oleastro ◽

Fernanda Domingues ◽

Susana Ferreira

Keyword(s):

Oxidative Stress ◽

Human Serum ◽

Ethidium Bromide ◽

Biofilm Formation ◽

Bacterial Resistance ◽

Efflux Pumps ◽

Bacterial Virulence ◽

Relative Fitness ◽

Mutant Strains

Aliarcobacter butzleri is an emergent enteropathogen that can be found in a range of environments. This bacterium presents a vast repertoire of efflux pumps, such as the ones belonging to the resistance nodulation cell division family, which may be associated with bacterial resistance, as well as virulence. Thus, this work aimed to evaluate the contribution of three RND efflux systems, AreABC, AreDEF and AreGHI, in the resistance and virulence of A. butzleri. Mutant strains were constructed by inactivation of the gene that encodes the inner membrane protein of these systems. The bacterial resistance profile of parental and mutant strains to several antimicrobials was assessed, as was the intracellular accumulation of the ethidium bromide dye. Regarding bacterial virulence, the role of these three efflux pumps on growth, strain fitness, motility, biofilm formation ability, survival in adverse conditions (oxidative stress and bile salts) and human serum and in vitro adhesion and invasion to Caco-2 cells was evaluated. We observed that the mutants from the three efflux pumps were more susceptible to several classes of antimicrobials than the parental strain and presented an increase in the accumulation of ethidium bromide, indicating a potential role of the efflux pumps in the extrusion of antimicrobials. The mutant strains had no bacterial growth defects; nonetheless, they presented a reduction in relative fitness. For the three mutants, an increase in the susceptibility to oxidative stress was observed, while only the mutant for AreGHI efflux pump showed a relevant role in bile stress survival. All the mutant strains showed an impairment in biofilm formation ability, were more susceptible to human serum and were less adherent to intestinal epithelial cells. Overall, the results support the contribution of the efflux pumps AreABC, AreDEF and AreGHI of A. butzleri to antimicrobial resistance, as well as to bacterial virulence.

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Relationship Between Membrane Vesicles, Extracellular ATP and Biofilm Formation in Antarctic Gram-Negative Bacteria

Microbial Ecology ◽

10.1007/s00248-020-01614-6 ◽

2020 ◽

Author(s):

Nicolas Baeza ◽

Elena Mercade

Keyword(s):

Biofilm Formation ◽

Membrane Vesicles ◽

Metabolic Cost ◽

Extracellular Atp ◽

Gram Negative Bacteria ◽

Bacterial Survival ◽

Gram Negative ◽

Two Factors ◽

And Control

Abstract Biofilms offer a safe environment that favors bacterial survival; for this reason, most pathogenic and environmental bacteria live integrated in biofilm communities. The development of biofilms is complex and involves many factors, which need to be studied in order to understand bacterial behavior and control biofilm formation when necessary. We used a collection of cold-adapted Antarctic Gram-negative bacteria to study whether their ability to form biofilms is associated with a capacity to produce membrane vesicles and secrete extracellular ATP. In most of the studied strains, no correlation was found between biofilm formation and these two factors. Only Shewanella vesiculosa M7T secreted high levels of extracellular ATP, and its membrane vesicles caused a significant increase in the speed and amount of biofilm formation. In this strain, an important portion of the exogenous ATP was contained in membrane vesicles, where it was protected from apyrase treatment. These results confirm that ATP influences biofilm formation. Although the role of extracellular ATP in prokaryotes is still not well understood, the metabolic cost of its production suggests it has an important function, such as a role in biofilm formation. Thus, the liberation of extracellular ATP through membrane vesicles and its function deserve further study.

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Escherichia coli tol and rcs genes participate in the complex network affecting curli synthesis

Microbiology ◽

10.1099/mic.0.27913-0 ◽

2005 ◽

Vol 151 (7) ◽

pp. 2487-2497 ◽

Cited By ~ 58

Author(s):

Anne Vianney ◽

Grégory Jubelin ◽

Sophie Renault ◽

Corine Dorel ◽

Philippe Lejeune ◽

...

Keyword(s):

Escherichia Coli ◽

Biofilm Formation ◽

Membrane Integrity ◽

Regulatory Proteins ◽

Gram Negative Bacteria ◽

Dependent Manner ◽

Dominant Effect ◽

Gram Negative ◽

E Coli

Curli are necessary for the adherence of Escherichia coli to surfaces, and to each other, during biofilm formation, and the csgBA and csgDEFG operons are both required for their synthesis. A recent survey of gene expression in Pseudomonas aeruginosa biofilms has identified tolA as a gene activated in biofilms. The tol genes play a fundamental role in maintaining the outer-membrane integrity of Gram-negative bacteria. RcsC, the sensor of the RcsBCD phosphorelay, is involved, together with RcsA, in colanic acid capsule synthesis, and also modulates the expression of tolQRA and csgDEFG. In addition, the RcsBCD phosphorelay is activated in tol mutants or when Tol proteins are overexpressed. These results led the authors to investigate the role of the tol genes in biofilm formation in laboratory and clinical isolates of E. coli. It was shown that the adherence of cells was lowered in the tol mutants. This could be the result of a drastic decrease in the expression of the csgBA operon, even though the expression of csgDEFG was slightly increased under such conditions. It was also shown that the Rcs system negatively controls the expression of the two csg operons in an RcsA-dependent manner. In the tol mutants, activation of csgDEFG occurred via OmpR and was dominant upon repression by RcsB and RcsA, while these two regulatory proteins repressed csgBA through a dominant effect on the activator protein CsgD, thus affecting curli synthesis. The results demonstrate that the Rcs system, previously known to control the synthesis of the capsule and the flagella, is an additional component involved in the regulation of curli. Furthermore, it is shown that the defect in cell motility observed in the tol mutants depends on RcsB and RcsA.

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The Role of HDAC6 in Autophagy and NLRP3 Inflammasome

Frontiers in Immunology ◽

10.3389/fimmu.2021.763831 ◽

2021 ◽

Vol 12 ◽

Author(s):

Panpan Chang ◽

Hao Li ◽

Hui Hu ◽

Yongqing Li ◽

Tianbing Wang

Keyword(s):

Nlrp3 Inflammasome ◽

Inflammatory Diseases ◽

Critical Role ◽

Histone Deacetylase 6 ◽

Physiological Processes ◽

Class Iib ◽

Underlying Mechanisms ◽

Nlrp3 Inflammasomes ◽

Insight Into

Autophagy fights against harmful stimuli and degrades cytosolic macromolecules, organelles, and intracellular pathogens. Autophagy dysfunction is associated with many diseases, including infectious and inflammatory diseases. Recent studies have identified the critical role of the NACHT, LRR, and PYD domain-containing protein 3 (NLRP3) inflammasomes activation in the innate immune system, which mediates the secretion of proinflammatory cytokines IL-1β/IL-18 and cleaves Gasdermin D to induce pyroptosis in response to pathogenic and sterile stimuli. Accumulating evidence has highlighted the crosstalk between autophagy and NLRP3 inflammasome in multifaceted ways to influence host defense and inflammation. However, the underlying mechanisms require further clarification. Histone deacetylase 6 (HDAC6) is a class IIb deacetylase among the 18 mammalian HDACs, which mainly localizes in the cytoplasm. It is involved in two functional deacetylase domains and a ubiquitin-binding zinc finger domain (ZnF-BUZ). Due to its unique structure, HDAC6 regulates various physiological processes, including autophagy and NLRP3 inflammasome, and may play a role in the crosstalk between them. In this review, we provide insight into the mechanisms by which HDAC6 regulates autophagy and NLRP3 inflammasome and we explored the possibility and challenges of HDAC6 in the crosstalk between autophagy and NLRP3 inflammasome. Finally, we discuss HDAC6 inhibitors as a potential therapeutic approach targeting either autophagy or NLRP3 inflammasome as an anti-inflammatory strategy, although further clarification is required regarding their crosstalk.

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Role of the Ubiquitin System in Chronic Pain

Frontiers in Molecular Neuroscience ◽

10.3389/fnmol.2021.674914 ◽

2021 ◽

Vol 14 ◽

Author(s):

Jiurong Cheng ◽

Yingdong Deng ◽

Jun Zhou

Keyword(s):

Chronic Pain ◽

Molecular Mechanisms ◽

Therapeutic Targets ◽

Public Health Issue ◽

Deubiquitinating Enzyme ◽

Ubiquitin System ◽

Significant Public Health ◽

Underlying Mechanisms ◽

Insight Into

As a significant public health issue, chronic pain, mainly neuropathic pain (NP) and inflammatory pain, has a severe impact. The underlying mechanisms of chronic pain are enigmatic at present. The roles of ubiquitin have been demonstrated in various physiological and pathological conditions and underscore its potential as therapeutic targets. The dysfunction of the component of the ubiquitin system that occurs during chronic pain is rapidly being discovered. These results provide insight into potential molecular mechanisms of chronic pain. Chronic pain is regulated by ubiquitination, SUMOylation, ubiquitin ligase, and deubiquitinating enzyme (DUB), etc. Insight into the mechanism of the ubiquitin system regulating chronic pain might contribute to relevant therapeutic targets and the development of novel analgesics.

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Electroacupuncture reduces scopolamine-induced amnesia via mediating the miR-210/SIN3A and miR-183/SIN3A signaling pathway

10.21203/rs.3.rs-31499/v5 ◽

2020 ◽

Author(s):

Fan Ye ◽

Shiming Tian ◽

Huimin Hu ◽

Zhengwen Yu

Keyword(s):

Object Recognition ◽

Treatment Efficacy ◽

Memory Function ◽

Inhibitory Effect ◽

Luciferase Assay ◽

Novel Object Recognition ◽

Quantitative Real Time Pcr ◽

Novel Object ◽

Underlying Mechanisms

Abstract Background: The expression of SIN3A is closely correlated with electroacupuncture (EA) treatment efficacy of scopolamine-induced amnesia (SIA), but its underlying mechanisms remain to be further explored. Methods: Quantitative real-time PCR was performed to analyze the expression of candidate microRNAs (miRNAs) and SIN3A mRNA in a rat model of SIA. Western blot was carried out to evaluate the differential expression of SIN3A proteins under different circumstances. Luciferase assay was used to explore the inhibitory role of certain miRNAs in SIN3A expression. A novel object recognition (NOR) test was performed to assess the memory function of SIA rats undergoing EA treatment. Immunohistochemistry was carried out to evaluate the expression of SIN3A in the hippocampus of SIA rats. Results: Rno-miR-183-5p, rno-miR-34c-3p and rno-miR-210-3p were significantly up-regulated in SIA rats treated with EA. In addition, rno-miR-183-5p and rno-miR-210-3p exerted an inhibitory effect on SIN3A expression. EA treatment of SIA rats effectively restored the dysregulated expression of rno-miR-183-5p, rno-miR-210-3p and SIN3A. EA treatment also promoted the inhibited expression of neuronal IEGs including Arc, Egr1, Homer1 and Narp in the hippocampus of SIA rats. Accordingly, the NOR test also confirmed the effect of EA treatment on the improvement of memory in SIA rats.Conclusion: In summary, the findings of this study demonstrated that scopolamine-induced amnesia was associated with downregulated expression of miR-210/miR-183 and upregulated expression of SIN3A. Furthermore, treatment with EA alleviated scopolamine-induced amnesia in rats and was associated with upregulated expression of miR-210/miR-183 and downregulated expression of SIN3A.

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Electroacupuncture Reduces Scopolamine-Induced Amnesia Via Mediating the miR-210/SIN3A and miR-183/SIN3A Signaling Pathway

10.21203/rs.3.rs-31499/v1 ◽

2020 ◽

Author(s):

Fan Ye ◽

Shiming Tian ◽

Huimin Hu ◽

Zhengwen Yu

Keyword(s):

Animal Model ◽

Western Blot ◽

Treatment Efficacy ◽

Inhibitory Effect ◽

Luciferase Assay ◽

Regulatory Pathway ◽

Quantitative Real Time Pcr ◽

Normal Expression ◽

Underlying Mechanisms

Abstract Background The expression of SIN3A is closely correlated with EA treatment efficacy of SIA, but its underlying mechanisms remain to be further explored.Methods Quantitative real-time PCR was performed to analyze the expression of candidate miRNAs and SIN3A mRNA in a rat model of SIA. Western blot was carried out to evaluate the differential expression of SIN3A proteins under distinct circumstances. Luciferase assay was used to explore the inhibitory role of certain miRNAs in SIN3A expression. NOR test was performed to assess the memorial ability of SIA rats undergoing EA treatment. Immunohistochemistry was carried out to evaluate the expression of SIN3A in the hippocampus of SIA rats.Results Rno-miR-183-5p, rno-miR-34c-3p and rno-miR-210-3p were significantly up-regulated in SIA rats treated with EA. In addition, rno-miR-183-5p and rno-miR-210-3p exerted an inhibitory effect on SIN3A expression. EA treatment of SIA rats effectively restored the normal expression of rno-miR-183-5p, rno-miR-210-3p and SIN3A. The NOR test also confirmed the effect of EA treatment on the improvement of memory in SIA rats.Conclusion In this study, an animal model of SIA was treated with EA to investigate its therapeutic effect. Moreover, our work presented solid evidence on the regulatory pathway of miR-183/SIN3A and miR-210/SIN3A in the pathogenesis of SIA.

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Electroacupuncture reduces scopolamine-induced amnesia via mediating the miR-210/SIN3A and miR-183/SIN3A signaling pathway

10.21203/rs.3.rs-31499/v3 ◽

2020 ◽

Author(s):

Fan Ye ◽

Shiming Tian ◽

Huimin Hu ◽

Zhengwen Yu

Keyword(s):

Object Recognition ◽

Treatment Efficacy ◽

Memory Function ◽

Inhibitory Effect ◽

Luciferase Assay ◽

Novel Object Recognition ◽

Quantitative Real Time Pcr ◽

Novel Object ◽

Underlying Mechanisms

Abstract Background: The expression of SIN3A is closely correlated with electroacupuncture (EA) treatment efficacy of scopolamine-induced amnesia (SIA), but its underlying mechanisms remain to be further explored. Methods: Quantitative real-time PCR was performed to analyze the expression of candidate microRNAs (miRNAs) and SIN3A mRNA in a rat model of SIA. Western blot was carried out to evaluate the differential expression of SIN3A proteins under different circumstances. Luciferase assay was used to explore the inhibitory role of certain miRNAs in SIN3A expression. A novel object recognition (NOR) test was performed to assess the memory function of SIA rats undergoing EA treatment. Immunohistochemistry was carried out to evaluate the expression of SIN3A in the hippocampus of SIA rats. Results: Rno-miR-183-5p, rno-miR-34c-3p and rno-miR-210-3p were significantly up-regulated in SIA rats treated with EA. In addition, rno-miR-183-5p and rno-miR-210-3p exerted an inhibitory effect on SIN3A expression. EA treatment of SIA rats effectively restored the dysregulated expression of rno-miR-183-5p, rno-miR-210-3p and SIN3A. EA treatment also promoted the inhibited expression of neuronal IEGs including Arc, Egr1, Homer1 and Narp in the hippocampus of SIA rats. Accordingly, the NOR test also confirmed the effect of EA treatment on the improvement of memory in SIA rats. Conclusion: In summary, the findings of this study demonstrated that scopolamine-induced amnesia was associated with downregulated expression of miR-210/miR-183 and upregulated expression of SIN3A. Furthermore, treatment with EA alleviated scopolamine-induced amnesia in rats and was associated with upregulated expression of miR-210/miR-183 and downregulated expression of SIN3A.

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