scholarly journals What Happens in the Staphylococcal Nucleoid under Oxidative Stress?

2019 ◽  
Vol 7 (12) ◽  
pp. 631 ◽  
Author(s):  
Kazuya Morikawa ◽  
Yuri Ushijima ◽  
Ryosuke L. Ohniwa ◽  
Masatoshi Miyakoshi ◽  
Kunio Takeyasu
Keyword(s):  
Oxidative Stress ◽  
Molecular Genetic ◽  
Oxygen Species ◽  
Human Pathogen ◽  
Phagocytic Cells ◽  
Force Microscopy ◽  
Atomic Force ◽  
Evolutionary Success ◽  
Opportunistic Human Pathogen ◽  
Protein Part

The evolutionary success of Staphylococcus aureus as an opportunistic human pathogen is largely attributed to its prominent abilities to cope with a variety of stresses and host bactericidal factors. Reactive oxygen species are important weapons in the host arsenal that inactivate phagocytosed pathogens, but S. aureus can survive in phagosomes and escape from phagocytic cells to establish infections. Molecular genetic analyses combined with atomic force microscopy have revealed that the MrgA protein (part of the Dps family of proteins) is induced specifically in response to oxidative stress and converts the nucleoid from the fibrous to the clogged state. This review collates a series of evidences on the staphylococcal nucleoid dynamics under oxidative stress, which is functionally and physically distinct from compacted Escherichia coli nucleoid under stationary phase. In addition, potential new roles of nucleoid clogging in the staphylococcal life cycle will be proposed.

scholarly journals Cyclo-(L-Phe-L-Pro), a Quorum-Sensing Signal ofVibrio vulnificus, Induces Expression of Hydroperoxidase through a ToxR-LeuO-HU-RpoS Signaling Pathway To Confer Resistance against Oxidative Stress

2018 ◽  
Vol 86 (9) ◽  
Author(s):  
In Hwang Kim ◽  
So-Yeon Kim ◽  
Na-Young Park ◽  
Yancheng Wen ◽  
Keun-Woo Lee ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Signaling Pathway ◽  
Virulence Factor ◽  
Vibrio Vulnificus ◽  
Transcriptional Regulator ◽  
Oxygen Species ◽  
Human Pathogen ◽  
Content Type ◽  
Opportunistic Human Pathogen ◽  
Bacterial Genes

ABSTRACTVibrio vulnificus, an opportunistic human pathogen, produces cyclo-(l-Phe-l-Pro) (cFP), which serves as a signaling molecule controlling the ToxR-dependent expression of innate bacterial genes, and also as a virulence factor eliciting pathogenic effects on human cells by enhancing intracellular reactive oxygen species levels. We found that cFP facilitated the protection ofV. vulnificusagainst hydrogen peroxide. At a concentration of 1 mM, cFP enhanced the level of the transcriptional regulator RpoS, which in turn induced expression ofkatG, encoding hydroperoxidase I, an enzyme that detoxifies H2O2to overcome oxidative stress. We found that cFP upregulated the transcription of the histone-like proteins vHUα and vHUβ through the cFP-dependent regulator LeuO. LeuO binds directly to upstream regions ofvhuAandvhuBto enhance transcription. vHUα and vHUβ then enhance the level of RpoS posttranscriptionally by stabilizing the mRNA. This cFP-mediated ToxR-LeuO-vHUαβ-RpoS pathway also upregulates genes known to be members of the RpoS regulon, suggesting that cFP acts as a cue for the signaling pathway responsible for both the RpoS and the LeuO regulons. Taken together, this study shows that cFP plays an important role as a virulence factor, as well as a signal for the protection of the cognate pathogen.

scholarly journals The Protective Role of 1,8-Dihydroxynaphthalene–Melanin on Conidia of the Opportunistic Human Pathogen Aspergillus fumigatus Revisited: No Role in Protection against Hydrogen Peroxide and Superoxides

mSphere ◽  
2022 ◽  
Author(s):  
E. M. Keizer ◽  
I. D. Valdes ◽  
B. L. McCann ◽  
E. M. Bignell ◽  
H. A. B. Wösten ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Aspergillus Fumigatus ◽  
Protective Role ◽  
Oxygen Species ◽  
Human Pathogen ◽  
Opportunistic Pathogens ◽  
Green Pigment ◽  
Content Type ◽  
Opportunistic Human Pathogen

Opportunistic pathogens like Aspergillus fumigatus have strategies to protect themselves against reactive oxygen species like hydrogen peroxides and superoxides that are produced by immune cells. DHN-melanin is the green pigment on conidia of Aspergillus fumigatus and more than 2 decades ago was reported to protect conidia against hydrogen peroxide.

scholarly journals Astaxanthin-Loaded Nanostructured Lipid Carriers for Preservation of Antioxidant Activity

Molecules ◽  
2018 ◽  
Vol 23 (10) ◽  
pp. 2601 ◽  
Author(s):  
Violeta Rodriguez-Ruiz ◽  
José Salatti-Dorado ◽  
Abolfazl Barzegari ◽  
Alba Nicolas-Boluda ◽  
Amel Houaoui ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Electron Microscopy ◽  
Antioxidant Activity ◽  
Charged Particles ◽  
Nanostructured Lipid Carriers ◽  
Green Process ◽  
Force Microscopy ◽  
Atomic Force ◽  
Interesting Candidate ◽  
Microscopy Techniques

Astaxanthin is a xanthophyll carotenoid showing efficient scavenging ability and represents an interesting candidate in the development of new therapies for preventing and treating oxidative stress-related pathologies. However, its high lipophilicity and thermolability often limits its antioxidant efficacy in human applications. Here, we developed a formulation of lipid carriers to protect astaxanthin’s antioxidant activity. The synthesis of natural astaxanthin-loaded nanostructured lipid carriers using a green process with sunflower oil as liquid lipid is presented. Their antioxidant activity was measured by α-Tocopherol Equivalent Antioxidant Capacity assay and was compared to those of both natural astaxanthin and α-tocopherol. Characterizations by dynamic light scattering, atomic force microscopy, and scattering electron microscopy techniques were carried out and showed spherical and surface negative charged particles with z-average and polydispersity values of ~60 nm and ~0.3, respectively. Astaxanthin loading was also investigated showing an astaxanthin recovery of more than 90% after synthesis of nanostructured lipid carriers. These results demonstrate the capability of the formulation to stabilize astaxanthin molecule and preserve and enhance the antioxidant activity.

Identification of Scedosporium boydii catalase A1 gene, a reactive oxygen species detoxification factor highly expressed in response to oxidative stress and phagocytic cells

2015 ◽  
Vol 119 (12) ◽  
pp. 1322-1333 ◽  
Author(s):  
Sara Mina ◽  
Cindy Staerck ◽  
Sènan M. d'Almeida ◽  
Agnès Marot ◽  
Yves Delneste ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Reactive Oxygen Species ◽  
Reactive Oxygen ◽  
Oxygen Species ◽  
Phagocytic Cells

scholarly journals Molecular strategy for blocking isopeptide bond formation in nascent pilin proteins

2018 ◽  
Vol 115 (37) ◽  
pp. 9222-9227 ◽  
Author(s):  
Jaime Andrés Rivas-Pardo ◽  
Carmen L. Badilla ◽  
Rafael Tapia-Rojo ◽  
Álvaro Alonso-Caballero ◽  
Julio M. Fernández
Keyword(s):  
Bond Formation ◽  
Host Cells ◽  
Human Pathogen ◽  
Gram Positive ◽  
Force Microscopy ◽  
Gram Positive Bacteria ◽  
Isopeptide Bond ◽  
Atomic Force ◽  
Isopeptide Bonds ◽  
Single Polypeptide

Bacteria anchor to their host cells through their adhesive pili, which must resist the large mechanical stresses induced by the host as it attempts to dislodge the pathogens. The pili of gram-positive bacteria are constructed as a single polypeptide made of hundreds of pilin repeats, which contain intramolecular isopeptide bonds strategically located in the structure to prevent their unfolding under force, protecting the pilus from degradation by extant proteases and oxygen radicals. Here, we demonstrate the design of a short peptide that blocks the formation of the isopeptide bond present in the pilin Spy0128 from the human pathogen Streptococcus pyogenes, resulting in mechanically labile pilin domains. We use a combination of protein engineering and atomic-force microscopy force spectroscopy to demonstrate that the peptide blocks the formation of the native isopeptide bond and compromises the mechanics of the domain. While an intact Spy0128 is inextensible at any force, peptide-modified Spy0128 pilins readily unfold at very low forces, marking the abrogation of the intramolecular isopeptide bond as well as the absence of a stable pilin fold. We propose that isopeptide-blocking peptides could be further developed as a type of highly specific antiadhesive antibiotics to treat gram-positive pathogens.

scholarly journals Determining the Cytotoxicity of Oxidized Lipids in Cultured Caco-2 Cells Using Bioimaging Techniques

Molecules ◽  
2020 ◽  
Vol 25 (7) ◽  
pp. 1693
Author(s):  
Rabia Alghazeer ◽  
Abdullah A. Burwaiss ◽  
Nazlin K. Howell ◽  
Wafa S. Alansari ◽  
Ghalia Shamlan ◽  
...  
Keyword(s):  
Lipid Membrane ◽  
Electron Spin Resonance Spectroscopy ◽  
Oxidized Lipids ◽  
Resonance Spectroscopy ◽  
Oxygen Species ◽  
Structural Alterations ◽  
Biochemical Alterations ◽  
Force Microscopy ◽  
Atomic Force ◽  
Spin Resonance

Fish lipids are comprised of considerable quantities of polyunsaturated acids and are prone to oxidation, producing reactive oxygen species and hydroperoxides. This study aimed to evaluate the biochemical and structural alterations in Caco-2 cells following exposure to 100 μg/mL methyl linoleate or fish oil, and then radiated for 24, 48 or 72 h. Electron spin resonance spectroscopy detected free radicals in the lipid membrane, Raman microscopy observed biochemical alterations and atomic force microscopy identified changes in morphology, such as the breakdown of DNA bonds. The study showed that bioimaging and biochemical techniques can be effective at detecting and diagnosing cellular injuries incurred by lipid peroxidation.

Rod-shaped gold nanoparticles exert potent candidacidal activity and decrease the adhesion of fungal cells

Nanomedicine ◽  
2020 ◽  
Author(s):  
Ewelina Piktel ◽  
Łukasz Suprewicz ◽  
Joanna Depciuch ◽  
Mateusz Cieśluk ◽  
Sylwia Chmielewska ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Fungicidal Activity ◽  
Fungal Infections ◽  
Drug Susceptibility ◽  
Host Cells ◽  
Oxygen Species ◽  
Au Nps ◽  
Force Microscopy ◽  
Atomic Force ◽  
Colony Counting

Aim: To investigate the fungicidal activity of rod-shaped gold nanoparticles (AuR NPs) against Candida strains isolated from hematooncological patients and representative strains of filamentous fungi. Methods: Colony-counting assays, colorimetric and fluorometric methods and atomic force microscopy were employed. Results: AuR NPs were characterized by their potent fungicidal activity against all tested isolates, regardless of the species or drug susceptibility, at concentrations that are nontoxic to the host cells. The membrane-permeabilizing properties of AuR NPs and induction of reactive oxygen species were recognized as crucial for fungicidal activity. Conclusions: The results provide a rationale for the development of nonspherical Au NPs as effective antifungals or drug-delivery carriers to improve therapy for fungal infections.

Structural and functional features of Rhodococcus ruber lipoarabinomannan

Microbiology ◽  
2003 ◽  
Vol 149 (6) ◽  
pp. 1437-1445 ◽  
Author(s):  
Kevin J. C. Gibson ◽  
Martine Gilleron ◽  
Patricia Constant ◽  
Germain Puzo ◽  
Jérôme Nigou ◽  
...  
Keyword(s):  
Cell Envelope ◽  
Anomeric Proton ◽  
Phylogenetic Group ◽  
Chemical Degradation ◽  
Rhodococcus Ruber ◽  
Human Pathogen ◽  
Phagocytic Cells ◽  
Isolation And Characterization ◽  
Functional Features ◽  
Opportunistic Human Pathogen

The genus Rhodococcus is part of the phylogenetic group nocardioform actinomycetes, which also includes the genus Mycobacterium. Members of this phylogenetic group have a characteristic cell envelope structure, which is dominated by various complex lipids. Among these, lipoglycans are of particular interest since mycobacterial lipoarabinomannans are important immunomodulatory molecules that are likely to be involved in the subsequent fate of mycobacterial bacilli once inside phagocytic cells. Rhodococcus ruber is a species closely related to an established opportunistic human pathogen, Rhodococcus equi. This paper reports the isolation and characterization of R. ruber lipoarabinomannan, designated as RruLAM. SDS-PAGE and gas chromatography analyses revealed that RruLAM was of an intermediate size between Mycobacterium tuberculosis lipoarabinomannan and lipomannan. Using a combination of chemical degradation and 1H, 13C-NMR experiments, the carbohydrate structure of RruLAM was unambiguously shown to be composed of a linear (α1→6)-Manp backbone substituted at some O-2 positions by a single t-α-Araf sugar unit. Integration of the anomeric proton signals provided an indication of the degree of branching as approximately 45 %. The RruLAM structure is much simpler than that established for M. tuberculosis lipoarabinomannan but is also different from that determined for the closely related species and opportunistic human pathogen, R. equi. RruLAM was unable to induce the production of TNF-α by either human or murine macrophage cell lines, suggesting that more sophisticated structures, such as phosphoinositol capping motifs, are required for such activity.

Sign in / Sign up

Export Citation Format

Share Document