scholarly journals Amino acid deprivation and central carbon metabolism regulate the production of outer membrane vesicles and tubes byFrancisella

2018 ◽  
Vol 107 (4) ◽  
pp. 523-541 ◽  
Author(s):  
Vinaya Sampath ◽  
William D. McCaig ◽  
David G. Thanassi
Keyword(s):  
Amino Acid ◽  
Outer Membrane ◽  
Carbon Metabolism ◽  
Membrane Vesicles ◽  
Central Carbon Metabolism ◽  
Outer Membrane Vesicles ◽  
Amino Acid Deprivation ◽  
Central Carbon

scholarly journals Transcriptomic Analysis of the Influence of Methanol Assimilation on the Gene Expression in the Recombinant Pichia pastoris Producing Hirudin Variant 3

Genes ◽  
2019 ◽  
Vol 10 (8) ◽  
pp. 606 ◽  
Author(s):  
Li ◽  
Ma ◽  
Xu ◽  
Wang ◽  
Wang ◽  
...  
Keyword(s):  
Gene Expression ◽  
Amino Acid ◽  
Pichia Pastoris ◽  
Carbon Metabolism ◽  
Fermentation Broth ◽  
Alcohol Oxidase ◽  
Central Carbon Metabolism ◽  
Recombinant Pichia Pastoris ◽  
Central Carbon ◽  
Almost All

Hirudin and its variants, as strong inhibitors against thrombin, are present in the saliva of leeches and are recognized as potent anticoagulants. However, their yield is far from the clinical requirement up to now. In this study, the production of hirudin variant 3 (HV3) was successfully realized by cultivating the recombinant Pichia pastoris GS115/pPIC9K-hv3 under the regulation of the promoter of AOX1 encoding alcohol oxidase (AOX). The antithrombin activity in the fermentation broth reached the maximum value of 5000 ATU/mL. To explore an effective strategy for improving HV3 production in the future, we investigated the influence of methanol assimilation on the general gene expression in this recombinant by transcriptomic study. The results showed that methanol was partially oxidized into CO2, and the rest was converted into glycerone-P which subsequently entered into central carbon metabolism, energy metabolism, and amino acid biosynthesis. However, the later metabolic processes were almost all down-regulated. Therefore, we propose that the up-regulated central carbon metabolism, energy, and amino acid metabolism should be beneficial for methanol assimilation, which would accordingly improve the production of HV3.

scholarly journals Outer Membrane Vesicles Released From Aeromonas Strains Are Involved in the Biofilm Formation

2021 ◽  
Vol 11 ◽  
Author(s):  
Soshi Seike ◽  
Hidetomo Kobayashi ◽  
Mitsunobu Ueda ◽  
Eizo Takahashi ◽  
Keinosuke Okamoto ◽  
...  
Keyword(s):  
Amino Acid ◽  
Outer Membrane ◽  
Biofilm Formation ◽  
Bacterial Species ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Amino Acid Sequences ◽  
Bacterial Biofilm ◽  
Gram Negative Bacteria ◽  
Gram Negative

Aeromonas spp. are Gram-negative rod-shaped bacteria ubiquitously distributed in diverse water sources. Several Aeromonas spp. are known as human and fish pathogens. Recently, attention has been focused on the relationship between bacterial biofilm formation and pathogenicity or drug resistance. However, there have been few reports on biofilm formation by Aeromonas. This study is the first to examine the in vitro formation and components of the biofilm of several Aeromonas clinical and environmental strains. A biofilm formation assay using 1% crystal violet on a polystyrene plate revealed that most Aeromonas strains used in this study formed biofilms but one strain did not. Analysis of the basic components contained in the biofilms formed by Aeromonas strains confirmed that they contained polysaccharides containing GlcNAc, extracellular nucleic acids, and proteins, as previously reported for the biofilms of other bacterial species. Among these components, we focused on several proteins fractionated by SDS-PAGE and determined their amino acid sequences. The results showed that some proteins existing in the Aeromonas biofilms have amino acid sequences homologous to functional proteins present in the outer membrane of Gram-negative bacteria. This result suggests that outer membrane components may affect the biofilm formation of Aeromonas strains. It is known that Gram-negative bacteria often release extracellular membrane vesicles from the outer membrane, so we think that the outer membrane-derived proteins found in the Aeromonas biofilms may be derived from such membrane vesicles. To examine this idea, we next investigated the ability of Aeromonas strains to form outer membrane vesicles (OMVs). Electron microscopic analysis revealed that most Aeromonas strains released OMVs outside the cells. Finally, we purified OMVs from several Aeromonas strains and examined their effect on the biofilm formation. We found that the addition of OMVs dose-dependently promoted biofilm formation, except for one strain that did not form biofilms. These results suggest that the OMVs released from the bacterial cells are closely related to the biofilm formation of Aeromonas strains.

scholarly journals Implications of central carbon metabolism in SARS-CoV-2 replication and disease severity

2021 ◽  
Author(s):  
Shuba Krishnan ◽  
Hampus Nordqvist ◽  
Anoop T. Ambikan ◽  
Soham Gupta ◽  
Maike Sperk ◽  
...  
Keyword(s):  
Amino Acid ◽  
Disease Severity ◽  
Carbon Metabolism ◽  
Metabolic Pathways ◽  
Central Carbon Metabolism ◽  
Lung Epithelial Cells ◽  
Metabolic Adaptation ◽  
Altered Expression ◽  
Central Carbon

AbstractViruses hijack host metabolic pathways for their replicative advantage. Several observational trans-omics analyses associated carbon and amino acid metabolism in coronavirus disease 2019 (COVID-19) severity in patients but lacked mechanistic insights. In this study, using patient- derived multi-omics data and in vitro infection assays, we aimed to understand i) role of key metabolic pathways in severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) reproduction and ii) its association with disease severity. Our data suggests that monocytes are key to the altered immune response during COVID-19. COVID-19 infection was associated with increased plasma glutamate levels, while glucose and mannose levels were determinants of the disease severity. Monocytes showed altered expression pattern of carbohydrate and amino acid transporters, GLUT1 and xCT respectively in severe COVID-19. Furthermore, lung epithelial cells (Calu-3) showed a strong acute metabolic adaptation following infection in vitro by modulating central carbon metabolism. We found that glycolysis and glutaminolysis are essential for virus replication and blocking these metabolic pathways caused significant reduction in virus production. Taken together, our study highlights that the virus utilizes and re-wires pathways governing central carbon metabolism leading to metabolic toxicity. Thus, the host metabolic perturbation could be an attractive strategy to limit the viral replication and disease severity.

Electrophysiological Characterization of Transport Across Outer Membrane Channels from Gram-Negative Bacteria in Their Native Environment

2019 ◽  
Author(s):  
Jiajun Wang ◽  
Rémi Terrasse ◽  
Jayesh Arun Bafna ◽  
Lorraine Benier ◽  
Mathias Winterhalter
Keyword(s):  
Outer Membrane ◽  
Lipid Membrane ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Multi Drug Resistance ◽  
Gram Negative Bacteria ◽  
Membrane Channels ◽  
Gram Negative ◽  
Electrophysiological Characterization

Multi-drug resistance in Gram-negative bacteria is often associated with low permeability of the outer membrane. To investigate the role of membrane channels in the uptake of antibiotics, we extract, purify and reconstitute them into artificial planar membranes. To avoid this time-consuming procedure, here we show a robust approach using fusion of native outer membrane vesicles (OMV) into planar lipid bilayer which moreover allows also to some extend the characterization of membrane protein channels in their native environment. Two major membrane channels from <i>Escherichia coli</i>, OmpF and OmpC, were overexpressed from the host and the corresponding OMVs were collected. Each OMV fusion revealed surprisingly single or only few channel activities. The asymmetry of the OMV´s translates after fusion into the lipid membrane with the LPS dominantly present at the side of OMV addition. Compared to conventional reconstitution methods, the channels fused from OMVs containing LPS have similar conductance but a much broader distribution. The addition of Enrofloxacin on the LPS side yields somewhat higher association (<i>k<sub>on</sub></i>) and lower dissociation (<i>k<sub>off</sub></i>) rates compared to LPS-free reconstitution. We conclude that using outer membrane vesicles is a fast and easy approach for functional and structural studies of membrane channels in the native membrane.

Sign in / Sign up

Export Citation Format

Share Document