scholarly journals Comparison of Sterol Import under Aerobic and Anaerobic Conditions in Three Fungal Species, Candida albicans, Candida glabrata, and Saccharomyces cerevisiae

2013 ◽  
Vol 12 (5) ◽  
pp. 725-738 ◽  
Author(s):  
Martin Zavrel ◽  
Sam J. Hoot ◽  
Theodore C. White
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Candida Albicans ◽  
Exponential Growth ◽  
Candida Glabrata ◽  
Fungal Species ◽  
Growth Phases ◽  
Anaerobic Conditions ◽  
Content Type ◽  
Aerobic And Anaerobic ◽  
Aerobic And Anaerobic Conditions

ABSTRACTSterol import has been characterized under various conditions in three distinct fungal species, the model organismSaccharomyces cerevisiaeand two human fungal pathogensCandida glabrataandCandida albicans, employing cholesterol, the sterol of higher eukaryotes, as well as its fungal equivalent, ergosterol. Import was confirmed by the detection of esterified cholesterol within the cells. Comparing the three fungal species, we observe sterol import under three different conditions. First, as previously well characterized, we observe sterol import under low oxygen levels inS. cerevisiaeandC. glabrata, which is dependent on the transcription factor Upc2 and/or its orthologs or paralogs. Second, we observe sterol import under aerobic conditions exclusively in the two pathogenic fungiC. glabrataandC. albicans. Uptake emerges during post-exponential-growth phases, is independent of the characterized Upc2-pathway and is slower compared to the anaerobic uptake inS. cerevisiaeandC. glabrata. Third, we observe under normoxic conditions inC. glabratathat Upc2-dependent sterol import can be induced in the presence of fetal bovine serum together with fluconazole. In summary,C. glabrataimports sterols both in aerobic and anaerobic conditions, and the limited aerobic uptake can be further stimulated by the presence of serum together with fluconazole.S. cerevisiaeimports sterols only in anaerobic conditions, demonstrating aerobic sterol exclusion. Finally,C. albicansimports sterols exclusively aerobically in post-exponential-growth phases, independent of Upc2. For the first time, we provide direct evidence of sterol import into the human fungal pathogenC. albicans, which until now was believed to be incapable of active sterol import.

scholarly journals Pseudomonas aeruginosa Regulatory Protein AnvM Controls Pathogenicity in Anaerobic Environments and Impacts Host Defense

mBio ◽  
2019 ◽  
Vol 10 (4) ◽  
Author(s):  
Yingchao Zhang ◽  
Chuan-min Zhou ◽  
Qinqin Pu ◽  
Qun Wu ◽  
Shirui Tan ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Immune Response ◽  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Anaerobic Conditions ◽  
Content Type ◽  
Sensing System ◽  
Quorum Sensing System ◽  
Aerobic And Anaerobic ◽  
Aerobic And Anaerobic Conditions

ABSTRACT Pseudomonas aeruginosa, one of the most common pathogens in hospital-acquired infections, is tightly controlled by a multilayered regulatory network, including the quorum sensing system (QS), the type VI secretion system (T6SS), and resistance to host immunity. We found that the P. aeruginosa 3880 (PA3880) gene, which encodes an unknown protein, acts as a regulator of anaerobic metabolism in response to oxidative stress and virulence in P. aeruginosa. More than 30 PA3880 homologs were found in other bacterial genomes, indicating that PA3880 is widely distributed in the Bacteria kingdom as a highly conserved gene. Deletion of the PA3880 gene changed the expression levels of more than 700 genes, including a group of virulence genes, under both aerobic and anaerobic conditions. To further study the mechanisms of PA3880-mediated regulation in virulence, we utilized a bacterial two-hybrid assay and found that the PA3880 protein interacted directly with QS regulator MvfR and anaerobic regulator Anr. Loss of the PA3880 protein significantly blunted the pathogenicity of P. aeruginosa, resulting in increased host survival, decreased bacterial burdens, reduced inflammatory responses, and fewer lung injuries in challenged mice hosts. Mechanistically, we found that Cys44 was a critical site for the full function of PA3880 in influencing alveolar macrophage phagocytosis and bacterial clearance. We also found that AnvM directly interacted with host receptors Toll-like receptor 2 (TLR2) and TLR5, which might lead to activation of the host immune response. Hence, we gave the name AnvM (anaerobic and virulence modulator) to the PA3880 protein. This characterization of AnvM could help to uncover new targets and strategies to treat P. aeruginosa infections. IMPORTANCE Infections by Pseudomonas aeruginosa, one of the most frequently isolated human pathogens, can create huge financial burdens. However, knowledge of the molecular mechanisms involved in the pathogenesis of P. aeruginosa remains elusive. We identified AnvM as a novel regulator of virulence in P. aeruginosa. Deletion of anvM altered the expression levels of more than 700 genes under aerobic and anaerobic conditions, including quorum sensing system genes and oxidative stress resistance genes. AnvM directly interacted with MvfR and Anr, thus regulating their downstream genes. More importantly, AnvM directly bound to TLR2 and TLR5, which turn on the host immune response. These findings provide insights into the significance of AnvM homologs in pathogenic bacteria and suggest a potential drug target against bacterial infection.

scholarly journals Development of a Stoichiometric Model for Estimation of Metabolic Fluxes in Saccharomyces cerevisiae during Tequila Production

2018 ◽  
Author(s):  
José Daniel Padilla-de la Rosa ◽  
Anne Gschaedler-Mathis ◽  
Abril Gomez-Guzman ◽  
Orfil González-Reynoso
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Flux Distribution ◽  
Central Metabolism ◽  
Anaerobic Conditions ◽  
Fermentation Processes ◽  
Distribution Maps ◽  
Stoichiometric Model ◽  
Metabolic Fluxes ◽  
Aerobic And Anaerobic ◽  
Aerobic And Anaerobic Conditions

In this study is developed an aerobic and anaerobic stoichiometric model for Saccharomyces cerevisiae, compartmentalized in mitochondria and cytosol. This model considers the central metabolism of S. cerevisiae and it possesses the peculiarity of having catabolic and anabolic biochemical reactions for the synthesis of the higher alcohols contained in tequila; involving 94 metabolites and 117 reactions; of which 93 correspond to biochemical internal reactions and 24 to transport fluxes between the medium and the cell. The model is validated under aerobic and anaerobic conditions for the main fermentation metabolites and it coincides with experimental results and those in silico reported in the literature. This model is used to obtain three different physiological states of S. cerevisiae through of estimation of its distributions of fluxes calculated from experimental data reported in literature of fermentation in continuous culture during the tequila production under different dilution rate (0.04-0.12 h-1). The model developed constitutes a tool for the estimation of flux distribution maps during fermentation processes for the production of tequila, which could permit estimate yields and visualize different fermentation scenarios.

Binary Interactions of Antagonistic Bacteria with Candida albicans Under Aerobic and Anaerobic Conditions

2015 ◽  
Vol 71 (3) ◽  
pp. 645-659 ◽  
Author(s):  
Eliska Benadé ◽  
Wendy Stone ◽  
Marnel Mouton ◽  
Ferdinand Postma ◽  
Jac Wilsenach ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Antagonistic Bacteria ◽  
Anaerobic Conditions ◽  
Aerobic And Anaerobic ◽  
Aerobic And Anaerobic Conditions

scholarly journals Aggregate Filamentous Growth Responses in Yeast

mSphere ◽  
2019 ◽  
Vol 4 (2) ◽  
Author(s):  
Jacky Chow ◽  
Heather M. Dionne ◽  
Aditi Prabhakar ◽  
Amit Mehrotra ◽  
Jenn Somboonthum ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Candida Albicans ◽  
Signaling Pathways ◽  
Budding Yeast ◽  
Filamentous Growth ◽  
Fungal Species ◽  
Fungal Pathogenesis ◽  
Invasive Growth ◽  
Content Type ◽  
Secreted Enzymes

ABSTRACTMany fungal species, including pathogens, undergo a morphogenetic response called filamentous growth, where cells differentiate into a specialized cell type to promote nutrient foraging and surface colonization. Despite the fact that filamentous growth is required for virulence in some plant and animal pathogens, certain aspects of this behavior remain poorly understood. By examining filamentous growth in the budding yeastSaccharomyces cerevisiaeand the opportunistic pathogenCandida albicans, we identify responses where cells undergo filamentous growth in groups of cells or aggregates. InS. cerevisiae, aggregate invasive growth was regulated by signaling pathways that control normal filamentous growth. These pathways promoted aggregation in part by fostering aspects of microbial cooperation. For example, aggregate invasive growth required cellular contacts mediated by the flocculin Flo11p, which was produced at higher levels in aggregates than cells undergoing regular invasive growth. Aggregate invasive growth was also stimulated by secreted enzymes, like invertase, which produce metabolites that are shared among cells. Aggregate invasive growth was also induced by alcohols that promote density-dependent filamentous growth in yeast. Aggregate invasive growth also required highly polarized cell morphologies, which may affect the packing or organization of cells. A directed selection experiment for aggregating phenotypes uncovered roles for the fMAPK and RAS pathways, which indicates that these pathways play a general role in regulating aggregate-based responses in yeast. Our study extends the range of responses controlled by filamentation regulatory pathways and has implications in understanding aspects of fungal biology that may be relevant to fungal pathogenesis.IMPORTANCEFilamentous growth is a fungal morphogenetic response that is critical for virulence in some fungal species. Many aspects of filamentous growth remain poorly understood. We have identified an aspect of filamentous growth in the budding yeastSaccharomyces cerevisiaeand the human pathogenCandida albicanswhere cells behave collectively to invade surfaces in aggregates. These responses may reflect an extension of normal filamentous growth, as they share the same signaling pathways and effector processes. Aggregate responses may involve cooperation among individual cells, because aggregation was stimulated by cell adhesion molecules, secreted enzymes, and diffusible molecules that promote quorum sensing. Our study may provide insights into the genetic basis of collective cellular responses in fungi. The study may have ramifications in fungal pathogenesis, in situations where collective responses occur to promote virulence.

Reduction of 2-substituted cyclohexanones by Saccharomyces cerevisiae under aerobic and anaerobic conditions

1992 ◽  
Vol 14 (3) ◽  
pp. 197-202 ◽  
Author(s):  
Zdeněk Wimmer ◽  
Tomáš Vaněk ◽  
Tomáš Macek ◽  
David Šaman ◽  
Aleš Svatoš
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Anaerobic Conditions ◽  
Aerobic And Anaerobic ◽  
Aerobic And Anaerobic Conditions

scholarly journals Effect of Intracellular Expression of Antimicrobial Peptide LL-37 on Growth of Escherichia coli Strain TOP10 under Aerobic and Anaerobic Conditions

2013 ◽  
Vol 57 (10) ◽  
pp. 4707-4716 ◽  
Author(s):  
Wei Liu ◽  
Shi Lei Dong ◽  
Fei Xu ◽  
Xue Qin Wang ◽  
T. Ryan Withers ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Growth Conditions ◽  
Anaerobic Growth ◽  
Anaerobic Conditions ◽  
Content Type ◽  
E Coli ◽  
Intracellular Expression ◽  
Aerobic And Anaerobic Growth ◽  
Aerobic And Anaerobic ◽  
Aerobic And Anaerobic Conditions

ABSTRACTAntimicrobial peptides (AMPs) can cause lysis of target bacteria by directly inserting themselves into the lipid bilayer. This killing mechanism confounds the identification of the intracellular targets of AMPs. To circumvent this, we used a shuttle vector containing the inducible expression of a human cathelicidin-related AMP, LL-37, to examine its effect onEscherichia coliTOP10 under aerobic and anaerobic growth conditions. Induction of LL-37 caused growth inhibition and alteration in cell morphology to a filamentous phenotype. Further examination of theE. colicell division protein FtsZ revealed that LL-37 did not interact with FtsZ. Moreover, intracellular expression of LL-37 results in the enhanced production of reactive oxygen species (ROS), causing lethal membrane depolarization under aerobic conditions. Additionally, the membrane permeability was increased after intracellular expression of LL37 under both aerobic and anaerobic conditions. Transcriptomic analysis revealed that intracellular LL-37 mainly affected the expression of genes related to energy production and carbohydrate metabolism. More specifically, genes related to oxidative phosphorylation under both aerobic and anaerobic growth conditions were affected. Collectively, our current study demonstrates that intracellular expression of LL-37 inE. colican inhibit growth under aerobic and anaerobic conditions. While we confirmed that the generation of ROS is a bactericidal mechanism for LL-37 under aerobic growth conditions, we also found that the intracellular accumulation of cationic LL-37 influences the redox and ion status of the cells under both growth conditions. These data suggest that there is a new AMP-mediated bacterial killing mechanism that targets energy metabolism.

The fate of linoleic acid on Saccharomyces cerevisiae metabolism under aerobic and anaerobic conditions

Metabolomics ◽  
2018 ◽  
Vol 14 (8) ◽  
Author(s):  
Francesca Casu ◽  
Farhana R. Pinu ◽  
Eliezer Stefanello ◽  
David R. Greenwood ◽  
Silas G. Villas-Bôas
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Linoleic Acid ◽  
Anaerobic Conditions ◽  
Aerobic And Anaerobic ◽  
Aerobic And Anaerobic Conditions

scholarly journals Antimicrobial Activity of Fosfomycin-Tobramycin Combination against Pseudomonas aeruginosa Isolates Assessed by Time-Kill Assays and Mutant Prevention Concentrations

2015 ◽  
Vol 59 (10) ◽  
pp. 6039-6045 ◽  
Author(s):  
María Díez-Aguilar ◽  
María Isabel Morosini ◽  
Ana P. Tedim ◽  
Irene Rodríguez ◽  
Zerrin Aktaş ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Wild Type ◽  
Anaerobic Conditions ◽  
Mutant Selection ◽  
Content Type ◽  
Mutant Prevention Concentration ◽  
Fosfomycin Resistance ◽  
Time Kill ◽  
Aerobic And Anaerobic ◽  
Aerobic And Anaerobic Conditions

ABSTRACTThe antibacterial activity of fosfomycin-tobramycin combination was studied by time-kill assay in eightPseudomonas aeruginosaclinical isolates belonging to the fosfomycin wild-type population (MIC = 64 μg/ml) but with different tobramycin susceptibilities (MIC range, 1 to 64 μg/ml). The mutant prevention concentration (MPC) and mutant selection window (MSW) were determined in five of these strains (tobramycin MIC range, 1 to 64 μg/ml) in aerobic and anaerobic conditions simulating environments that are present in biofilm-mediated infections. Fosfomycin-tobramycin was synergistic and bactericidal for the isolates with mutations in themexZrepressor gene, with a tobramycin MIC of 4 μg/ml. This effect was not observed in strains displaying tobramycin MICs of 1 to 2 μg/ml due to the strong bactericidal effect of tobramycin alone. Fosfomycin presented higher MPC values (range, 2,048 to >2,048 μg/ml) in aerobic and anaerobic conditions than did tobramycin (range, 16 to 256 μg/ml). Interestingly, the association rendered narrow or even null MSWs in the two conditions. However, for isolates with high-level tobramycin resistance that harbored aminoglycoside nucleotidyltransferases, time-kill assays showed no synergy, with wide MSWs in the two environments.glpTgene mutations responsible for fosfomycin resistance inP. aeruginosawere determined in fosfomycin-susceptible wild-type strains and mutant derivatives recovered from MPC studies. All mutant derivatives had changes in the GlpT amino acid sequence, which resulted in a truncated permease responsible for fosfomycin resistance. These results suggest that fosfomycin-tobramycin can be an alternative for infections due toP. aeruginosasince it has demonstrated synergistic and bactericidal activity in susceptible isolates and those with low-level tobramycin resistance. It also prevents the emergence of resistant mutants in either aerobic or anaerobic environments.

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