scholarly journals Disrupting folate metabolism alters the capacity of bacteria in exponential growth to develop persisters to antibiotics

2018 ◽  
Author(s):  
Jasmine Morgan ◽  
Matthew Smith ◽  
Mark T. Mc Auley ◽  
J. Enrique Salcedo-Sora
Keyword(s):  
Gene Expression ◽  
Exponential Growth ◽  
Folate Metabolism ◽  
Exponential Growth Phase ◽  
Clinical Settings ◽  
Aberrant Expression ◽  
Enzyme Gene ◽  
Gene Expression Analyses ◽  
Folate Biosynthesis ◽  
High Doses

AbstractBacteria can survive high doses of antibiotics through stochastic phenotypic diversification.We present initial evidence that folate metabolism could be involved with the formation of persisters. The aberrant expression of the folate enzyme genefauseems to reduce the incidence of persisters to antibiotics. Folate impaired bacteria had a lower generation rate for persisters to both antibiotics ampicillin and ofloxacin. Persister bacteria were detectable from the outset of the exponential growth phase in the complex media. Gene expression analyses showed tentatively distinctive profiles in exponential growth at times when bacteria persisters were observed. Levels of persisters were assessed in bacteria with altered, genetically and pharmacologically, folate metabolism. This work shows that by disrupting folate biosynthesis and usage, bacterial tolerance to antibiotics seems to be diminished. Based on these findings there is a possibility that bacteriostatic antibiotics such as antifolates could have a role to play in clinical settings where the incidence of antibiotic persisters seem to drive recalcitrant infections.

scholarly journals Gene expression analysis of Alcaligenes faecalis during induction of heterotrophic nitrification

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Shuhei Tsujino ◽  
Hideo Dohra ◽  
Taketomo Fujiwara
Keyword(s):  
Gene Expression ◽  
Growth Phase ◽  
Exponential Growth ◽  
Alcaligenes Faecalis ◽  
Heterotrophic Nitrification ◽  
Exponential Growth Phase ◽  
Primary Metabolism ◽  
Valuable Insight ◽  
Gene Encoding ◽  
Expression Levels

AbstractAlcaligenes faecalis is a heterotrophic nitrifying bacterium that oxidizes ammonia and generates nitrite and nitrate. When A. faecalis was cultivated in a medium containing pyruvate and ammonia as the sole carbon and nitrogen sources, respectively, high concentrations of nitrite accumulated in the medium whose carbon/nitrogen (C/N) ratio was lower than 10 during the exponential growth phase, while the accumulation was not observed in the medium whose C/N ratio was higher than 15. Comparative transcriptome analysis was performed using nitrifying and non-nitrifying cells of A. faecalis cultivated in media whose C/N ratios were 5 and 20, respectively, to evaluate the fluctuations of gene expression during induction of heterotrophic nitrification. Expression levels of genes involved in primary metabolism did not change significantly in the cells at the exponential growth phase under both conditions. We observed a significant increase in the expression levels of four gene clusters: pod cluster containing the gene encoding pyruvic oxime dioxygenase (POD), podh cluster containing the gene encoding a POD homolog (PODh), suf cluster involved in an iron-sulfur cluster biogenesis, and dnf cluster involved in a novel hydroxylamine oxidation pathway in the nitrifying cells. Our results provide valuable insight into the biochemical mechanism of heterotrophic nitrification.

scholarly journals Interplay of CodY and ScoC in the Regulation of Major Extracellular Protease Genes of Bacillus subtilis

2016 ◽  
Vol 198 (6) ◽  
pp. 907-920 ◽  
Author(s):  
Giulia Barbieri ◽  
Alessandra M. Albertini ◽  
Eugenio Ferrari ◽  
Abraham L. Sonenshein ◽  
Boris R. Belitsky
Keyword(s):  
Gene Expression ◽  
Bacillus Subtilis ◽  
Growth Phase ◽  
Exponential Growth ◽  
Degradation Products ◽  
Transcriptional Regulator ◽  
Complex Medium ◽  
Exponential Growth Phase ◽  
Content Type ◽  
In Cells

ABSTRACTAprE and NprE are two major extracellular proteases inBacillus subtiliswhose expression is directly regulated by several pleiotropic transcriptional factors, including AbrB, DegU, ScoC, and SinR. In cells growing in a rich, complex medium, theaprEandnprEgenes are strongly expressed only during the post-exponential growth phase; mutations in genes encoding the known regulators affect the level of post-exponential-phase gene expression but do not permit high-level expression during the exponential growth phase. Using DNA-binding assays and expression and mutational analyses, we have shown that the genes for both exoproteases are also under strong, direct, negative control by the global transcriptional regulator CodY. However, because CodY also repressesscoC, little or no derepression ofaprEandnprEwas seen in acodYnull mutant due to overexpression ofscoC. Thus, CodY is also an indirect positive regulator of these genes by limiting the synthesis of a second repressor. In addition, in cells growing under conditions that activate CodY, ascoCnull mutation had little effect onaprEornprEexpression; full effects ofscoCorcodYnull mutations could be seen only in the absence of the other regulator. However, even thecodY scoCdouble mutant did not show high levels ofaprEandnprEgene expression during exponential growth phase in a rich, complex medium. Only a third mutation, inabrB, allowed such expression. Thus, three repressors can contribute to reducing exoprotease gene expression during growth in the presence of excess nutrients.IMPORTANCEThe majorBacillus subtilisexoproteases, AprE and NprE, are important metabolic enzymes whose genes are subject to complex regulation by multiple transcription factors. We show here that expression of theaprEandnprEgenes is also controlled, both directly and indirectly, by CodY, a global transcriptional regulator that responds to the intracellular pools of amino acids. Direct CodY-mediated repression explains a long-standing puzzle, that is, why exoproteases are not produced when cells are growing exponentially in a medium containing abundant quantities of proteins or their degradation products. Indirect regulation ofaprEandnprEthrough CodY-mediated repression of thescoCgene, encoding another pleiotropic repressor, serves to maintain a significant level of repression of exoprotease genes when CodY loses activity.

scholarly journals Global gene expression analysis of Streptococcus agalactiae at exponential growth phase

2020 ◽  
Author(s):  
Inês Silvestre ◽  
Vítor Borges ◽  
Sílvia Duarte ◽  
Alexandra Nunes ◽  
Rita Sobral ◽  
...  
Keyword(s):  
Gene Expression ◽  
Growth Phase ◽  
Exponential Growth ◽  
Streptococcus Agalactiae ◽  
Molecular Mechanisms ◽  
Reference Strain ◽  
Global Gene Expression ◽  
Exponential Growth Phase ◽  
Expression Levels

AbstractStreptococcus agalactiae is a leading cause of neonatal infections and an increasing cause of infections in adults with underlying diseases. One of the first S. agalactiae isolates to be subjected to whole genome sequencing was NEM316, a strain responsible for a fatal case of septicemia that has been widely used as reference strain for in vitro assays. Whole transcriptome analyses may provide an essential contribute to the understanding of the molecular mechanisms responsible for bacteria adaptation and pathogenicity, still, so far, very few studies were dedicated to the analysis of global gene expression of S. agalactiae. Here, we applied RNA-sequencing to perform a comparative overview of the global gene expression levels of the S. agalactiae reference strain NEM316 at the exponential growth phase. Genes were ranked by expression level and grouped by functional category and 46% of the top-100 expressed genes encode proteins involved in “Translation, ribosomal structure and biogenesis”. Among the group of highly expressed genes were also represented genes with no assigned functional category. Although this result warrants further investigation, most of them might be implicated in stress response. As very little is known about the molecular mechanisms behind the release of DNase’s in vitro and in vivo, we also performed preliminary assays to understand whether direct DNA exposure affects the gene expression of strain NEM316 at the exponential growth phase. No differentially expressed genes were detected, which indicates that follow-up studies are needed to disclose the complex molecular pathways (and stimuli) triggering the release of DNase’s. In general, we provide data on the global expression levels of NEM316 at exponential growth phase that may contribute to better understand S. agalactiae adaptation and virulence.

scholarly journals Aberrant expression of USF2 in refractory rheumatoid arthritis and its regulation of proinflammatory cytokines in Th17 cells

2020 ◽  
Vol 117 (48) ◽  
pp. 30639-30648
Author(s):  
Dan Hu ◽  
Emily C. Tjon ◽  
Karin M. Andersson ◽  
Gabriela M. Molica ◽  
Minh C. Pham ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Gene Expression ◽  
T Cells ◽  
Transcription Factor ◽  
Proinflammatory Cytokines ◽  
Th17 Cells ◽  
Gene Set Enrichment Analysis ◽  
Aberrant Expression ◽  
Signature Genes ◽  
The Impact

IL-17–producing Th17 cells are implicated in the pathogenesis of rheumatoid arthritis (RA) and TNF-α, a proinflammatory cytokine in the rheumatoid joint, facilitates Th17 differentiation. Anti-TNF therapy ameliorates disease in many patients with rheumatoid arthritis (RA). However, a significant proportion of patients do not respond to this therapy. The impact of anti-TNF therapy on Th17 responses in RA is not well understood. We conducted high-throughput gene expression analysis of Th17-enriched CCR6+CXCR3−CD45RA−CD4+T (CCR6+T) cells isolated from anti-TNF–treated RA patients classified as responders or nonresponders to therapy. CCR6+T cells from responders and nonresponders had distinct gene expression profiles. Proinflammatory signaling was elevated in the CCR6+T cells of nonresponders, and pathogenic Th17 signature genes were up-regulated in these cells. Gene set enrichment analysis on these signature genes identified transcription factor USF2 as their upstream regulator, which was also increased in nonresponders. Importantly, short hairpin RNA targetingUSF2in pathogenic Th17 cells led to reduced expression of proinflammatory cytokines IL-17A, IFN-γ, IL-22, and granulocyte-macrophage colony-stimulating factor (GM-CSF) as well as transcription factor T-bet. Together, our results revealed inadequate suppression of Th17 responses by anti-TNF in nonresponders, and direct targeting of the USF2-signaling pathway may be a potential therapeutic approach in the anti-TNF refractory RA.

scholarly journals Silymarin-Enriched Biostimulant Foliar Application Minimizes the Toxicity of Cadmium in Maize by Suppressing Oxidative Stress and Elevating Antioxidant Gene Expression

Biomolecules ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 465
Author(s):  
Hesham F. Alharby ◽  
Hassan S. Al-Zahrani ◽  
Khalid R. Hakeem ◽  
Hameed Alsamadany ◽  
El-Sayed M. Desoky ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Gene Expression ◽  
Lipid Peroxidation ◽  
Antioxidative Enzymes ◽  
Irrigation Water ◽  
Foliar Spray ◽  
Cd Stress ◽  
Enzyme Gene ◽  
Maize Plants ◽  
Maize Grain

For maize, the potential preventive role of foliar spraying with an extract derived from maize grain (MEg, 2%), silymarin (Sm, 0.5 mM), or silymarin-enriched MEg (MEg-Sm) in attenuating the stress effects of cadmium (Cd, 0.5 mM) was examined using a completely randomized design layout. Under normal conditions, foliar spraying with MEg, Sm, or MEg-Sm was beneficial (with MEg-Sm preferred) for maize plants, whereas the benefit was more pronounced under Cd stress. The use of Cd through irrigation water decreased plant growth traits, photosynthetic efficiency, including instantaneous carboxylation efficiency, Fv/Fm, and pigment contents, and hormonal contents (e.g., auxin, gibberellins, cytokinins including trans-zeatin, and salicylic acid). These undesired findings were due to an increase in Cd content, leading to increased levels of oxidative stress (O2•− and H2O2), ionic leakage, and lipid peroxidation. Therefore, this damage resulted in an increase in the activities of nonenzymatic antioxidants, Sm, antioxidative enzymes, and enzyme gene expression. However, under Cd stress, although foliar spray with MEg or Sm had better findings than control, MEg-Sm had better findings than MEg or Sm. Application of MEg-Sm greatly increased photosynthesis efficiency, restored hormonal homeostasis, and further increased the activities of various antioxidants, Sm, antioxidative enzymes, and enzyme gene expression. These desired findings were due to the suppression of the Cd content, and thus the levels of O2•−, H2O2, ionic leakage, and lipid peroxidation, which were positively reflected in the growth and accumulation of dry matter in maize plants. The data obtained in this study recommend applying silymarin-enriched maize grain extract (MEg-Sm at 0.24 g Sm L−1 of MEg) as a spray solution to maize plants when exposed to excess Cd in soil or irrigation water.

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