scholarly journals Global effects of homocysteine on transcription in Escherichia coli: induction of the gene for the major cold-shock protein, CspA

Microbiology ◽  
2006 ◽  
Vol 152 (8) ◽  
pp. 2221-2231 ◽  
Author(s):  
Katy R. Fraser ◽  
Nina L. Tuite ◽  
Arvind Bhagwat ◽  
Conor P. O'Byrne
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Growth Medium ◽  
Amino Acid Metabolism ◽  
Cold Shock ◽  
Acid Metabolism ◽  
Cold Shock Protein ◽  
Rt Pcr ◽  
Life Threatening ◽  
The Impact

Homocysteine (Hcy) is a thiol-containing amino acid that is considered to be medically important because it is linked to the development of several life-threatening diseases in humans, including cardiovascular disease and stroke. It inhibits the growth of Escherichia coli when supplied in the growth medium. Growth inhibition is believed to arise as a result of partial starvation for isoleucine, which occurs because Hcy perturbs the biosynthesis of this amino acid. This study attempted to further elucidate the inhibitory mode of action of Hcy by examining the impact of exogenously supplied Hcy on the transcriptome. Using gene macroarrays the transcript levels corresponding to 68 genes were found to be reproducibly altered in the presence of 0.5 mM Hcy. Of these genes, the biggest functional groups affected were those involved in translation (25 genes) and in amino acid metabolism (19 genes). Genes involved in protection against oxidative stress were repressed in Hcy-treated cells and this correlated with a decrease in catalase activity. The gene showing the strongest induction by Hcy was cspA, which encodes the major cold-shock protein CspA. RT-PCR and reporter fusion experiments confirmed that cspA was induced by Hcy. Induction of cspA by Hcy was not caused by nutritional upshift, a stimulus known to induce CspA expression, nor was it dependent on the presence of a functional CspA protein. The induction of cspA by Hcy was suppressed when isoleucine was included in the growth medium. These data suggest that the induction of CspA expression in the presence of Hcy occurs because of a limitation for isoleucine. The possibility that Hcy-induced cspA expression is triggered by translational stalling that occurs when the cells are limited for isoleucine is discussed.

scholarly journals Impact of Classical Strain Improvement of Penicillium rubens on Amino Acid Metabolism during β-Lactam Production

2019 ◽  
Vol 86 (3) ◽  
Author(s):  
Min Wu ◽  
Ciprian G. Crismaru ◽  
Oleksandr Salo ◽  
Roel A. L. Bovenberg ◽  
Arnold J. M. Driessen
Keyword(s):  
Amino Acid ◽  
Amino Acid Metabolism ◽  
Acid Metabolism ◽  
Strain Improvement ◽  
Tryptophan Synthase ◽  
Cysteine Biosynthesis ◽  
Penicillin Production ◽  
Content Type ◽  
Classical Strain ◽  
The Impact

ABSTRACT To produce high levels of β-lactams, the filamentous fungus Penicillium rubens (previously named Penicillium chrysogenum) has been subjected to an extensive classical strain improvement (CSI) program during the last few decades. This has led to the accumulation of many mutations that were spread over the genome. Detailed analysis reveals that several mutations targeted genes that encode enzymes involved in amino acid metabolism, in particular biosynthesis of l-cysteine, one of the amino acids used for β-lactam production. To examine the impact of the mutations on enzyme function, the respective genes with and without the mutations were cloned and expressed in Escherichia coli, purified, and enzymatically analyzed. Mutations severely impaired the activities of a threonine and serine deaminase, and this inactivates metabolic pathways that compete for l-cysteine biosynthesis. Tryptophan synthase, which converts l-serine into l-tryptophan, was inactivated by a mutation, whereas a mutation in 5-aminolevulinate synthase, which utilizes glycine, was without an effect. Importantly, CSI caused increased expression levels of a set of genes directly involved in cysteine biosynthesis. These results suggest that CSI has resulted in improved cysteine biosynthesis by the inactivation of the enzymatic conversions that directly compete for resources with the cysteine biosynthetic pathway, consistent with the notion that cysteine is a key component during penicillin production. IMPORTANCE Penicillium rubens is an important industrial producer of β-lactam antibiotics. High levels of penicillin production were enforced through extensive mutagenesis during a classical strain improvement (CSI) program over 70 years. Several mutations targeted amino acid metabolism and resulted in enhanced l-cysteine biosynthesis. This work provides a molecular explanation for the interrelation between secondary metabolite production and amino acid metabolism and how classical strain improvement has resulted in improved production strains.

Escherichia coli O157:H7 Cells Exposed to Lettuce Leaf Lysate in Refrigerated Conditions Exhibit Differential Expression of Selected Virulence and Adhesion-Related Genes with Altered Mammalian Cell Adherence

2016 ◽  
Vol 79 (7) ◽  
pp. 1259-1265 ◽  
Author(s):  
NICOLE M. KENNEDY ◽  
NABANITA MUKHERJEE ◽  
PRATIK BANERJEE
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Mammalian Cells ◽  
Pathogenic Bacteria ◽  
Cold Shock ◽  
Cold Shock Protein ◽  
Toxin Gene ◽  
Adhesion Assay ◽  
Escherichia Coli O157 ◽  
The Impact

ABSTRACT Contamination by and persistence of pathogenic bacteria in ready-to-eat produce have emerged as significant food safety and public health concerns. Viable produceborne pathogens cope with several stresses (e.g., temperature fluctuations and low-temperature storage) during production and storage of the commodities. In this study, we investigated the impact of transient cold shock on Escherichia coli O157:H7 (EcO157) cells in a produce matrix (romaine lettuce leaf lysate). EcO157 cells were exposed to 25°C for 1 h, 4°C for 1 h, and 4°C for 10 min in lettuce lysate. The expression of selected genes coding for virulence, stress response, and heat and cold shock proteins was quantified by real-time quantitative reverse transcription PCR assay. Treated EcO157 cells adhered to MAC-T mammalian cells were enumerated by in vitro bioassay. Expression of the Shiga toxin 1 gene (stx1a) was upregulated significantly (P < 0.05) upon cold shock treatments, but virulence genes related to EcO157 attachment (eaeA, lpfA, and hcpA) were down-regulated. Two key members of the cold shock regulon, cold shock protein (cspA) and gyrA, were significantly induced (P < 0.05) at the refrigeration temperature (4°C). Significant upregulation of an SOS response gene, recA, was also observed. E. coli heat shock regulon member grpE was induced, but a universal stress protein (uspA) was down-regulated at the refrigeration temperatures in lettuce lysate. The adhesion assay revealed a temperature-dependent reduction in the attachment of cold-shocked EcO157 cells. The results of the current study indicate a reduction in the attachment of cold-shocked EcO157 to epithelial cells and higher levels of Shiga toxin gene expression at the molecular level.

scholarly journals Trophic cooperation promotes bacterial survival of Staphylococcus aureus and Pseudomonas aeruginosa

2020 ◽  
Author(s):  
Laura Camus ◽  
Paul Briaud ◽  
Sylvère Bastien ◽  
Sylvie Elsen ◽  
Anne Doléans-Jordheim ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Staphylococcus Aureus ◽  
Pseudomonas Aeruginosa ◽  
Amino Acid ◽  
Amino Acid Metabolism ◽  
Acid Metabolism ◽  
Metabolic Process ◽  
Bacterial Survival ◽  
Beneficial Effects ◽  
The Impact

AbstractIn the context of infection, Pseudomonas aeruginosa and Staphylococcus aureus are frequently co-isolated, particularly in cystic fibrosis (CF) patients. Within lungs, the two pathogens exhibit a range of competitive and coexisting interactions. In the present study, we explored the impact of S. aureus on the physiology of P. aeruginosa in the context of coexistence. Transcriptomic analyses showed that S. aureus significantly and specifically affects the expression of numerous genes involved in P. aeruginosa carbon and amino acid metabolism. In particular, 65% of the strains presented considerable overexpression of the genes involved in the acetoin catabolic (aco) pathway. We demonstrated that acetoin is (i) produced by clinical S. aureus strains, (ii) detected in sputa from CF patients, and (iii) involved in P. aeruginosa’s aco system induction. Furthermore, acetoin is catabolized by P. aeruginosa, a metabolic process that improves the survival of both pathogens by providing a new carbon source for P. aeruginosa and avoiding the toxic accumulation of acetoin on S. aureus. Due to its beneficial effects on both bacteria, acetoin catabolism could testify to the establishment of trophic cooperation between S. aureus and P. aeruginosa in the CF lung environment, thus promoting their persistence.

scholarly journals Suppression of a Thermosensitive zipA Cell Division Mutant by Altering Amino Acid Metabolism

2017 ◽  
Vol 200 (2) ◽  
Author(s):  
Daniel E. Vega ◽  
William Margolin
Keyword(s):  
Escherichia Coli ◽  
Cell Division ◽  
Amino Acid ◽  
Amino Acid Metabolism ◽  
Acid Metabolism ◽  
Cytoplasmic Membrane ◽  
Amino Acid Biosynthesis ◽  
Acid Biosynthesis ◽  
Content Type ◽  
Cell Division Protein

ABSTRACTZipA is essential for cell division inEscherichia coli, acting early in the process to anchor polymers of FtsZ to the cytoplasmic membrane. Along with FtsA, FtsZ and ZipA form a proto-ring at midcell that recruits additional proteins to eventually build the division septum. Cells carrying the thermosensitivezipA1allele divide fairly normally at 30°C in rich medium but cease dividing at temperatures above 34°C, forming long filaments. In a search for suppressors of thezipA1allele, we found that deletions of specific genes involved in amino acid biosynthesis could partially rescue cell growth and division at 34°C or 37°C but not at 42°C. Notably, although a diverse group of amino acid biosynthesis gene deletions could partially rescue the growth ofzipA1cells at 34°C, only deletions of genes related to the biosynthesis of threonine, glycine, serine, and methionine could rescue growth at 37°C. Adding exogenous pyridoxal 5-phosphate (PLP), a cofactor for many of the enzymes affected by this study, partially suppressedzipA1mutant thermosensitivity. For many of the deletions, PLP had an additive rescuing effect on thezipA1mutant. Moreover, added PLP partially suppressed the thermosensitivity offtsQandftsKmutants and weakly suppressed anftsImutant, but it failed to suppressftsAorftsZthermosensitive mutants. Along with the ability of a deletion ofmetCto partially suppress theftsKmutant, our results suggest that perturbations of amino acid metabolic pathways, particularly those that redirect the flow of carbon away from the synthesis of threonine, glycine, or methionine, are able to partially rescue some cell division defects.IMPORTANCECell division of bacteria, such asEscherichia coli, is essential for their successful colonization. It is becoming increasingly clear that nutritional status and central metabolism can affect bacterial size and shape; for example, a metabolic enzyme (OpgH) can moonlight as a regulator of FtsZ, an essential cell division protein. Here, we demonstrate a link between amino acid metabolism and ZipA, another essential cell division protein that binds directly to FtsZ and tethers it to the cytoplasmic membrane. Our evidence suggests that altering flux through the methionine-threonine-glycine-serine pathways and supplementing with the enzyme cofactor pyridoxal-5-phosphate can partially compensate for an otherwise lethal defect in ZipA, as well as several other cell division proteins.

scholarly journals Use of the flux model of amino acid metabolism of Escherichia coli

2006 ◽  
Vol 71 (11) ◽  
pp. 1256-1260 ◽  
Author(s):  
A. V. Lyubetskaya ◽  
L. I. Rubanov ◽  
M. S. Gelfand
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Amino Acid Metabolism ◽  
Acid Metabolism ◽  
Flux Model

scholarly journals Microarray analysis of the genomic effect of eugenol on methicillin resistant Staphylococcus aureus

2021 ◽  
Author(s):  
Sunday Ayuba Buru ◽  
Mallikarjuna Rao Pichika ◽  
Kavitha Mohandas
Keyword(s):  
Staphylococcus Aureus ◽  
Amino Acid ◽  
Amino Acid Metabolism ◽  
Antimicrobial Agents ◽  
Acid Metabolism ◽  
Global Gene Expression ◽  
Toxic Shock ◽  
Methicillin Resistant ◽  
Life Threatening ◽  
Dna Microarray System

Abstract Background: Staphylococcus aureus is a highly adaptive human pathogen responsible for serious hospital and community acquired infectious diseases ranging from skin and soft tissue infections to complicated and life - threatening conditions such as endocarditis and toxic shock syndrome (TSS). The rapid resistance of this organism to available antibiotics over the last few decades has necessitated a constant search for more efficacious antibacterial agents. Eugenol [4- Allyl-2-methoxyphenol] belongs to the class of chemical compounds called phenylpropanoids. It is a pure to pale yellow oily liquid substance mostly extracted as an essential oil from natural products such as clove, cinnamon, nutmeg, basil and bay leaf. Eugenol has previously been shown to have antimicrobial activity against methicillin resistant Staphylococcus aureus. However, the mechanism of S. aureus has not, as yet, been elucidated – hence, the expediency of this study.Results: Global gene expression outlines in response to sub - inhibitory concentrations of eugenol were analysed using the agilent DNA microarray system to identify gene targets, most importantly essential genes involved in unique metabolic pathways. Transcriptomic analysis of fluctuating genes revealed those involved in Amino acid metabolism, fatty acid metabolism, translation and ribosomal pathways. In Amino acid metabolism for instance, the argC gene encodes for N-acetyl-gamma-glutamyl-phosphate reductase. The argC gene plays an important role in the biosynthesis of arginine from glutamate in the amino acid metabolic pathway. It is the enzyme that catalyses the third step in the latter reaction and without this process, the production of N-acetylglutamate 5-semialdehyde will not be complete from the NADP-dependent reduction of N-acetyl-5-glutamyl phosphate, which is essential for the survival of some microorganisms and plants. Conclusion: This study has enabled us to examine complete global transcriptomal responses in MRSA against eugenol. It has revealed novel information with the potential to further benefit the exploratory quest for novel targets against this pathogen, in view to the development of efficacious antimicrobial agents for the treatment of associated infections.

scholarly journals Sulfur Amino Acid Metabolism in Pregnancy: The Impact of Methionine in the Maternal Diet

2006 ◽  
Vol 136 (6) ◽  
pp. 1701S-1705S ◽  
Author(s):  
William D. Rees ◽  
Fiona A. Wilson ◽  
Christopher A. Maloney
Keyword(s):  
Amino Acid ◽  
Amino Acid Metabolism ◽  
Acid Metabolism ◽  
Maternal Diet ◽  
Sulfur Amino Acid ◽  
The Impact ◽  
In Pregnancy
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