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1.
World J Microbiol Biotechnol ; 40(9): 285, 2024 Jul 29.
Artículo en Inglés | MEDLINE | ID: mdl-39073503

RESUMEN

The accelerated spread of antimicrobial-resistant bacteria has caused a serious health problem and rendered antimicrobial treatments ineffective. Innovative approaches are crucial to overcome the health threat posed by resistant pathogens and prevent the emergence of untreatable infections. Triggering stress responses in bacteria can diminish susceptibility to various antimicrobials by inducing resistance mechanisms. Therefore, a thorough understanding of stress response control, especially in relation to antimicrobial resistance, offers valuable perspectives for innovative and efficient therapeutic approaches to combat antimicrobial resistance. The aim of this study was to evaluate the stress responses of 8 different bacteria by analyzing reporter metabolites, around which significant alterations were observed, using a pathway-driven computational approach. For this purpose, the transcriptomic data that the bacterial pathogens were grown under 11 different stress conditions mimicking the human host environments were integrated with the genome-scale metabolic models of 8 pathogenic species (Enterococcus faecalis OG1R, Escherichia coli EPEC O127:H6 E2348/69, Escherichia coli ETEC H10407, Escherichia coli UPEC 536, Klebsiella pneumoniae MGH 78578, Pseudomonas aeruginosa PAO1, Staphylococcus aureus MRSA252, and Staphylococcus aureus MSSA476). The resulting reporter metabolites were enriched in multiple metabolic pathways, with cofactor biosynthesis being the most important. The results of this study will serve as a guide for the development of antimicrobial agents as they provide a first insight into potential drug targets.


Asunto(s)
Antibacterianos , Bacterias , Estrés Fisiológico , Bacterias/efectos de los fármacos , Bacterias/genética , Bacterias/metabolismo , Antibacterianos/farmacología , Farmacorresistencia Bacteriana , Regulación Bacteriana de la Expresión Génica/efectos de los fármacos , Redes y Vías Metabólicas , Humanos , Pseudomonas aeruginosa/efectos de los fármacos , Pseudomonas aeruginosa/genética , Klebsiella pneumoniae/efectos de los fármacos , Klebsiella pneumoniae/genética , Transcriptoma , Escherichia coli/efectos de los fármacos , Escherichia coli/genética , Pruebas de Sensibilidad Microbiana , Perfilación de la Expresión Génica
2.
Int Microbiol ; 2024 Jun 19.
Artículo en Inglés | MEDLINE | ID: mdl-38898189

RESUMEN

Microbes play an essential role in soil fertility by replenishing the nutrients; they encounter various biotic and abiotic stresses disrupting their cellular homeostasis, which expedites activating a conserved signaling pathway for transient over-expression of heat shock proteins (HSPs). In the present study, a versatile soil bacterium Bacillus subtilis strain PSK.A2 was isolated and characterized. Further, the isolated bacterium was exposed with several stresses, viz., heat, salt, acid, alkaline, and antibiotics. Stress-attributed cellular morphological modifications such as swelling, shrinkage, and clump formation were observed under the scanning electron microscope. The comparative protein expression pattern was studied by SDS-PAGE, relative protein stabilization was assessed by protein aggregation assay, and relative survival was mapped by single spot dilution and colony-counting method under control, stressed, lethal, and stressed lethal conditions of the isolate. The findings demonstrated that bacterial stress tolerance was maintained via the activation of various HSPs of molecular weight ranging from 17 to 115 kD to respective stimuli. The treatment of subinhibitory dose of antibiotics not interfering protein synthesis (amoxicillin and ciprofloxacin) resulted in the expression of eight HSPs of molecular weight ranging from 18 to 71 kD. The pre-treatment of short stress dosage showed endured overall tolerance of bacterium to lethal conditions, as evidenced by moderately enhanced total soluble intracellular protein content, better protein stabilization, comparatively over-expressed HSPs, and relatively enhanced cell survival. These findings hold an opportunity for developing novel approaches towards enhancing microbial resilience in a variety of conditions, including industrial bioprocessing, environmental remediation, and infectious disease management.

3.
bioRxiv ; 2024 May 30.
Artículo en Inglés | MEDLINE | ID: mdl-38853858

RESUMEN

Toxin-antitoxin modules are present in many bacterial pathogens. The VapBC family is particularly abundant in members of the Mycobacterium tuberculosis complex, with 50 modules present in the M. tuberculosis genome. In type IIA modules the VapB antitoxin protein binds to and inhibits the activity of the co-expressed cognate VapC toxin protein. VapB proteins also bind to promoter region sequences and repress expression of the vapB-vapC operon. Though VapB-VapC interactions can control the amount of free VapC toxin in the bacterial cell, the mechanisms that affect this interaction are poorly understood. Based on our recent finding of Ser/Thr phosphorylation of VapB proteins in M. tuberculosis, we substituted phosphomimetic or phosphoablative amino acids at the phosphorylation sites of two VapB proteins. We found that phosphomimetic substitution of VapB27 and VapB46 resulted in decreased interaction with their respective cognate VapC proteins, whereas phosphoablative substitution did not alter binding. Similarly, we determined that phosphomimetic substitution interfered with VapB binding to promoter region DNA sequences. Both decreased VapB-VapC interaction and decreased VapB repression of vapB-vapC operon transcription would result in increased free VapC in the M. tuberculosis cell. M. tuberculosis strains expressing vapB46-vapC46 constructs containing a phosphoablative vapB mutation resulted in lower toxicity compared to a strain expressing native vapB46, whereas similar or greater toxicity was observed in the strain expressing the phosphomimetic vapB mutation. These results identify a novel mechanism by which VapC toxicity activity can be regulated by VapB phosphorylation, potentially in response to extracytoplasmic as well as intracellular signals.

4.
Res Microbiol ; 175(7): 104214, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38740236

RESUMEN

The diversity of the biological activity of volatile organic compounds (VOCs), including unsaturated ketone ß-ionone, promising pharmacological, biotechnological, and agricultural agent, has aroused considerable interest. However, the functional role and mechanisms of action of VOCs remain insufficiently studied. In this work, the response of bacterial cells to the action of ß-ionone was studied using specific bioluminescent lux-biosensors containing stress-sensitive promoters. We determined that in Escherichia coli cells, ß-ionone induces oxidative stress (PkatG and Pdps promoters) through a specific response mediated by the OxyR/OxyS regulon, but not SoxR/SoxS (PsoxS promoter). It has been shown that ß-ionone at high concentrations (50 µM and above) causes a weak induction of the expression from the PibpA promoter and slightly induces the PcolD promoter in the E. coli biosensors; the observed effect is enhanced in the ΔoxyR mutants. This indicates the presence of some damage to proteins and DNA. ß-Ionone was found to inhibit the bichaperone-dependent DnaKJE-ClpB refolding of heat-inactivated bacterial luciferase in E. coli wild-type and ΔibpB mutant strains. In the cells of the Gram-positive bacterium Bacillus subtilis 168 pNK-MrgA ß-ionone does not cause oxidative stress. Thus, in this work, the specificity of bacterial cell stress responses to the action of ß-ionone was shown.


Asunto(s)
Técnicas Biosensibles , Escherichia coli , Regulación Bacteriana de la Expresión Génica , Norisoprenoides , Estrés Oxidativo , Regiones Promotoras Genéticas , Escherichia coli/genética , Escherichia coli/efectos de los fármacos , Escherichia coli/metabolismo , Norisoprenoides/farmacología , Norisoprenoides/metabolismo , Regulación Bacteriana de la Expresión Génica/efectos de los fármacos , Estrés Oxidativo/efectos de los fármacos , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Compuestos Orgánicos Volátiles/metabolismo , Compuestos Orgánicos Volátiles/farmacología
5.
Microorganisms ; 12(4)2024 Mar 22.
Artículo en Inglés | MEDLINE | ID: mdl-38674581

RESUMEN

Global rewiring of bacterial gene expressions in response to environmental cues is mediated by regulatory proteins such as the CsrA global regulator from E. coli. Several direct mRNA and sRNA targets of this protein have been identified; however, high-throughput studies suggest an expanded RNA targetome for this protein. In this work, we demonstrate that CsrA can extend its network by directly binding and regulating the evgA and acnA transcripts, encoding for regulatory proteins. CsrA represses EvgA and AcnA expression and disrupting the CsrA binding sites of evgA and acnA, results in broader gene expression changes to stress response networks. Specifically, altering CsrA-evgA binding impacts the genes related to acidic stress adaptation, and disrupting the CsrA-acnA interaction affects the genes involved in metal-induced oxidative stress responses. We show that these interactions are biologically relevant, as evidenced by the improved tolerance of evgA and acnA genomic mutants depleted of CsrA binding sites when challenged with acid and metal ions, respectively. We conclude that EvgA and AcnA are intermediate regulatory hubs through which CsrA can expand its regulatory role. The indirect CsrA regulation of gene networks coordinated by EvgA and AcnA likely contributes to optimizing cellular resources to promote exponential growth in the absence of stress.

6.
Biomolecules ; 14(1)2024 Jan 08.
Artículo en Inglés | MEDLINE | ID: mdl-38254676

RESUMEN

The acquisition and expression of antibiotic resistance implies changes in bacterial cell physiology, imposing fitness costs. Many human opportunistic pathogenic bacteria, such as those causing urinary tract or bloodstream infections, colonize the gut. In this opinionated review, we will examine the various types of stress that these bacteria might suffer during their intestinal stay. These stresses, and their compensatory responses, probably have a fitness cost, which might be additive to the cost of expressing antibiotic resistance. Such an effect could result in a disadvantage relative to antibiotic susceptible populations that might replace the resistant ones. The opinion proposed in this paper is that the effect of these combinations of fitness costs should be tested in antibiotic resistant bacteria with susceptible ones as controls. This testing might provide opportunities to increase the bacterial gut stress boosting physiological biomolecules or using dietary interventions. This approach to reduce the burden of antibiotic-resistant populations certainly must be answered empirically. In the end, the battle against antibiotic resistance should be won by antibiotic-susceptible organisms. Let us help them prevail.


Asunto(s)
Antibacterianos , Sepsis , Humanos , Antibacterianos/farmacología , Ansiedad , Farmacorresistencia Microbiana , Ejercicio Físico
7.
Int J Mol Sci ; 24(24)2023 Dec 11.
Artículo en Inglés | MEDLINE | ID: mdl-38139177

RESUMEN

The alternative sigma factor RpoS is considered to be one of the major regulators providing stress resistance and cross-protection in bacteria. In phytopathogenic bacteria, the effects of RpoS have not been analyzed with regard to cross-protection, and genes whose expression is directly or indirectly controlled by RpoS have not been determined at the whole-transcriptome level. Our study aimed to determine RpoS-regulated genes and phenotypes in the phytopathogenic bacterium Pectobacterium atrosepticum. Knockout of the rpoS gene in P. atrosepticum affected the long-term starvation response, cross-protection, and virulence toward plants with enhanced immune status. The whole-transcriptome profiles of the wild-type P. atrosepticum strain and its ΔrpoS mutant were compared under different experimental conditions, and functional gene groups whose expression was affected by RpoS were determined. The RpoS promoter motif was inferred within the promoter regions of the genes affected by rpoS deletion, and the P. atrosepticum RpoS regulon was predicted. Based on RpoS-controlled phenotypes, transcriptome profiles, and RpoS regulon composition, the regulatory role of RpoS in P. atrosepticum is discussed.


Asunto(s)
Proteínas Bacterianas , Pectobacterium , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Transcriptoma , Pectobacterium/metabolismo , Fenotipo , Factor sigma/genética , Factor sigma/metabolismo , Regulación Bacteriana de la Expresión Génica
8.
J Biol Chem ; 299(12): 105429, 2023 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-37926282

RESUMEN

Virtually all bacterial species synthesize (p)ppGpp (guanosine penta- or tetraphosphate), a pleiotropic regulator of the so-called stringent response, which controls many aspects of cellular physiology and metabolism. In Escherichia coli, (p)ppGpp levels are controlled by two homologous enzymes: the (p)ppGpp synthetase RelA and the bifunctional synthetase/hydrolase SpoT. We recently identified several protein candidates that can modulate (p)ppGpp levels in E. coli. In this work, we show that the putative two-component system connector protein YmgB can promote SpoT-dependent accumulation of ppGpp in E. coli. Importantly, we determined that the control of SpoT activities by YmgB is independent of its proposed role in the two-component Rcs system, and these two functions can be uncoupled. Using genetic and structure-function analysis, we show that the regulation of SpoT activities by YmgB occurs by functional and direct binding in vivo and in vitro to the TGS and Helical domains of SpoT. These results further support the role of these domains in controlling the reciprocal enzymatic states.


Asunto(s)
Proteínas de Escherichia coli , Escherichia coli , Escherichia coli/metabolismo , Guanosina Pentafosfato/genética , Bacterias/metabolismo , Guanosina Tetrafosfato , Hidrolasas/metabolismo , Ligasas/genética , Ligasas/metabolismo , Regulación Bacteriana de la Expresión Génica , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo
9.
Curr Biol ; 33(24): 5404-5414.e9, 2023 12 18.
Artículo en Inglés | MEDLINE | ID: mdl-38029757

RESUMEN

Cellular responses to environmental changes are often highly heterogeneous and exhibit seemingly random dynamics. The astonishing insight of chaos theory is that such unpredictable patterns can, in principle, arise without the need for any random processes, i.e., purely deterministically without noise. However, while chaos is well understood in mathematics and physics, its role in cell biology remains unclear because the complexity and noisiness of biological systems make testing difficult. Here, we show that chaos explains the heterogeneous response of Escherichia coli cells to oxidative stress. We developed a theoretical model of the gene expression dynamics and demonstrate that chaotic behavior arises from rapid molecular feedbacks that are coupled with cell growth dynamics and cell-cell interactions. Based on theoretical predictions, we then designed single-cell experiments to show we can shift gene expression from periodic oscillations to chaos on demand. Our work suggests that chaotic gene regulation can be employed by cell populations to generate strong and variable responses to changing environments.


Asunto(s)
Modelos Teóricos , Dinámicas no Lineales
10.
Biotechnol Biofuels Bioprod ; 16(1): 147, 2023 Oct 03.
Artículo en Inglés | MEDLINE | ID: mdl-37789404

RESUMEN

BACKGROUND: Alcohol is a good and environment-friendly fuel that can be microbially produced, capable of eliminating many of the limitations of the present-day fossil fuels. However, the inherent toxic nature of alcohols to the microbial cells leads to end-product inhibition that limits large-scale alcohol production by fermentation. Fundamental knowledge about the stress responses of microorganisms to alcohols would greatly facilitate to improve the microbial alcohol tolerance. The current study elucidates and compares the changes in the membrane proteome of Escherichia coli in response to a range of alcohols. RESULTS: Although alcohol toxicity increased exponentially with alcohol chain length (2-6 carbon), similar stress responses were observed in the inner and outer membrane proteome of E. coli in the presence of 2-, 4- and 6-carbon alcohols at the MIC50. This pertains to: (1) increased levels of inner membrane transporters for uptake of energy-producing metabolites, (2) reduced levels of non-essential proteins, associated with anaerobic, carbon starvation and osmotic stress, for energy conservation, (3) increased levels of murein degrading enzymes (MltA, EmtA, MliC and DigH) promoting cell elongation and 4) reduced levels of most outer membrane ß-barrel proteins (LptD, FadL, LamB, TolC and BamA). Major outer membrane ß-barrel protein OmpC, which is known to contribute to ethanol tolerance and membrane integrity, was notably reduced by alcohol stress. While LPS is important for OmpC trimerisation, LPS release by EDTA did not lower OmpC levels. This suggests that LPS release, which is reported under alcohol stress, does not contribute to the reduced levels of OmpC in the presence of alcohol. CONCLUSIONS: Since alcohol primarily targets the integrity of the membrane, maintenance of outer membrane OmpC levels in the presence of alcohol might help in the survival of E. coli to higher alcohol concentrations. The study provides important information about the membrane protein responses of E. coli to a range of alcohols, which can be used to develop targeted strategies for increased microbial alcohol tolerance and hence bioalcohol production.

11.
Open Biol ; 13(7): 230020, 2023 07.
Artículo en Inglés | MEDLINE | ID: mdl-37491940

RESUMEN

Min oscillations are a fascinating mechanism used by Escherichia coli to find their middle. Beyond their biological role, they provide a convenient and relatively unexplored method to monitor the effect of sublethal environmental challenges on bacterial physiology in real-time and at the single-cell level. In this review, we discuss the original papers that put forward the idea of using Min oscillations as a reporting tool to monitor the effect of extracellular cationic compounds, including antibiotics. More recent work from our laboratory explores this tool to follow bacterial response to other challenges such as weak mechanical interactions with nanomaterials or photodynamic treatment. We discuss the physiological meaning of the changes in Min oscillation period, likely related to membrane potential dynamics, as well as the benefits and limitations of using oscillations as a reporter in fluorescence microscopy. Overall, Min oscillations are a useful addition to the fluorescence microscopy toolbox in order to visualize stress responses in E. coli, and have the potential to provide full mechanistic understanding of the events that lead to bacterial cell death in different contexts.


Asunto(s)
Proteínas de Escherichia coli , Escherichia coli , Escherichia coli/genética , Escherichia coli/metabolismo , Proteínas de Escherichia coli/metabolismo , Bacterias/genética , Bacterias/metabolismo , Microscopía Fluorescente , Antibacterianos
12.
Annu Rev Chem Biomol Eng ; 14: 265-281, 2023 06 08.
Artículo en Inglés | MEDLINE | ID: mdl-37289561

RESUMEN

Oxidative stress is an important and pervasive physical stress encountered by all kingdoms of life, including bacteria. In this review, we briefly describe the nature of oxidative stress, highlight well-characterized protein-based sensors (transcription factors) of reactive oxygen species that serve as standards for molecular sensors in oxidative stress, and describe molecular studies that have explored the potential of direct RNA sensitivity to oxidative stress. Finally, we describe the gaps in knowledge of RNA sensors-particularly regarding the chemical modification of RNA nucleobases. RNA sensors are poised to emerge as an essential layer of understanding and regulating dynamic biological pathways in oxidative stress responses in bacteria and, thus, also represent an important frontier of synthetic biology.


Asunto(s)
Bacterias , Estrés Oxidativo , Oxidación-Reducción , Bacterias/genética , Bacterias/metabolismo , Factores de Transcripción/metabolismo , ARN/metabolismo
13.
Res Microbiol ; 174(7): 104093, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37343614

RESUMEN

Cells have evolved strategies to safeguard their genome integrity. We describe a mechanism to counter double strand breaks in the chromosome that involves the protection of an essential housekeeping enzyme from external agents. YacG is a DNA gyrase inhibitory protein from Escherichia coli that protects the bacterium from the cytotoxic effects of catalytic inhibitors as well as cleavage-complex stabilizers of DNA gyrase. By virtue of blocking the primary DNA binding site of the enzyme, YacG prevents the accumulation of double strand breaks induced by gyrase poisons. It also enables the bacterium to resist the growth-inhibitory property of novobiocin. Gyrase poison-induced oxidative stress upregulates YacG production, probably as a cellular response to counter DNA damage. YacG-mediated protection of the genome is specific for gyrase targeting agents as the protection is not observed from the action of general DNA damaging agents. YacG also intensifies the transcription stress induced by rifampicin substantiating the importance of gyrase activity during transcription. Although essential for bacterial survival, DNA gyrase often gets entrapped by external inhibitors and poisons, resulting in cell death. The existence of YacG to specifically protect an essential housekeeping enzyme might be a strategy adopted by bacteria for competitive fitness advantage.

14.
Int J Biol Macromol ; 242(Pt 1): 124682, 2023 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-37164133

RESUMEN

Glycoalkaloids (GAs), including α-solanine and α-chaconine, are secondary metabolites found in potato, which are toxic to higher animals. In a previous study, Alkalihalobacillus clausii PA21 showed the capacity to degrade GAs. Herein, the transcriptome response of PA21 to α-solanine or α-chaconine was evaluated. In total, 3170 and 2783 differential expressed genes (DEGs) were found in α-solanine- and α-chaconine-treated groups, respectively, with most DEGs upregulated. Moreover, GAs activated transmembrane transport, carbohydrate metabolism, transcription, quorum sensing, and bacterial chemotaxis in PA21 to withstand GA-induced stress and promote GAs degradation. Furthermore, qRT-PCR analysis confirmed the upregulation of degrading enzymes and components involved in GA degradation in PA21. In addition, the GAs-degrading enzymes were heterologous expressed, purified, and incubated with GAs to analyze the degradation products. The results showed that α-solanine was degraded to ß1-solanine, ß2-solanine, γ-solanine, and solanidine by ß-glucosidase, α-rhamnosidase, and ß-galactosidase. Meanwhile, α-chaconine was degraded to ß1-chaconine, ß2-chaconine, γ-chaconine, and solanidine by ß-glucosidase and α-rhamnosidase. Overall, the molecular mechanism underlying GAs degradation by PA21 was revealed by RNAseq combined with protein expression and function studies, thus providing the basis for the development of engineered bacteria that can efficiently degrade GAs to promote their application in the control of GAs in potatoes.


Asunto(s)
Celulasas , Solanina , Solanum tuberosum , Animales , Solanina/análisis , Solanina/metabolismo , Solanina/farmacología , Solanum tuberosum/genética , Solanum tuberosum/metabolismo , Bacterias/metabolismo , Perfilación de la Expresión Génica , Redes y Vías Metabólicas , Celulasas/metabolismo
15.
Microorganisms ; 11(4)2023 Apr 03.
Artículo en Inglés | MEDLINE | ID: mdl-37110353

RESUMEN

Listeria monocytogenes is a deadly and costly foodborne pathogen that has a high fatality rate in the elderly, pregnant women, and people with weakened immunity. It can survive under various stress conditions and is a significant concern for the food industry. In this work, a data analysis approach was developed with existing tools and databases and used to create individual and combined protein interaction networks to study stress response, virulence, and antimicrobial resistance and their interaction with L. monocytogenes. The networks were analyzed, and 28 key proteins were identified that may serve as potential targets for new strategies to combat L. monocytogenes. Five of the twenty-eight proteins (i.e., sigB, flaA, cheA, cheY, and lmo0693) represent the most promising targets because they are highly interconnected within the combined network. The results of this study provide a new set of targets for future work to identify new strategies to improve food preservation methods and treatments for L. monocytogenes.

16.
mBio ; 14(1): e0280522, 2023 02 28.
Artículo en Inglés | MEDLINE | ID: mdl-36598190

RESUMEN

tRNAs and ribosomal RNAs are often considered stable RNAs. In contrast to this view, we recently proposed that tRNAs are degraded during amino acid starvation and drug-induced transcription inhibition. However, reevaluation of our experimental approach revealed that common RNA extraction methods suffer from alarming extraction and size biases that can lead to gross underestimation of RNA levels in starved Escherichia coli populations. Quantification of tRNAs suffers additional biases due to differing fractions of tRNAs with base modifications in growing versus starved bacteria. Applying an improved methodology, we measured tRNA levels after starvation for amino acids, glucose, phosphate, or ammonium and transcription inhibition by rifampicin. We report that tRNA levels remain largely unaffected in all tested conditions, including several days of starvation. This confirms that tRNAs are remarkably stable RNAs and serves as a cautionary tale about quantification of RNA from cells cultured outside the steady-state growth regime. rRNA, conversely, is extensively degraded during starvation. Thus, E. coli downregulates the translation machinery in response to starvation by reducing the ribosome pool through rRNA degradation, while a high concentration of tRNAs available to supply amino acids to the remaining ribosomes is maintained. IMPORTANCE We show that E. coli tRNAs are remarkably stable during several days of nutrient starvation, although rRNA is degraded extensively under these conditions. The levels of these two major RNA classes are considered to be strongly coregulated at the level of transcription. We demonstrate that E. coli can control the ratio of tRNAs per ribosome under starvation by means of differential degradation rates. The question of tRNA stability in stressed E. coli cells has become subject to debate. Our in-depth analysis of RNA quantification methods reveals hidden technical pitfalls at every step of the analysis, from RNA extraction to target detection and normalization. Most importantly, starved E. coli populations were more resilient to RNA extraction than unstarved populations. The current results underscore that the seemingly trivial task of quantifying an abundant RNA species is not straightforward for cells cultured outside the exponential growth regime.


Asunto(s)
Escherichia coli , ARN de Transferencia , Escherichia coli/genética , Escherichia coli/metabolismo , ARN de Transferencia/metabolismo , Aminoácidos/metabolismo , Ribosomas/metabolismo , ARN Ribosómico/genética
17.
mBio ; 13(6): e0296322, 2022 12 20.
Artículo en Inglés | MEDLINE | ID: mdl-36468870

RESUMEN

Escherichia coli associates with humans early in life and can occupy several body niches either as a commensal in the gut and vagina, or as a pathogen in the urinary tract. As such, E. coli has an arsenal of acid response mechanisms that allow it to withstand the different levels of acid stress encountered within and outside the host. Here, we report the discovery of an additional acid response mechanism that involves the deamination of l-serine to pyruvate by the conserved l-serine deaminases SdaA and SdaB. l-serine is the first amino acid to be imported in E. coli during growth in laboratory media. However, there remains a lack in knowledge as to how l-serine is utilized. Using a uropathogenic strain of E. coli, UTI89, we show that in acidified media, l-serine is brought into the cell via the SdaC transporter. We further demonstrate that deletion of the l-serine deaminases SdaA and SdaB renders E. coli susceptible to acid stress, similar to other acid stress deletion mutants. The pyruvate produced by l-serine deamination activates the pyruvate sensor BtsS, which in concert with the noncognate response regulator YpdB upregulates the putative transporter YhjX. Based on these observations, we propose that l-serine deamination constitutes another acid response mechanism in E. coli. IMPORTANCE The observation that l-serine uptake occurs as E. coli cultures grow is well established, yet the benefit E. coli garners from this uptake remains unclear. Here, we report a novel acid tolerance mechanism where l-serine is deaminated to pyruvate and ammonia, promoting survival of E. coli under acidic conditions. This study is important as it provides evidence of the use of l-serine as an acid response strategy, not previously reported for E. coli.


Asunto(s)
Proteínas de Escherichia coli , Serina , Escherichia coli Uropatógena , Femenino , Humanos , Desaminación , Proteínas de Escherichia coli/metabolismo , L-Serina Deshidratasa/metabolismo , Proteínas de Transporte de Membrana/metabolismo , Ácido Pirúvico/metabolismo , Serina/metabolismo , Escherichia coli Uropatógena/metabolismo
18.
Front Microbiol ; 13: 1007143, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-36406458

RESUMEN

Previous studies have reported that spaceflight specific conditions such as microgravity lead to changes in bacterial physiology and resistance behavior including increased expression of virulence factors, enhanced biofilm formation and decreased susceptibility to antibiotics. To assess if spaceflight induced physiological changes can manifest in human-associated bacteria, we compared three spaceflight relevant Staphylococcus capitis isolates (DSM 111179, ISS; DSM 31028, clean room; DSM 113836; artificial gravity bedrest study) with the type strain (DSM 20326T). We tested the three strains regarding growth, colony morphology, metabolism, fatty acid and polar lipid pattern, biofilm formation, susceptibility to antibiotics and survival in different stress conditions such as treatment with hydrogen peroxide, exposure to desiccation, and irradiation with X-rays and UV-C. Moreover, we sequenced, assembled, and analyzed the genomes of all four strains. Potential genetic determinants for phenotypic differences were investigated by comparative genomics. We found that all four strains show similar metabolic patterns and the same susceptibility to antibiotics. All four strains were considered resistant to fosfomycin. Physiological differences were mainly observed compared to the type strain and minor differences among the other three strains. The ISS isolate and the bedrest study isolate exhibit a strong delayed yellow pigmentation, which is absent in the other two strains. Pigments were extracted and analyzed by UV/Vis spectroscopy showing characteristic carotenoid spectra. The ISS isolate showed the highest growth rate as well as weighted average melting temperature (WAMT) of fatty acids (41.8°C) of all strains. The clean room isolate showed strongest biofilm formation and a high tolerance to desiccation. In general, all strains survived desiccation better in absence of oxygen. There were no differences among the strains regarding radiation tolerance. Phenotypic and genomic differences among the strains observed in this study are not inevitably indicating an increased virulence of the spaceflight isolate. However, the increased growth rate, higher WAMT and colony pigmentation of the spaceflight isolate are relevant phenotypes that require further research within the human spaceflight context. We conclude that combining genetic analysis with classical microbiological methods allows the detailed assessment of the potential threat of bacteria in highly regulated and extreme environments such as spaceflight environments.

19.
Front Mol Biosci ; 9: 945724, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35911964

RESUMEN

Manganese (Mn) plays a multifaceted role in the survival of pathogenic and symbiotic bacteria in eukaryotic hosts, and it is also important for free-living bacteria to grow in stressful environments. Previous research has uncovered components of the bacterial Mn homeostasis systems that control intracellular Mn levels, many of which are important for virulence. Multiple studies have also identified proteins that use Mn once it is inside the cell, including Mn-specific enzymes and enzymes transiently loaded with Mn for protection during oxidative stress. Emerging evidence continues to reveal proteins involved in maintaining Mn homeostasis, as well as enzymes that can bind Mn. For some of these enzymes, Mn serves as an essential cofactor. For other enzymes, mismetallation with Mn can lead to inactivation or poor activity. Some enzymes may even potentially be regulated by differential metallation with Mn or zinc (Zn). This review focuses on new developments in regulatory mechanisms that affect Mn homeostasis and usage, additional players in Mn import that increase bacterial survival during pathogenesis, and the interplay between Mn and other metals during Mn-responsive physiological processes. Lastly, we highlight lessons learned from fundamental research that are now being applied to bacterial interactions within larger microbial communities or eukaryotic hosts.

20.
Pathogens ; 11(7)2022 Jun 27.
Artículo en Inglés | MEDLINE | ID: mdl-35889976

RESUMEN

Ralstonia solanacearum (Rs), the causative agent of devastating wilt disease in several major and minor economic crops, is considered one of the most destructive bacterial plant pathogens. However, the mechanism(s) by which Rs counteracts host-associated environmental stress is still not clearly elucidated. To investigate possible stress management mechanisms, orthologs of stress-responsive genes in the Rs genome were searched using a reference set of known genes. The genome BLAST approach was used to find the distributions of these orthologs within different Rs strains. BLAST results were first confirmed from the KEGG Genome database and then reconfirmed at the protein level from the UniProt database. The distribution pattern of these stress-responsive factors was explored through multivariate analysis and STRING analysis. STRING analysis of stress-responsive genes in connection with different secretion systems of Rs was also performed. Initially, a total of 28 stress-responsive genes of Rs were confirmed in this study. STRING analysis revealed an additional 7 stress-responsive factors of Rs, leading to the discovery of a total of 35 stress-responsive genes. The segregation pattern of these 35 genes across 110 Rs genomes was found to be almost homogeneous. Increasing interactions of Rs stress factors were observed in six distinct clusters, suggesting six different types of stress responses: membrane stress response (MSR), osmotic stress response (OSR), oxidative stress response (OxSR), nitrosative stress response (NxSR), and DNA damage stress response (DdSR). Moreover, a strong network of these stress responses was observed with type 3 secretion system (T3SS), general secretory proteins (GSPs), and different types of pili (T4P, Tad, and Tat). To the best of our knowledge, this is the first report on overall stress response management by Rs and the potential connection with secretion systems.

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