scholarly journals Growth Phase Dependent Chromosome Condensation and H-NS Protein Redistribution in E. coli Under Osmotic Stress

2019 ◽  
Author(s):  
Nafiseh Rafiei ◽  
Martha Cordova ◽  
William Wiley Navarre ◽  
Joshua N. Milstein
Keyword(s):  
Osmotic Stress ◽  
Growth Phase ◽  
Sigma Factor ◽  
Transcriptional Regulator ◽  
Extended Period ◽  
Dna Gyrase ◽  
E Coli ◽  
Heat Stable ◽  
Spatial Reorganization ◽  
Sigma Factor Rpos

AbstractThe heat-stable nucleoid-structuring (H-NS) protein is a global transcriptional regulator implicated in coordinating the expression of over 200 genes in E. coli bacteria. We have applied super-resolved microscopy to quantify the intracellular, spatial reorganization of H-NS in response to osmotic stress. We find that H-NS shows a growth phase dependent response to hyperosmotic shock. In stationary phase, H-NS detaches from a tightly compacted bacterial chromosome and is excluded from the nucleoid volume over an extended period of time. This behaviour is absent during rapid growth but may be induced by exposing the osmotically stressed culture to the DNA gyrase inhibitor, coumermycin. This compaction/H-NS exclusion phenomenon occurs in the presence of either potassium or sodium ions and is independent of the stress responsive sigma factor RpoS, or the H-NS paralog StpA.

scholarly journals Growth Phase-Dependent Chromosome Condensation and Heat-Stable Nucleoid-Structuring Protein Redistribution in Escherichia coli under Osmotic Stress

2019 ◽  
Vol 201 (23) ◽  
Author(s):  
Nafiseh Rafiei ◽  
Martha Cordova ◽  
William Wiley Navarre ◽  
Joshua N. Milstein
Keyword(s):  
Escherichia Coli ◽  
Osmotic Stress ◽  
Growth Phase ◽  
Extended Period ◽  
Bacterial Chromosome ◽  
Chromosomal Dna ◽  
Content Type ◽  
Heat Stable ◽  
Expression Of Genes ◽  
Spatial Reorganization

ABSTRACT The heat-stable nucleoid-structuring (H-NS) protein is a global transcriptional regulator implicated in coordinating the expression of over 200 genes in Escherichia coli, including many involved in adaptation to osmotic stress. We have applied superresolved microscopy to quantify the intracellular and spatial reorganization of H-NS in response to a rapid osmotic shift. We found that H-NS showed growth phase-dependent relocalization in response to hyperosmotic shock. In stationary phase, H-NS detached from a tightly compacted bacterial chromosome and was excluded from the nucleoid volume over an extended period of time. This behavior was absent during rapid growth but was induced by exposing the osmotically stressed culture to a DNA gyrase inhibitor, coumermycin. This chromosomal compaction/H-NS exclusion phenomenon occurred in the presence of either potassium or sodium ions and was independent of the presence of stress-responsive sigma factor σS and of the H-NS paralog StpA. IMPORTANCE The heat-stable nucleoid-structuring (H-NS) protein coordinates the expression of over 200 genes in E. coli, with a large number involved in both bacterial virulence and drug resistance. We report on the novel observation of a dynamic compaction of the bacterial chromosome in response to exposure to high levels of salt. This stress response results in the detachment of H-NS proteins and their subsequent expulsion to the periphery of the cells. We found that this behavior is related to mechanical properties of the bacterial chromosome, in particular, to how tightly twisted and coiled is the chromosomal DNA. This behavior might act as a biomechanical response to stress that coordinates the expression of genes involved in adapting bacteria to a salty environment.

scholarly journals Variation in Resistance to High Hydrostatic Pressure andrpoS Heterogeneity in Natural Isolates ofEscherichia coli O157:H7

2001 ◽  
Vol 67 (10) ◽  
pp. 4901-4907 ◽  
Author(s):  
Marianne Robey ◽  
Amparo Benito ◽  
Roger H. Hutson ◽  
Cristina Pascual ◽  
Simon F. Park ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Hydrostatic Pressure ◽  
Stationary Phase ◽  
Sigma Factor ◽  
High Hydrostatic Pressure ◽  
E Coli ◽  
Commensal Strain ◽  
Natural Isolates ◽  
Pressure Resistance ◽  
Sigma Factor Rpos

ABSTRACT Several natural isolates of Escherichia coliO157:H7 have previously been shown to exhibit stationary-phase-dependent variation in their resistance to inactivation by high hydrostatic pressure. In this report we demonstrate that loss of the stationary-phase-inducible sigma factor RpoS resulted in decreased resistance to pressure inE. coli O157:H7 and in a commensal strain. Furthermore, variation in the RpoS activity of the natural isolates of O157:H7 correlated with the pressure resistance of those strains. Heterogeneity was noted in the rpoS alleles of the natural isolates that may explain the differences in RpoS activity. These results are consistent with a role for rpoS in mediating resistance to high hydrostatic pressure in E. coliO157:H7.

scholarly journals Stress sigma factor RpoS degradation and translation are sensitive to the state of central metabolism

2015 ◽  
Vol 112 (16) ◽  
pp. 5159-5164 ◽  
Author(s):  
Aurelia Battesti ◽  
Nadim Majdalani ◽  
Susan Gottesman
Keyword(s):  
Pyruvate Dehydrogenase ◽  
Sigma Factor ◽  
Small Rnas ◽  
Start Codon ◽  
Central Metabolism ◽  
Acetyl Coa ◽  
E Coli ◽  
A Subunit ◽  
Low Levels ◽  
Sigma Factor Rpos

RpoS, the stationary phase/stress sigma factor ofEscherichia coli, regulates a large cohort of genes important for the cell to deal with suboptimal conditions. Its level increases quickly in the cell in response to many stresses and returns to low levels when growth resumes. Increased RpoS results from increased translation and decreased RpoS degradation. Translation is positively regulated by small RNAs (sRNAs). Protein stability is positively regulated by anti-adaptors, which prevent the RssB adaptor-mediated degradation of RpoS by the ClpXP protease. Inactivation ofaceE, a subunit of pyruvate dehydrogenase (PDH), was found to increase levels of RpoS by affecting both translation and protein degradation. The stabilization of RpoS inaceEmutants is dependent on increased transcription and translation of IraP and IraD, two known anti-adaptors. TheaceEmutation also leads to a significant increase inrpoStranslation. The sRNAs known to positively regulate RpoS are not responsible for the increased translation; sequences around the start codon are sufficient for the induction of translation. PDH synthesizes acetyl-CoA; acetate supplementation allows the cell to synthesize acetyl-CoA by an alternative, less favored pathway, in part dependent upon RpoS. Acetate addition suppressed the effects of theaceEmutant on induction of the anti-adaptors, RpoS stabilization, andrpoStranslation. Thus, the bacterial cell responds to lowered levels of acetyl-CoA by inducing RpoS, allowing reprogramming ofE. colimetabolism.

Heat stable toxin of E. coli (STa) stimulates duodenal mucosal bicarbonate secretion in cystic fibrosis knockout mice

2001 ◽  
Vol 120 (5) ◽  
pp. A137-A137
Author(s):  
D CHILDS ◽  
D CROMBIE ◽  
V PRATHA ◽  
Z SELLERS ◽  
D HOGAN ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Knockout Mice ◽  
Bicarbonate Secretion ◽  
E Coli ◽  
Heat Stable

scholarly journals Growth phase-specific changes in the composition of E. coli transcription complexes

2019 ◽  
Vol 1109 ◽  
pp. 155-165 ◽  
Author(s):  
Isaac R. Eason ◽  
Harman P. Kaur ◽  
Katherine A. Alexander ◽  
Maxim V. Sukhodolets
Keyword(s):  
Growth Phase ◽  
E Coli ◽  
Transcription Complexes

Cloning the gene for the heat shock response positiwe regulator (sigma 32 homolog) from Pseudomonas aeruginosa

1995 ◽  
Vol 41 (1) ◽  
pp. 75-87 ◽  
Author(s):  
Zerlina M. Naczynski ◽  
Andrew M. Kropinski ◽  
Chris Mueller
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Heat Shock ◽  
Sigma Factor ◽  
Oligonucleotide Probe ◽  
In Vitro Transcription ◽  
Translation System ◽  
Amino Acid Homology ◽  
E Coli ◽  
Transcriptional Start Sites

A 31 base pair synthetic oligonucleotide based on the genes for the Escherichia coli heat shock sigma factor (rpoH) and the Pseudomonas aeruginosa housekeeping sigma factor (rpoD) was employed in conjunction with the Tanaka et al. (K. Tanaka, T. Shiina, and H. Takahashi, 1988. Science (Washington, D.C.), 242: 1040–1042) RpoD box probe to identify the location of the rpoH gene in P. aeruginosa genomic digests. This gene was cloned into plasmid pGEM3Z(f+), sequenced, and found to share 67% nucleotide identity and 77% amino acid homology with the rpoH gene and its product (σ32) of E. coli. The plasmid containing the rpoH gene complemented the function of σ32 in an E. coli rpoH deletion mutant. Furthermore, this plasmid directed the synthesis of a 32-kDa protein in an E. coli S-30 in vitro transcription–translation system. Primer extension studies were used to identify the transcriptional start sites under control and heat-stressed (45 and 50 °C) conditions. Two promoter sites were identified having sequence homology to the E. coli σ70 and σ24 consensus sequences.Key words: heat shock, Pseudomonas aeruginosa, sigma factor, transcription, oligonucleotide probe.

Comparison of colony and stool blots for detection of enteropathogens by DNA probes

1991 ◽  
Vol 37 (5) ◽  
pp. 407-410
Author(s):  
Mônica A. M. Vieira ◽  
Beatriz E. C. Guth ◽  
Tânia A. T. Gomes
Keyword(s):  
Escherichia Coli ◽  
Key Words ◽  
Sensitivity And Specificity ◽  
Dna Probes ◽  
Type I ◽  
Enteropathogenic Escherichia Coli ◽  
Key Words Dna ◽  
E Coli ◽  
Heat Stable

DNA probes that identify genes coding for heat-labile type I (LT-I) and heat-stable type 1 (ST-I) enterotoxins, enteropathogenic Escherichia coli adherence factor (EAF), and Shigella-like, invasiveness (INV) are used to evaluate the sensitivity and specificity of stool blots in comparison with the sensitivity and specificity of colony blots in detecting enteropathoghens. The sensitivities of the probes in stool blots are 91.7% for the LT-I probe, 76.9% for the ST-I probes, 78.9% for the EAF probe, and 45.5% for the INV probe. The specificity of all probes is higher than 95%. In general, the stool blot method identifies as many if not more LT-I-, ST-I-, and EAF-producing E. coli infections than the colony blots. Key words: DNA probes, stool blots, enteropathogens, diagnosis.

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