scholarly journals GFP plasmid-induced defects in Salmonella invasion depend on plasmid architecture, not protein expression

Microbiology ◽  
2009 ◽  
Vol 155 (2) ◽  
pp. 461-467 ◽  
Author(s):  
Leann Clark ◽  
Isabel Martinez-Argudo ◽  
Tom J. Humphrey ◽  
Mark A. Jepson
Keyword(s):  
Gene Expression ◽  
Optimal Growth ◽  
Growth Conditions ◽  
Gfp Expression ◽  
Antibiotic Resistance Marker ◽  
Chloramphenicol Resistance ◽  
Cultured Epithelial Cells ◽  
Induced Defects ◽  
The Impact ◽  
Plasmid Carriage

We have investigated the impact of plasmids and GFP expression on invasion of cultured epithelial cells by Salmonella enterica Typhimurium strain SL1344. The invasiveness of SL1344 carrying plasmids derived from pBR322, encoding promoterless GFP or constitutively expressed rpsM-GFP, was compared under optimal growth conditions with that of SL1344(pBR322), unmodified SL1344 and a strain with chromosome-integrated rpsM-GFP. The strain carrying pBR322 exhibited normal invasion, but the presence of modified plasmids impaired invasiveness, and impairment was exacerbated by plasmid-encoded chloramphenicol resistance (CmR). Using a different antibiotic resistance marker, kanamycin (KmR), did not impair invasiveness. Despite the effect of plasmid-encoded CmR, the strain containing chromosomally encoded GFP, also carrying a CmR gene, was as invasive as the wild-type. To investigate the mechanism by which plasmid carriage decreases invasion, we monitored SPI-1 gene expression using prgH promoter activity as an index of SPI-1 activity. An SL1344 strain with a chromosome-integrated prgH : : gfp reporter construct exhibited lower GFP expression during exponential phase when carrying plasmids incorporating CmR or gfp, mirroring invasion data. These data provide evidence that suppression of SPI-1 gene expression is a major factor in the loss of invasiveness associated with plasmid carriage. Our findings also indicate that some plasmids, especially those carrying CmR , should be used with caution, as virulence traits and gene expression may be affected by their presence. Integration of reporter proteins into the bacterial chromosome, however, appears to circumvent the adverse effects observed with plasmids.

Water and Temperature Stress Impact Fitness of Acetohydroxyacid Synthase–Inhibiting Herbicide-Resistant Populations of Eastern Black Nightshade (Solanum ptychanthum)

Weed Science ◽  
2011 ◽  
Vol 59 (3) ◽  
pp. 341-348 ◽  
Author(s):  
Jamshid Ashigh ◽  
François J. Tardif
Keyword(s):  
Seed Production ◽  
Optimal Growth ◽  
Growth Conditions ◽  
Stress Conditions ◽  
Acetohydroxyacid Synthase ◽  
Eastern Black Nightshade ◽  
Black Nightshade ◽  
Reproductive Ability ◽  
Temperature Regimes ◽  
The Impact

Many substitutions in the herbicide target enzyme acetohydroxyacid synthase (AHAS) confer whole-plant resistance and may reduce plant fitness. This study was done to determine the impact of different watering and temperature regimes on the germination, growth, and seed production of eastern black nightshade populations resistant (R) to AHAS inhibitors as conferred by an Ala205Val substitution in their AHAS. Growth and reproductive ability of four R and four susceptible (S) populations were determined in growth-cabinet and greenhouse studies. The R populations had lower total berry and viable seed production per plant than S under optimal conditions because of slower berry maturation. Seed production of both S and R populations decreased under lower or higher than optimal watering regimes; however, this reduction was more pronounced for the S populations so that seed production was comparable across S and R. The R populations had significantly higher germination and vegetative growth under cooler alternating temperature regimes. Although there were no differences between R and S plants under stress conditions, under optimal growth conditions, the Ala205Val substitution comes at a significant cost in eastern black nightshade. Under optimal growth conditions and in the absence of herbicide selection, S populations should eventually dominate over R; however, the lack of fitness differences under stress conditions could enhance the persistence of the R individuals.

scholarly journals The first study on the impact of osmolytes in whole cells of high temperature-adapted microorganisms

Soft Matter ◽  
2019 ◽  
Vol 15 (41) ◽  
pp. 8381-8391 ◽  
Author(s):  
Marta Salvador-Castell ◽  
Maksym Golub ◽  
Nicolas Martinez ◽  
Jacques Ollivier ◽  
Judith Peters ◽  
...  
Keyword(s):  
High Temperature ◽  
Optimal Growth ◽  
Growth Conditions ◽  
Structural Rearrangements ◽  
Whole Cells ◽  
The Impact

The presence of the osmolyte mannosylglycerate in alive cells of Thermococcus barophilus, a hyperthermophile and piezophile, limits the structural rearrangements of its proteome under the archaeon optimal growth conditions, i.e. 358 K and 40 MPa.

scholarly journals Rpb4p, a Subunit of RNA Polymerase II, Mediates mRNA Export during Stress

2003 ◽  
Vol 14 (7) ◽  
pp. 2744-2755 ◽  
Author(s):  
Marganit Farago ◽  
Tal Nahari ◽  
Christopher Hammel ◽  
Charles N. Cole ◽  
Mordechai Choder
Keyword(s):  
Gene Expression ◽  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Mrna Export ◽  
Optimal Growth ◽  
Cellular Responses ◽  
Growth Conditions ◽  
Stress Conditions ◽  
Major Mechanism ◽  
A Subunit

Changes in gene expression represent a major mechanism by which cells respond to stress. We and other investigators have previously shown that the yeast RNA polymerase II subunit Rpb4p is required for transcription under various stress conditions, but not under optimal growth conditions. Here we show that, in addition to its role in transcription, Rpb4p is also required for mRNA export, but only when cells are exposed to stress conditions. The roles of Rpb4p in transcription and in mRNA export can be uncoupled genetically by specific mutations in Rpb4p. Both functions of Rpb4p are required to maintain cell viability during stress. We propose that Rpb4p participates in the cellular responses to stress at the interface of the transcription and the export machineries.

scholarly journals Clinically Relevant Plasmid-Host Interactions Indicate that Transcriptional and Not Genomic Modifications Ameliorate Fitness Costs of Klebsiella pneumoniae Carbapenemase-Carrying Plasmids

mBio ◽  
2018 ◽  
Vol 9 (2) ◽  
Author(s):  
Michelle M. C. Buckner ◽  
Howard T. H. Saw ◽  
Rachael N. Osagie ◽  
Alan McNally ◽  
Vito Ricci ◽  
...  
Keyword(s):  
Gene Expression ◽  
Antimicrobial Resistance ◽  
Klebsiella Pneumoniae ◽  
Selection Pressure ◽  
Natural Host ◽  
Fitness Costs ◽  
Content Type ◽  
Resistance Plasmids ◽  
The Impact ◽  
Plasmid Carriage

ABSTRACT The rapid dissemination of antimicrobial resistance (AMR) around the globe is largely due to mobile genetic elements, such as plasmids. They confer resistance to critically important drugs, including extended-spectrum beta-lactams, carbapenems, and colistin. Large, complex resistance plasmids have evolved alongside their host bacteria. However, much of the research on plasmid-host evolution has focused on small, simple laboratory plasmids in laboratory-adapted bacterial hosts. These and other studies have documented mutations in both host and plasmid genes which occur after plasmid introduction to ameliorate fitness costs of plasmid carriage. We describe here the impact of two naturally occurring variants of a large AMR plasmid (pKpQIL) on a globally successful pathogen. In our study, after pKpQIL plasmid introduction, no changes in coding domain sequences were observed in their natural host, Klebsiella pneumoniae . However, significant changes in chromosomal and plasmid gene expression may have allowed the bacterium to adapt to the acquisition of the AMR plasmid. We hypothesize that this was sufficient to ameliorate the associated fitness costs of plasmid carriage, as pKpQIL plasmids were maintained without selection pressure. The dogma that removal of selection pressure (e.g., antimicrobial exposure) results in plasmid loss due to bacterial fitness costs is not true for all plasmid/host combinations. We also show that pKpQIL impacted the ability of K. pneumoniae to form a biofilm, an important aspect of virulence. This study used highly relevant models to study the interaction between AMR plasmids and pathogens and revealed striking differences from results of studies done on laboratory-adapted plasmids and strains. IMPORTANCE Antimicrobial resistance is a serious problem facing society. Many of the genes that confer resistance can be shared between bacteria through mobile genetic elements, such as plasmids. Our work shows that when two clinically relevant AMR plasmids enter their natural host bacteria, there are changes in gene expression, rather than changes to gene coding sequences. These changes in gene expression ameliorate the potential fitness costs of carriage of these AMR plasmids. In line with this, the plasmids were stable within their natural host and were not lost in the absence of selective pressure. We also show that better understanding of the impact of resistance plasmids on fundamental pathogen biology, including biofilm formation, is crucial for fighting drug-resistant infections.

scholarly journals Heavy Water Reduces GFP Expression in Prokaryotic Cell-Free Assays at the Translation Level While Stimulating Its Transcription

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Luisa S. Hohlefelder ◽  
Tobias Stögbauer ◽  
Madeleine Opitz ◽  
Thomas M. Bayerl ◽  
Joachim O. Rädler
Keyword(s):  
Gene Expression ◽  
Heavy Water ◽  
Expression System ◽  
Inhibitory Effect ◽  
Dependent Manner ◽  
Gfp Expression ◽  
Antiproliferative Agent ◽  
Underlying Mechanisms ◽  
The Impact

Thein vitroproliferation of prokaryotic and eukaryotic cells is remarkably hampered in the presence of heavy water (D2O). Impairment of gene expression at the transcription or translation level can be the base for this effect. However, insights into the underlying mechanisms are lacking. Here, we employ a cell-free expression system for the quantitative analysis of the effect of increasing percentages of D2O on the kinetics ofin-vitroGFP expression. Experiments are designed to discriminate the rates of transcription, translation, and protein folding using pDNA and mRNA vectors, respectively. We find that D2O significantly stimulates GFP expression at the transcription level but acts as a suppressor at translation and maturation (folding) in a linear dose-dependent manner. At a D2O concentration of 60%, the GFP expression rate was reduced to 40% of an undisturbed sample. We observed a similar inhibition of GFP expression by D2O in a recombinantEscherichia colistrain, although the inhibitory effect is less pronounced. These results demonstrate the suitability of cell-free systems for quantifying the impact of heavy water on gene expression and establish a platform to further assess the potential therapeutic use of heavy water as antiproliferative agent.

scholarly journals Consequences of a Deletion in dspA on Transcript Accumulation in Synechocystis sp. Strain PCC6803

2004 ◽  
Vol 186 (12) ◽  
pp. 3889-3902 ◽  
Author(s):  
Chao-Jung Tu ◽  
Jeffrey Shrager ◽  
Robert L. Burnap ◽  
Bradley L. Postier ◽  
Arthur R. Grossman
Keyword(s):  
Gene Expression ◽  
Light Exposure ◽  
Optimal Growth ◽  
Growth Conditions ◽  
High Light ◽  
Stress Conditions ◽  
Light Conditions ◽  
Wild Type ◽  
Transcript Accumulation ◽  
Low Light

ABSTRACT A sensor histidine kinase of Synechococcus sp. strain PCC7942, designated nblS, was previously identified and shown to be critical for the acclimation of cells to high-light and nutrient limitation conditions and to influence the expression of a number of light-responsive genes. The nblS orthologue in Synechocystis sp. strain PCC6803 is designated dspA (also called hik33). We have generated a dspA null mutant and analyzed global gene expression in both the mutant and wild-type strains under high- and low-light conditions. The mutant is aberrant for the expression of many genes encoding proteins critical for photosynthesis, phosphate and carbon acquisition, and the amelioration of stress conditions. Furthermore, transcripts from a number of genes normally detected only during exposure of wild-type cells to high-light conditions become partially constitutive in the low-light-grown dspA mutant. Other genes for which transcripts decline upon exposure of wild-type cells to high light are already lower in the mutant during growth in low light. These results suggest that DspA may influence gene expression in both a positive and a negative manner and that the dspA mutant behaves as if it were experiencing stress conditions (e.g., high-light exposure) even when maintained at near-optimal growth conditions for wild-type cells. This is discussed with respect to the importance of DspA for regulating the responses of the cell to environmental cues.

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.

Sign in / Sign up

Export Citation Format

Share Document