scholarly journals Biotic Factors Affecting Expression of the 2,4-Diacetylphloroglucinol Biosynthesis Gene phlA in Pseudomonas fluorescens Biocontrol Strain CHA0 in the Rhizosphere

2001 ◽  
Vol 91 (9) ◽  
pp. 873-881 ◽  
Author(s):  
R. Notz ◽  
M. Maurhofer ◽  
U. Schnider-Keel ◽  
B. Duffy ◽  
D. Haas ◽  
...  
Keyword(s):  
Gene Expression ◽  
Pseudomonas Fluorescens ◽  
Reporter Gene ◽  
Pythium Ultimum ◽  
Disease Suppression ◽  
Biotic Factors ◽  
Host Genotype ◽  
Bacterial Gene ◽  
Bacterial Gene Expression

Production of the polyketide antimicrobial metabolite 2,4-diacetyl-phloroglucinol (DAPG) is a key factor in the biocontrol activity of Pseudomonas fluorescens CHA0. Strain CHA0 carrying a translational phlA′-′lacZ fusion was used to monitor expression of the phl biosynthetic genes in vitro and in the rhizosphere. Expression of the reporter gene accurately reflected actual production of DAPG in vitro and in planta as determined by direct extraction of the antimicrobial compound. In a gnotobiotic system containing a clay and sand-based artificial soil, reporter gene expression was significantly greater in the rhizospheres of two monocots (maize and wheat) compared with gene expression in the rhizospheres of two dicots (bean and cucumber). We observed this host genotype effect on bacterial gene expression also at the level of cultivars. Significant differences were found among six additional maize cultivars tested under gnotobiotic conditions. There was no difference between transgenic maize expressing the Bacillus thuringiensis insecticidal gene cry1Ab and the near-isogenic parent line. Plant age had a significant impact on gene expression. Using maize as a model, expression of the phlA′-′lacZ reporter gene peaked at 24 h after planting of pregerminated seedlings, and dropped to a fourth of that value within 48 h, remaining at that level throughout 22 days of plant growth. Root infection by Pythium ultimum stimulated bacterial gene expression on both cucumber and maize, and this was independent of differences in rhizosphere colonization on these host plants. To our knowledge, this is the first comprehensive evaluation of how biotic factors that commonly confront bacterial inoculants in agricultural systems (host genotype, host age, and pathogen infection) modulate the expression of key biocontrol genes for disease suppression.

scholarly journals Measurement of bacterial gene expression in vivo

2000 ◽  
Vol 355 (1397) ◽  
pp. 601-611 ◽  
Author(s):  
Isabelle Hautefort ◽  
Jay C. D. Hinton
Keyword(s):  
Gene Expression ◽  
Dynamic Environment ◽  
Subtractive Hybridization ◽  
Fluorescence Induction ◽  
Infection Process ◽  
Bacterial Gene ◽  
Technology System ◽  
Bacterial Gene Expression

The complexities of bacterial gene expression during mammalian infection cannot be addressed by in vitro experiments. We know that the infected host represents a complex and dynamic environment, which is modified during the infection process, presenting a variety of stimuli to which the pathogen must respond if it is to be successful. This response involves hundreds of ivi (in vivo– induced) genes which have recently been identified in animal and cell culture models using a variety of technologies including in vivo expression technology, differential fluorescence induction, subtractive hybridization and differential display. Proteomic analysis is beginning to be used to identify IVI proteins, and has benefited from the availability of genome sequences for increasing numbers of bacterial pathogens. The patterns of bacterial gene expression during infection remain to be investigated. Are ivi genes expressed in an organ–specific or cell–type–specific fashion ? New approaches are required to answer these questions. The uses of the immunologically based in vivo antigen technology system, in situ PCR and DNA microarray analysis are considered. This review considers existing methods for examining bacterial gene expression in vivo, and describes emerging approaches that should further our understanding in the future.

USE OF DNA-DIRECTED IN VITRO SYSTEMS TO STUDY BACTERIAL GENE EXPRESSION

1981 ◽  
pp. 215-243
Author(s):  
Herbert Weissbach ◽  
Tanya Zarucki-Schulz ◽  
Hsiang-fu Kung ◽  
Carlos Spears ◽  
Betty Redfield ◽  
...  
Keyword(s):  
Gene Expression ◽  
Bacterial Gene ◽  
Bacterial Gene Expression ◽  
In Vitro Systems

Impact of Genomic Technologies on Studies of Bacterial Gene Expression

2002 ◽  
Vol 56 (1) ◽  
pp. 599-624 ◽  
Author(s):  
Virgil Rhodius ◽  
Tina K. Van Dyk ◽  
Carol Gross ◽  
Robert A. LaRossa
Keyword(s):  
Gene Expression ◽  
Bacterial Gene ◽  
Bacterial Gene Expression ◽  
Genomic Technologies

Concurrence between the gene expression pattern of Actinobacillus actinomycetemcomitans in localized aggressive periodontitis and in human epithelial cells

2005 ◽  
Vol 54 (5) ◽  
pp. 497-504 ◽  
Author(s):  
Joseph Richardson ◽  
Justin Corey Craighead ◽  
Sam Linsen Cao ◽  
Martin Handfield
Keyword(s):  
Gene Expression ◽  
Epithelial Cell ◽  
Epithelial Cells ◽  
Expression Pattern ◽  
Gene Expression Pattern ◽  
Aggressive Periodontitis ◽  
Actinobacillus Actinomycetemcomitans ◽  
Bacterial Gene ◽  
Bacterial Gene Expression

Actinobacillus actinomycetemcomitans is a facultatively intracellular pathogen and the aetiological agent of localized aggressive periodontitis. Screening of the genome of A. actinomycetemcomitans for in vivo-induced antigen determinants previously demonstrated that the proteome of this organism differs in laboratory culture compared with conditions found during active infection. The aim of the present study was to determine whether the bacterial gene expression pattern inferred with in vivo-induced antigen technology (IVIAT) in human infections was consistent with the gene expression pattern occurring upon epithelial cell association. To this end, a real-time PCR method was developed and used to quantify absolute and relative bacterial gene expression of A. actinomycetemcomitans grown extra- and intracellularly in two human epithelial cell lines (HeLa and IHGK). The amount of template used in the assay was normalized using the total count of viable bacteria (c.f.u.) as a reference point and performed in duplicate in at least two independent experiments. Controls for this experiment included 16S rRNA and gapdh. Transcription of all eight ORFs tested increased significantly (P < 0.05) in HeLa and IHGK cells compared with bacteria grown extracellularly. The concurrence of gene expression patterns found in the two models suggests that these epithelial cells are valid in vitro models of infection for the genes tested. IVIAT is an experimental platform that can be used as a validation tool to assess the reliability of animal and other models of infection and is applicable to most pathogens.

Protein phosphatase 2A potentiates activity of promoters containing AP-1-binding elements

1993 ◽  
Vol 13 (4) ◽  
pp. 2104-2112
Author(s):  
A S Alberts ◽  
T Deng ◽  
A Lin ◽  
J L Meinkoth ◽  
A Schönthal ◽  
...  
Keyword(s):  
Gene Expression ◽  
Reporter Gene ◽  
Protein Phosphatase ◽  
Signal Transduction Pathways ◽  
Marker Genes ◽  
Direct Mechanism ◽  
Phosphatase 2A ◽  
Beta Galactosidase ◽  
Regulatory Sites

The involvement of serine/threonine protein phosphatases in signaling pathways which modulate the activity of the transcription factor AP-1 was examined. Purified protein phosphatase types 1 (PP1) and 2A (PP2A) were microinjected into cell lines containing stably transfected lacZ marker genes under the control of an enhancer recognized by AP-1. Microinjection of PP2A potentiated serum-stimulated beta-galactosidase expression from the AP-1-regulated promoter. Similarly, transient expression of the PP2A catalytic subunit with c-Jun resulted in a synergistic transactivation of an AP-1-regulated reporter gene. PP2A, but not PP1, potentiated serum-induced c-Jun expression, which has been previously shown to be autoregulated by AP-1 itself. Consistent with these results, PP2A dephosphorylated c-Jun on negative regulatory sites in vitro, suggesting one possible direct mechanism for the effects of PP2A on AP-1 activity. Microinjection of PP2A had no effect on cyclic AMP (cAMP)-induced expression of a reporter gene containing a cAMP-regulated promoter, while PP1 injection abolished cAMP-induced gene expression. Taken together, these results suggest a specific role for PP2A in signal transduction pathways that regulate AP-1 activity and c-Jun expression.

scholarly journals Regulation of asymmetries in the kinetics and protein numbers of bacterial gene expression

2019 ◽  
Vol 1862 (2) ◽  
pp. 119-128 ◽  
Author(s):  
Sofia Startceva ◽  
Vinodh K. Kandavalli ◽  
Ari Visa ◽  
Andre S. Ribeiro
Keyword(s):  
Gene Expression ◽  
Bacterial Gene ◽  
Bacterial Gene Expression

scholarly journals Synergistic activation of ADH2 expression is sensitive to upstream activation sequence 2 (UAS2) orientation, copy number and UAS1-UAS2 helical phasing.

1995 ◽  
Vol 15 (6) ◽  
pp. 3442-3449 ◽  
Author(s):  
M S Donoviel ◽  
N Kacherovsky ◽  
E T Young
Keyword(s):  
Gene Expression ◽  
Binding Site ◽  
Reporter Gene ◽  
Copy Number ◽  
Glucose Repression ◽  
Regulatory Protein ◽  
Regulatory Region ◽  
Upstream Regulatory Region ◽  
Specific Sequence

The alcohol dehydrogenase 2 (ADH2) gene of Saccharomyces cerevisiae is under stringent glucose repression. Two cis-acting upstream activation sequences (UAS) that function synergistically in the derepression of ADH2 gene expression have been identified. UAS1 is the binding site for the transcriptional regulator Adr1p. UAS2 has been shown to be important for ADH2 expression and confers glucose-regulated, ADR1-independent activity to a heterologous reporter gene. An analysis of point mutations within UAS2, in the context of the entire ADH2 upstream regulatory region, showed that the specific sequence of UAS2 is important for efficient derepression of ADH2, as would be expected if UAS2 were the binding site for a transcriptional regulatory protein. In the context of the ADH2 upstream regulatory region, including UAS1, working in concert with the ADH2 basal promoter elements, UAS2-dependent gene activation was dependent on orientation, copy number, and helix phase. Multimerization of UAS2, or its presence in reversed orientation, resulted in a decrease in ADH2 expression. In contrast, UAS2-dependent expression of a reporter gene containing the ADH2 basal promoter and coding sequence was enhanced by multimerization of UAS2 and was independent of UAS2 orientation. The reduced expression caused by multimerization of UAS2 in the native promoter was observed only in the presence of ADR1. Inhibition of UAS2-dependent gene expression by Adr1p was also observed with a UAS2-dependent ADH2 reporter gene. This inhibition increased with ADR1 copy number and required the DNA-binding activity of Adr1p. Specific but low-affinity binding of Adr1p to UAS2 in vitro was demonstrated, suggesting that the inhibition of UAS2-dependent gene expression observed in vivo could be a direct effect due to Adr1p binding to UAS2.

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