scholarly journals Broad-Host-Range Shuttle Vectors for Screening of Regulated Promoter Activity in Viridans Group Streptococci: Isolation of a pH-Regulated Promoter

2000 ◽  
Vol 66 (2) ◽  
pp. 535-542 ◽  
Author(s):  
Aldwin J. M. Vriesema ◽  
René Brinkman ◽  
Jan Kok ◽  
Jacob Dankert ◽  
Sebastian A. J. Zaat
Keyword(s):  
Gene Expression ◽  
Host Range ◽  
Pathogenic Bacteria ◽  
Genomic Library ◽  
Regulation Of Gene Expression ◽  
Broad Host Range ◽  
Oral Flora ◽  
Specific Stimulus ◽  
Bacterial Gene ◽  
Viridans Group Streptococci

ABSTRACT Viridans group streptococci are major constituents of the normal human oral flora and are also identified as the predominant pathogenic bacteria in native valve infective endocarditis. Little information is available regarding the regulation of gene expression in viridans group streptococci, either in response to changes in the oral environment or during development of endocarditis. We therefore constructed a set of broad-host-range vectors for the isolation of promoters from viridans group streptococci that are activated by specific environmental stimuli in vitro or in vivo. A genomic library of Streptococcus gordonii strain CH1 was constructed in one of the new vectors, and this library was introduced into a homologous bacterium by using an optimized electroporation protocol for viridans group streptococci. Because viridans group streptococci entering the bloodstream from the oral cavity encounter an increase in pH, we selected promoters upregulated by this specific stimulus. One of the selected promoter sequences showed homology to the promoter region of thehydA gene from Clostridium acetobutylicum, the expression of which is known to be regulated by the environmental pH. The isolation of this pH-regulated promoter shows that S. gordonii can sense an increase in the environmental pH, which serves as a signal for bacterial gene activation. Furthermore, this demonstrates the usefulness of these new selection vectors in research on adaptive gene expression of viridans group streptococci and possibly also of other gram-positive bacteria.

scholarly journals Broad-Host-Range Plasmids for Constitutive and Inducible Gene Expression in the Absence of Antibiotic Selection

2019 ◽  
Vol 8 (36) ◽  
Author(s):  
Lindsey Burbank ◽  
Wei Wei
Keyword(s):  
Gene Expression ◽  
Host Range ◽  
Gene Function ◽  
Bacterial Species ◽  
Limited Range ◽  
Broad Host Range ◽  
Bacterial Gene ◽  
Antibiotic Selection ◽  
Broad Host Range Plasmids ◽  
Inducible Gene

Plasmid vectors are a valuable research tool for characterizing bacterial gene function, but there is a limited range of plasmids that are functional in nonmodel bacterial species. Described here is a set of broad-host-range plasmids modified for stability in the absence of antibiotic selection and for gene expression manipulation.

scholarly journals Construction of a Broad-Host-Range Tn7-Based Vector for Single-Copy PBAD-Controlled Gene Expression in Gram-Negative Bacteria

2012 ◽  
Vol 79 (2) ◽  
pp. 718-721 ◽  
Author(s):  
F. Heath Damron ◽  
Elizabeth S. McKenney ◽  
Herbert P. Schweizer ◽  
Joanna B. Goldberg
Keyword(s):  
Gene Expression ◽  
Pseudomonas Aeruginosa ◽  
Host Range ◽  
Single Copy ◽  
Broad Host Range ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Content Type ◽  
Delivery Vector ◽  
Inducible Gene

ABSTRACTWe describe a mini-Tn7-based broad-host-range expression cassette for arabinose-inducible gene expression from the PBADpromoter. This delivery vector, pTJ1, can integrate a single copy of a gene into the chromosome of Gram-negative bacteria for diverse genetic applications, of which several are discussed, usingPseudomonas aeruginosaas the model host.

scholarly journals The Sinorhizobium (Ensifer) fredii HH103 Nodulation Outer Protein NopI Is a Determinant for Efficient Nodulation of Soybean and Cowpea Plants

2016 ◽  
Vol 83 (5) ◽  
Author(s):  
Irene Jiménez-Guerrero ◽  
Francisco Pérez-Montaño ◽  
Carlos Medina ◽  
Francisco Javier Ollero ◽  
Francisco Javier López-Baena
Keyword(s):  
Adenylate Cyclase ◽  
Host Cell ◽  
Host Range ◽  
Pathogenic Bacteria ◽  
Defense Responses ◽  
Host Cells ◽  
Broad Host Range ◽  
Sinorhizobium Fredii ◽  
Symbiotic Efficiency ◽  
Content Type

ABSTRACT The type III secretion system (T3SS) is a specialized secretion apparatus that is commonly used by many plant and animal pathogenic bacteria to deliver proteins, termed effectors, to the interior of the host cells. These effectors suppress host defenses and interfere with signal transduction pathways to promote infection. Some rhizobial strains possess a functional T3SS, which is involved in the suppression of host defense responses, host range determination, and symbiotic efficiency. The analysis of the genome of the broad-host-range rhizobial strain Sinorhizobium fredii HH103 identified eight genes that code for putative T3SS effectors. Three of these effectors, NopL, NopP, and NopI, are Rhizobium specific. In this work, we demonstrate that NopI, whose amino acid sequence shows a certain similarity with NopP, is secreted through the S. fredii HH103 T3SS in response to flavonoids. We also determined that NopL can be considered an effector since it is directly secreted to the interior of the host cell as demonstrated by adenylate cyclase assays. Finally, the symbiotic phenotype of single, double, and triple nopI, nopL, and nopP mutants in soybean and cowpea was assayed, showing that NopI plays an important role in determining the number of nodules formed in both legumes and that the absence of both NopL and NopP is highly detrimental for symbiosis. IMPORTANCE The paper is focused on three Rhizobium-specific T3SS effectors of Sinorhizobium fredii HH103, NopL, NopP, and NopI. We demonstrate that S. fredii HH103 is able to secrete through the T3SS in response to flavonoids the nodulation outer protein NopI. Additionally, we determined that NopL can be considered an effector since it is secreted to the interior of the host cell as demonstrated by adenylate cyclase assays. Finally, nodulation assays of soybean and cowpea indicated that NopI is important for the determination of the number of nodules formed and that the absence of both NopL and NopP negatively affected nodulation.

Disease Resistance Against a Broad-Host-Range Pathogen

2013 ◽  
Vol 14 (1) ◽  
pp. 32
Author(s):  
Jonathan M. Jacobs ◽  
Caitilyn Allen
Keyword(s):  
Disease Resistance ◽  
Host Range ◽  
Bacterial Wilt ◽  
Ralstonia Solanacearum ◽  
Pathogenic Bacteria ◽  
Resistance Breeding ◽  
Wilt Disease ◽  
Family Type ◽  
Broad Host Range ◽  
Bacterial Wilt Disease

The bacterial wilt pathogen Ralstonia solanacearum causes major agricultural losses on many crop hosts worldwide. Resistance breeding is the best way to control bacterial wilt disease, but the biological basis for bacterial wilt resistance is unknown. We found that R. solanacearum uses an AvrE-family, Type III-secreted effector called PopS to overcome plant defenses and cause disease on tomato. Orthologs of PopS are widely conserved across distinct classes of plant pathogenic bacteria and could provide novel, durable targets for resistance. Accepted for publication 25 September 2013. Published 25 November 2013.

scholarly journals H-NS is a part of a thermally controlled mechanism for bacterial gene regulation

2005 ◽  
Vol 391 (2) ◽  
pp. 203-213 ◽  
Author(s):  
Shusuke Ono ◽  
Martin D. Goldberg ◽  
Tjelvar Olsson ◽  
Diego Esposito ◽  
Jay C. D. Hinton ◽  
...  
Keyword(s):  
Gene Expression ◽  
Thermal Activation ◽  
Pathogenic Bacteria ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Virulence Gene ◽  
Bacterial Gene ◽  
Virulence Gene Expression ◽  
Serovar Typhimurium ◽  
Micro Organisms ◽  
Dna Binding Properties

Temperature is a primary environmental stress to which micro-organisms must be able to adapt and respond rapidly. Whereas some bacteria are restricted to specific niches and have limited abilities to survive changes in their environment, others, such as members of the Enterobacteriaceae, can withstand wide fluctuations in temperature. In addition to regulating cellular physiology, pathogenic bacteria use temperature as a cue for activating virulence gene expression. This work confirms that the nucleoid-associated protein H-NS (histone-like nucleoid structuring protein) is an essential component in thermoregulation of Salmonella. On increasing the temperature from 25 to 37 °C, more than 200 genes from Salmonella enterica serovar Typhimurium showed H-NS-dependent up-regulation. The thermal activation of gene expression is extremely rapid and change in temperature affects the DNA-binding properties of H-NS. The reduction in gene repression brought about by the increase in temperature is concomitant with a conformational change in the protein, resulting in the decrease in size of high-order oligomers and the appearance of increasing concentrations of discrete dimers of H-NS. The present study addresses one of the key complex mechanisms by which H-NS regulates gene expression.

A generic intron increases gene expression in transgenic mice

1991 ◽  
Vol 11 (6) ◽  
pp. 3070-3074
Author(s):  
T Choi ◽  
M Huang ◽  
C Gorman ◽  
R Jaenisch
Keyword(s):  
Gene Expression ◽  
Transgenic Mice ◽  
Transgene Expression ◽  
Integration Site ◽  
Regulation Of Gene Expression ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
Transcription Unit ◽  
Histone H4 ◽  
Bacterial Gene

To investigate the role of splicing in the regulation of gene expression, we have generated transgenic mice carrying the human histone H4 promoter linked to the bacterial gene for chloramphenicol acetyltransferase (CAT), with or without a heterologous intron in the transcription unit. We found that CAT activity is 5- to 300-fold higher when the transgene incorporates a hybrid intron than with an analogous transgene precisely deleted for the intervening sequences. This hybrid intron, consisting of an adenovirus splice donor and an immunoglobulin G splice acceptor, stimulated expression in a broad range of tissues in the animal. Although the presence of the hybrid intron increased the frequency of transgenics with significant CAT activity, it did not affect the integration site-dependent variation commonly seen in transgene expression. To determine whether the enhancement is a general outcome of splicing or is dependent on the particular intron, we also produced equivalent transgenics carrying the widely used simian virus 40 small-t intron. We found that the hybrid intron is significantly more effective in elevating transgene expression. Our results suggest that inclusion of the generic intron in cDNA constructs may be valuable in achieving high levels of expression in transgenic mice.

Analysis of the DRR230 family of pea defensins: gene expression pattern and evidence of broad host-range antifungal activity

Plant Science ◽  
2002 ◽  
Vol 163 (4) ◽  
pp. 855-864 ◽  
Author(s):  
Fang-Ming Lai ◽  
Catherine DeLong ◽  
Kangfeng Mei ◽  
Tracy Wignes ◽  
Pierre R. Fobert
Keyword(s):  
Gene Expression ◽  
Antifungal Activity ◽  
Host Range ◽  
Expression Pattern ◽  
Gene Expression Pattern ◽  
Broad Host Range

scholarly journals Characterization of novel bacteriophage phiC119 capable of lysing multidrug-resistant Shiga toxin-producingEscherichia coliO157:H7

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e2423 ◽  
Author(s):  
Luis Amarillas ◽  
Cristóbal Chaidez ◽  
Arturo González-Robles ◽  
Yadira Lugo-Melchor ◽  
Josefina León-Félix
Keyword(s):  
Host Range ◽  
Shiga Toxin ◽  
Pathogenic Bacteria ◽  
Genetic Material ◽  
Multidrug Resistant ◽  
Broad Host Range ◽  
Antibiotic Resistant ◽  
E Coli ◽  
Tract Infections

BackgroundShiga toxin-producingEscherichia coli(STEC) is one of the most common and widely distributed foodborne pathogens that has been frequently implicated in gastrointestinal and urinary tract infections. Moreover, high rates of multiple antibiotic-resistantE. colistrains have been reported worldwide. Due to the emergence of antibiotic-resistant strains, bacteriophages are considered an attractive alternative to biocontrol pathogenic bacteria. Characterization is a preliminary step towards designing a phage for biocontrol.MethodsIn this study, we describe the characterization of a bacteriophage designated phiC119, which can infect and lyse several multidrug-resistant STEC strains and someSalmonellastrains. The phage genome was screened to detect thestx-genes using PCR, morphological analysis, host range was determined, and genome sequencing were carried out, as well as an analysis of the cohesive ends and identification of the type of genetic material through enzymatic digestion of the genome.ResultsAnalysis of the bacteriophage particles by transmission electron microscopy showed that it had an icosahedral head and a long tail, characteristic of the familySiphoviridae. The phage exhibits broad host range against multidrug-resistant and highly virulentE. coliisolates. One-step growth experiments revealed that the phiC119 phage presented a large burst size (210 PFU/cell) and a latent period of 20 min. Based on genomic analysis, the phage contains a linear double-stranded DNA genome with a size of 47,319 bp. The phage encodes 75 putative proteins, but lysogeny and virulence genes were not found in the phiC119 genome.ConclusionThese results suggest that phage phiC119 may be a good biological control agent. However, further studies are required to ensure its control of STEC and to confirm the safety of phage use.

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