Search results for "(Escherichia coli)"

Prephenate dehydratase from the aphid endosymbiont (Buchnera) displays changes in the regulatory domain that suggest its desensitization to inhibitio…

2000

ABSTRACT Buchnera aphidicola , the prokaryotic endosymbiont of aphids, complements dietary deficiencies with the synthesis and provision of several essential amino acids. We have cloned and sequenced a region of the genome of B. aphidicola isolated from Acyrthosiphon pisum which includes the two-domain aroQ/pheA gene. This gene encodes the bifunctional chorismate mutase-prephenate dehydratase protein, which plays a central role in l -phenylalanine biosynthesis. Two changes involved in the overproduction of this amino acid have been detected. First, the absence of an attenuator region suggests a constitutive expression of this gene. Second, the regulatory domain of the Buchnera prephenate de…

Multiple Site-Specific Binding of Fis Protein to Escherichia coli nuoA-N Promoter DNA and its Impact on DNA Topology Visualised by Means of Scanning …

2004

A multiplex RTi-PCR reaction for simultaneous detection of Escherichia coli O157:H7, Salmonella spp. and Staphylococcus aureus on fresh, minimally pr…

2007

In this work, a new multiplex single-tube real-time PCR approach is presented for the detection of Escherichia coli O157:H7, Salmonella spp. and Staphylococcus aureus, three of the more frequent food-borne bacterial pathogens that are usually investigated in a variety of food matrices. The study includes the design and specificity testing, of a new primer and probe specific for Salmonella spp. Reaction conditions were adjusted for the simultaneous amplification and detection of specific fragments in the beta-glucuronidase (uidA, E. coli) and Thermonulease (nuc, Sta. aureus) genes, and in the replication origin sequence (oriC, Salmonella spp.). Melting-curve analysis using a SYBR Green I RTi…

rRNA probing of chromosomal DNA of epidemic and sporadic isolates of Salmonella enterica subsp. Enterica serovar kottbus from Northern and Southern I…

1990

Fifty-two strains of Salmonella enterica subsp. enterica serovar Kottbus, identified at the Centres of Enterobacteriaceae of Northern and Southern Italy, were investigated by molecular genetic methods. Thirteen isolates were recovered during two food-poisoning outbreaks that occurred in May 1987 in Lombardy. The rDNA gene restriction patterns, obtained by probing endonuclease cleaved chromosomal DNA with photobiotin labeled Escherichia coli rRNA, revealed some heterogeneity among strains isolated from Southern Italy, whereas Northern Italy isolates exhibited virtually identical banding patterns.

Comparison of Four Commercial DNA Extraction Kits for PCR Detection of Listeria monocytogenes, Salmonella, Escherichia coli O157:H7, and Staphylococc…

2008

Four commercial DNA extraction methods, PrepMan Ultra (Applied Biosystems), InstaGene Matrix (BioRad), DNeasy Tissue kit (Qiagen), and UltraClean (MoBio), were tested for PCR detection of Listeria monocytogenes, Escherichia coli O157: H7, Salmonella, and Staphylococcus aureus in fresh, minimally processed vegetables. For comparative purposes, sensitivity assays with specific PCRs were carried out after DNA extraction with the four methods in green pepper, broccoli, and onion artificially inoculated with the four pathogens separately. As confirmed by statistical analysis, the DNeasy Tissue kit rendered the highest sensitivity values in the three matrices assayed for Salmonella, L. monocytoge…

Phosphorylation and DNA binding of the regulator DcuR of the fumarate-responsive two-component system DcuSR of Escherichia coli

2004

The function of the response regulator DcuR of the DcuSR fumarate two-component sensory system of Escherichia coli was analysed in vitro. Isolated DcuR protein was phosphorylated by the sensory histidine kinase, DcuS, and ATP, or by acetyl phosphate. In gel retardation assays with target promoters (frdA, dcuB, dctA), phosphoryl DcuR (DcuR-P) formed a high-affinity complex, with an apparent K D (app. K D) of 0·2–0·3 μM DcuR-P, and a low-affinity (app. K D 0·8–2 μM) complex. The high-affinity complex was formed only with promoters transcriptionally-regulated by DcuSR, whereas low-affinity binding was seen also with some DcuSR-independent promoters. The binding site of DcuR-P at the dcuB promo…

Inducible metabolism of phenolic acids in Pediococcus pentosaceus is encoded by an autoregulated operon which involves a new class of negative transc…

2000

ABSTRACTPediococcus pentosaceusdisplays a substrate-inducible phenolic acid decarboxylase (PAD) activity onp-coumaric acid. Based on DNA sequence homologies between the three PADs previously cloned, a DNA probe of theLactobacillus plantarum pdcgene was used to screen aP. pentosaceusgenomic library in order to clone the corresponding gene of this bacteria. One clone detected with this probe displayed a low PAD activity. Subcloning of this plasmid insertion allowed us to determine the part of the insert which contains a 534-bp open reading frame (ORF) coding for a 178-amino-acid protein presenting 81.5% of identity withL. plantarumPDC enzyme. This ORF was identified as thepadAgene. A second O…

Identification of Critical Genes for Growth in Olive Brine by Transposon Mutagenesis of Lactobacillus pentosus C11

2013

ABSTRACT Olive brine represents a stressful environment due to the high NaCl concentration, presence of phenolic compounds known as antimicrobials, and low availability of nutrients. Thus, only a few strains of lactic acid bacteria (LAB) are adapted to grow in and ferment table olives. To identify the mechanisms by which these few strains are able to grow in olive brine, Lactobacillus pentosus C11, a particularly resistant strain isolated from naturally fermented table olives, was mutagenized by random transposition using the P junc -TpaseIS 1223 system (H. Licandro-Seraut, S. Brinster, M. van de Guchte, H. Scornec, E. Maguin, P. Sansonetti, J. F. Cavin, and P. Serror, Appl. Environ. Microb…

LrhA as a new transcriptional key regulator of flagella, motility and chemotaxis genes in Escherichia coli

2002

The function of the LysR-type regulator LrhA of Escherichia coli was defined by comparing whole-genome mRNA profiles from wild-type E. coli and an isogenic lrhA mutant on a DNA microarray. In the lrhA mutant, a large number (48) of genes involved in flagellation, motility and chemotaxis showed relative mRNA abundances increased by factors between 3 and 80. When a representative set of five flagellar, motility and chemotaxis genes was tested in lacZ reporter gene fusions, similar factors for derepression were found in the lrhA mutant. In gel retardation experiments, the LrhA protein bound specifically to flhD and lrhA promoter DNA (apparent K-D approximate to 20 nM), whereas the promoters of…

Cloning and expression of the putative aggregation factor from the marine sponge Geodia cydonium.

2001

Sponges (phylum Porifera) have extensively been used as a model system to study cell-cell interaction on molecular level. Recently, we identified and cloned the putative aggregation receptor (AR) of the sponge Geodia cydonium, which interacts in a heterophilic way with the aggregation factor (AF) complex. In the present study, antibodies against this complex have been raised that abolish the adhesion function of the enriched sponge AF, the AF-Fraction 6B. Using this antibody as a tool, a complete 1.7 kb long cDNA, GEOCYAF, could be isolated from a cDNA library that encodes the putative AF. Its deduced aa sequence in the N-terminal section comprises high similarity to amphiphysin/BIN1 sequen…