The HilC and HilD proteins of Salmonella enterica serovar Typhimurium are members the AraC/XylS family transcription regulators. They encoded on pathogenicity island 1 (SPI1) control expression hilA gene, which encodes major transcriptional activator for many genes SPI1 elsewhere that contribute to invasion host cells. Gel electrophoretic shift DNase footprinting assays revealed purified can bind multiple regions in hilC promoters a single region hilD promoter. Although both -D same DNA...

The coordinate expression of Salmonella enterica invasion genes on pathogenicity island 1 is under the control complex circuits regulation that involve AraC/XylS family transcriptional activators HilD, HilC, and RtsA nucleoid-associated proteins. Single-copy transcription fusions were used to assess effects proteins Hha H-NS hilD, hilC, rtsA expression. data show all three genes, rtsA, repressed by and/or Hha. repression was highest among tested genes. level rtsA-lac equally elevated in hns...

ABSTRACT Clostridium difficile infection (CDI) is a serious diarrheal disease that often develops following prior antibiotic usage. One of the major problems with current therapies (oral vancomycin and metronidazole) high rate recurrence. Nitazoxanide (NTZ), an inhibitor pyruvate:ferredoxin oxidoreductase (PFOR) in anaerobic bacteria, parasites, Helicobacter pylori , Campylobacter jejuni also shows clinical efficacy against CDI. From library ∼250 analogues NTZ, we identified leads increased...

Metronidazole (MTZ) is widely used in combination therapies against the human gastric pathogen Helicobacter pylori. Resistance to this drug common among clinical isolates and results from loss-of-function mutations rdxA, which encodes an oxygen-insensitive nitroreductase. The RdxA-associated MTZ-reductase activity of H. pylori lost upon cell disruption. Here we provide a mechanistic explanation for phenomenon. Under aerobic conditions, His6-tagged RdxA protein (purified Escherichia coli),...

The R dx A oxygen‐insensitive nitroreductase of the human gastric pathogen H elicobacter pylori is responsible for susceptibility this organism to redox active prodrug metronidazole [2‐(2‐methyl‐5‐nitro‐1 ‐imidazol‐1‐yl)ethanol]. Loss‐of‐function mutations in rdxA are primarily resistance therapeutic. exhibits potent NADPH oxidase activity under aerobic conditions and reductase strictly anaerobic conditions. In present study, we report crystal structure , which a homodimer exhibiting domain...

ABSTRACT Metronidazole (MTZ) is often used in combination therapies to treat infections caused by the gastric pathogen Helicobacter pylori . Resistance MTZ results from loss-of-function mutations genes encoding RdxA and FrxA nitroreductases. MTZ-resistant strains, when cultured at sub-MICs of (5 20 μg/ml), show dose-dependent defects bacterial growth; depressed activities many Krebs cycle enzymes, including pyruvate:ferredoxin oxidoreductase (PFOR); low transcript levels porGDAB (primer...

Abstract A library composed of nitazoxanide‐based analogues was synthesized and assayed for increased antibacterial efficacy against the pyruvate–ferredoxin oxidoreductase (PFOR) using microorganisms Helicobacter pylori , Campylobacter jejuni Clostridium difficile . Derivatives were found to recapitulate improve activity these organisms select tested their ability disrupt PFOR enzyme directly. The also screened staphylococci resulted in identification capable inhibiting both all at low...

Emerging evidence has suggested a critical role for activator protein-1 (AP)-1 in regulating various cellular functions. The goal of this study was to investigate the effects Helicobacter pylori and mitogen-activated protein kinases (MAPK) on AP-1 subcomponents expression DNA-binding activity gastric epithelial cells. We found that H. infection resulted time- dose-dependent increase proteins c-Jun, JunB, JunD, Fra-1, c-Fos, which make up major AGS MKN45 cells, while levels Fra-2 FosB...

Amixicile shows efficacy in the treatment of Clostridium difficile infections (CDI) a mouse model, with no recurrence CDI. Since amixicile selectively inhibits action B vitamin (thiamine pyrophosphate) cofactor pyruvate:ferredoxin oxidoreductase (PFOR), it may both escape mutation-based drug resistance and spare beneficial probiotic gut bacteria that do not express this enzyme. is water-soluble derivative nitazoxanide (NTZ), an antiparasitic therapeutic also against CDI humans. In...

Helicobacter pylori establishes lifelong infections of the gastric mucosa, a niche considered hostile to most microbes. While responses acidity and local inflammation are understood, little is known as how they integrated into homeostatic control cell division growth-stage gene expression. Here we investigate essential orphan response regulator HP1043, member OmpR/PhoB subfamily transcriptional regulators that unique Epsilonproteobacteria lacks phosphorylation domains. To test hypothesis...

Amixicile is a promising derivative of nitazoxanide (an antiparasitic therapeutic) developed to treat systemic infections caused by anaerobic bacteria, parasites, and members the Epsilonproteobacteria (Campylobacter Helicobacter). selectively inhibits pyruvate-ferredoxin oxidoreductase (PFOR) related enzymes inhibiting function vitamin B1 cofactor (thiamine pyrophosphate) novel mechanism. Here, we interrogate amixicile scaffold, guided docking simulations, direct PFOR inhibition assays, MIC...

ABSTRACT Fundamental questions in bacterial gene regulation concern how multiple regulatory proteins interact with the transcription apparatus at a single promoter and what are roles of protein contacts RNA polymerase changes DNA conformation. Transcription Escherichia coli uhpT gene, encoding inducible sugar phosphate transporter, is dependent on response regulator UhpA stimulated by cyclic AMP receptor (CAP). binds to sites between positions −80 −32 upstream start site, CAP site centered...

ABSTRACT The histidine kinase (HK) component of many two-component regulatory systems exhibits regulated ability to phosphorylate itself and participate in transfer phosphate from its cognate response regulator. signaling system that controls expression the UhpT sugar transporter Escherichia coli external glucose 6-phosphate includes HK protein UhpB polytopic membrane UhpC, a homolog which is required for responsiveness an inducer activation UhpB. existence UhpBC complex suggested by...

Expression of invasion genes in Salmonella pathogenicity island 1 (SPI-1) is mainly driven by the transcriptional activator HilA. Transcription hilA subject to complex control and stimulated SPI-1-encoded HilC HilD proteins. The C-terminal domain RpoA contributes activation HilC/D under certain inducing conditions.

TrpI protein, the activator of transcription trpBA operon fluorescent pseudomonads, bends DNA when it forms either two well-characterized complexes with regulatory region. In complex 1, bound only to its strong binding site (site I), calculated bending angle is 65 67 degrees and center in middle I. 2, which required for activation promoter, both I weaker II, increased 89 90 at I-site II boundary. Indoleglycerol phosphate (InGP), strongly stimulates formation 2 activation, does not affect...

Tn5 insertion mutants defective in regulation of the Pseudomonas putida trpE and trpGDC operons by tryptophan were found to contain insertions P. miaA gene, whose product (in Escherichia coli) modifies tRNA(Trp) is required for attenuation. Nucleotide sequences upstream trpG encode putative leader peptides similar sequence other bacterial species, phenotypes strongly suggest that transcription these regulated solely

ABSTRACT UhpA, a member of the NarL family response regulators, activates transcription Escherichia coli uhpT gene for sugar phosphate transporter UhpT in to extracellular glucose-6-phosphate. UhpA binds with different affinities adjacent regions promoter, termed strong-binding (S) region from −80 −50 and weak-binding (W) −32. Transcription activation by is stimulated catabolite activator protein (CAP)-cyclic AMP complex depends on C-terminal domains RNA polymerase RpoA RpoD subunits....