Novel evidence for the specific interaction between cholesterol and α-haemolysin of Escherichia coli

2014 ◽  
Vol 458 (3) ◽  
pp. 481-489 ◽  
Author(s):  
Romina F. Vazquez ◽  
Sabina M. Maté ◽  
Laura S. Bakás ◽  
Marisa M. Fernández ◽  
Emilio L. Malchiodi ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Specific Interaction ◽  
Conformational State ◽  
First Time

The present study shows, for the first time, the interaction of HlyA with cholesterol. This interaction seems to favour a conformational state of the protein that allows its correct insertion into the membrane and its further oligomerization to form pores.

Iso-octenidine: Promising Octenidine Analogue with Improved Solubility

2020 ◽  
Vol 17 ◽  
Author(s):  
Igor K. Yakuschenko ◽  
Nataliya N. Pozdeeva ◽  
Viktoriya A. Mumyatova ◽  
Alexey A. Terentiev ◽  
Svyatoslav Ya. Gadomsky
Keyword(s):  
Escherichia Coli ◽  
Antibacterial Activity ◽  
Micrococcus Luteus ◽  
Octenidine Dihydrochloride ◽  
First Time

: Iso-octenidine, an isomer of octenidine dihydrochloride, was synthesized and studied for the first time. Isooctenidine was demonstrated to be 3-fold more soluble in water in comparison to original octenidine, and both substances had remarkably similar antibacterial activity (tested on Escherichia Coli and Micrococcus luteus).

scholarly journals Structure of the master regulator Rns reveals an inhibitor of enterotoxigenic Escherichia coli virulence regulons

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Charles R. Midgett ◽  
Kacey Marie Talbot ◽  
Jessica L. Day ◽  
George P. Munson ◽  
F. Jon Kull
Keyword(s):  
Escherichia Coli ◽  
Small Molecules ◽  
Family Member ◽  
Shigella Flexneri ◽  
Decanoic Acid ◽  
Enterotoxigenic Escherichia Coli ◽  
Gram Negative Bacteria ◽  
Enteric Infections ◽  
First Time ◽  
Arac Family

AbstractEnteric infections caused by the gram-negative bacteria enterotoxigenic Escherichia coli (ETEC), Vibrio cholerae, Shigella flexneri, and Salmonella enterica are among the most common and affect billions of people each year. These bacteria control expression of virulence factors using a network of transcriptional regulators, some of which are modulated by small molecules as has been shown for ToxT, an AraC family member from V. cholerae. In ETEC the expression of many types of adhesive pili is dependent upon the AraC family member Rns. We present here the 3 Å crystal structure of Rns and show it closely resembles ToxT. Rns crystallized as a dimer via an interface similar to that observed in other dimeric AraC’s. Furthermore, the structure of Rns revealed the presence of a ligand, decanoic acid, that inhibits its activity in a manner similar to the fatty acid mediated inhibition observed for ToxT and the S. enterica homologue HilD. Together, these results support our hypothesis that fatty acids regulate virulence controlling AraC family members in a common manner across a number of enteric pathogens. Furthermore, for the first time this work identifies a small molecule capable of inhibiting the ETEC Rns regulon, providing a basis for development of therapeutics against this deadly human pathogen.

scholarly journals Large domain movements upon UvrD dimerization and helicase activation

2017 ◽  
Vol 114 (46) ◽  
pp. 12178-12183 ◽  
Author(s):  
Binh Nguyen ◽  
Yerdos Ordabayev ◽  
Joshua E. Sokoloski ◽  
Elizabeth Weiland ◽  
Timothy M. Lohman
Keyword(s):  
Escherichia Coli ◽  
Single Molecule ◽  
Self Assembly ◽  
Total Internal Reflection ◽  
Dna Helicase ◽  
Conformational State ◽  
Helicase Activity ◽  
Multiple Conformations ◽  
Dna Substrate

Escherichia coli UvrD DNA helicase functions in several DNA repair processes. As a monomer, UvrD can translocate rapidly and processively along ssDNA; however, the monomer is a poor helicase. To unwind duplex DNA in vitro, UvrD needs to be activated either by self-assembly to form a dimer or by interaction with an accessory protein. However, the mechanism of activation is not understood. UvrD can exist in multiple conformations associated with the rotational conformational state of its 2B subdomain, and its helicase activity has been correlated with a closed 2B conformation. Using single-molecule total internal reflection fluorescence microscopy, we examined the rotational conformational states of the 2B subdomain of fluorescently labeled UvrD and their rates of interconversion. We find that the 2B subdomain of the UvrD monomer can rotate between an open and closed conformation as well as two highly populated intermediate states. The binding of a DNA substrate shifts the 2B conformation of a labeled UvrD monomer to a more open state that shows no helicase activity. The binding of a second unlabeled UvrD shifts the 2B conformation of the labeled UvrD to a more closed state resulting in activation of helicase activity. Binding of a monomer of the structurally similar Escherichia coli Rep helicase does not elicit this effect. This indicates that the helicase activity of a UvrD dimer is promoted via direct interactions between UvrD subunits that affect the rotational conformational state of its 2B subdomain.

Non-specific Interaction of Fpg Protein from Escherichia coli with DNA. Affinity and Dynamics Study

2000 ◽  
Vol 28 (5) ◽  
pp. A164-A164
Author(s):  
O. S. Fedorova ◽  
V. V. Koval ◽  
A. A. Ishchenko ◽  
K. T. Douglas ◽  
G. A. Nevinsky
Keyword(s):  
Escherichia Coli ◽  
Specific Interaction

A unique environmental occurrence of hydrogen sulfide positive Escherichia coli

1980 ◽  
Vol 26 (2) ◽  
pp. 232-234
Author(s):  
Nell C. Roberts ◽  
Beverly O. Freeman ◽  
Henry B. Bradford Jr.
Keyword(s):  
Escherichia Coli ◽  
Hydrogen Sulfide ◽  
Clinical Interest ◽  
First Time

For the first time in nearly 4 decades of surveillance, H2S positive Escherichia coli have been isolated from Calcasieu Lake and River. These results are reported because of recent clinical interest in these organisms.

scholarly journals A Novel Six-Rhodopsin System in a Single Archaeon

2010 ◽  
Vol 192 (22) ◽  
pp. 5866-5873 ◽  
Author(s):  
Hsu-Yuan Fu ◽  
Yu-Cheng Lin ◽  
Yung-Ning Chang ◽  
Hsiaochu Tseng ◽  
Ching-Che Huang ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Global Environment ◽  
Diverse Group ◽  
Ion Transporters ◽  
Haloarcula Marismortui ◽  
Resource Limited ◽  
New Type ◽  
Ion Transportation ◽  
Proton Transporters ◽  
First Time

ABSTRACT Microbial rhodopsins, a diverse group of photoactive proteins found in Archaea, Bacteria, and Eukarya, function in photosensing and photoenergy harvesting and may have been present in the resource-limited early global environment. Four different physiological functions have been identified and characterized for nearly 5,000 retinal-binding photoreceptors, these being ion transporters that transport proton or chloride and sensory rhodopsins that mediate light-attractant and/or -repellent responses. The greatest number of rhodopsins previously observed in a single archaeon had been four. Here, we report a newly discovered six-rhodopsin system in a single archaeon, Haloarcula marismortui, which shows a more diverse absorbance spectral distribution than any previously known rhodopsin system, and, for the first time, two light-driven proton transporters that respond to the same wavelength. All six rhodopsins, the greatest number ever identified in a single archaeon, were first shown to be expressed in H. marismortui, and these were then overexpressed in Escherichia coli. The proteins were purified for absorption spectra and photocycle determination, followed by measurement of ion transportation and phototaxis. The results clearly indicate the existence of a proton transporter system with two isochromatic rhodopsins and a new type of sensory rhodopsin-like transducer in H. marismortui.

scholarly journals Influence of High Pressure on the Dimerization of ToxR, a Protein Involved in Bacterial Signal Transduction

2008 ◽  
Vol 74 (24) ◽  
pp. 7821-7823 ◽  
Author(s):  
Kai Linke ◽  
Nagarajan Periasamy ◽  
Matthias Ehrmann ◽  
Roland Winter ◽  
Rudi F. Vogel
Keyword(s):  
Escherichia Coli ◽  
Signal Transduction ◽  
High Pressure ◽  
Structure And Function ◽  
Transmembrane Segments ◽  
Bacterial Signal Transduction ◽  
Reporter Strains ◽  
And Function ◽  
First Time

ABSTRACT High hydrostatic pressure (HHP) is suggested to influence the structure and function of membranes and/or integrated proteins. We demonstrate for the first time HHP-induced dimer dissociation of membrane proteins in vivo with Vibrio cholerae ToxR variants in Escherichia coli reporter strains carrying ctx::lacZ fusions. Dimerization ceased at 20 to 50 MPa depending on the nature of the transmembrane segments rather than on changes in the ToxR lipid bilayer environment.

scholarly journals Effects of distortions by A-tracts of promoter B-DNA spacer region on the kinetics of open complex formation by Escherichia coli RNA polymerase.

2003 ◽  
Vol 50 (4) ◽  
pp. 909-920 ◽  
Author(s):  
Iwona K Kolasa ◽  
Tomasz Łoziński ◽  
Kazimierz L Wierzchowski
Keyword(s):  
Escherichia Coli ◽  
Rna Polymerase ◽  
Transcription Initiation ◽  
Specific Interaction ◽  
Structural Data ◽  
Structural Morphology ◽  
Promoter Dna ◽  
Sigma Subunit ◽  
Kinetics Of

A-tracts in DNA due to their structural morphology distinctly different from the canonical B-DNA form play an important role in specific recognition of bacterial upstream promoter elements by the carboxyl terminal domain of RNA polymerase alpha subunit and, in turn, in the process of transcription initiation. They are only rarely found in the spacer promoter regions separating the -35 and -10 recognition hexamers. At present, the nature of the protein-DNA contacts formed between RNA polymerase and promoter DNA in transcription initiation can only be inferred from low resolution structural data and mutational and crosslinking experiments. To probe these contacts further, we constructed derivatives of a model Pa promoter bearing in the spacer region one or two An (n = 5 or 6) tracts, in phase with the DNA helical repeat, and studied the effects of thereby induced perturbation of promoter DNA structure on the kinetics of open complex (RPo) formation in vitro by Escherichia coli RNA polymerase. We found that the overall second-order rate constant ka of RPo formation, relative to that at the control promoter, was strongly reduced by one to two orders of magnitude only when the A-tracts were located in the nontemplate strand. A particularly strong 30-fold down effect on ka was exerted by nontemplate A-tracts in the -10 extended promoter region, where an involvement of nontemplate TG (-14, -15) sequence in a specific interaction with region 3 of sigma-subunit is postulated. A-tracts in the latter location caused also 3-fold slower isomerization of the first closed transcription complex into the intermediate one that precedes formation of RPo, and led to two-fold faster dissociation of the latter. All these findings are discussed in relation to recent structural and kinetic models of RPo formation.

scholarly journals Biogenic synthesis of silver nanoparticles from waste banana plant stems and their antibacterial activity against Escherichia coli and Staphylococcus Epidermis

2017 ◽  
Vol 5 (9) ◽  
pp. 3769 ◽  
Author(s):  
Huu Dang ◽  
Derek Fawcett ◽  
Gerrard Eddy Jai Poinern
Keyword(s):  
Escherichia Coli ◽  
Antibacterial Activity ◽  
Ag Nanoparticles ◽  
Inhibition Zone ◽  
Gram Negative Bacteria ◽  
Banana Plant ◽  
Biogenic Synthesis ◽  
Maximum Inhibition ◽  
Staphylococcus Epidermis ◽  
First Time

Background: This study for the first time presents an eco-friendly and room temperature procedure for biologically synthesizing silver (Ag) nanoparticles from waste banana plant stems.Methods: A simple and straightforward green chemistry based technique used waste banana plant stems to act as both reducing agent and capping agent to produce Ag nanoparticles, which were subsequently characterized. In addition, antibacterial studies were conducted using the Kirby-Bauer sensitivity method.Results: Advanced characterisation revealed the Ag nanoparticles had a variety of shapes including cubes, truncated triangular and hexagonal plates, and ranged in size from 70 nm up to 600 nm. The gram-negative bacteria Escherichia coli showed the maximum inhibition zone of 12 mm.Conclusions: The study has shown that waste banana plant stems can generate Ag nanoparticles with antibacterial activity against Escherichia coli and Staphylococcus epidermis.

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