One-step synthesis of positively charged bifunctional carbon dot/silver composite nanoparticles for killing and fluorescence imaging of Gram-negative bacteria

2019 ◽  
Vol 30 (36) ◽  
pp. 365603 ◽  
Author(s):  
Hong-Yi Fang ◽  
Wei-Ming Huang ◽  
Dong-Hwang Chen
Keyword(s):  
Fluorescence Imaging ◽  
Composite Nanoparticles ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Carbon Dot ◽  
One Step ◽  
Positively Charged ◽  
Silver Composite

One-step synthesis of amikacin modified fluorescent carbon dots for the detection of Gram-negative bacteria like Escherichia coli

RSC Advances ◽  
2016 ◽  
Vol 6 (76) ◽  
pp. 72471-72478 ◽  
Author(s):  
Soumen Chandra ◽  
Angshuman Ray Chowdhuri ◽  
Triveni Kumar Mahto ◽  
Arpita Samui ◽  
Sumanta kumar Sahu
Keyword(s):  
Escherichia Coli ◽  
Carbon Dots ◽  
Pathogenic Bacteria ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
One Step ◽  
Fluorescent Carbon Dots ◽  
Fluorescent Carbon

In this paper, we report a one-step strategy to synthesize amikacin modified fluorescent carbon dots (CDs@amikacin) for assaying pathogenic bacteria, Escherichia coli.

scholarly journals One-step high-throughput assay for quantitative detection of β-galactosidase activity in intact Gram-negative bacteria, yeast, and mammalian cells

BioTechniques ◽  
2006 ◽  
Vol 40 (4) ◽  
pp. 433-440 ◽  
Author(s):  
Faustino Vidal-Aroca ◽  
Michele Giannattasio ◽  
Elisa Brunelli ◽  
Alessandro Vezzoli ◽  
Paolo Plevani ◽  
...  
Keyword(s):  
High Throughput ◽  
Mammalian Cells ◽  
Quantitative Detection ◽  
Gram Negative Bacteria ◽  
Galactosidase Activity ◽  
Gram Negative ◽  
One Step ◽  
High Throughput Assay

scholarly journals Gram-negative trimeric porins have specific LPS binding sites that are essential for porin biogenesis

2016 ◽  
Vol 113 (34) ◽  
pp. E5034-E5043 ◽  
Author(s):  
Wanatchaporn Arunmanee ◽  
Monisha Pathania ◽  
Alexandra S. Solovyova ◽  
Anton P. Le Brun ◽  
Helen Ridley ◽  
...  
Keyword(s):  
Binding Sites ◽  
Calcium Ion ◽  
Gram Negative Bacteria ◽  
Core Oligosaccharide ◽  
Gram Negative ◽  
X Ray ◽  
Cross Links ◽  
Phosphate Groups ◽  
Positively Charged ◽  
Lps Binding

The outer membrane (OM) of gram-negative bacteria is an unusual asymmetric bilayer with an external monolayer of lipopolysaccharide (LPS) and an inner layer of phospholipids. The LPS layer is rigid and stabilized by divalent cation cross-links between phosphate groups on the core oligosaccharide regions. This means that the OM is robust and highly impermeable to toxins and antibiotics. During their biogenesis, OM proteins (OMPs), which function as transporters and receptors, must integrate into this ordered monolayer while preserving its impermeability. Here we reveal the specific interactions between the trimeric porins of Enterobacteriaceae and LPS. Isolated porins form complexes with variable numbers of LPS molecules, which are stabilized by calcium ions. In earlier studies, two high-affinity sites were predicted to contain groups of positively charged side chains. Mutation of these residues led to the loss of LPS binding and, in one site, also prevented trimerization of the porin, explaining the previously observed effect of LPS mutants on porin folding. The high-resolution X-ray crystal structure of a trimeric porin–LPS complex not only helps to explain the mutagenesis results but also reveals more complex, subtle porin–LPS interactions and a bridging calcium ion.

scholarly journals The crystal structure of the TonB-dependent transporter YncD reveals a positively charged substrate-binding site

2020 ◽  
Vol 76 (5) ◽  
pp. 484-495
Author(s):  
Rhys Grinter ◽  
Trevor Lithgow
Keyword(s):  
Binding Site ◽  
Outer Membrane ◽  
Substrate Binding ◽  
Outer Membrane Proteins ◽  
Ferric Citrate ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Substrate Binding Site ◽  
E Coli ◽  
Positively Charged

The outer membrane of Gram-negative bacteria is highly impermeable to hydrophilic molecules of larger than 600 Da, protecting these bacteria from toxins present in the environment. In order to transport nutrients across this impermeable membrane, Gram-negative bacteria utilize a diverse family of outer-membrane proteins called TonB-dependent transporters. The majority of the members of this family transport iron-containing substrates. However, it is becoming increasingly clear that TonB-dependent transporters target chemically diverse substrates. In this work, the structure and phylogenetic distribution of the TonB-dependent transporter YncD are investigated. It is shown that while YncD is present in some enteropathogens, including Escherichia coli and Salmonella spp., it is also widespread in Gammaproteobacteria and Betaproteobacteria of environmental origin. The structure of YncD was determined, showing that despite a distant evolutionary relationship, it shares structural features with the ferric citrate transporter FecA, including a compact positively charged substrate-binding site. Despite these shared features, it is shown that YncD does not contribute to the growth of E. coli in pure culture under iron-limiting conditions or with ferric citrate as an iron source. Previous studies of transcriptional regulation in E. coli show that YncD is not induced under iron-limiting conditions and is unresponsive to the ferric uptake regulator (Fur). These observations, combined with the data presented here, suggest that YncD is not responsible for the transport of an iron-containing substrate.

scholarly journals Detection of Bacteria in Water with β-Galactosidase-Coated Magnetic Nanoparticles

2018 ◽  
Vol 23 (6) ◽  
pp. 624-630
Author(s):  
Mingyue Cui ◽  
Hao Chang ◽  
Yang Zhong ◽  
Min Wang ◽  
Tianze Wu ◽  
...  
Keyword(s):  
Drinking Water ◽  
Bacterial Infections ◽  
Cost Effective ◽  
Clinical Settings ◽  
Enzyme Complex ◽  
Gram Negative Bacteria ◽  
Effective Strategy ◽  
Gram Negative ◽  
Positively Charged ◽  
Pathogenic Contamination

Pathogenic contamination and resistant bacterial infections remain critical concerns in both developed and developing countries. Rapid and sensitive detection of pathogens is still a key requirement for both environmental and clinical settings. This article introduces a simple, colorimetric, cost-effective, and high-throughput system based on a positively charged iron oxide/enzyme complex for the detection of both gram-positive and gram-negative bacteria in water between 103 and 108 cfu/mL. This study provides an effective strategy for the identification and purification of pathogen contamination in drinking water.

scholarly journals The crystal structure of the TonB-dependent transporter YncD reveals a positively charged substrate binding site

2020 ◽  
Author(s):  
Rhys Grinter ◽  
Trevor Lithgow
Keyword(s):  
Binding Site ◽  
Outer Membrane ◽  
Substrate Binding ◽  
Outer Membrane Proteins ◽  
Evolutionary Relationship ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Substrate Binding Site ◽  
E Coli ◽  
Positively Charged

AbstractThe outer membrane of Gram-negative bacteria is highly impermeable to hydrophilic molecules larger than 600 Da, protecting these bacteria from toxins present in the environment. In order to transport nutrients across this impermeable membrane, Gram-negative bacteria utilise a diverse family of outer-membrane proteins called TonB-dependent transporters. The majority of this family transport iron-containing substrates. However, it is becoming increasingly clear that TonB-dependent transporters target chemically diverse substrates. In this work, we investigate the structure and phylogenetic distribution of the TonB-dependent transporter YncD. We show that while YncD is present in some enteropathogens including E. coli and Salmonella spp., it is also widespread in Gamma and Betaproteobacteria of environmental origin. We determine the structure of YncD, showing that despite a distant evolutionary relationship, it shares structural features with the ferriccitrate transporter FecA, including a compact positively-charged substrate-binding site. Despite these shared features, we show that YncD does not contribute to the growth of E. coli in pure culture under-iron limiting conditions or with ferric-citrate as an iron source. Previous studies on transcriptional regulation in E. coli show that YncD is not induced under iron-limiting conditions and is unresponsive to the Ferric uptake regulator (Fur). These observations combined with the data we present, suggest that YncD is not responsible for the transport of an iron-containing substrate.

scholarly journals Improved activity of a synthetic indolicidin analog.

1997 ◽  
Vol 41 (4) ◽  
pp. 771-775 ◽  
Author(s):  
T J Falla ◽  
R E Hancock
Keyword(s):  
Escherichia Coli ◽  
Amino Acids ◽  
Candida Albicans ◽  
Short Length ◽  
Gram Negative Bacteria ◽  
Cationic Peptide ◽  
Gram Negative ◽  
Beta Galactosidase ◽  
Bovine Neutrophil ◽  
Positively Charged

A novel cationic peptide, CP-11, based on the structure of the bovine neutrophil peptide indolicidin, was designed to increase the number of positively charged residues, maintain the short length (13 amino acids), and enhance the amphipathicity relative to those of indolicidin. CP-11, and especially its carboxymethylated derivative, CP-11C, demonstrated improved activity against gram-negative bacteria and Candida albicans, while it maintained the activity of indolicidin against staphylococci and demonstrated a reduced ability to lyse erythrocytes. In Escherichia coli, CP-11 was better able than indolicidin to permeabilize both the outer membrane, as indicated by the enhancement of uptake of 1-N-phenylnaphthylamine, and the inner membrane, as determined by the unmasking of cytoplasmic beta-galactosidase, providing an explanation for its improved activity.

scholarly journals BIOKONVERSI SEFALOSPORIN C MENJADI ASAM 7-AMINOSEFALOSPORANAT DENGAN SEFALOSPORIN ASILASE

2016 ◽  
Vol 3 (2) ◽  
pp. 89 ◽  
Author(s):  
Dudi Hardianto ◽  
Bima Wedana Isdiyono ◽  
Fransiskus Xaverius Ivan
Keyword(s):  
Genetic Engineering ◽  
Bacillus Megaterium ◽  
Acid Oxidase ◽  
Gram Negative Bacteria ◽  
Pseudomonas Sp ◽  
Enzymatic Method ◽  
Amino Acid Oxidase ◽  
Gram Positive ◽  
Gram Negative ◽  
One Step

Cephalosporins are the most widely used class of β-lactam antibiotic in the world and clinically active against gram positive and gram negative bacteria. Cephalosporin C (CPC) is naturally produced by fungus Cephalosporiun acremonium. CPC has moderate antibacterial activity with minimum inhibitory concentration values of 25-100 µg/mL and 12-25 µg/mL for gram-positive and for gram-negative bacteria, respectively. CPC can be converted into 7-aminocephalosporonic acid (7-ACA) as intermediate compound for cephalosporin derivatives by two-steps or one-step enzymatic method. Two-step enzymatic method uses D-amino acid oxidase (DAAO) to produce glutaryl-7-amino cephalosporanic acid (GL 7-ACA) for the first step and GL-7-ACA acylase to produce 7-ACA for the second step. One-step enzymatic method uses CPC acylase to convert CPC into 7-ACA directly. Some microorganisms produce CPC acylase, such as Pseudomonas sp., Bacillus megaterium, Aeromonas sp., dan Arthrobacler. A natural CPC acylase has low activity and genetic engineering was used to increase its activity.Keywords: Cephalosporin, cephalosporin acylase, 7-ACA, genetic engineering, mutation ABSTRAKSefalosporin merupakan antibiotik golongan β-laktam yang paling banyak digunakan di dunia dan secara klinis aktif terhadap bakteri gram positif dan gram negatif. Sefalosporin C merupakan sefalosporin alami yang dihasilkan oleh kapang Cephalosporium acremonium. Sefalosporin C mempunyai aktivitas antibakteri moderat dengan nilai konsentrasi hambat minimum 25-100 µg/mL untuk bakteri gram positif dan 12-25 µg/mL untuk bakteri gram negatif. Sefalosporin C dapat diubah menjadi asam 7-aminosefalosporanat (7-ACA) sebagai senyawa antara untuk pembuatan turunan sefalosporin dengan metode enzimatik secara dua atau satu tahap. Produksi 7-ACA secara enzimatik dapat menggunakan metode dua tahap dan satu tahap enzimatik. Metode enzimatik secara dua tahap menggunakan enzim asam D-amino oksidase (DAAO) untuk menghasilkan asam glutaril-7-aminosefalosporinat (GL-7-ACA) pada tahap pertama dan menggunakan asam glutaril-7-aminosefalosporinat asilase untuk menghasilkan 7-ACA pada tahap kedua. Metode enzimatik secara satu tahap menggunakan sefalosporin asilase untuk mengubah CPC menjadi 7-ACA secara langsung. Beberapa mikroorganisme penghasil sefalosporin asilase yaitu Pseudomonas sp., Bacillus megaterium, Aeromonas sp., dan Arthrobacter. Aktivitas CPC asilase alami sangat rendah dan rekayasa genetik digunakan untuk meningkatkan aktivitasnya.Kata kunci : Sefalosporin, sefalosporin asilase, 7-ACA, rekayasa genetik, mutasi

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