Characterization of lipopolysaccharide transport protein complex

2014 ◽  
Vol 9 (2) ◽  
pp. 131-138
Author(s):  
Quanju Xiang ◽  
Haiyan Wang ◽  
Zhongshan Wang ◽  
Yizheng Zhang ◽  
Changjiang Dong
Keyword(s):  
Transport Mechanism ◽  
Transport Proteins ◽  
Gram Negative Bacteria ◽  
Inner Membrane ◽  
Toxic Compounds ◽  
Outer Membranes ◽  
Harsh Conditions ◽  
Cytoplasmic Side

AbstractLipopolysaccharide (LPS) is an essential component of the outer membranes (OM) of most Gram-negative bacteria, which plays a crucial role in protection of the bacteria from toxic compounds and harsh conditions. The LPS is biosynthesized at the cytoplasmic side of inner membrane (IM), and then transported across the aqueous periplasmic compartment and assembled correctly at the outer membrane. This process is accomplished by seven LPS transport proteins (LptA-G), but the transport mechanism remains poorly understood. Here, we present findings by pull down assays in which the periplasmic component LptA interacts with both the IM complex LptBFGC and the OM complex LptDE in vitro, but not with complex LptBFG. Using purified Lpt proteins, we have successfully reconstituted the seven transport proteins as a complex in vitro. In addition, the LptC may play an essential role in regulating the conformation of LptBFG to secure the lipopolysaccharide from the inner membrane. Our results contribute to the understanding of lipopolysaccharide transport mechanism and will provide a platform to study the detailed mechanism of the LPS transport in vitro.

scholarly journals Structural insights into a novel family of integral membrane siderophore reductases

2021 ◽  
Vol 118 (34) ◽  
pp. e2101952118
Author(s):  
Inokentijs Josts ◽  
Katharina Veith ◽  
Vincent Normant ◽  
Isabelle J. Schalk ◽  
Henning Tidow
Keyword(s):  
Iron Uptake ◽  
Bacterial Species ◽  
Gram Negative Bacteria ◽  
Inner Membrane ◽  
Gram Negative ◽  
Inner Membrane Protein ◽  
Uptake Studies ◽  
Structural Insights

Gram-negative bacteria take up the essential ion Fe3+ as ferric-siderophore complexes through their outer membrane using TonB-dependent transporters. However, the subsequent route through the inner membrane differs across many bacterial species and siderophore chemistries and is not understood in detail. Here, we report the crystal structure of the inner membrane protein FoxB (from Pseudomonas aeruginosa) that is involved in Fe-siderophore uptake. The structure revealed a fold with two tightly bound heme molecules. In combination with in vitro reduction assays and in vivo iron uptake studies, these results establish FoxB as an inner membrane reductase involved in the release of iron from ferrioxamine during Fe-siderophore uptake.

scholarly journals Characterization of Novel Antimicrobial Peptoids

1999 ◽  
Vol 43 (6) ◽  
pp. 1429-1434 ◽  
Author(s):  
Bob Goodson ◽  
Anton Ehrhardt ◽  
Simon Ng ◽  
John Nuss ◽  
Kirk Johnson ◽  
...  
Keyword(s):  
Antibacterial Activities ◽  
Membrane Disruption ◽  
Infection Model ◽  
Gram Negative Bacteria ◽  
Positional Isomers ◽  
Bacterial Growth Inhibition ◽  
Alpha Carbon

ABSTRACT Peptoids differ from peptides in that peptoids are composed of N-substituted rather than alpha-carbon-substituted glycine units. In this paper we report the in vitro and in vivo antibacterial activities of several antibacterial peptoids discovered by screening combinatorial chemistry libraries for bacterial growth inhibition. In vitro, the peptoid CHIR29498 and some of its analogues were active in the range of 3 to 12 μg/ml against a panel of gram-positive and gram-negative bacteria which included isolates which were resistant to known antibiotics. Peptoid antimicrobial activity againstStaphylococcus aureus was rapid, bactericidal, and independent of protein synthesis. β-Galactosidase and propidium iodide leakage assays indicated that the membrane is the most likely target of activity. Positional isomers of an active peptoid were also active, consistent with a mode of action, such as membrane disruption, that does not require a specific fit between the molecule and its target. In vivo, CHIR29498 protected S. aureus-infected mice in a simple infection model.

scholarly journals Antimicrobial and Drug Releasing Studies of Novel Acrylate Polymer based on Triazine

2021 ◽  
Vol 33 (11) ◽  
pp. 2707-2714
Author(s):  
P. Uma ◽  
J. Suresh ◽  
Revathi Selvaraj ◽  
A. Arun
Keyword(s):  
Average Molecular Weight ◽  
Synthesis And Characterization ◽  
Gram Negative Bacteria ◽  
The Novel ◽  
Acrylate Monomer ◽  
Weight Average Molecular Weight ◽  
Drug Molecules ◽  
Acrylate Polymer

This work is focused on the synthesis and characterization of versatile acrylate polymer of chalcone based triazine for their antibacterial activity and cumulative drug release behaviour studies. The novel acrylate monomer 4-(3-(4-((4-(4-(3-(4-((7-chloroquinolin-4-yl)amino)-phenyl)-3-oxoprop-1-en-1- yl)phenoxy)-6-((4-nitrophenyl)amino)-1,3,5-triazin-2-yl)oxy)phenyl)-3-oxoprop-1-en-1- yl)phenylacrylate (SCP) is from novel chalcone and acryloyl chloride. Homo and copolymers of SCP were prepared using acrylic acid and hydroxyethyl acrylate. Physical characterization confirms the formation of the above compounds. Prepared drug molecules possess chalcone moiety as well as quinoline so it has the greater effect to inhibit the growth of the Gram-negative bacteria (15.63 ± 0.4 μg/mL) was confirmed by MIC method. The weight average molecular weight of the polymer is 10,000 g/mol. The polymer decomposes at 325 ºC. Drug releasing in vitro behaviour of the synthesized drug is controlled by the nature of comonomer, pH and the temperature.

scholarly journals Porin from Pseudomonas aeruginosaInduces Apoptosis in an Epithelial Cell Line Derived from Rat Seminal Vesicles

1999 ◽  
Vol 67 (9) ◽  
pp. 4794-4800 ◽  
Author(s):  
Elisabetta Buommino ◽  
Francesco Morelli ◽  
Salvatore Metafora ◽  
Fabio Rossano ◽  
Brunella Perfetto ◽  
...  
Keyword(s):  
Epithelial Cell ◽  
Cell Line ◽  
Transcriptional Activity ◽  
Tissue Transglutaminase ◽  
Seminal Vesicles ◽  
Epithelial Cell Line ◽  
Gram Negative Bacteria ◽  
Outer Membranes ◽  
Rat Seminal Vesicle

ABSTRACT Micromolar concentrations of porin, purified from the outer membranes of Pseudomonas aeruginosa, induced in vitro the classic morphological and biochemical signs of apoptosis in an epithelial cell line (SVC1) derived from the rat seminal vesicle secretory epithelium. The programmed cell death (PCD) was p53 independent and associated with significant decrease ofbcl-2 expression, a marked increase of c-myctranscriptional activity, and an absence of the mRNA coding for tissue transglutaminase. The Ca2+ influx, caused by the porin treatment of SVC1 cells, appears to play an important role in the triggering of apoptosis in our biological model. The possibility that the porin property of inducing PCD plays a role in the infertility of individuals chronically infected by gram-negative bacteria is discussed.

scholarly journals Inhibition of the β-barrel assembly machine by a peptide that binds BamD

2015 ◽  
Vol 112 (7) ◽  
pp. 2011-2016 ◽  
Author(s):  
Christine L. Hagan ◽  
Joseph S. Wzorek ◽  
Daniel Kahne
Keyword(s):  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Outer Membranes ◽  
Essential Proteins ◽  
Growth Defects ◽  
Substrate Protein ◽  
Assembly Mechanism ◽  
New Antibiotics

The protein complex that assembles integral membrane β-barrel proteins in the outer membranes of Gram-negative bacteria is an attractive target in the development of new antibiotics. This complex, the β-barrel assembly machine (Bam), contains two essential proteins, BamA and BamD. We have identified a peptide that inhibits the assembly of β-barrel proteins in vitro by characterizing the interaction of BamD with an unfolded substrate protein. This peptide is a fragment of the substrate protein and contains a conserved amino acid sequence. We have demonstrated that mutations of this sequence in the full-length substrate protein impair the protein’s assembly, implying that BamD’s interaction with this sequence is an important part of the assembly mechanism. Finally, we have found that in vivo expression of a peptide containing this sequence causes growth defects and sensitizes Escherichia coli to antibiotics to which they are normally resistant. Therefore, inhibiting the binding of substrates to BamD is a viable strategy for developing new antibiotics directed against Gram-negative bacteria.

scholarly journals Characterization of aMycobacterium aviumsubsp.aviumOperon Associated with Virulence and Drug Detoxification

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Mariana Noelia Viale ◽  
Kun Taek Park ◽  
Belén Imperiale ◽  
Andrea Karina Gioffre ◽  
María Alejandra Colombatti Olivieri ◽  
...  
Keyword(s):  
Mycobacterium Avium ◽  
Efflux Pump ◽  
Mice Model ◽  
Toxic Compounds ◽  
Drug Detoxification ◽  
Insight Into ◽  
Knockout Mutation

ThelprG-p55operon ofMycobacterium tuberculosisandMycobacterium bovisis involved in the transport of toxic compounds. P55 is an efflux pump that provides resistance to several drugs, while LprG is a lipoprotein that modulates the host's immune response against mycobacteria. The knockout mutation of this operon severely reduces the replication of both mycobacterial species during infection in mice and increases susceptibility to toxic compounds. In order to gain insight into the function of LprG in theMycobacterium aviumcomplex, in this study, we assayed the effect of the deletion oflprG gene in the D4ER strain ofMycobacterium aviumsubsp.avium. The replacement oflprG gene with a hygromycin cassette caused a polar effect on the expression ofp55. Also, a twofold decrease in ethidium bromide susceptibility was observed and the resistance to the antibiotics rifampicin, amikacin, linezolid, and rifabutin was impaired in the mutant strain. In addition, the mutation decreased the virulence of the bacteria in macrophagesin vitroand in a mice modelin vivo. These findings clearly indicate that functional LprG and P55 are necessary for the correct transport of toxic compounds and for the survival of MAAin vitroandin vivo.

scholarly journals Synthesis and Characterization of Some New Pyrazoline and Isoxazoline Derivatives as Antibacterial Agents

2016 ◽  
Vol 13 (3) ◽  
pp. 568-577
Author(s):  
Baghdad Science Journal
Keyword(s):  
Sodium Hydroxide ◽  
Antibacterial Agents ◽  
Amine Hydrochloride ◽  
Gram Negative Bacteria ◽  
Gram Positive Bacteria ◽  
In Vitro Antibacterial Activity ◽  
Derivatives Of ◽  
Number Of Bacteria

In this paper some chalcones (C1-C8) are prepared based on the reaction of one mole of substituted acetophenone with one mole of substituted benzaldehydes in the presence of (40%) sodium hydroxide as a base. Pyrazolines (P1–P8) are prepared from the reaction of chalcones (C1-C8) with hydrazine hydrate. Isoxazoline (I1-I8) is prepared from the reaction of chalcones (C1-C8) with hydroxyl amine hydrochloride in the presence of (10%) sodium hydroxide as a base. These compounds are characterized by using various physical and spectral methods. The compounds are screened for their in vitro antibacterial activity using gram-positive bacteria and gram-negative bacteria. Several derivatives of pyrazolines and isoxazolines are produced well to moderate activities against number of bacteria.

scholarly journals Synthesis, Characterization of Biologically Potent Novel Chalcones Bearing Urea, Thiourea and Acetamide Linkages

2014 ◽  
Vol 36 ◽  
pp. 281-294
Author(s):  
Nirali S. Mewada ◽  
Dhruvin R. Shah ◽  
Kishor H. Chikhalia
Keyword(s):  
Antifungal Activity ◽  
Dilution Method ◽  
Gram Negative Bacteria ◽  
Antibacterial And Antifungal Activity ◽  
Gram Positive Bacteria ◽  
H Nmr ◽  
Antibacterial And Antifungal ◽  
Antimicrobial And Antifungal Activities

Three series of some novel chalcone based urea, thiourea and acetamide derivatives were designed, synthesized and screened for their antimicrobial and antifungal activities. All the synthesized compounds are first reported. The structures of the compounds were elucidated with the aid of elemental analysis and spectral methods including IR, 1H-NMR spectral data. The prepared compounds were evaluated for antibacterial activity against two Gram-positive bacteria (Staphylococcus aureus, Staphylococcus pyogenus), two Gram-negative bacteria (Pseudomonas aeruginosa, Escherichia coli). The title compounds were also investigated for their antifungal activity using the broth micro dilution method. The bioassay results showed that compounds a few compounds showed good to superior in vitro antibacterial and antifungal activity.

scholarly journals Characterization of Plasmids in Extensively Drug-Resistant Acinetobacter Strains Isolated in India and Pakistan

2014 ◽  
Vol 59 (2) ◽  
pp. 923-929 ◽  
Author(s):  
Lim S. Jones ◽  
Maria J. Carvalho ◽  
Mark A. Toleman ◽  
P. Lewis White ◽  
Thomas R. Connor ◽  
...  
Keyword(s):  
Selection Pressure ◽  
Gram Negative Bacteria ◽  
Drug Resistant ◽  
Content Type ◽  
Extensively Drug Resistant ◽  
Extensive Drug Resistance ◽  
Acinetobacter Haemolyticus ◽  
Insight Into

ABSTRACTTheblaNDM-1gene is associated with extensive drug resistance in Gram-negative bacteria. This probably spread toEnterobacteriaceaefromAcinetobacterspp., and we characterized plasmids associated withblaNDM-1inAcinetobacterspp. to gain insight into their role in this dissemination. Four clinical NDM-1-producingAcinetobacterspecies strains from India and Pakistan were investigated. A plasmid harboringblaNDM-1, pNDM-40-1, was characterized by whole-genome sequencing ofAcinetobacter bereziniaeCHI-40-1 and comparison with related plasmids. The presence of similar plasmids in strains from Pakistan was sought by PCR and sequencing of amplicons. Conjugation frequency was tested and stability of pNDM-40-1 investigated by real-time PCR of isolates passaged with and without antimicrobial selection pressure.A. bereziniaeandAcinetobacter haemolyticusstrains contained plasmids similar to the pNDM-BJ01-like plasmids identified inAcinetobacterspp. in China. The backbone of pNDM-40-1 was almost identical to that of pNDM-BJ01-like plasmids, but the transposon harboringblaNDM-1, Tn125, contained two short deletions.Escherichia coliandAcinetobacterpittiitransconjugants were readily obtained. Transconjugants retained pNDM-40-1 after a 14-day passage experiment, although stability was greater with meropenem selection. Fragments of pNDM-BJ01-like plasmid backbones are found nearblaNDM-1in some genetic contexts fromEnterobacteriaceae, suggesting that cross-genus transfer has occurred. pNDM-BJ01-like plasmids have been described in isolates originating from a wide geographical region in southern Asia.In vitrodata on plasmid transfer and stability suggest that these plasmids could have contributed to the spread ofblaNDM-1intoEnterobacteriaceae.

scholarly journals Structure-Guided Discovery of Novel Aminoglycoside Mimetics as Antibacterial Translation Inhibitors

2005 ◽  
Vol 49 (12) ◽  
pp. 4942-4949 ◽  
Author(s):  
Yuefen Zhou ◽  
Vlad E. Gregor ◽  
Zhongxiang Sun ◽  
Benjamin K. Ayida ◽  
Geoffrey C. Winters ◽  
...  
Keyword(s):  
Respiratory Pathogen ◽  
Gram Negative Bacteria ◽  
The Novel ◽  
Guided Discovery ◽  
Initial Characterization ◽  
Low Toxicity ◽  
Translation Inhibitor

ABSTRACT We report the structure-guided discovery, synthesis, and initial characterization of 3,5-diamino-piperidinyl triazines (DAPT), a novel translation inhibitor class that targets bacterial rRNA and exhibits broad-spectrum antibacterial activity. DAPT compounds were designed as structural mimetics of aminoglycoside antibiotics which bind to the bacterial ribosomal decoding site and thereby interfere with translational fidelity. We found that DAPT compounds bind to oligonucleotide models of decoding-site RNA, inhibit translation in vitro, and induce translation misincorporation in vivo, in agreement with a mechanism of action at the ribosomal decoding site. The novel DAPT antibacterials inhibit growth of gram-positive and gram-negative bacteria, including the respiratory pathogen Pseudomonas aeruginosa, and display low toxicity to human cell lines. In a mouse protection model, an advanced DAPT compound demonstrated efficacy against an Escherichia coli infection at a 50% protective dose of 2.4 mg/kg of body weight by single-dose intravenous administration.

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