Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P43026 (lipopolysaccharide)
 62,215 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The suppressor mutation, named sfhC21, that allows Escherichia coli ftsH null mutant cells to survive was found to be an allele of fabZ encoding R-3-hydroxyacyl-ACP dehydrase, involved in a key step of fatty acid biosynthesis, and appears to upregulate the dehydrase. The ftsH1(Ts) mutation increased the amount of lipopolysaccharide at 42 degrees C. This was accompanied by a dramatic increase in the amount of UDP-3-O-(R-3-hydroxymyristoyl)-N-acetylglucosamine deacetylase [the IpxC (envA) gene product] involved in the committed step of lipid A biosynthesis. Pulse-chase experiments and in vitro assays with purified components showed that FtsH, the AAA-type membrane-bound metalloprotease, degrades the deacetylase. Genetic evidence also indicated that the FtsH protease activity for the deacetylase might be affected when acyl-ACP pools were altered. The biosynthesis of phospholipids and the lipid A moiety of lipopolysaccharide, both of which derive their fatty acyl chains from the same R-3-hydroxyacyl-ACP pool, is regulated by FtsH.
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PMID:Balanced biosynthesis of major membrane components through regulated degradation of the committed enzyme of lipid A biosynthesis by the AAA protease FtsH (HflB) in Escherichia coli. 1004 27

Lipid A is the hydrophobic anchor of lipopolysaccharide (LPS) and forms the major lipid component of the outer monolayer of the outer membrane of gram-negative bacteria. Lipid A is required for bacterial growth and virulence, and inhibition of its biosynthesis is lethal to bacteria. UDP-3-O-(R-3-hydroxymyristoyl)-N-acetylglucosamine deacetylase (LpxC) is a metalloenzyme that catalyzes the second step in the biosynthesis of lipid A. Inhibitors of LpxC have previously been shown to have antibiotic activities. We have screened a metalloenzyme inhibitor library for antibacterial activities against an Escherichia coli strain with reduced LpxC activity. From this screen, a series of sulfonamide derivatives of the alpha-(R)-amino hydroxamic acids, exemplified by BB-78484 and BB-78485, have been identified as having potent inhibitory activities against LpxC in an in vitro assay. Leads from this series showed gram-negative selective activities against members of the Enterobacteriaceae, Serratia marcescens, Morganella morganii, Haemophilus influenzae, Moraxella catarrhalis, and Burkholderia cepacia. BB-78484 was bactericidal against E. coli, achieving 3-log killing in 4 h at a concentration 4 times above the MIC, as would be predicted for an inhibitor of lipid A biosynthesis. E. coli mutants with decreased susceptibility to BB-78484 were selected. Analysis of these mutants revealed that resistance arose as a consequence of mutations in the fabZ or lpxC genes. These data confirm the antibacterial target of BB-78484 and BB-78485 and validate LpxC as a target for gram-negative selective antibacterials.
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PMID:Antibacterial activities and characterization of novel inhibitors of LpxC. 1201 92

The outer leaflet of the outer membrane of the Gram-negative bacterium serves as a permeability barrier and is composed of lipopolysaccharide, also known as endotoxin. The membrane anchor of lipopolysaccharide is lipid A, the biosynthesis of which is essential for cell viability. The first committed step in lipid A biosynthesis is catalyzed by UDP-(3-O-(R-3-hydroxymyristoyl))-N-acetylglucosamine deacetylase (LpxC), a zinc-dependent deacetylase. Here we report the crystal structure of LpxC from Aquifex aeolicus, which reveals a new alpha+beta fold reflecting primordial gene duplication and fusion, as well as a new zinc-binding motif. The catalytic zinc ion resides at the base of an active-site cleft and adjacent to a hydrophobic tunnel occupied by a fatty acid. This tunnel accounts for the specificity of LpxC toward substrates and inhibitors bearing appropriately positioned 3-O-fatty acid substituents. Notably, simple inhibitors designed to target interactions in the hydrophobic tunnel bind with micromolar affinity, thereby representing a step toward the structure-based design of a potent, broad-spectrum antibacterial drug.
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PMID:Crystal structure of LpxC, a zinc-dependent deacetylase essential for endotoxin biosynthesis. 1281 49

The zinc-dependent UDP-3-O-acyl-N-acetylglucosamine deacetylase (LpxC) catalyzes the first committed step in the biosynthesis of lipid A, the hydrophobic anchor of lipopolysaccharide (LPS) that constitutes the outermost monolayer of Gram-negative bacteria. As LpxC is crucial for the survival of Gram-negative organisms and has no sequence homology to known mammalian deacetylases or amidases, it is an excellent target for the design of new antibiotics. The solution structure of LpxC from Aquifex aeolicus in complex with a substrate-analog inhibitor, TU-514, reveals a novel alpha/beta fold, a unique zinc-binding motif and a hydrophobic passage that captures the acyl chain of the inhibitor. On the basis of biochemical and structural studies, we propose a catalytic mechanism for LpxC, suggest a model for substrate binding and provide evidence that mobility and dynamics in structural motifs close to the active site have key roles in the capture of the substrate.
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PMID:Structure of the LpxC deacetylase with a bound substrate-analog inhibitor. 1283 53

The cell wall in Gram-negative bacteria is surrounded by an outer membrane comprised of charged lipopolysaccharide (LPS) molecules that prevent entry of hydrophobic agents into the cell and protect the bacterium from many antibiotics. The hydrophobic anchor of LPS is lipid A, the biosynthesis of which is essential for bacterial growth and viability. UDP-3-O-(R-3-hydroxymyristoyl)-N-acetylglucosamine deacetylase (LpxC) is an essential zinc-dependant enzyme that catalyzes the conversion of UDP-3-O-(R-3-hydroxymyristoyl)-N-acetylglucosamine to UDP-3-O-(R-3-hydroxymyristoyl)glucosamine and acetate in the biosynthesis of lipid A, and for this reason, LpxC is an attractive target for antibacterial drug discovery. Here we disclose a 1.9 A resolution crystal structure of LpxC from Pseudomonas aeruginosa (paLpxC) in a complex with the potent BB-78485 inhibitor. To our knowledge, this is the first crystal structure of LpxC with a small-molecule inhibitor that shows antibacterial activity against a wide range of Gram-negative pathogens. Accordingly, this structure can provide important information for lead optimization and rational design of the effective small-molecule LpxC inhibitors for successful treatment of Gram-negative infections.
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PMID:Crystal structure of LpxC from Pseudomonas aeruginosa complexed with the potent BB-78485 inhibitor. 1828 78

A high-throughput mass spectrometry assay to measure the catalytic activity of UDP-3-O-(R-3-hydroxymyristoyl)-N-acetylglucosamine deacetylase, LpxC, is described. This reaction is essential in the biosynthesis of lipopolysaccharide (LPS) of gram-negative bacteria and is an attractive target for the development of new antibacterial agents. The assay uses the RapidFire mass spectrometry platform to measure the native LpxC substrate and the reaction product and thereby generates a ratiometric readout with minimal artifacts due to detection interference. The assay was robust in a high-throughput screen of a library of more than 700,000 compounds arrayed as orthogonal mixtures, with a median Z' factor of 0.74. Selected novel inhibitors from the screening campaign were confirmed as binding to LpxC by biophysical measurements using a thermal stability shift assay. Some inhibitors showed whole-cell antimicrobial activity against a sensitive strain of Escherichia coli with reduced LpxC activity (strain D22; minimum inhibitory concentrations ranging from 0.625-20 microg/mL). The results show that mass spectrometry-based screening is a valuable high-throughput screening tool for detecting inhibitors of enzymatic targets involving difficult to detect reactions.
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PMID:Screening for antibacterial inhibitors of the UDP-3-O-(R-3-hydroxymyristoyl)-N-acetylglucosamine deacetylase (LpxC) using a high-throughput mass spectrometry assay. 2001 90

Antibiotic resistant hospital acquired infections are on the rise, creating an urgent need for novel bactericidal drugs. Enzymes involved in lipopolysaccharide (LPS) biosynthesis are attractive antibacterial targets since LPS is the major structural component of the outer membrane of Gram-negative bacteria. Lipid A is an essential hydrophobic anchor of LPS and the first committed step in lipid A biosynthesis is catalyzed by a unique zinc dependent metalloamidase, UDP-3-O-(R-3-hydroxymyristoyl)-N-acetylglucosamine deacetylase (LpxC). LpxC is an attractive Gram-negative only target that has been chemically validated by potent bactericidal hydroxamate inhibitors that work by coordination of the enzyme's catalytic zinc ion. An exploratory chemistry effort focused on expanding the SAR around hydroxamic acid zinc-binding 'warheads' lead to the identification of novel compounds with enzyme potency and antibacterial activity similar to CHIR-090.
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PMID:Design and synthesis of potent Gram-negative specific LpxC inhibitors. 2127 67

Aimed at identification and structural characterization of novel putative therapeutic targets in H. pylori, the etiological agent of numerous gastrointestinal diseases including peptic ulcer and gastric cancer, the present study comprised of three phases. First, through subtractive analysis of metabolic pathways of Helicobacter pylori HPAG1 and human, as documented in the KEGG database, 11 pathogen-specific pathways were identified. Next, all proteins involved in these pathogen-specific pathways were scrutinized in search of promising targets and the study yielded 25 candidate target proteins that are likely to be essential for the pathogen viability, but have no homolog in human. The lipopolysaccharide (LPS) biosynthesis pathway was found to be the largest contributor (nine proteins) to this list of candidate proteins. Considering the importance of LPS in H. pylori virulence, 3D structural models of three predicted target enzymes of this pathway, namely 2-dehydro-3-deoxy-phosphooctonate aldolase, UDP-3-O-[3-hydroxymyristoyl] N-acetylglucosamine deacetylase and Phosphoheptose isomerase, were then built up using the homology modeling approaches. Binding site analysis and docking of the known biological substrate PEP to 2-dehydro-3-deoxyphosphooctonate aldolase revealed the potential binding pocket present in the single monomeric form of the enzyme and identified 11 amino acid residues that might play the key roles in this protein-ligand interaction.
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PMID:In silico quest for putative drug targets in Helicobacter pylori HPAG1: molecular modeling of candidate enzymes from lipopolysaccharide biosynthesis pathway. 2185 May 71

The rapid increase of human infections by multidrug-resistant (MDR) Gram-negative pathogens poses a serious health threat and demands the identification of new strategies, molecular targets, and agents for the treatment of Gram-negative bacterial infections. The biosynthesis of lipid A, the membrane-anchoring portion of lipopolysaccharide (LPS), is one promising target for novel antibiotic design because lipid A is essential for LPS assembly in most Gram-negative bacteria. The first three enzymes in the biosynthesis of lipid A, UDP-N-acetylglucosamine acyltransferase (LpxA), UDP-3-O-(R-3-hydroxyacyl)-N-acetylglucosamine deacetylase (LpxC) and UDP- 3-O-(R-3-hydroxyacyl)glucosamine N-acyltransferase (LpxD), have emerged as an attractive Gram-negative antibacterial molecular target. In this article, we review recent advances in the studies on the structures and the structure-based drug designs of the three enzymes.
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PMID:Lipid a biosynthesis of multidrug-resistant pathogens - a novel drug target. 2382 74

In Gram-negative bacteria, the cell wall is surrounded by an outer membrane, the outer leaflet of which is comprised of charged lipopolysaccharide (LPS) molecules. Lipid A, a component of LPS, anchors this molecule to the outer membrane. UDP-3-O-(R-3-hydroxymyristoyl)-N-acetylglucosamine deacetylase (LpxC) is a zinc-dependent metalloamidase that catalyzes the first committed step of biosynthesis of Lipid A, making it a promising target for antibiotic therapy. Formation of soluble aggregates of Pseudomonas aeruginosa LpxC protein when overexpressed in Escherichia coli has limited the availability of high quality protein for X-ray crystallography. Expression of LpxC in the presence of an inhibitor dramatically increased protein solubility, shortened crystallization time and led to a high-resolution crystal structure of LpxC bound to the inhibitor. However, this approach required large amounts of compound, restricting its use. To reduce the amount of compound needed, an overexpression strain of E. coli was created lacking acrB, a critical component of the major efflux pump. By overexpressing LpxC in the efflux deficient strain in the presence of LpxC inhibitors, several structures of P. aeruginosa LpxC in complex with different compounds were solved to accelerate structure-based drug design.
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PMID:Overexpression of Pseudomonas aeruginosa LpxC with its inhibitors in an acrB-deficient Escherichia coli strain. 2524 Aug 55


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