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

Gonorrhea has been known since antiquity. Today, this disease is the most commonly reported infectious disease in the U.S. The natural environment of the etiological agent, Neisseria gonorrhoeae, is man. In this host, the organism usually parasitizes mucosal surfaces populated by columnar epithelial cells. Under certain conditions, the gonococcus may disseminate or spread to adjacent organs. The gonococcus is well adapted to its environment and is a successful parasite. Until recently, gonococci were uniformly sensitive to penicilin. However, a plasmid encoding beta-lactamase has been identified in some isolates. Most strains exhibit specific requirements for various amino acids, vitamins, purines, and pyrimidines. Only glucose, pyruvate, and lactate are utilized as sources of energy. Glucose is dissimilated by a combination of the Entner-Doudoroff and pentose phosphate pathways. A tricarboxylic acid cycle is also present and active under certain conditions. Structurally, the cell envelope of the gonococcus resembles that of a typical Gram-negative bacterium. Gonococci are highly autolytic, especially in older cultures or after depletion of the energy source. Autolysis is not due solely to peptidoglycan hydrolysis, but appears to involve a destabilization of the outer membrane as well. Cell surface components such as pili, lipopolysaccharide, outer membrane proteins, and a capsule are associated with the virulence and pathogenicity of this organism.
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PMID:The biology of the gonococcus. 11 74

R-plasmid RP1 was transferred to Pseudomonas aeruginosa cells, as indicated by their resistance to carbenicillin, ampicillin, cephaloridine, kanamycin, and tetracycline, and by the presence of a periplasmic beta-lactamase. The wild-type cells (RP1-) were lysed by ethylenediaminetetraacetic acid but not by ethylene-glycol-bis(2-aminoethyl ether)-N,N-tetraacetic acid, whereas cells carrying the plasmid (RP1+) were resistant to both these chelating agents. RP1+ and RP1- strains were both sensitive to the lytic action of polymyxin B and the lethal action of cold shock, but the effect was less marked in the RP1+ cultures. A proportion of the RP1+ cells surviving cold shock lost resistance to carbenicillin, tetracycline, and kanamycin. The chemical composition of whole cells and cell walls of RP1+ differed from that RP1- in the content of cation, phospholipid, and markers for lipopolysaccharide and peptidoglycan. Differences in cell wall composition, response to ethylenediaminetetraacetic acid and polymyxin B, and the effects of cold shock are all compatible with the hypothesis that RP1 confers changes in the cell envelope, probably in the outer membrane, of P. aeruginosa.
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PMID:Influence of R-plasmid RP1 of Pseudomonas aeruginosa on cell wall composition, drug resistance, and sensitivity to cold shock. 12 23

A study recently conducted across Canada showed that 64 of 2,503 clinical isolates of Haemophilus influenzae were resistant to beta-lactams without production of a beta-lactamase (L. D. Tremblay, J. L'Ecuyer, P. Provencher, M. G. Bergeron, and Canadian Study Group, Can. Med. Assoc. J. 143:895-900, 1990). The beta-lactamase-negative strains formed three distinct groups, with ampicillin MICs of 0.5 to 1, 2 to 4, and greater than or equal to 8 micrograms/ml for groups I, II, and III, respectively. We have investigated the mechanisms of resistance for eight strains originating from different infections and geographic areas. These strains were representative of groups I to III. Five strains were nontypeable, two were type B, and one was non-B. Chromosomal DNA extracted from each strain was used to transform the laboratory strain Rd. Transformants were selected on beta-lactam-containing plates and showed the same level of resistance to ampicillin as the donor strains. Differences in outer membrane proteins, porins, and lipopolysaccharide profiles on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) did not change with resistance. Functional analyses of purified porins in artificial lipid bilayer experiments did not explain resistance. Peptidoglycan synthesis was measured by incorporation of [14C]alanine into trichloroacetic acid-insoluble cell wall material in the presence of chloramphenicol. The growth rate and the rate of peptidoglycan synthesis observed for the transformants of the isogenic set did not correlate with resistance. Whole-cell labeling with 125I-penicillin revealed modifications in penicillin-binding proteins (PBPs) among the transformants. In particular, PBPs 3A and 3B (65 and 63 kDa, respectively) showed a decrease in affinity for beta-lactams in all transformants (groups I, II, and III) and correlated with an increased MIC except in the transformant of group III, which showed higher levels of resistance. Partial purification and proteolytic digestion of 125I-penicillin-labeled PBP 3B led to two types of CnBr peptide profiles on SDS-PAGE, the profiles of the transformed strains from groups I and II being different from those of the control group and group III. Finally, electron microscopy revealed a distinct cell filamentation for the group III transformants. These data clearly indicate that changes in PBPs are a common mechanism that results in a significant level of non-beta-lactamase-mediated beta-lactam resistance in H. influenzae despite serotype, origin of isolation, or geographic distribution.
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PMID:Molecular basis of the non-beta-lactamase-mediated resistance to beta-lactam antibiotics in strains of Haemophilus influenzae isolated in Canada. 151 Apr 47

Resistant variants of three clinical Pseudomonas aeruginosa isolates were obtained in the presence of aztreonam. The variants exhibited a four- to eightfold increase in the minimal inhibitory concentrations to beta-lactam antibiotics (except imipenem) to quinolones, such as norfloxacin and fleroxacin, chloramphenicol and tetracycline, but not to gentamicin and polymyxin B. beta-Lactamase production was barely detectable in both wild-type strains and the resistant clones. Only ampicillin, cefoxitin and imipenem increased the production of beta-lactamase, whereas various other beta-lactams did not. Penicillin-binding proteins remained unchanged in the aztreonam-resistant clones. The analysis of the outer membrane proteins did not reveal differences in the outer membrane proteins between the wild-type strains and the aztreonam-resistant clones. Two of the three antibiotic-resistant isogenic clones contained less lipopolysaccharides (LPSs) than their corresponding wild-type strains. Moreover, it could be demonstrated that the ratio of 2-keto-3-deoxy octonate to carbohydrate of the LPS changed in any case between the wild-type strains and the aztreonam-resistant clones. These alterations were accompanied by a decrease in surface hydrophobicity of the resistant clones as compared to the wild-type strains. Therefore, quantitative as well as qualitative alterations in the LPS may provide an explanation for the resistant phenotype observed.
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PMID:Lipopolysaccharide alterations responsible for combined quinolone and beta-lactam resistance in Pseudomonas aeruginosa. 159 50

Immunoglobulin penicillinase conjugate for the detection of Fr. tularensis antigen in enzyme immunoassay has been prepared. Its sensitivity is 0.7-1.0 ng/ml of Fr. tularensis lipopolysaccharide. The technique for the preparation of this conjugate is simpler than for that of peroxidase conjugate.
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PMID:[An immunoglobulin-penicillinase conjugate for detecting the antigen of the causative agent of tularemia]. 169 40

Previous work ascribed antibiotic hypersensitivity of the envA1 mutant to lowered lipopolysaccharide levels and exposure of the lipid bilayer. In the detailed characterization of the EnvA permeability phenotype presented here, the envA1 mutation was shown to confer leakage of the periplasmic enzymes beta-lactamase and RNase I. Leakage was observed in three different genetic backgrounds, including the original envA1 strain and its parent. In contrast, no detectable leakage of the cytoplasmic enzyme beta-galactosidase was observed. Sensitivity of envA1 strains to a range of antibiotics not previously reported was tested, and lipophilicity (partition coefficient) of a number of antibiotics was determined. On the basis of observations of periplasmic leakage and sensitivity to large hydrophilic antibiotics and lysozyme, part of the permeability phenotype of the envA1 mutant is proposed to be due to transient rupture and resealing of the EDTA-sensitive outer membrane layer. In this regard, the EnvA permeability phenotype falls into a general class of permeability/leaky mutants of both Escherichia coli and Salmonella typhimurium.
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PMID:Leakage of periplasmic enzymes from envA1 strains of Escherichia coli. 190 54

The extensive characterization of 2 clinical Enterobacter aerogenes isolates resistant to all beta-lactam antibiotics including imipenem revealed that imipenem resistance could not be attributed to overproduction of the chromosomal beta-lactamase; moreover, it was lost after subcultivation and can be thus considered as unstable. The comparison of sensitive and resistant clones revealed that the beta-lactamase in the resistant clones was less inducible in the resistant clones and moreover, there was an altered 2-keto-3-deoxyoctonate/carbohydrate ratio in the resistant clones as compared to the imipenem-sensitive clones, thus suggesting alterations in the lipopolysaccharide (LPS). Neither enzymatic degradation of both imipenem and meropenem nor alterations of the outer membrane proteins could be observed. These findings make it apparent that this type of resistance is likely due to an impaired uptake of the agents due to LPS alterations.
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PMID:Carbapenem resistance in Enterobacter aerogenes is due to lipopolysaccharide alterations. 203 67

Extraction of whole cells of Salmonella typhimurium and Escherichia coli with 1 M NaCl released 8 to 13% of their total cellular polyamines (putrescine, cadaverine, and spermidine). This extraction did not cause significant cell lysis, release of outer membrane (OM) constituents, or leakage of periplasmic beta-lactamase. The extraction released nearly equal amounts of polyamines from mdo (membrane-derived oligosaccharide) mutants and wild type. These findings suggest that the released polyamines are apparently bound to the cell envelope. NaCl (1 M) was as effective as trichloroacetic acid in releasing polyamines from isolated OM and lipopolysaccharide (LPS). Isolated OM contained four times more polyamines than the cytoplasmic membrane. The increased binding to the OM is apparently due to the association of polyamines with the polyanionic LPS. Nearly identical amounts of polyamines were found in the OM and LPS preparations (as quantified per milligram of LPS). These amounts are equal to those released from the intact cells by 1 M NaCl (quantitation as above). However, redistribution of polyamines took place after cell disruption, because the relative proportions of different polyamines varied in the OM and LPS preparations. These results indicate that polyamines released from intact cells during 1 M NaCl extraction are preferentially derived from the OM.
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PMID:Polyamines as constituents of the outer membranes of Escherichia coli and Salmonella typhimurium. 205 Jun 29

A Pseudomonas aeruginosa (isolate 416) from a patient with pneumonia, was initially susceptible to imipenem (MIC: 2 mg/l) but became resistant to this antibiotic (isolate 470, MIC: 32 mg/l) during imipenem therapy. Treatment failed. No parallel increases in MIC were observed for other antimicrobials tested. Isolates 416 and 470 shared the same pyocin type and serotype, produced small amounts of an inducible beta-lactamase, and had similar lipopolysaccharide compositions. On electrophoresis of outer membrane proteins, the porin F, identified by the monoclonal antibody MA4-4, was expressed similarly by the two isolates but the production of one band (apparent molecular weight: 47,000) was diminished in isolate 470. [14C]-Imipenem labelling of intact cells proceeded more slowly in 470 than in 416, especially when bacterial cells were treated by antibody MA4-4 to block the porin F channel. [14C]-Imipenem labelling of penicillin binding proteins (PBP) showed that the band identified as PBP-4 bound markedly less radioactivity in isolate 470 than in 416. After isolate 470 was passaged several times in antibiotic-free broth, the imipenem MIC was decreased from 32 to 8 mg/l, and the [14C]-imipenem PBP pattern recovered the initial profile as exhibited by isolate 416. Two resistance mechanisms, affecting imipenem electively, could have combined their effect in the post-therapy isolate, altered target protein and reduced permeability.
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PMID:Novel resistance to imipenem associated with an altered PBP-4 in a Pseudomonas aeruginosa clinical isolate. 210 15

The growth inhibition of four Pseudomonas aeruginosa strains by liposome-trapped penicillin-G was investigated. There were indications of an association of the efficacy of liposomal penicillin-G with the nature of the 0-antigenic polymeric side chain. Namely, P28-800 and PCF-95 strains, characterized by a rough polysaccharide chain, were the most susceptible, whereas strain P28-0, possessing an intact lipopolysaccharide, resisted the activity of the entrapped drug. Among the rough strains, P642, a beta-lactamase producer, was not affected by the encapsulated drug. The composition of liposomes seems to have a significant impact in arresting the growth of the P. aeruginosa strain.
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PMID:Enhanced in-vitro activity of liposome-trapped penicillin-G against Pseudomonas aeruginosa. 211 42


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