Legionella pneumophila cell envelope: Permeability to hydrophobic molecules

Miller, Richard D.

doi:10.1007/bf01588833

Cited by 11 publications

(9 citation statements)

References 24 publications

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“…In vivo, the reduction of these disulfide bonds is an essential step in the developmental cycle (11). It is conceivable that variability in interchain disulfide bonding among subunits of the L. pneumophila porin may contribute to the noted phenotypic differences between virulent and avirulent strains, such as tolerance of sodium ions (5), hydrophobicity (22), and sensitivity to reducing agents (14). Many of the questions relating to the assembly and function of this protein might be addressed in future studies with the cloned gene through site-directed mutagenesis and phenotypically through allelic exchange mutagenesis.…”

Section: Discussionmentioning

confidence: 99%

Molecular characterization of the 28- and 31-kilodalton subunits of the Legionella pneumophila major outer membrane protein

Hoffman

Butler

1992

J Bacteriol

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The major outer membrane protein of LegioneHla pneumophila exhibits an apparent molcular mass of 100 kDa. Previous studies revealed the oligomer to be composed of 28-and 31-kDa subunits; the latter subunit is covalently bound to peptidoglycan. These proteins exhibit cross-reactivity with polyclonal anti-31-kDa protein serum. In this study, we present evidence to confirm that the 31-kDa subunit is a 28-kDa subunit containing a bound fragment of peptidoglycan. Peptide maps of purified proteins were generated following cyanogen bromide cleavage or proteolysis with staphylococcal V8 protease. A comparison of the banding patterns resulting from sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) revealed a common pattern. Selected peptide fragments were sequenced on a gas phase microsequencer, and the sequence was compared with the sequence obtained for the 28-kDa protein. While the amino terminus of the 31-kDa protein was blocked, peptide fragments generated by cyanogen bromide treatment exhibited a sequence identical to that of the amino terminus of the 28-kDa protein, but beginning at amino acid four (glycine), which is preceded by methionine at the third position. This sequence, (Gly-Thr-Met)-Gly-Pro-Val-Trp-ThrP Gly-Asn .... confirms that these proteins have a common amino terminus. An oligonucleotide synthesized from the codons of the common N-terminal amino acid sequence was used to establish by Southern and Northern (RNA) blot analyses that a single gene coded for both proteins. With regard to the putative porin stucture, we have identified two major bands at 70 kDa and at approximately 120 kDa by nonreducing SDS-PAGE. The former may represent the typical trimeric motif, while the latter may represent either a double trimer or an aggregate. Analysis of these two forms by two-dimensional SDS-PAGE (first dimension, nonreducing; second dimension, reducing) established that both were composed of 31-and 28-kDa subunits cross-linked via interchain disulfide bonds. These studies confirm that the novel L. pneumophila major outer membrane protein is covalently bound to peptidoglycan via a modified 28-kDa subunit (31-kDa anchor protein) and cross-linked to other 28-kDa subunits via interchain disulfide bonds.

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Section: Discussionmentioning

confidence: 99%

Molecular characterization of the 28- and 31-kilodalton subunits of the Legionella pneumophila major outer membrane protein

Hoffman

Butler

1992

J Bacteriol

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“…Notable exceptions include Neisseria gonorrhoeae (22) and Legionella pneumophila (25), which have been'shown to be susceptible to hydrophobic compounds. The inability of P. multocida to grow on MacConkey agar (5), coupled with its high in vivo (13) and in vitro (7,9,13) permeability properties are likely due to anomalies in cell envelope chemical composition, because the organism exhibits otherwise typical gram-negative ultrastructure (3,31).…”

mentioning

confidence: 99%

Susceptibility to hydrophobic molecules and phospholipid composition in Pasteurella multocida and Actinobacillus lignieresii

Hart

Champlin

1988

Antimicrob Agents Chemother

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Despite its typically gram-negative cell envelope ultrastructure, Pasteurella multocida is susceptible to the hydrophobic antibiotic novobiocin and is unable to initiate growth on MacConkey agar, a parameter often used to effect its differentiation from other members of the family Pasteurellaceae such as Actinobacillus lignieresii. However, growth on basal medium supplemented with individual selective factors and an agar diffusion assay revealed the bile salts contained in MacConkey agar to be toxic to both organisms. Four P. multocida surface hydrophobicity variants exhibited consistent in vitro susceptibility to the hydrophobic antibiotics novobiocin, rifamycin SV, and actinomycin D as determined by broth dilution. Readily extractable lipid fractions were obtained by chloroform-methanol extraction of freeze-dried whole cells from exponential-phase cultures. No major differences in total cellular readily extractable lipid content were observed among the P. multocida and A. lignieresii stra,ins examined, although hydrophobic P. multocida strains appeared to contain slightly more than did hydrophilic strains. Analytical thin-layer chromatography and quantitation of resolved readily extractable lipid components revealed the major cell envelope phospholipids of both organisms to be phosphatidylethanolamine and phosphatidylglycerol in a molar ratio of approximately 4:1 regardless of cell surface hydrophobicity properties. Similar results were obtained for Pseudomonas aeruginosa, which is notably refractory to hydrophobic molecules. These data support the conclusion that the permeability of the P. multocida cell envelope to structurally unrelated, hydrophobic molecules is not dependent on cell surface hydrophobicity and cannot be explained on the basis of anomalous polar lipid composition.

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“…is more hydrophobic than that of other Gram-negative bacteria. [17][18][19] In particular, the O-polysaccharide portion of L. pneumophila (serogroup 1) lipopolysaccharide is a homopolymer of 5-acetamide-7-acetamide-8-acetyl-3,5,7,9-tetradeoxy-L-glycero-D-galacto-nonnulosonic acid, [20][21][22] which completely lacks free hydroxyl groups and is therefore highly hydrophobic. In addition, the lipopolysaccharide contains a highly O-acetylated core structure 23) that is also hydrophobic.…”

Section: Discussionmentioning

confidence: 99%

“…relative to that of other Gram-negative bacteria and may explain its unusual permeability to hydrophobic compounds. [16][17][18][19] The exceptional hydrophobicity of the cell surface might be responsible for the higher susceptibility of Legionella spp. to hydrophobic oakmoss and its components compared to other Gram-negative bacteria.…”

Section: Discussionmentioning

confidence: 99%

The Antibacterial Activity of Compounds Isolated from Oakmoss against <i>Legionella pneumophila</i> and Other <i>Legionella</i> spp.

Nomura

Isshiki

Sakuda³

et al. 2012

Biological & Pharmaceutical Bulletin

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Oakmoss is a natural fragrance ingredient exhibiting highly specific, potent antibacterial activity against Legionella pneumophila, a causative agent of severe water-bone pneumonia. In the present study, the antibacterial activity of individual compounds isolated from oakmoss was investigated against L. pneumophila and other Legionella spp. A total of 18 known compounds and two minor novel compounds (i.e., 3-methoxy-5-methylphenyl-2,4-dihydroxy-6-methylbenzoate (compound 9) and 8-(2,4-dihydroxy-6-(2-oxoheptyl)-phenoxy)-6-hydroxy-3-pentyl-1H-isochromen-1-one (compound 20)) were purified from oakmoss. The minimum inhibitory concentrations (MICs) against clinical and environmental isolates of L. pneumophila, L. bozemanii, L. micdadei, L. longbeachae, and L. dumoffii for 11 of the 20 compounds were less than 100 µg/mL (range 0.8-64.0 µg/mL). Novel compounds 9 and 20 exhibited potent antibacterial activity against L. pneumophila strains (MIC ranges of 1.3-8.0 µg/mL and 3.3-13.3 µg/mL, respectively) and also against four other Legionella species (MIC ranges of 0.8-8.0 µg/mL and 3.3-21.3 µg/mL, respectively). Time-kill assays indicated that compounds 9 and 20 kill bacteria at a concentration equivalent to 2 MIC after 1 h and 6 h co-incubations, respectively. While oakmoss and the purified components exhibited antibacterial activity against Legionella spp., they were not active against other Gram-negative and -positive bacteria such as Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis and Staphylococcus aureus.

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Legionella pneumophila cell envelope: Permeability to hydrophobic molecules

Cited by 11 publications

References 24 publications

Molecular characterization of the 28- and 31-kilodalton subunits of the Legionella pneumophila major outer membrane protein

Molecular characterization of the 28- and 31-kilodalton subunits of the Legionella pneumophila major outer membrane protein

Susceptibility to hydrophobic molecules and phospholipid composition in Pasteurella multocida and Actinobacillus lignieresii

The Antibacterial Activity of Compounds Isolated from Oakmoss against <i>Legionella pneumophila</i> and Other <i>Legionella</i> spp.

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