Thermodynamic Analysis of the Lipopolysaccharide-Dependent Resistance of Gram-Negative Bacteria against Polymyxin B

Howe, Jörg; Andrä, Jörg; Conde, Raquel Díaz-Meco; Iriarte, Maite; Garidel, Patrick; Koch, Michel H. J.; Gutsmann, Thomas; Moriyón, Ignacio; Brandenburg, Klaus

doi:10.1529/biophysj.106.095711

Cited by 54 publications

(42 citation statements)

References 37 publications

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“…2). The entropy-driven complex formation at 25°C between LPS and peptide had been reported earlier (37,38). In this work, the temperature was kept below the phase transition temperature (ϳ37°C) of LPS favoring endothermic binding reactions.…”

Section: Design Of Peptides-mentioning

confidence: 57%

Designed β-Boomerang Antiendotoxic and Antimicrobial Peptides

Bhunia

Mohanram

Domadia

et al. 2009

Journal of Biological Chemistry

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Lipopolysaccharide (LPS), an integral part of the outer membrane of Gram-negative bacteria, is involved in a variety of biological processes including inflammation, septic shock, and resistance to host-defense molecules. LPS also provides an environment for folding of outer membrane proteins. In this work, we describe the structure-activity correlation of a series of 12-residue peptides in LPS. NMR structures of the peptides derived in complex with LPS reveal boomerang-like ␤-strand conformations that are stabilized by intimate packing between the two aromatic residues located at the 4 and 9 positions. This structural feature renders these peptides with a high ability to neutralize endotoxicity, >80% at 10 nM concentration, of LPS. Replacements of these aromatic residues either with Ala or with Leu destabilizes the boomerang structure with the concomitant loss of antiendotoxic and antimicrobial activities. Furthermore, the aromatic packing stabilizing the ␤-boomerang structure in LPS is found to be maintained even in a truncated octapeptide, defining a structured LPS binding motif. The mode of action of the active designed peptides correlates well with their ability to perturb LPS micelle structures. Fourier transform infrared spectroscopy studies of the peptides delineate ␤-type conformations and immobilization of phosphate head groups of LPS. Trp fluorescence studies demonstrated selective interactions with LPS and the depth of insertion into the LPS bilayer. Our results demonstrate the requirement of LPS-specific structures of peptides for endotoxin neutralizations. In addition, we propose that structures of these peptides may be employed to design proteins for the outer membrane.

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Section: Design Of Peptides-mentioning

confidence: 57%

Designed β-Boomerang Antiendotoxic and Antimicrobial Peptides

Bhunia

Mohanram

Domadia

et al. 2009

Journal of Biological Chemistry

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“…S3A to C, top panels, in the supplemental material). Usually, entropy-driven or endothermic binding has been observed for LPS-AMP interactions with the gel phase of LPS at 25°C (66,67). Interestingly, the inactive peptide…”

Section: Resultsmentioning

confidence: 99%

Resurrecting Inactive Antimicrobial Peptides from the Lipopolysaccharide Trap

Mohanram

Bhattacharjya

2014

Antimicrob Agents Chemother

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Host defense antimicrobial peptides (AMPs) are a promising source of antibiotics for the treatment of multiple-drug-resistant pathogens. Lipopolysaccharide (LPS), the major component of the outer leaflet of the outer membrane of Gram-negative bacteria, functions as a permeability barrier against a variety of molecules, including AMPs. Further, LPS or endotoxin is the causative agent of sepsis killing 100,000 people per year in the United States alone. LPS can restrict the activity of AMPs inducing aggregations at the outer membrane, as observed for frog AMPs, temporins, and also in model AMPs. Aggregated AMPs, "trapped" by the outer membrane, are unable to traverse the cell wall, causing their inactivation. In this work, we show that these inactive AMPs can overcome LPS-induced aggregations while conjugated with a short LPS binding ␤-boomerang peptide motif and become highly bactericidal. The generated hybrid peptides exhibit activity against Gram-negative and Gram-positive bacteria in high-salt conditions and detoxify endotoxin. Structural and biophysical studies establish the mechanism of action of these peptides in LPS outer membrane. Most importantly, this study provides a new concept for the development of a potent broad-spectrum antibiotic with efficient outer membrane disruption as the mode of action.

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“…Several ITC studies dealing with the binding of AMPs to LPS were reported (53)(54)(55). To keep conditions similar to those used in the biological assays, we conducted ITC measurements at a physiological temperature (38°C) at which the species of LPS used are in the liquid crystalline phase.…”

Section: Resultsmentioning

confidence: 99%

Lipopolysaccharide, a Key Molecule Involved in the Synergism between Temporins in Inhibiting Bacterial Growth and in Endotoxin Neutralization

Mangoni

Epand

Rosenfeld

et al. 2008

Journal of Biological Chemistry

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Lipopolysaccharide (LPS) is the major structural component of the outer membrane of Gram-negative bacteria and shields them from a variety of host defense factors, including antimicrobial peptides (AMPs). LPS is also recognized by immune cells as a pathogen-associated molecular pattern and stimulates them to secrete pro-inflammatory cytokines that, in extreme cases, lead to a harmful host response known as septic shock. Previous studies have revealed that a few isoforms of the AMP temporin, produced within the same frog specimen, can synergize to overcome bacterial resistance imposed by the physical barrier of LPS. Here we found that temporins can synergize in neutralizing the LPS-induced macrophage activation. Furthermore, the synergism between temporins, to overcome the protective function of LPS as well as its endotoxic effect, depends on the length of the polysaccharide chain of LPS. Importantly, mode of action studies, using spectroscopic and thermodynamic methods, have pointed out different mechanisms underlying the synergism of temporins in antimicrobial and anti-endotoxin activities. To the best of our knowledge, such a dual synergism between isoforms of AMPs from the same species has not been observed before, and it might explain the ability of such amphibians to resist a large repertoire of microorganisms.

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Thermodynamic Analysis of the Lipopolysaccharide-Dependent Resistance of Gram-Negative Bacteria against Polymyxin B

Cited by 54 publications

References 37 publications

Designed β-Boomerang Antiendotoxic and Antimicrobial Peptides

Designed β-Boomerang Antiendotoxic and Antimicrobial Peptides

Resurrecting Inactive Antimicrobial Peptides from the Lipopolysaccharide Trap

Lipopolysaccharide, a Key Molecule Involved in the Synergism between Temporins in Inhibiting Bacterial Growth and in Endotoxin Neutralization

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