Surface Acoustic Wave Biosensor as a Tool to Study the Interaction of Antimicrobial Peptides with Phospholipid and Lipopolysaccharide Model Membranes

Andrä, Jörg; Böhling, Arne; Gronewold, Thomas M. A.; Schlecht, U.; Perpeet, M.; Gutsmann, Thomas

doi:10.1021/la801252t

Cited by 52 publications

(45 citation statements)

References 32 publications

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“…The results shown are representative of three independent experiments. The SAW biosensor system (Biosensor GmbH, Bonn, Germany) was used as described before (1). Briefly, in the SAW biosensor a SAW is propagated along a sensor surface and the modification of its phase and amplitude induced by binding of molecules to the surface is a measure for mass adsorption and change of viscoelastic properties, respectively.…”

Section: Methodsmentioning

confidence: 99%

Dermcidin-Derived Peptides Show a Different Mode of Action than the Cathelicidin LL-37 against Staphylococcus aureus

Senyürek

Paulmann

Sinnberg

et al. 2009

Antimicrob Agents Chemother

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Dermcidin (DCD) is an antimicrobial peptide which is constitutively expressed in eccrine sweat glands. By postsecretory proteolytic processing in sweat, the DCD protein gives rise to anionic and cationic DCD peptides with a broad spectrum of antimicrobial activity. Many antimicrobial peptides induce membrane permeabilization as part of their killing mechanism, which is accompanied by a loss of the bacterial membrane potential. In this study we show that there is a time-dependent bactericidal activity of anionic and cationic DCD-derived peptides which is followed by bacterial membrane depolarization. However, DCD-derived peptides do not induce pore formation in the membranes of gram-negative and gram-positive bacteria. This is in contrast to the mode of action of the cathelicidin LL-37. Interestingly, LL-37 as well as DCD-derived peptides inhibit bacterial macromolecular synthesis, especially RNA and protein synthesis, without binding to microbial DNA or RNA. Binding studies with components of the cell envelope of gram-positive and gram-negative bacteria and with model membranes indicated that DCD-derived peptides bind to the bacterial envelope but show only a weak binding to lipopolysaccharide (LPS) from gram-negative bacteria or to peptidoglycan, lipoteichoic acid, and wall teichoic acid, isolated from Staphylococcus aureus. In contrast, LL-37 binds strongly in a dosedependent fashion to these components. Altogether, these data indicate that the mode of action of DCD-derived peptides is different from that of the cathelicidin LL-37 and that components of the bacterial cell envelope play a role in the antimicrobial activity of DCD.

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Section: Methodsmentioning

confidence: 99%

Dermcidin-Derived Peptides Show a Different Mode of Action than the Cathelicidin LL-37 against Staphylococcus aureus

Senyürek

Paulmann

Sinnberg

et al. 2009

Antimicrob Agents Chemother

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“…We immobilized LPS onto carboxymethylated dextran (CM3) chips and used surface plasmon resonance (SPR) to monitor interactions (Fig. 4A) (33). When chips derivatized with LPS are subjected to injections of polymyxin B, a cyclic LPS-binding peptide (34), it remained on the surface as indicated by the change in mass adhered to the chip (measured in resonance units), whereas RNase A, known to recognize other negatively charged sugars, is not retained by LPS.…”

Section: Positively Charged Residues At the Extracellular Side Of Lptmentioning

confidence: 99%

LptE binds to and alters the physical state of LPS to catalyze its assembly at the cell surface

Malojcic

Andres

Grabowicz

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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The assembly of lipopolysaccharide (LPS) on the surface of Gramnegative bacterial cells is essential for their viability and is achieved by the seven-protein LPS transport (Lpt) pathway. The outer membrane (OM) lipoprotein LptE and the β-barrel membrane protein LptD form a complex that assembles LPS into the outer leaflet of the OM. We report a crystal structure of the Escherichia coli OM lipoprotein LptE at 2.34 Å. The structure reveals homology to eukaryotic LPS-binding proteins and allowed for the prediction of an LPS-binding site, which was confirmed by genetic and biophysical experiments. Specific point mutations at this site lead to defects in OM biogenesis. We show that wild-type LptE disrupts LPS-LPS interactions in vitro and that these mutations decrease the ability of LptE to disaggregate LPS. Transmission electron microscopic imaging shows that LptE can disrupt LPS aggregates even at substoichiometric concentrations. We propose a model in which LptE functions as an LPS transfer protein in the OM translocon by disaggregating LPS during transport to allow for its insertion into the OM.

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“…Although earlier reports suggested that LPS modulates bacterial cell compressibility and helps prevent catastrophic structural failure due to mechanical stress (1,52), no direct physical evidence of its involvement in these processes has yet been presented. Therefore, monitoring biofilm viscoelasticity is crucial for demonstrating how well biofilms resist stresses, due to, for instance, fluid shear and antimicrobial peptides (5,6). To date, quantitative data on how LPS affects viscoelastic properties of biofilms are lacking, and existing studies have merely focused on elasticity measurements (7,52).…”

mentioning

confidence: 99%

Differential Lipopolysaccharide Core Capping Leads to Quantitative and Correlated Modifications of Mechanical and Structural Properties in Pseudomonas aeruginosa Biofilms

Lau¹,

Lindhout²,

Beveridge³

et al. 2009

J Bacteriol

103

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Bacterial biofilms are responsible for the majority of all microbial infections and have profound impact on industrial and geochemical processes. While many studies documented phenotypic differentiation and gene regulation of biofilms, the importance of their structural and mechanical properties is poorly understood. Here we investigate how changes in lipopolysaccharide (LPS) core capping in Pseudomonas aeruginosa affect biofilm structure through modification of adhesive, cohesive, and viscoelastic properties at an early stage of biofilm development. Microbead force spectroscopy and atomic force microscopy were used to characterize P. aeruginosa biofilm interactions with either glass substrata or bacterial lawns. Using isogenic migA, wapR, and rmlC mutants with defined LPS characteristics, we observed significant changes in cell mechanical properties among these strains compared to wild-type strain PAO1. Specifically, truncation of core oligosaccharides enhanced both adhesive and cohesive forces by up to 10-fold, whereas changes in instantaneous elasticity were correlated with the presence of O antigen. Using confocal laser scanning microscopy to quantify biofilm structural changes with respect to differences in LPS core capping, we observed that textural parameters varied with adhesion or the inverse of cohesion, while areal and volumetric parameters were linked to adhesion, cohesion, or the balance between them. In conclusion, this report demonstrated for the first time that changes in LPS expression resulted in quantifiable cellular mechanical changes that were correlated with structural changes in bacterial biofilms. Thus, the interplay between architectural and functional properties may be an important contributor to bacterial community survival.Biofilms are sessile microbial communities growing on a surface or at an interface, often enmeshed in polymeric substances. Being the predominant mode of microbial growth in nature, bacterial biofilms are particularly problematic in the context of human health, accounting for up to 80% of all bacterial infections. In industrial processes, bacterial biofilms cause corrosion and biofouling, resulting in considerable loss of productivity. In the natural environment, biofilms play a role in modulating worldwide geochemical cycles. Given the impact of biofilms in these diverse areas, the need for developing effective strategies to control them is of paramount importance. Since bacterial cell surface structures are convenient targets for control agents, their roles in influencing biofilm function and architecture warrant in-depth investigations. To date, most studies of biofilms have focused on genetic regulation, phenotypic differentiation and their contribution to antibiotic resistance. In contrast, the mechanical and structural properties that link the genotypes to phenotypes of bacterial biofilms are not well understood and rarely studied in a quantitative and correlated manner.Pseudomonas aeruginosa is a gram-negative opportunistic pathogen implicated in serious infe...

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Surface Acoustic Wave Biosensor as a Tool to Study the Interaction of Antimicrobial Peptides with Phospholipid and Lipopolysaccharide Model Membranes

Cited by 52 publications

References 32 publications

Dermcidin-Derived Peptides Show a Different Mode of Action than the Cathelicidin LL-37 against Staphylococcus aureus

Dermcidin-Derived Peptides Show a Different Mode of Action than the Cathelicidin LL-37 against Staphylococcus aureus

LptE binds to and alters the physical state of LPS to catalyze its assembly at the cell surface

Differential Lipopolysaccharide Core Capping Leads to Quantitative and Correlated Modifications of Mechanical and Structural Properties in Pseudomonas aeruginosa Biofilms

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