@article {2390, title = {Effect of Membrane Composition on Antimicrobial Peptides Aurein 2.2 and 2.3 From Australian Southern Bell Frogs}, journal = {Biophysical Journal}, volume = {96}, number = {2}, year = {2009}, note = {ISI Document Delivery No.: 450BYTimes Cited: 8Cited Reference Count: 96Cheng, John T. J. Hale, John D. Elliot, Melissa Hancock, Robert E. W. Straus, Suzana K.}, month = {Jan}, pages = {552-565}, type = {Article}, abstract = {The effects of hydrophobic thickness and the molar phosphatidylglycerol (PG) content of lipid bilayers on the structure and membrane interaction of three cationic antimicrobial peptides were examined: aurein 2.2, aurein 2.3 (almost identical to aurein 2.2, except for a point mutation at residue 13), and a carboxy C-terminal analog of aurein 2.3. Circular dichroism results indicated that all three peptides adopt an a-helical structure in the presence of a 3:1 molar mixture of 1,2-dimyristoyi-sn-glycero3-phosphocholine/1,2-dimyristoyi-sn-glycero-3- [phospho-rac-(1-glycerol)] (DMPC/DMPG), and 1:1 and 3:1 molar mixtures of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine/1-paimitoyl-2-oleoyl-sn -glycero-3-[phospho-rac-(1-glycerol)] (POPC/POPG). Oriented circular dichroism data for three different lipid compositions showed that all three peptides were surface-adsorbed at low peptide concentrations, but were inserted into the membrane at higher peptide concentrations. The (31)p solid-state NMR data of the three peptides in the DMPC/DMPG and POPC/POPG bilayers showed that all three peptides significantly perturbed lipid headgroups, in a peptide or lipid composition-dependent manner. Differential scanning calorimetry results demonstrated that both amidated aurein peptides perturbed the overall phase structure of DMPC/DMPG bilayers, but perturbed the POPC/POPG chains less. The nature of the perturbation of DMPC/DMPG bilayers was most likely micellization, and for the POPC/POPG bilayers, distorted toroidal pores or localized membrane aggregate formation. Calcein release assay results showed that aurein peptide-induced membrane leakage was more severe in DMPC/DMPG liposomes than in POPC/POPG liposomes, and that aurein 2.2 induced higher calcein release than aurein 2.3 and aurein 2.3-COOH from 1:1 and 3:1 POPC/POPG liposomes. Finally, DiSC(3)5 assay data further delineated aurein 2.2 from the others by showing that it perturbed the lipid membranes of intact S. aureus C622 most efficiently, whereas aurein 2.3 had the same efficiency as gramicidin S, and aurein 2.3-COOH was the least efficient. Taken together, these data show that the membrane interactions of aurein peptides are affected by the hydrophobic thickness of the lipid bilayers and the PG content.}, keywords = {ANTIBIOTIC PEPTIDES, CIRCULAR-DICHROISM SPECTROSCOPY, HOST-DEFENSE PEPTIDES, LIPID-COMPOSITION, MEMBRANES, MODEL, PHOSPHOLIPID-BILAYER MEMBRANES, PROTEIN SECONDARY STRUCTURE, SOLID-STATE NMR, STAPHYLOCOCCUS-AUREUS, TREE-FROG}, isbn = {0006-3495}, url = {://000266377200025}, author = {Cheng, J. T. J. and Hale, J. D. and Elliot, M. and Hancock, R. E. W. and Straus, S. K.} } @article {2117, title = {Lipid-specific binding of the calcium-dependent antibiotic daptomycin leads to changes in lipid polymorphism of model membranes}, journal = {Chemistry and Physics of Lipids}, volume = {154}, number = {2}, year = {2008}, note = {ISI Document Delivery No.: 336MXTimes Cited: 8Cited Reference Count: 41Jung, David Powers, Jon Paul Straus, Suzana K. Hancock, Robert E. W.}, month = {Aug}, pages = {120-128}, type = {Article}, abstract = {Daptomycin is a cyclic anionic lipopeptide with an antibiotic activity that is completely dependent on the presence of calcium (as Ca2+). In a previous study [Jung et al., 2004. Chem. Biol. 11, 949-957], it was concluded that daptomycin underwent two Ca2+-dependent structural transitions, whereby the first transition was solely dependent on Ca2+, while the second transition was dependent on both Ca2+ and the presence of negatively charged lipids that allowed daptomycin to insert into and perturb bilayer membranes with acidic character. Differences in the interaction of daptomycin with acidic and neutral membranes were further investigated by spectroscopic means. The lack of quenching of intrinsic fluorescence by the water-soluble quencher, KI, confirmed the insertion of the daptomycin Trp residue into the membrane bilayer, while the kynurenine residue was inaccessible even in an aqueous environment. Differential scanning calorimetry (DSC) indicated that the binding of daptomycin to neutral bilayers occurred through a combination of electrostatic and hydrophobic interactions, while the binding of daptomycin to Mayers containing acidic lipids primarily involved electrostatic interactions. The binding of daptomycin to acidic membranes led to the induction of non-lamellar lipid phases and membrane fusion. (C) 2008 Elsevier Ireland Ltd. All rights reserved.}, keywords = {ANTIMICROBIAL PEPTIDES, Daptomycin, DSC, FLUORESCENCE, lipopeptide, LY146032, membrane fusion, MIMETIC SYSTEMS, MODEL MEMBRANES, P-31 NMR, PHASE-TRANSITIONS, PHOSPHOLIPIDS, RESONANCE ENERGY-TRANSFER, STAPHYLOCOCCUS-AUREUS, X-RAY-DIFFRACTION}, isbn = {0009-3084}, url = {://000258369200006}, author = {Jung, D. and Powers, J. P. and Straus, S. K. and Hancock, R. E. W.} } @article {1578, title = {Mode of action of the new antibiotic for Gram-positive pathogens daptomycin: Comparison with cationic antimicrobial peptides and lipopeptides}, journal = {Biochimica Et Biophysica Acta-Biomembranes}, volume = {1758}, number = {9}, year = {2006}, note = {ISI Document Delivery No.: 098LXTimes Cited: 54Cited Reference Count: 97Straus, Suzana K. Hancock, Robert E. W.}, month = {Sep}, pages = {1215-1223}, type = {Review}, abstract = {With the steady rise in the number of antibiotic-resistant Gram-positive pathogens, it has become increasingly important to find new antibacterial agents which are highly active and have novel and diversified mechanisms of action. Two classes will be discussed here: the cationic antimicrobial peptides, which are amphiphilic in nature, targeting membranes and increasing their permeability; and lipopeptides, which consist of linear or cyclic peptides with an N-terminus that is acylated with a fatty acid side chain. One member of the cyclic lipopeptide family, the anionic molecule daptomycin, has been extensively studied and is the major focus of this review. Models will be presented on its mode of action and comparisons will be made to the known modes of action of cationic antimicrobial peptides and other lipopeptides. (c) 2006 Elsevier B.V. All rights reserved.}, keywords = {BACTERICIDAL ACTIVITY, cationic peptide, Daptomycin, ENTEROCOCCUS-FAECIUM, FATTY-ACID, Gram-positive pathogen, INVITRO ACTIVITY, LIPID-BILAYER DISRUPTION, lipopeptide, LY146032 DAPTOMYCIN, mechanism of action, POLYMYXIN-B, SOLID-STATE NMR, STAPHYLOCOCCUS-AUREUS, VALVE ENDOCARDITIS}, isbn = {0005-2736}, url = {://000241523100005}, author = {Straus, S. K. and Hancock, R. E. W.} }