Cholesterol-Phospholipid Interactions: New Insights from Surface X-Ray Scattering Data

Ivankin, Andrey; Kuzmenko, Ivan; Gidalevitz, David

doi:10.1103/physrevlett.104.108101

Cited by 75 publications

(55 citation statements)

References 22 publications

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“…Once the monolayer was compressed the chamber containing the Langmuir trough was sealed and purged with helium to lower the oxygen levels in the chamber, which minimizes background X-ray scattering during the X-ray experiments. [58, 66]…”

Section: Methodsmentioning

confidence: 99%

Guanidino groups greatly enhance the action of antimicrobial peptidomimetics against bacterial cytoplasmic membranes

Andreev

Bianchi

Laursen

et al. 2014

Biochimica et Biophysica Acta (BBA) - Biomembranes

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A promising class of potential new antibiotics are the antimicrobial peptides or their synthetic mimics. Herein we assess the effect of the type of cationic side chain (i.e., guanidino vs. amino groups) on the membrane perturbing mechanism of antimicrobial α-peptide–β-peptoid chimeras. Two separate Langmuir monolayers composed of 1,2-dipalmitoyl-sn-glycero-3-phosphatidylglycerol (DPPG) and lipopolysaccharide Kdo2-lipid A were applied to model the outer membranes of Gram-positive and Gram-negative bacteria, respectively. We report the results of the measurements using an array of techniques, including high-resolution synchrotron surface X-ray scattering, epifluorescence microscopy, and in vitro antimicrobial activity to study the molecular mechanisms of peptidomimetic interaction with bacterial membranes. We found guanidino group-containing chimeras to exhibit greater disruptive activity on DPPG monolayers than the amino group-containing analogues. However, this effect was not observed for lipopolysaccharide monolayers where the difference was negligible. Furthermore, the addition of the nitrobenzoxadiazole fluorophore did not reduce the insertion activity of these antimicrobials into both model membrane systems examined, which may be useful for future cellular localization studies.

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Section: Methodsmentioning

confidence: 99%

Guanidino groups greatly enhance the action of antimicrobial peptidomimetics against bacterial cytoplasmic membranes

Andreev

Bianchi

Laursen

et al. 2014

Biochimica et Biophysica Acta (BBA) - Biomembranes

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“…Nanodomains have also been observed in DPPC–cholesterol monolayers using X-ray diffraction 36, 37 . It is important to note that many experimental techniques, such as spectroscopic ones, do not provide information on the size and the arrangement of the ordered domains.…”

Section: Introductionmentioning

confidence: 99%

Nanoscale Membrane Domain Formation Driven by Cholesterol

Javanainen

Martinez‐Seara

Vattulainen

2017

Sci Rep

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Biological membranes generate specific functions through compartmentalized regions such as cholesterol-enriched membrane nanodomains that host selected proteins. Despite the biological significance of nanodomains, details on their structure remain elusive. They cannot be observed via microscopic experimental techniques due to their small size, yet there is also a lack of atomistic simulation models able to describe spontaneous nanodomain formation in sufficiently simple but biologically relevant complex membranes. Here we use atomistic simulations to consider a binary mixture of saturated dipalmitoylphosphatidylcholine and cholesterol — the “minimal standard” for nanodomain formation. The simulations reveal how cholesterol drives the formation of fluid cholesterol-rich nanodomains hosting hexagonally packed cholesterol-poor lipid nanoclusters, both of which show registration between the membrane leaflets. The complex nanodomain substructure forms when cholesterol positions itself in the domain boundary region. Here cholesterol can also readily flip–flop across the membrane. Most importantly, replacing cholesterol with a sterol characterized by a less asymmetric ring region impairs the emergence of nanodomains. The model considered explains a plethora of controversial experimental results and provides an excellent basis for further computational studies on nanodomains. Furthermore, the results highlight the role of cholesterol as a key player in the modulation of nanodomains for membrane protein function.

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“…Further methods applied to visualize domains in the micrometer range in these films are Brewster angle microscopy [16,17] and fluorescence microscopy [18]. Detailed information about molecular structures and orientations in Langmuir films can be achieved by infrared reflection absorption spectroscopy [13,14] and X-ray or neutron reflectivity measurements [8,15,19]. After transfer of the Langmuir films onto solid supports by using the Langmuir-Blodgett (LB) technique, morphological information of the resulting LB films can be studied in the nanometer range by atomic force microscopy (AFM) [6,[20][21][22][23].…”

Section: Introductionmentioning

confidence: 99%

Mixed layers of DPPC and a linear poly(ethylene glycol)-b-hyperbranched poly(glycerol) block copolymer having a cholesteryl end group

et al. 2012

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Interactions of the phospholipid 1,2-dipalmitoylsn-glycero-3-phosphocholine (DPPC) with the amphiphilic diblock copolymer Ch-lPEG 30 -b-hbPG 24 (ChP) are studied at the air-water interface by surface pressure-mean molecular area (π-mmA) measurements of mixed Langmuir films and adsorption measurements of ChP to the air-water interface covered with DPPC monolayers at different initial surface pressure values π 0 . ChP is composed of a single hydrophobic cholesteryl (Ch) moiety covalently bound to a diblock copolymer consisting of a hydrophilic linear poly (ethylene glycol) (lPEG) block and a hydrophilic hyperbranched poly(glycerol) (hbPG) block. Langmuir isotherms and compression moduli of the mixed Langmuir films of different molar ratios reveal distinct interactions between DPPC and ChP during compression. It is demonstrated that the behavior of the DPPC/ChP mixtures is dominated by DPPC up to a molar ratio of 10:1, whereas the behavior is predominantly governed by ChP in mixtures with lower DPPC content (molar ratios of 5:1, 2:1, and 1:1). In adsorption measurements, a strong affinity of ChP to DPPC is observed after injection into the water subphase. The surface pressure value π in up to which ChP is able to penetrate into DPPC monolayers is determined to the remarkably high value of 48.2 mN/m which attests the favorable interactions between DPPC and the Ch moiety of ChP. Atomic force microscopy on LB films of DPPC/ChP mixtures of different molar ratios transferred onto hydrophilic substrates confirms the presence of two different phases, a DPPC-rich phase and a ChP-rich phase.

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Cholesterol-Phospholipid Interactions: New Insights from Surface X-Ray Scattering Data

Cited by 75 publications

References 22 publications

Guanidino groups greatly enhance the action of antimicrobial peptidomimetics against bacterial cytoplasmic membranes

Guanidino groups greatly enhance the action of antimicrobial peptidomimetics against bacterial cytoplasmic membranes

Nanoscale Membrane Domain Formation Driven by Cholesterol

Mixed layers of DPPC and a linear poly(ethylene glycol)-b-hyperbranched poly(glycerol) block copolymer having a cholesteryl end group

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