De-pake-ing of NMR spectra

Sternin, Edward; Bloom, Myer; MacKay, Alexander L.

doi:10.1016/0022-2364(83)90239-1

Cited by 187 publications

(210 citation statements)

References 6 publications

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“…A detailed picture of the effects of the LAH peptides on the lipid chains in model membranes can be obtained by acquiring wide-line 2 H echo spectra of PE-PG lipid mixes in the absence and presence of peptide at acidic and neutral pHs. By keeping the peptide concentration constant, at a level (2.5 mol%) where an effect on the fatty acyl chain order could be observed by solid-state NMR methods but without disintegration of the membrane, as previously observed using static 31 P NMR on similarly prepared vesicles FIG. 1.…”

Section: Resultsmentioning

confidence: 62%

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Enhanced Membrane Disruption and Antibiotic Action against Pathogenic Bacteria by Designed Histidine-Rich Peptides at Acidic pH

Mason

Gasnier

Kichler

et al. 2006

Antimicrob Agents Chemother

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The histidine-rich amphipathic cationic peptide LAH4 has antibiotic and DNA delivery capabilities. Here, we explore the interaction of peptides from this family with model membranes as monitored by solid-state 2 H nuclear magnetic resonance and their antibiotic activities against a range of bacteria. At neutral pH, the membrane disruption is weak, but at acidic pH, the peptides strongly disturb the anionic lipid component of bacterial membranes and cause bacterial lysis. The peptides are effective antibiotics at both pH 7.2 and pH 5.5, although the antibacterial activity is strongly affected by the change in pH. At neutral pH, the LAH peptides were active against both methicillin-resistant and -sensitive Staphylococcus aureus strains but ineffective against Pseudomonas aeruginosa. In contrast, the LAH peptides were highly active against P. aeruginosa in an acidic environment, as is found in the epithelial-lining fluid of cystic fibrosis patients. Our results show that modest antibiotic activity of histidine-rich peptides can be dramatically enhanced by inducing membrane disruption, in this case by lowering the pH, and that histidine-rich peptides have potential as future antibiotic agents.With the dramatic rise of antibiotic resistance in pathogenic bacteria, there is no doubt that there is an urgent requirement for the development of novel antibiotics. The lungs of cystic fibrosis patients are chronically infected by lineages of Pseudomonas aeruginosa with high mutation rates that can readily become resistant to current antibiotics (20,25), while the impact of methicillin-resistant Staphylococcus aureus (MRSA) has been well documented (2). These bacteria, therefore, represent significant targets for new classes of antibiotics.Cationic antimicrobial peptides play a central role in preventing the onset of infection in many organisms, and following the introduction of a number of such peptides in clinical trials (16), it seems likely that development of these peptides will provide the basis for a new class of antibiotics. LAH4, a histidine-rich amphipathic ␣-helical peptide (4), has been shown to possess both antibiotic (34) and DNA delivery (17, 18) capabilities. This dual functionality could be exploited in therapeutic strategies for a number of diseases, a notable example being cystic fibrosis, where LAH4 or a derivative thereof could form part of a gene delivery vehicle while concomitantly fighting microbial infections that result from the underlying condition. Therefore, a fundamental understanding of the antibiotic strategies employed by cationic antimicrobial peptides such as LAH4 will aid the design of more powerful antibiotics that may eventually become frontline treatments for a variety of infectious diseases.To understand in greater detail how histidine-rich peptides operate against their microbial targets, we synthesized a series of derivatives of LAH4 and combined biophysical studies of their interactions using model membranes from solid-state nuclear magnetic resonance (NMR) of chain-deuterated lipid...

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Section: Resultsmentioning

confidence: 62%

“…Spectra were zero filled to 8,192 points, and 50-Hz exponential line broadening was applied. Smoothed deuterium order parameter profiles were obtained from symmetrized and dePaked 2 H NMR powder spectra using published procedures (29,30,31).…”

Section: Methodsmentioning

confidence: 99%

Enhanced Membrane Disruption and Antibiotic Action against Pathogenic Bacteria by Designed Histidine-Rich Peptides at Acidic pH

Mason

Gasnier

Kichler

et al. 2006

Antimicrob Agents Chemother

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“…DePaked spectra were calculated by using the iterative method described in ref. 28. The precise lipid compositions and lipid/cholesterol ratios were determined by dissolving samples in chloroform and conducting high-resolution 1 H NMR experiments.…”

Section: Methodsmentioning

confidence: 99%

Critical fluctuations in domain-forming lipid mixtures

Veatch

Soubias

Keller

et al. 2007

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

430

525

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Critical fluctuations are investigated in lipid membranes near miscibility critical points in bilayers composed of dioleoylphosphatidylcholine, chain perdeuterated dipalmitoylphosphatidylcholine, and cholesterol. Phase boundaries are mapped over the temperature range from 10°C to 60°C by deuterium NMR. Tie-lines and three-phase triangles are evaluated across two-phase and three-phase regions, respectively. In addition, a line of miscibility critical points is identified. NMR resonances are broadened in the vicinity of critical points, and broadening is attributed to increased transverse relaxation rates arising from modulation of chain order with correlation times on a microsecond time scale. We conclude that spectral broadening arises from composition fluctuations in the membrane plane with dimensions of <50 nm and speculate that similar fluctuations are commonly found in cholesterolcontaining membranes.lipid rafts ͉ liquid-immiscibility ͉ NMR relaxation ͉ phase diagram ͉ critical behavior T he first direct observation of immiscible liquid phases in model bilayer membranes was presented only recently, for membranes containing three or more components (1, 2). However, by the early 1970s, it was already clear that lipids in membranes with elevated cholesterol have high chain order yet diffuse as in a liquid (3-6). This liquid-ordered (L o ) phase of lipids (7) is distinguished from the familiar liquid-disordered phase (L ␣ or L d ) found in bilayers of pure lipids above the chain melting temperature (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14). Pure lipids below the chain melting temperature are in the solid or ''gel'' phase (S o ). Coexisting liquid-ordered and liquid-disordered phases are easily visualized in giant unilamellar vesicles by fluorescence microscopy when membranes contain cholesterol and two types of lipids: one with a high gel-fluid transition temperature and one with a low gel-f luid transition temperature (15-21). Coexisting liquid phases are also easily visualized in membranes of plasma membrane vesicles containing a wide spectrum of lipid and protein components (22).The research presented here represents a culmination of several years' work in our laboratories on ternary membranes of dioleoylphosphatidylcholine (DOPC), chain perdeuterated dipalmitoylphosphatidylcholine (DPPC-d 62 ), and cholesterol (Chol) (15-18, 23, 24). It has resulted in a straightforward thermodynamic description of micrometer-sized coexisting phases and of submicrometer composition fluctuations in membranes containing cholesterol. Here we use deuterium ( 2 H) NMR to assemble the DOPC/DPPC-d 62 /Chol phase diagram. NMR allows us to directly measure differences in ordering and partitioning of DPPC-d 62 between coexisting phases. In addition, NMR produces results free from artifacts associated with fluorescent probes (24) or oxidation of unsaturated lipid chains (15,25). We use our NMR data to identify quantitative miscibility phase boundaries and to solve for a large array of tie-lines. Tie-line endpoints yield quantitative co...

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“…Powder pattern 2 H NMR spectra were de-Paked (74,75). The order parameter S(n) of the C-D bonds were calculated according to the following formula:…”

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confidence: 99%

Structural interactions of a voltage sensor toxin with lipid membranes

Mihailescu

Krepkiy

Milescu

et al. 2014

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

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Protein toxins from tarantula venom alter the activity of diverse ion channel proteins, including voltage, stretch, and ligandactivated cation channels. Although tarantula toxins have been shown to partition into membranes, and the membrane is thought to play an important role in their activity, the structural interactions between these toxins and lipid membranes are poorly understood. Here, we use solid-state NMR and neutron diffraction to investigate the interactions between a voltage sensor toxin (VSTx1) and lipid membranes, with the goal of localizing the toxin in the membrane and determining its influence on membrane structure. Our results demonstrate that VSTx1 localizes to the headgroup region of lipid membranes and produces a thinning of the bilayer. The toxin orients such that many basic residues are in the aqueous phase, all three Trp residues adopt interfacial positions, and several hydrophobic residues are within the membrane interior. One remarkable feature of this preferred orientation is that the surface of the toxin that mediates binding to voltage sensors is ideally positioned within the lipid bilayer to favor complex formation between the toxin and the voltage sensor.voltage sensor toxin | voltage-activated ion channel | toxin-membrane interaction | membrane structure | neutron diffraction P rotein toxins from venomous organisms have been invaluable tools for studying the ion channel proteins they target. For example, in the case of voltage-activated potassium (Kv) channels, pore-blocking scorpion toxins were used to identify the pore-forming region of the channel (1, 2), and gating modifier tarantula toxins that bind to S1-S4 voltage-sensing domains have helped to identify structural motifs that move at the protein-lipid interface (3-5). In many instances, these toxin-channel interactions are highly specific, allowing them to be used in target validation and drug development (6-8).Tarantula toxins are a particularly interesting class of protein toxins that have been found to target all three families of voltageactivated cation channels (3, 9-12), stretch-activated cation channels (13-15), as well as ligand-gated ion channels as diverse as acid-sensing ion channels (ASIC) (16-21) and transient receptor potential (TRP) channels (22, 23). The tarantula toxins targeting these ion channels belong to the inhibitor cystine knot (ICK) family of venom toxins that are stabilized by three disulfide bonds at the core of the molecule (16,17,(24)(25)(26)(27)(28)(29)(30)(31). Although conventional tarantula toxins vary in length from 30 to 40 aa and contain one ICK motif, the recently discovered double-knot toxin (DkTx) that specifically targets TRPV1 channels contains two separable lobes, each containing its own ICK motif (22, 23).One unifying feature of all tarantula toxins studied thus far is that they act on ion channels by modifying the gating properties of the channel. The best studied of these are the tarantula toxins targeting voltage-activated cation channels, where the toxins bind to the S3b-S4 vol...

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De-pake-ing of NMR spectra

Cited by 187 publications

References 6 publications

Enhanced Membrane Disruption and Antibiotic Action against Pathogenic Bacteria by Designed Histidine-Rich Peptides at Acidic pH

Enhanced Membrane Disruption and Antibiotic Action against Pathogenic Bacteria by Designed Histidine-Rich Peptides at Acidic pH

Critical fluctuations in domain-forming lipid mixtures

Structural interactions of a voltage sensor toxin with lipid membranes

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