Quadrupolar Echo Deuteron Magnetic Resonance Spectroscopy in Ordered Hydrocarbon Chains

DAVIS, J. H.; Jeffrey, Kenneth R.; BLOOM, M.; VALIC, M. I.; HIGGS, T. P.

doi:10.1021/bk-1976-0034.ch007

Cited by 200 publications

(238 citation statements)

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“…Bilayer alignment within each sample was confirmed using 31 P NMR at 50 °C on a Bruker (Billerica, MA) Avance 300 spectrometer. Deuterium NMR spectra were recorded at 50 °C using both β = 0° (bilayer normal parallel to magnetic field) and β = 90° macroscopic sample orientations on a Bruker Avance 300 spectrometer utilizing a quadrupolar echo pulse sequence 22 with 90 ms recycle delay, 3.2 μs pulse length, and 115 μs echo delay. Between 0.6 and 1.5 million scans were accumulated during each 2 H NMR experiment.…”

Section: Materials and Methodsmentioning

confidence: 99%

Comparisons of Interfacial Phe, Tyr, and Trp Residues as Determinants of Orientation and Dynamics for GWALP Transmembrane Peptides

et al. 2014

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Aromatic amino acids often flank the transmembrane alpha helices of integral membrane proteins. By favoring locations within the membrane–water interface of the lipid bilayer, aromatic residues Trp, Tyr, and sometimes Phe may serve as anchors to help stabilize a transmembrane orientation. In this work, we compare the influence of interfacial Trp, Tyr, or Phe residues upon the properties of tilted helical transmembrane peptides. For such comparisons, it has been critical to start with no more than one interfacial aromatic residue near each end of a transmembrane helix, for example, that of GWALP23 (acetyl-GGALW5(LA)6LW19LAGA-[ethanol]amide). To this end, we have employed 2H-labeled alanines and solid-state NMR spectroscopy to investigate the consequences of moving or replacing W5 or W19 in GWALP23 with selected Tyr, Phe, or Trp residues at the same or proximate locations. We find that GWALP23 peptides having F5, Y5, or W5 exhibit essentially the same average tilt and similar dynamics in bilayer membranes of 1,2-dilauroylphosphatidylcholine (DLPC) or 1,2-dioleoylphosphatidylcholine (DOPC). When double Tyr anchors are present, in Y4,5GWALP23 the NMR observables are markedly more subject to dynamic averaging and at the same time are less responsive to the bilayer thickness. Decreased dynamics are nevertheless observed when ring hydrogen bonding is removed, such that F4,5GWALP23 exhibits a similar extent of low dynamic averaging as GWALP23 itself. When F5 is the sole aromatic group in the N-interfacial region, the dynamic averaging is (only) slightly more extensive than with W5, Y5, or Y4 alone or with F4,5, yet it is much less than that observed for Y4,5GWALP23. Interestingly, moving Y5 to Y4 or W19 to W18, while retaining only one hydrogen-bond-capable aromatic ring at each interface, maintains the low level of dynamic averaging but alters the helix azimuthal rotation. The rotation change is about 40° for Y4 regardless of whether the host lipid bilayer is DLPC or DOPC. The rotational change (Δρ) is more dramatic and more complex when W19 is moved to W18, as Δρ is about +90° in DLPC but about −60° in DOPC. Possible reasons for this curious lipid-dependent helix rotation could include not only the separation distances between flanking aromatic or hydrophobic residues but also the absolute location of the W19 indole ring. For the more usual cases, when the helix azimuthal rotation shows little dependence on the host bilayer identity, excepting W18GWALP23, the transmembrane helices adapt to different lipids primarily by changing the magnitude of their tilt. We conclude that, in the absence of other functional groups, interfacial aromatic residues determine the preferred orientations and dynamics of membrane-spanning peptides. The results furthermore suggest possibilities for rotational and dynamic control of membrane protein function.

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Section: Materials and Methodsmentioning

confidence: 99%

Comparisons of Interfacial Phe, Tyr, and Trp Residues as Determinants of Orientation and Dynamics for GWALP Transmembrane Peptides

et al. 2014

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“…The bilayer alignment of a sample was assessed by means of 31 P NMR spectra recorded using a Bruker (Billerica, MA) Avance 300 MHz spectrometer (see Figure S2 of the Supplementary Material). Deuterium NMR spectra were recorded on a Bruker Avance 300 MHz spectrometer at 50 °C with β = 90° and β = 0° macroscopic sample orientations using a quadrupolar echo pulse sequence [24] with a 90 ms recycle delay, 3.2 μs pulse length, and 115 μs echo delay. Between 0.6 and 1 million free induction decays were recorded for each 2 H experiment.…”

Section: Methodsmentioning

confidence: 99%

Influence of glutamic acid residues and pH on the properties of transmembrane helices

Rajagopalan¹,

Greathouse²,

Koeppe³

2017

Biochimica et Biophysica Acta (BBA) - Biomembranes

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Negatively charged side chains are important for the function of particular ion channels and certain other membrane proteins. To investigate the influence of single glutamic acid side chains on helices that span lipid-bilayer membranes, we have employed GWALP23 (acetyl-GGALW5LALALALALALALW19LAGA-amide) as a favorable host peptide framework. We substituted individual Leu residues with Glu residues (L12E or L14E or L16E) and incorporated specific 2H-labeled alanine residues within the core helical region or near the ends of the sequence. Solid-state 2H-NMR spectra reveal little change for the core labels in GWALP23-E12, –E14 and –E16 over a pH range of 4 to 12.5, with the spectra being broader for samples in DOPC compared to DLPC bilayers. The spectra for samples with deuterium labels near the helix ends on alanines 3 and 21 show modest pH-dependent changes in the extent of unwinding of the helix terminals in DLPC and DOPC bilayers. The combined results indicate minor overall responses of these transmembrane helices to changes in pH, with the most buried residue E12 showing no pH dependence. While the Glu residues E14 and E16 may have high pKa values in the lipid bilayer environment, it is also possible that a paucity of helix response is masking the pKa values. Interestingly, when E16 is present, spectral changes at high pH report significant local unwinding of the core helix. Our results are consistent with the expectation that buried carboxyl groups aggressively hold their protons and/or waters of hydration.

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“…Samples were allowed to equilibrate for 30 min at 25°C before the NMR signal was acquired. Deuterium NMR experiments were performed by means of the quadrupolar echo pulse sequence 90° x - τ -90° y-τ -acq [22]. 31 P-NMR spectra were acquired using a phase-cycled Hahn-echo pulse sequence with gated broadband proton decoupling [23].…”

Section: Methodsmentioning

confidence: 99%

Biophysical Investigation of the Membrane-Disrupting Mechanism of the Antimicrobial and Amyloid-Like Peptide Dermaseptin S9

et al. 2013

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Dermaseptin S9 (Drs S9) is an atypical cationic antimicrobial peptide with a long hydrophobic core and with a propensity to form amyloid-like fibrils. Here we investigated its membrane interaction using a variety of biophysical techniques. Rather surprisingly, we found that Drs S9 induces efficient permeabilisation in zwitterionic phosphatidylcholine (PC) vesicles, but not in anionic phosphatidylglycerol (PG) vesicles. We also found that the peptide inserts more efficiently in PC than in PG monolayers. Therefore, electrostatic interactions between the cationic Drs S9 and anionic membranes cannot explain the selectivity of the peptide towards bacterial membranes. CD spectroscopy, electron microscopy and ThT fluorescence experiments showed that the peptide adopts slightly more β-sheet and has a higher tendency to form amyloid-like fibrils in the presence of PC membranes as compared to PG membranes. Thus, induction of leakage may be related to peptide aggregation. The use of a pre-incorporation protocol to reduce peptide/peptide interactions characteristic of aggregates in solution resulted in more α-helix formation and a more pronounced effect on the cooperativity of the gel-fluid lipid phase transition in all lipid systems tested. Calorimetric data together with 2H- and 31P-NMR experiments indicated that the peptide has a significant impact on the dynamic organization of lipid bilayers, albeit slightly less for zwitterionic than for anionic membranes. Taken together, our data suggest that in particular in membranes of zwitterionic lipids the peptide binds in an aggregated state resulting in membrane leakage. We propose that also the antimicrobial activity of Drs S9 may be a result of binding of the peptide in an aggregated state, but that specific binding and aggregation to bacterial membranes is regulated not by anionic lipids but by as yet unknown factors.

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Quadrupolar Echo Deuteron Magnetic Resonance Spectroscopy in Ordered Hydrocarbon Chains

Cited by 200 publications

References 0 publications

Comparisons of Interfacial Phe, Tyr, and Trp Residues as Determinants of Orientation and Dynamics for GWALP Transmembrane Peptides

Comparisons of Interfacial Phe, Tyr, and Trp Residues as Determinants of Orientation and Dynamics for GWALP Transmembrane Peptides

Influence of glutamic acid residues and pH on the properties of transmembrane helices

Biophysical Investigation of the Membrane-Disrupting Mechanism of the Antimicrobial and Amyloid-Like Peptide Dermaseptin S9

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