Geometry and Intrinsic Tilt of a Tryptophan-Anchored Transmembrane α-Helix Determined by 2H NMR

Wel, Patrick C.A. van der; Strandberg, Erik; Killian, J. Antoinette; Koeppe, Roger E.

doi:10.1016/s0006-3495(02)73918-0

Cited by 166 publications

(479 citation statements)

References 40 publications

(46 reference statements)

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“…[19][20][21]49 We have neglected the possibility of the cylindrical inclusions to tilt. While tilt has been suggested to occur for positive mismatch 3 a recent study 50 showed that modifications in the degree of hydrophobic mismatch need not necessarily affect the tilt angle of a single transmembrane peptide. Hence, it is currently not clear whether experimentally observed tilt of membrane inclusions is induced by hydrophobic mismatch or whether it is an intrinsic property that arises from an asymmetry of the inclusion itself.…”

Section: Single Isolated Inclusionmentioning

confidence: 99%

Interaction between two cylindrical inclusions in a symmetric lipid bilayer

Bohinc

Kralj‐Iglič

May

2003

The Journal of Chemical Physics

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We calculate the membrane-mediated interaction between two cylindrical inclusions in a symmetric lipid bilayer. Our theory takes two contributions to the free energy into account, the elastic behavior of the membrane and the conformational restrictions that the flexible hydrocarbon chains of the lipids experience in the vicinity of a rigid inclusion. The description of the elastic behavior is based on two order parameters, the hydrophobic thickness of the membrane and a director field that characterizes the average tilt of the lipid chains. Conformational restrictions of the lipid chains are taken into account by a simple director model. We show that the short-range interaction potential between two inclusions sensitively depends on the degree of hydrophobic mismatch and on the spontaneous curvature of the lipid layers. In particular, we find pronounced attraction if the hydrophobic mismatch is positive. For negative mismatch the attraction is much less pronounced and, additionally, an energetic barrier appears. The inclusions prefer a small but notable negative hydrophobic mismatch. Positive spontaneous curvature amplifies these behaviors.

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Section: Single Isolated Inclusionmentioning

confidence: 99%

Interaction between two cylindrical inclusions in a symmetric lipid bilayer

Bohinc

Kralj‐Iglič

May

2003

The Journal of Chemical Physics

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“…The proper alignment of the lipid bilayers in each glass plate sample was confirmed by 31 P NMR measurements as described in Ref. 40. The 2 H experiments were done using a quadrupolar echo pulse sequence (41) with an echo delay of 65 s, 1.5 million scans, and with 30-ms interpulse time.…”

Section: Solid State 2 H Nmrmentioning

confidence: 99%

The Preference of Tryptophan for Membrane Interfaces

Sun

Greathouse

Andersen

et al. 2008

Journal of Biological Chemistry

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To better understand the structural and functional roles of tryptophan at the membrane/water interface in membrane proteins, we examined the structural and functional consequences of Trp 3 1-methyl-tryptophan substitutions in membranespanning gramicidin A channels. Gramicidin A channels are miniproteins that are anchored to the interface by four Trps near the C terminus of each subunit in a membrane-spanning dimer. We masked the hydrogen bonding ability of individual or multiple Trps by 1-methylation of the indole ring and examined the structural and functional changes using circular dichroism spectroscopy, size exclusion chromatography, solid state 2 H NMR spectroscopy, and single channel analysis. N-Methylation causes distinct changes in the subunit conformational preference, channel-forming propensity, single channel conductance and lifetime, and average indole ring orientations within the membrane-spanning channels. The extent of the local ring dynamic wobble does not increase, and may decrease slightly, when the indole NH is replaced by the non-hydrogen-bonding and more bulky and hydrophobic N-CH 3 group. The changes in conformational preference, which are associated with a shift in the distribution of the aromatic residues across the bilayer, are similar to those observed previously with Trp 3 Phe substitutions. We conclude that indole N-H hydrogen bonding is of major importance for the folding of gramicidin channels. The changes in ion permeability, however, are quite different for Trp 3 Phe and Trp 3 1-methyl-tryptophan substitutions, indicating that the indole dipole moment and perhaps also ring size and are important for ion permeation through these channels.

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“…This method, called geometric analysis of labeled alanines (GALA), allows for very accurate determination of tilt angles of WALP peptides in either oriented or nonoriented PC bilayers (11,14). In addition, the direction in which the peptides are tilted, as determined by their 1 Abbreviations: PC, phosphatidylcholine; NMR, nuclear magnetic resonance; TFA, trifluoroacetic acid; TFE, 2,2,2-trifluoroethanol; HEPES, N-(2-hydroxyethyl)piperazine-N′-2-ethanesulfonic acid; tBu, tert-butyl; d 4-Ala, deuterated L-alanine-d4; Fmoc, 9-fluorenylmethyloxycarbonyl; di-C12:0-PC, 1,2-dilauroyl-sn-glycero-3-phosphocholine; di-C13:0-PC, 1,2-ditridecanoyl-sn-glycero-3-phosphocholine; di-C14: 0-PC, 1,2-dimyristoyl-sn-glycero-3-phosphocholine; di-C18:1-PC, 1,2-dioleoyl-sn-glycero-3-phosphocholine.…”

Section: Reviewed In Refs 2-4)mentioning

confidence: 99%

“…As in (11), the splitting of the backbone deuteron could not be observed, and the 2 H NMR signals were assigned to the deuterons of the alanine side chain methyl group. The data were fitted to a model R-helix, similar to that in previous studies (10,11,14,16). In particular, data were fitted to the equation ∆ν q is the quadrupolar splitting as measured in unoriented samples.…”

Section: Nmr Sample Preparationmentioning

confidence: 99%

“…In particular, the so-called WALP peptides have been used as tools to monitor the consequence of hydrophobic mismatch for the organization of peptides and lipids in model membranes (reviewed in ref 15). WALP peptides are a family of R-helical transmembrane model peptides made of a central leucine alanine stretch that is flanked by two tryptophan residues on each side.Recently, a technique based on solid-state 2 H NMR using deuterated alanines has been developed to analyze structural properties of transmembrane peptides in model membranes (10,11,14,16). This method, called geometric analysis of labeled alanines (GALA), allows for very accurate determination of tilt angles of WALP peptides in either oriented or…”

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Influence of Flanking Residues on Tilt and Rotation Angles of Transmembrane Peptides in Lipid Bilayers. A Solid-State ²H NMR Study

et al. 2004

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To gain insight into the parameters that determine the arrangement of proteins in membranes, 2 H NMR experiments were performed to analyze tilt and rotation angles of membrane-spanning R-helical model peptides upon incorporation in diacylphosphatidylcholine bilayers with varying thickness. The peptides consisted of the sequence acetyl-GW 2 (LA) 8 LW 2 A-NH 2 (WALP23) and analogues thereof, in which the interfacial Trp residues were replaced by Lys (KALP23) and/or the hydrophobic sequence was replaced by Leu (WLP23 and KLP23). The peptides were synthesized with a single deuterium-labeled alanine at four different positions along the hydrophobic segment. For all peptides a small but systematic increase in tilt angle was observed upon decreasing the bilayer thickness. However, significantly larger tilt angles were obtained for the Lys-flanked KALP23 than for the Trp-flanked WALP23, suggesting that interfacial anchoring interactions of Trp may inhibit tilting. Increasing the hydrophobicity resulted in an increase in tilt angle for the Trp-flanked analogue only. For all peptides the maximum tilt angle obtained was remarkably small (less than 12°), suggesting that further tilting is inhibited, most likely due to unfavorable packing of lipids around a tilted helix. The results furthermore showed that the direction of tilt is determined almost exclusively by the flanking residues: Trp-and Lys-flanked peptides were found to have very different rotation angles, which were influenced significantly neither by hydrophobicity of the peptides nor by the extent of hydrophobic mismatch. Finally, very small changes in the side chain angles of the deuterated alanine probes were observed in Trp-flanked peptides, suggesting that these peptides may decrease their hydrophobic length to help them to adapt to thin membranes.Membrane proteins carry out many essential functions in cells. In the specific case of integral proteins, the membrane spanning parts of these molecules are in direct contact with acyl chains and headgroups of the surrounding lipids. Consequently, the lipid environment can modulate structure and dynamics and, hence, activity of membrane proteins (1). For example, changes in hydrophobic thickness of a lipid bilayer can affect the structure of an integral membrane protein by causing a hydrophobic mismatch between the bilayer thickness and the length of the membrane spanning parts of that protein (reviewed in refs 2-4). Understanding the molecular basis of how lipids influence membrane proteins requires precise information on structural properties of transmembrane segments of proteins and knowledge of how these properties are sensitive to protein and lipid composition. It is most suitable to perform such experiments on model membranes of synthetic lipids and transmembrane peptides, since the composition of both the lipids and the peptides can be systematically varied. Model membranes, made of phosphatidylcholine derivatives (PC) 1 and model transmembrane peptides, have already been extensively studied to inves...

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Geometry and Intrinsic Tilt of a Tryptophan-Anchored Transmembrane α-Helix Determined by 2H NMR

Cited by 166 publications

References 40 publications

Interaction between two cylindrical inclusions in a symmetric lipid bilayer

Interaction between two cylindrical inclusions in a symmetric lipid bilayer

The Preference of Tryptophan for Membrane Interfaces

Influence of Flanking Residues on Tilt and Rotation Angles of Transmembrane Peptides in Lipid Bilayers. A Solid-State ²H NMR Study

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Geometry and Intrinsic Tilt of a Tryptophan-Anchored Transmembrane α-Helix Determined by 2H NMR

Cited by 166 publications

References 40 publications

Interaction between two cylindrical inclusions in a symmetric lipid bilayer

Interaction between two cylindrical inclusions in a symmetric lipid bilayer

The Preference of Tryptophan for Membrane Interfaces

Influence of Flanking Residues on Tilt and Rotation Angles of Transmembrane Peptides in Lipid Bilayers. A Solid-State 2H NMR Study

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Influence of Flanking Residues on Tilt and Rotation Angles of Transmembrane Peptides in Lipid Bilayers. A Solid-State ²H NMR Study