Influence of Proline upon the Folding and Geometry of the WALP19 Transmembrane Peptide

Thomas, Rachel; Vostrikov, Vitaly V.; Greathouse, Denise V.; Koeppe, Roger E.

doi:10.1021/bi9016395

Cited by 29 publications

(61 citation statements)

References 51 publications

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“…The 2 H NMR spectra of GWALP23-R14, in addition to strong C β -D 3 peaks, furthermore exhibit some weaker signals from backbone C α -D (Figure 2). This observation is noteworthy, since C α -D signals have been observed also when proline is introduced near the center of WALP19,32 but otherwise not in WALP family peptides, including GWALP23 11,14,33. The result could signify that the motional regime of GWALP23-R14 is different from other WALP family peptides that lack Arg or Pro.…”

Section: Resultsmentioning

confidence: 91%

Changes in Transmembrane Helix Alignment by Arginine Residues Revealed by Solid-State NMR Experiments and Coarse-Grained MD Simulations

et al. 2010

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Independent experimental and computational approaches show agreement concerning arginine/membrane interactions when a single arginine is introduced at selected positions within the membrane-spanning region of acetyl-GGALW5LALALAL12AL14ALALW19LAGA-ethanolamide, designated GWALP23. Peptide sequence isomers having Arg in position 12 or position 14 display markedly different behaviors, as deduced by both solid-state NMR experiments and coarse-grained molecular dynamics (CG-MD) simulations. With respect to the membrane normal of DOPC or DPPC lipid bilayer membranes, GWALP23-R14 shows one major state whose apparent average tilt is ~10° greater than that of GWALP23. The presence of R14 furthermore induces bilayer thinning and peptide displacement to “lift” the charged guanidinium toward the bilayer surface. By contrast, GWALP23-R12 exhibits multiple states that are in slow exchange on the NMR time scale, with CG-MD simulations indicating two distinct positions with different screw rotation angles in the membrane, along with an increased tendency to exit the lipid bilayer.

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Section: Resultsmentioning

confidence: 91%

Changes in Transmembrane Helix Alignment by Arginine Residues Revealed by Solid-State NMR Experiments and Coarse-Grained MD Simulations

et al. 2010

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“…Indeed, the GALA analysis of quadrupolar splittings returns tilt angles as large as 30° (Table 3). Low RMSD values for fitting the side-chain quadrupolar splittings suggest that the α-helical conformation is maintained throughout the core sequence, between the Trp residues 34 . (The higher RMSD values for backbone groups may reflect limitations in the treatment of the dynamics; see Discussion.)…”

Section: Resultsmentioning

confidence: 99%

Accommodation of a Central Arginine in a Transmembrane Peptide by Changing the Placement of Anchor Residues

et al. 2012

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Both Trp and Arg in transmembrane protein domains make important interactions with lipids at the membrane/water interface, but at different depths. Derivatives of the designed peptide GWALP23, acetyl-GGALW5LALALALALALALW19LAGA-amide, with single Trp anchors, have proven useful for characterizing such interactions. Indeed previous work revealed quite different effects emanating from Arg substitutions at positions 12 and 14 within GWALP23, with the R12 peptide exhibiting multiple positions and orientations with respect to DOPC bilayer membranes (Vostrikov et al. [2010] J. Am. Chem. Soc. 132, 5803–5811). To gain further understanding of the multi-state behavior, we moved the Trp “anchor” residues to more outer positions 3 and 21 in GWALP23 itself, and in the R12 and R14 derivatives. The locations and orientations of the peptides with respect to lipid bilayer membranes of differing thickness were investigated by means of solid-state 2H NMR spectroscopy, using labeled alanines, and coarse-grained molecular dynamics simulations. Interestingly, relatively intense and narrow 2H resonances from selected backbone Cα deuterons were observed over quite narrow ranges of frequency and sample orientation. The backbone resonances reflect dynamic complexities and at the same time provide important contributions for the analysis of peptide transmembrane orientation. With the Trp3,21 anchors relatively far from the peptide and bilayer center, the results indicate significantly large apparent tilt angles, for example close to 30° for the new R12 and R14 peptides with respect to the bilayer normal of DLPC membranes. The R12 side chain indeed is “rescued” to a stable position, where it is accommodated within the transmembrane helix, when the Trp anchors are moved outward and to another face of the helix. At the same time, the R14 side chain of transmembrane GW3,21ALP23 also retains a stable favored position.

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“…Deuterium NMR signals from C ␤ D 3 groups of Ala-d 4 residues in XWALP23 peptides were analyzed according to the geometric analysis of labeled alanines (GALA) method, implemented in Microsoft Excel (18,27). The analysis is based on a relationship between the alanine C ␤ D 3 quadrupolar splitting (⌬ q ) and the angle between the alanine C ␣ -C ␤ bond vector and the applied magnetic field…”

Section: Methodsmentioning

confidence: 99%

Charged or Aromatic Anchor Residue Dependence of Transmembrane Peptide Tilt

Vostrikov

Daily

Greathouse

et al. 2010

Journal of Biological Chemistry

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185

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The membrane-spanning segments of integral membrane proteins often are flanked by aromatic or charged amino acid residues, which may "anchor" the transmembrane orientation. Single spanning transmembrane peptides such as those of the WALP family, acetyl-GWW(LA) n LWWA-amide, furthermore adopt a moderate average tilt within lipid bilayer membranes. To understand the anchor residue dependence of the tilt, we introduce Leu-Ala "spacers" between paired anchors and in some cases replace the outer tryptophans. The resulting peptides, acetyl-GX 2 ALW(LA) 6 LWLAX 22 A-amide, have Trp, Lys, Arg, or Gly in the two X positions. The apparent average orientations of the core helical sequences were determined in oriented phosphatidylcholine bilayer membranes of varying thickness using solid-state 2 H NMR spectroscopy. When X is Lys, Arg, or Gly, the direction of the tilt is essentially constant in different lipids and presumably is dictated by the tryptophans (Trp 5 and Trp 19 ) that flank the inner helical core. The Leu-Ala spacers are no longer helical. The magnitude of the apparent helix tilt furthermore scales nicely with the bilayer thickness except when X is Trp. When X is Trp, the direction of tilt is less well defined in each phosphatidylcholine bilayer and varies up to 70°among 1,2-dioleoyl-sn-glycero-3-phosphocholine, 1,2-dimyristoyl-sn-glycero-3-phosphocholine, and 1,2-dilauroylsn-glycero-3-phosphocholine bilayer membranes. Indeed, the X ‫؍‬ Trp case parallels earlier observations in which WALP family peptides having multiple Trp anchors show little dependence of the apparent tilt magnitude on bilayer thickness. The results shed new light on the interactions of arginine, lysine, tryptophan, and even glycine at lipid bilayer membrane interfaces.The lipid bilayer environment has a profound influence on the properties of peptides and proteins found within it. It is significant that many membrane-spanning proteins have bands of aromatic and/or positively charged residues at the membrane interface, which could serve as anchors for the protein orientation and promote favorable protein-lipid interactions. This anchoring is a widespread characteristic that is observed for a variety of proteins having both ␣ and ␤ transmembrane folds (1-5). Furthermore, polar amino acids influence the topology of membrane proteins as the direction of insertion is driven by the asymmetric positioning of basic residues (Lys and Arg), giving rise to the "positive inside" rule for helical membrane proteins (6). Little is known, nevertheless, about the contributions of these residues in defining the orientations of the transmembrane segments within lipid bilayers (7).Due to the inherent complexity of membrane proteins in the native biological membrane environment, model systems provide meaningful ways to address specific questions about protein/lipid interactions. In particular, model peptides of the WALP family, having the general sequence acetyl-GWW-(LA) n LWWA- [ethanol]amide, have yielded valuable information about peptide orientations, dynam...

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Influence of Proline upon the Folding and Geometry of the WALP19 Transmembrane Peptide

Cited by 29 publications

References 51 publications

Changes in Transmembrane Helix Alignment by Arginine Residues Revealed by Solid-State NMR Experiments and Coarse-Grained MD Simulations

Changes in Transmembrane Helix Alignment by Arginine Residues Revealed by Solid-State NMR Experiments and Coarse-Grained MD Simulations

Accommodation of a Central Arginine in a Transmembrane Peptide by Changing the Placement of Anchor Residues

Charged or Aromatic Anchor Residue Dependence of Transmembrane Peptide Tilt

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