Sequence‐dependent backbone dynamics of a viral fusogen transmembrane helix

Stelzer, Walter; Langosch, Dieter

doi:10.1002/pro.2094

Cited by 6 publications

(8 citation statements)

References 39 publications

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“…56,57 Since hydrophobic peptides precipitate in water, we dissolved the APP TMDs in 80% (v/v) trifluoroethanol (TFE) in aqueous buffer, as exercised previously with other TMD peptides. 30,33,58 The TFE water mixture mimics the aqueous environment while maintaining helicity and preventing aggregation. Circular dichroism (CD) spectroscopy revealed that A28−55 and A37−55 form ∼70% helix, while the helicity of A28−44 is decreased to ∼55% in favor of random coil (Figure 3B).…”

Section: ■ Resultsmentioning

confidence: 96%

“…The helical APP TMD is thought to be located within a water-filled cavity at the active site of presenilin 56,57 . Since hydrophobic peptides precipitate in water, we dissolved the APP TMDs in 80% (v/v) trifluoroethanol (TFE) in aqueous buffer as exercised previously with other TMD peptides 30,33,58 . The TFE water mixture mimics the aqueous environment while maintaining helicity and preventing aggregation.…”

Section: Resultsmentioning

confidence: 99%

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The Backbone Dynamics of the Amyloid Precursor Protein Transmembrane Helix Provides a Rationale for the Sequential Cleavage Mechanism of γ-Secretase

et al. 2013

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The etiology of Alzheimer’s disease depends on the relative abundance of different amyloid-β (Aβ) peptide species. These peptides are produced by sequential proteolytic cleavage within the transmembrane helix of the 99 residue C-terminal fragment of the amyloid precursor protein (C99) by the intramembrane protease γ-secretase. Intramembrane proteolysis is thought to require local unfolding of the substrate helix, which has been proposed to be cleaved as a homodimer. Here, we investigated the backbone dynamics of the substrate helix. Amide exchange experiments of monomeric recombinant C99 and of synthetic transmembrane domain peptides reveal that the N-terminal Gly-rich homodimerization domain exchanges much faster than the C-terminal cleavage region. MD simulations corroborate the differential backbone dynamics, indicate a bending motion at a di-glycine motif connecting dimerization and cleavage regions, and detect significantly different H-bond stabilities at the initial cleavage sites. Our results are consistent with the following hypotheses about cleavage of the substrate. First, the GlyGly hinge may precisely position the substrate within γ-secretase such that its catalytic center must start proteolysis at the known initial cleavage sites. Second, the ratio of cleavage products formed by subsequent sequential proteolysis could be influenced by differential extents of solvation and by the stabilities of H-bonds at alternate initial sites. Third, the flexibility of the Gly-rich domain may facilitate substrate movement within the enzyme during sequential proteolysis. Fourth, dimerization may affect substrate processing by decreasing the dynamics of the dimerization region and by increasing that of the C-terminal part of the cleavage region.

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Section: ■ Resultsmentioning

confidence: 96%

Section: Resultsmentioning

confidence: 99%

The Backbone Dynamics of the Amyloid Precursor Protein Transmembrane Helix Provides a Rationale for the Sequential Cleavage Mechanism of γ-Secretase

et al. 2013

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“…Studies of simple hydrophobic peptides have provided insights into many aspects of membrane protein behavior, − and hydrophobic helices flanked by hydrophilic segments have also been shown to cross membranes (as first shown by ref ). Various artificial helices have been used to investigate peptide self-insertion in which the peptide interconverts between TM and non-TM inserted states, and these interconversion events involve movement of the hydrophilic juxtamembrane (JM) segments across the lipid bilayer.…”

Section: Introductionmentioning

confidence: 92%

Highly Hydrophilic Segments Attached to Hydrophobic Peptides Translocate Rapidly across Membranes

LeBarron

London

2016

Langmuir

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Hydrophilic segments attached to transmembrane helices often cross membranes. In an increasing number of cases, it has become apparent that this occurs in a biologically relevant post-translational event. In this study, we investigate whether juxta-membrane (JM) hydrophilic sequences attached to hydrophobic helices are able to rapidly cross lipid bilayers via their ability or inability to block hydrophobic helix interconversion between a transmembrane (TM) and non-TM membrane-associated state. Interconversion was triggered by changing the protonation state of an Asp residue in the hydrophobic core of the peptides, and peptide configuration was monitored by the fluorescence of a Trp residue at the center of the hydrophobic sequence. In POPC vesicles, conversion of the TM to non-TM state at high pH and the non-TM to TM state at low pH was rapid (seconds or less) for KK, KKNN, and the KKNNNNNN flanking sequences on both N- and C-termini and the KLFAGHQ sequence that flanks the spontaneously TM-inserting 3A protein of polio virus. In vesicles composed of 6:4 (mol/mol) POPC/cholesterol, interconversion was still rapid, with the exception of the peptide flanked by KKNNNNNN sequences, for which the half time of interconversion slowed to minutes. This behavior suggests that, at least in membranes with low levels of cholesterol, movement of hydrophilic JM segments (and analogous hydrophobic loops in multipass TM proteins) across membranes may be more facile than previously thought. This may have important biological implications.

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“…This sequence is present in the TMDs of both HIV-1 gp41 [ 88 ] and VSV G [ 89 ]. It increases helix backbone dynamics in synthetic VSV G TMD peptides and may yield highly mobile TMD helices in full-length VSV G that could interact strongly with the aliphatic chains of membrane lipids and cause lipid splaying [ 99 ], wherein the two lipid tails are pulled apart during fusion to facilitate lipid bilayer mixing. Indeed, replacement of the VSV G glycines additively impairs fusion pore formation, with complete inactivity resulting from the loss of both glycines [ 89 ].…”

Section: Regulatory Regions Of Gbmentioning

confidence: 99%

Herpesvirus gB: A Finely Tuned Fusion Machine

Cooper

Heldwein

2015

Viruses

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Enveloped viruses employ a class of proteins known as fusogens to orchestrate the merger of their surrounding envelope and a target cell membrane. Most fusogens accomplish this task alone, by binding cellular receptors and subsequently catalyzing the membrane fusion process. Surprisingly, in herpesviruses, these functions are distributed among multiple proteins: the conserved fusogen gB, the conserved gH/gL heterodimer of poorly defined function, and various non-conserved receptor-binding proteins. We summarize what is currently known about gB from two closely related herpesviruses, HSV-1 and HSV-2, with emphasis on the structure of the largely uncharted membrane interacting regions of this fusogen. We propose that the unusual mechanism of herpesvirus fusion could be linked to the unique architecture of gB.

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Sequence‐dependent backbone dynamics of a viral fusogen transmembrane helix

Cited by 6 publications

References 39 publications

The Backbone Dynamics of the Amyloid Precursor Protein Transmembrane Helix Provides a Rationale for the Sequential Cleavage Mechanism of γ-Secretase

The Backbone Dynamics of the Amyloid Precursor Protein Transmembrane Helix Provides a Rationale for the Sequential Cleavage Mechanism of γ-Secretase

Highly Hydrophilic Segments Attached to Hydrophobic Peptides Translocate Rapidly across Membranes

Herpesvirus gB: A Finely Tuned Fusion Machine

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