Virus membrane-fusion proteins: more than one way to make a hairpin

Kielian, Margaret; Rey, F.A.

doi:10.1038/nrmicro1326

Cited by 514 publications

(534 citation statements)

References 97 publications

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“…The ratio of 2-3 deduced from the above numbers is well compatible with recent observations that 1-3 SNARE complexes are sufficient to achieve membrane fusion (66,74). In line with the present results, the inhibition of fusion observed after depletion of cholesterol, both in SNARE-mediated (75) and viral fusion (76,77), as well an increase of the docking efficiency in SNARE-mediated vesicle fusion upon higher PE content (78), may result from the effects of these lipids on the hydration barrier W hyd .…”

Section: Discussionsupporting

confidence: 81%

Energetics of stalk intermediates in membrane fusion are controlled by lipid composition

Aeffner

Reusch²,

Weinhausen³

et al. 2012

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

164

246

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We have used X-ray diffraction on the rhombohedral phospholipid phase to reconstruct stalk structures in different pure lipids and lipid mixtures with unprecedented resolution, enabling a quantitative analysis of geometry, as well as curvature and hydration energies. Electron density isosurfaces are used to study shape and curvature properties of the bent lipid monolayers. We observe that the stalk structure is highly universal in different lipid systems. The associated curvatures change in a subtle, but systematic fashion upon changes in lipid composition. In addition, we have studied the hydration interaction prior to the transition from the lamellar to the stalk phase. The results indicate that facilitating dehydration is the key to promote stalk formation, which becomes favorable at an approximately constant interbilayer separation of 9.0 AE 0.5 Å for the investigated lipid compositions.curvature energy | hydration force | lipid bilayer | E xocytosis, intracellular transport, neurotransmission, fertilization, or viral entry, require that two membranes merge into one. This event, membrane fusion, involves a complex interplay of different membrane lipids, proteins, and water molecules on length scales of few nm. Following the "lipidic pore hypothesis", it is now well accepted that membrane fusion involves a sequence of lipidic nonbilayer intermediates, whose formation is catalyzed and guided by a specialized protein machinery (1, 2). A stage termed "hemifusion" in which the lipids of the outer leaflets of two membrane-enclosed compartments about to fuse can mix, whereas the inner leaflets and the enclosed content remain unaltered (3), has been confirmed by a variety of methods including conical electron tomography (4) and, more indirectly; e.g., by electron spin resonance (5) and fluorescence recovery after photobleaching (6). Studying the fusion of protein-free bilayers of well defined lipid composition can contribute useful insights into the physical principles governing the merger of their more complex biological counterparts and clarify the effect of individual lipid species.The first connection between two lipid bilayers is the so-called stalk sketched in Fig. 1A (7). The proximal lipid monolayers have merged into one strongly curved monolayer, whereas the distal ones are still separated and intact. A persistent problem in membrane biophysics is to determine the precise structure of stalks and the free energy barrier for stalk formation. In a long series of papers (8-16), this determination has been attempted within the framework of the continuum theory of membrane elasticity (17, 18). More recently, with the advent of sufficient computational power, simulations including molecular details have become feasible [e.g. (19, 20) and references therein]. While stalk formation between lipid bilayers in close contact is generally accepted as the initial step in possibly all membrane fusion reactions (7), the subsequent stages from stalk to complete fusion are still debated and different pathways may exist (21)....

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Section: Discussionsupporting

confidence: 81%

Energetics of stalk intermediates in membrane fusion are controlled by lipid composition

Aeffner

Reusch²,

Weinhausen³

et al. 2012

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

164

246

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“…Upon lowpH exposure, dimers dissociate and the protomers reassociate in a trimeric structure [46,47]. Similar to the structure of post-fusion class I proteins [48], the fusion loops and the transmembrane domains are then located at the same end of an elongated molecule that is now perpendicular to the membrane [49,50] ( Fig. 2B).…”

Section: Class I and Class Ii Fusion Proteinsmentioning

confidence: 89%

Structures of vesicular stomatitis virus glycoprotein: membrane fusion revisited

Roche

Albertini

Lepault

et al. 2008

Cell. Mol. Life Sci.

127

138

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Abstract. Glycoprotein G of the vesicular stomatitis virus (VSV) is involved in receptor recognition at the host cell surface and then, after endocytosis of the virion, triggers membrane fusion via a low pHinduced structural rearrangement. G is an atypical fusion protein, as there is a pH-dependent equilibrium between its pre-and post-fusion conformations. The atomic structures of these two conformations reveal that it is homologous to glycoprotein gB of herpesviruses and that it combines features of the previously characterized class I and class II fusion proteins.Comparison of the structures of G pre-and postfusion states shows a dramatic reorganization of the molecule that is reminiscent of that of paramyxovirus fusion protein F. It also allows identification of conserved key residues that constitute pH-sensitive molecular switches. Besides the similarities with other viral fusion machineries, the fusion properties and structures of G also reveal some striking particularities that invite us to reconsider a few dogmas concerning fusion proteins.

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“…In eukaryotes, fusion and fission play central roles in a broad array of cell biological processes, including exocytosis, endocytosis, cytokinesis, and intracellular membrane trafficking (Chernomordik and Kozlov 2003;Sü dhof and Rothman 2009;Kozlov et al 2010). They are also critical for the entry and exit of enveloped viruses into (and out of) their host (Kielian and Rey 2006;Harrison 2008). In contrast, virtually nothing is known about how bacteria remodel their membranes during growth and differentiation despite the fact that they undergo membrane fission in every cell division cycle.…”

mentioning

confidence: 99%

FisB mediates membrane fission during sporulation in Bacillus subtilis

et al. 2013

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How bacteria catalyze membrane fission during growth and differentiation is an outstanding question in prokaryotic cell biology. Here, we describe a protein (FisB, for fission protein B) that mediates membrane fission during the morphological process of spore formation in Bacillus subtilis. Sporulating cells divide asymmetrically, generating a large mother cell and smaller forespore. After division, the mother cell membranes migrate around the forespore in a phagocytic-like process called engulfment. Membrane fission releases the forespore into the mother cell cytoplasm. Cells lacking FisB are severely and specifically impaired in the fission reaction. Moreover, GFP-FisB forms dynamic foci that become immobilized at the site of fission. Purified FisB catalyzes lipid mixing in vitro and is only required in one of the fusing membranes, suggesting that FisB-lipid interactions drive membrane remodeling. Consistent with this idea, the extracytoplasmic domain of FisB binds with remarkable specificity to cardiolipin, a lipid enriched in the engulfing membranes and regions of negative curvature. We propose that membrane topology at the final stage of engulfment and FisB-cardiolipin interactions ensure that the mother cell membranes are severed at the right time and place. The unique properties of FisB set it apart from the known fission machineries in eukaryotes, suggesting that it represents a new class of fission proteins.

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Virus membrane-fusion proteins: more than one way to make a hairpin

Cited by 514 publications

References 97 publications

Energetics of stalk intermediates in membrane fusion are controlled by lipid composition

Energetics of stalk intermediates in membrane fusion are controlled by lipid composition

Structures of vesicular stomatitis virus glycoprotein: membrane fusion revisited

FisB mediates membrane fission during sporulation in Bacillus subtilis

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