Structural basis for membrane fusion by enveloped viruses

Weissenhorn, Winfríed; Dessen, Andréa; Calder, Lesley J.; Harrison, Stephen C.; Skehel, J.J.; Wiley, Don C.

doi:10.1080/096876899294706

Cited by 363 publications

(348 citation statements)

References 70 publications

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“…A conformational change in the gp41/gp120 oligomer allows the fusion peptide sequence, located on the N terminus of gp41, to insert into the membrane of the target cell (3). The gp41 ectodomain is then thought to undergo a series of conformational changes to form the fusion-active state, which is believed to bring the viral and cellular membranes into closer proximity to facilitate membrane fusion (2,3). Crystallographic studies provide support for a model where gp41 adopts a six-helix bundle structure late in the fusion process (4)(5)(6), and this structure is likely involved in the final steps before fusion.…”

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confidence: 87%

“…H IV type 1 (HIV-1) fusion is mediated by a complex set of interactions involving cellular receptors and viral glycoproteins (1,2). The precise nature of these interactions remains unclear, but in the current model, viral attachment occurs via an interaction between gp120 and CD4, along with chemokine receptors (such as CCR5 or CXCR4) that act as viral coreceptors for HIV-1.…”

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confidence: 99%

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Design of helical, oligomeric HIV-1 fusion inhibitor peptides with potent activity against enfuvirtide-resistant virus

Dwyer¹,

Wilson²,

Davison³

et al. 2007

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

225

244

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Enfuvirtide (ENF), the first approved fusion inhibitor (FI) for HIV, is a 36-aa peptide that acts by binding to the heptad repeat 1 (HR1) region of gp41 and preventing the interaction of the HR1 and HR2 domains, which is required for virus-cell fusion. Treatmentacquired resistance to ENF highlights the need to create FI therapeutics with activity against ENF-resistant viruses and improved durability. Using rational design, we have made a series of oligomeric HR2 peptides with increased helical structure and with exceptionally high HR1/HR2 bundle stability. The engineered peptides are found to be as much as 3,600-fold more active than ENF against viruses that are resistant to the HR2 peptides ENF, T-1249, or T-651. Passaging experiments using one of these peptides could not generate virus with decreased sensitivity, even after >70 days in culture, suggesting superior durability as compared with ENF. In addition, the pharmacokinetic properties of the engineered peptides were improved up to 100-fold. The potent antiviral activity against resistant viruses, the difficulty in generating resistant virus, and the extended half-life in vivo make this class of fusion inhibitor peptide attractive for further development.coiled coil ͉ gp41 HIV-1 ͉ viral entry ͉ drug design

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confidence: 87%

mentioning

confidence: 99%

Design of helical, oligomeric HIV-1 fusion inhibitor peptides with potent activity against enfuvirtide-resistant virus

Dwyer¹,

Wilson²,

Davison³

et al. 2007

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

225

244

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“…This general architecture is observed in other viral fusion proteins, such as other retroviruses Fass and Kim, 1995;Lu et al, 1995;Fass et al, 1996;Malashkevich et al, 1998), Ebola GP (Wiessenhorn et al., 1998Malashkevich et al, 1999), paramyxovirus F (Joshi et al, 1998Baker et al, 1999;Dutch et al, 1999), and influenza hemagglutinin (HA) proteins (Carr and Kim, 1993;Bullough et al, 1994). Conversion of fusion proteins to a rod-like structure via formation of a long trimeric coiled coil upon low pH application has been observed and forms the basis of a proposed spring-loaded mechanism by which hydrophobic amino-terminal "fusion peptides" are projected into the target membrane, ultimately resulting in fusion of the viral envelope with the target cell membrane (Carr and Kim 1993;Chan et al, 1997;Weissenhorn et al, 1997Weissenhorn et al, , 1999.For paramyxoviruses and HIV, evidence suggests that the hydrophobic 4-3 heptad repeats are directly involved in the viral fusion process. Single leucine-to-alanine mutations of the F proteins from paramyxoviruses do not block fusion, but multiple leucine-to-alanine mutations do abolish fusion activity of the protein but do not negatively affect F protein oligomerization or cell surface expression (Buckland et al, 1992;Sergel-Germano et al, 1994;Reitter et al, 1995).…”

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confidence: 99%

A Discrete Stage of Baculovirus GP64-mediated Membrane Fusion

Kingsley

Behbahani

Rashtian

et al. 1999

MBoC

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Viral fusion protein trimers can play a critical role in limiting lipids in membrane fusion. Because the trimeric oligomer of many viral fusion proteins is often stabilized by hydrophobic 4-3 heptad repeats, higher-order oligomers might be stabilized by similar sequences. There is a hydrophobic 4-3 heptad repeat contiguous to a putative oligomerization domain of Autographa californica multicapsid nucleopolyhedrovirus envelope glycoprotein GP64. We performed mutagenesis and peptide inhibition studies to determine if this sequence might play a role in catalysis of membrane fusion. First, leucine-to-alanine mutants within and flanking the amino terminus of the hydrophobic 4-3 heptad repeat motif that oligomerize into trimers and traffic to insect Sf9 cell surfaces were identified. These mutants retained their wild-type conformation at neutral pH and changed conformation in acidic conditions, as judged by the reactivity of a conformationally sensitive mAb. These mutants, however, were defective for membrane fusion. Second, a peptide encoding the portion flanking the GP64 hydrophobic 4-3 heptad repeat was synthesized. Adding peptide led to inhibition of membrane fusion, which occurred only when the peptide was present during low pH application. The presence of peptide during low pH application did not prevent low pH-induced conformational changes, as determined by the loss of a conformationally sensitive epitope. In control experiments, a peptide of identical composition but different sequence, or a peptide encoding a portion of the Ebola GP heptad motif, had no effect on GP64-mediated fusion. Furthermore, when the hemagglutinin (X31 strain) fusion protein of influenza was functionally expressed in Sf9 cells, no effect on hemagglutinin-mediated fusion was observed, suggesting that the peptide does not exert nonspecific effects on other fusion proteins or cell membranes. Collectively, these studies suggest that the specific peptide sequences of GP64 that are adjacent to and include portions of the hydrophobic 4-3 heptad repeat play a dynamic role in membrane fusion at a stage that is downstream of the initiation of protein conformational changes but upstream of lipid mixing. INTRODUCTIONThe mechanism of membrane fusion is currently a field of intense investigation, both for intracellular trafficking and enveloped viral infection. For viral fusion protein function, we have previously suggested that fusion protein oligomers form transient and cooperative higher-order structures or rings . These transient ring structures are proposed to facilitate conversion of kinetic energy, released during protein conformational change, into work on the target and host membranes required for membrane fusion. Indeed, biochemical evidence for baculovirus GP64 aggregates during membrane fusion has recently been reported (Markovic et al. 1998). Whether and how viral fusion proteins might function in a coordinated and cooperative manner is a major question in the field of membrane fusion. Because hydrophobic 4-3 heptad repeats are observed...

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“…Although the understanding of enveloped-virus entry via membrane fusion has seen many advances (1)(2)(3), the entry mechanisms of nonenveloped animal viruses remain elusive. Mammalian orthoreovirus (reovirus) is a large nonenveloped virus with a 10-segmented dsRNA genome.…”

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confidence: 99%

Mammalian reovirus, a nonfusogenic nonenveloped virus, forms size-selective pores in a model membrane

Agosto

Ivanovic

Nibert

2006

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

109

173

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During cell entry, reovirus particles with a diameter of 70 -80 nm must penetrate the cellular membrane to access the cytoplasm. The mechanism of penetration, without benefit of membrane fusion, is not well characterized for any such nonenveloped animal virus. Lysis of RBCs is an in vitro assay for the membrane perforation activity of reovirus; however, the mechanism of lysis has been unknown. In this report, osmotic-protection experiments using PEGs of different sizes revealed that reovirus-induced lysis of RBCs occurs osmotically, after formation of small size-selective lesions or ''pores.'' Consistent results were obtained by monitoring leakage of fluorophore-tagged dextrans from the interior of resealed RBC ghosts. Gradient fractionations showed that whole virus particles, as well as the myristoylated fragment 1N that is released from particles, are recruited to RBC membranes in association with pore formation. We propose that formation of small pores is a discrete, intermediate step in the reovirus membrane-penetration pathway, which may be shared by other nonenveloped animal viruses.cell entry ͉ hemolysis ͉ membrane penetration ͉ reoviridae

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Structural basis for membrane fusion by enveloped viruses

Cited by 363 publications

References 70 publications

Design of helical, oligomeric HIV-1 fusion inhibitor peptides with potent activity against enfuvirtide-resistant virus

Design of helical, oligomeric HIV-1 fusion inhibitor peptides with potent activity against enfuvirtide-resistant virus

A Discrete Stage of Baculovirus GP64-mediated Membrane Fusion

Mammalian reovirus, a nonfusogenic nonenveloped virus, forms size-selective pores in a model membrane

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